Merge branch 'timers/urgent' into timers/core

Reason: Get upstream fixes and kfree_rcu which is necessary for a
follow up patch.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

3 files changed, 8104 insertions, 0 deletions

diff --git a/kernel/events/Makefile b/kernel/events/Makefile
new file mode 100644
index 000000000000..1ce23d3d8394
--- /dev/null
+++ b/kernel/events/Makefile
@@ -0,0 +1,6 @@
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_core.o = -pg
+endif
+
+obj-y := core.o
+obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
diff --git a/kernel/events/core.c b/kernel/events/core.c
new file mode 100644
index 000000000000..c09767f7db3e
--- /dev/null
+++ b/kernel/events/core.c
@@ -0,0 +1,7439 @@
+/*
+ * Performance events core code:
+ *
+ *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
+ *  Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
+ *  Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
+ *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
+ *
+ * For licensing details see kernel-base/COPYING
+ */
+
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+#include <linux/idr.h>
+#include <linux/file.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/hash.h>
+#include <linux/sysfs.h>
+#include <linux/dcache.h>
+#include <linux/percpu.h>
+#include <linux/ptrace.h>
+#include <linux/reboot.h>
+#include <linux/vmstat.h>
+#include <linux/device.h>
+#include <linux/vmalloc.h>
+#include <linux/hardirq.h>
+#include <linux/rculist.h>
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+#include <linux/anon_inodes.h>
+#include <linux/kernel_stat.h>
+#include <linux/perf_event.h>
+#include <linux/ftrace_event.h>
+#include <linux/hw_breakpoint.h>
+
+#include <asm/irq_regs.h>
+
+struct remote_function_call {
+        struct task_struct      *p;
+        int                     (*func)(void *info);
+        void                    *info;
+        int                     ret;
+};
+
+static void remote_function(void *data)
+{
+        struct remote_function_call *tfc = data;
+        struct task_struct *p = tfc->p;
+
+        if (p) {
+                tfc->ret = -EAGAIN;
+                if (task_cpu(p) != smp_processor_id() || !task_curr(p))
+                        return;
+        }
+
+        tfc->ret = tfc->func(tfc->info);
+}
+
+/**
+ * task_function_call - call a function on the cpu on which a task runs
+ * @p:          the task to evaluate
+ * @func:       the function to be called
+ * @info:       the function call argument
+ *
+ * Calls the function @func when the task is currently running. This might
+ * be on the current CPU, which just calls the function directly
+ *
+ * returns: @func return value, or
+ *          -ESRCH  - when the process isn't running
+ *          -EAGAIN - when the process moved away
+ */
+static int
+task_function_call(struct task_struct *p, int (*func) (void *info), void *info)
+{
+        struct remote_function_call data = {
+                .p      = p,
+                .func   = func,
+                .info   = info,
+                .ret    = -ESRCH, /* No such (running) process */
+        };
+
+        if (task_curr(p))
+                smp_call_function_single(task_cpu(p), remote_function, &data, 1);
+
+        return data.ret;
+}
+
+/**
+ * cpu_function_call - call a function on the cpu
+ * @func:       the function to be called
+ * @info:       the function call argument
+ *
+ * Calls the function @func on the remote cpu.
+ *
+ * returns: @func return value or -ENXIO when the cpu is offline
+ */
+static int cpu_function_call(int cpu, int (*func) (void *info), void *info)
+{
+        struct remote_function_call data = {
+                .p      = NULL,
+                .func   = func,
+                .info   = info,
+                .ret    = -ENXIO, /* No such CPU */
+        };
+
+        smp_call_function_single(cpu, remote_function, &data, 1);
+
+        return data.ret;
+}
+
+#define PERF_FLAG_ALL (PERF_FLAG_FD_NO_GROUP |\
+                       PERF_FLAG_FD_OUTPUT  |\
+                       PERF_FLAG_PID_CGROUP)
+
+enum event_type_t {
+        EVENT_FLEXIBLE = 0x1,
+        EVENT_PINNED = 0x2,
+        EVENT_ALL = EVENT_FLEXIBLE | EVENT_PINNED,
+};
+
+/*
+ * perf_sched_events : >0 events exist
+ * perf_cgroup_events: >0 per-cpu cgroup events exist on this cpu
+ */
+struct jump_label_key perf_sched_events __read_mostly;
+static DEFINE_PER_CPU(atomic_t, perf_cgroup_events);
+
+static atomic_t nr_mmap_events __read_mostly;
+static atomic_t nr_comm_events __read_mostly;
+static atomic_t nr_task_events __read_mostly;
+
+static LIST_HEAD(pmus);
+static DEFINE_MUTEX(pmus_lock);
+static struct srcu_struct pmus_srcu;
+
+/*
+ * perf event paranoia level:
+ *  -1 - not paranoid at all
+ *   0 - disallow raw tracepoint access for unpriv
+ *   1 - disallow cpu events for unpriv
+ *   2 - disallow kernel profiling for unpriv
+ */
+int sysctl_perf_event_paranoid __read_mostly = 1;
+
+/* Minimum for 512 kiB + 1 user control page */
+int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */
+
+/*
+ * max perf event sample rate
+ */
+#define DEFAULT_MAX_SAMPLE_RATE 100000
+int sysctl_perf_event_sample_rate __read_mostly = DEFAULT_MAX_SAMPLE_RATE;
+static int max_samples_per_tick __read_mostly =
+        DIV_ROUND_UP(DEFAULT_MAX_SAMPLE_RATE, HZ);
+
+int perf_proc_update_handler(struct ctl_table *table, int write,
+                void __user *buffer, size_t *lenp,
+                loff_t *ppos)
+{
+        int ret = proc_dointvec(table, write, buffer, lenp, ppos);
+
+        if (ret || !write)
+                return ret;
+
+        max_samples_per_tick = DIV_ROUND_UP(sysctl_perf_event_sample_rate, HZ);
+
+        return 0;
+}
+
+static atomic64_t perf_event_id;
+
+static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
+                              enum event_type_t event_type);
+
+static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
+                             enum event_type_t event_type,
+                             struct task_struct *task);
+
+static void update_context_time(struct perf_event_context *ctx);
+static u64 perf_event_time(struct perf_event *event);
+
+void __weak perf_event_print_debug(void)        { }
+
+extern __weak const char *perf_pmu_name(void)
+{
+        return "pmu";
+}
+
+static inline u64 perf_clock(void)
+{
+        return local_clock();
+}
+
+static inline struct perf_cpu_context *
+__get_cpu_context(struct perf_event_context *ctx)
+{
+        return this_cpu_ptr(ctx->pmu->pmu_cpu_context);
+}
+
+#ifdef CONFIG_CGROUP_PERF
+
+/*
+ * Must ensure cgroup is pinned (css_get) before calling
+ * this function. In other words, we cannot call this function
+ * if there is no cgroup event for the current CPU context.
+ */
+static inline struct perf_cgroup *
+perf_cgroup_from_task(struct task_struct *task)
+{
+        return container_of(task_subsys_state(task, perf_subsys_id),
+                        struct perf_cgroup, css);
+}
+
+static inline bool
+perf_cgroup_match(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+
+        return !event->cgrp || event->cgrp == cpuctx->cgrp;
+}
+
+static inline void perf_get_cgroup(struct perf_event *event)
+{
+        css_get(&event->cgrp->css);
+}
+
+static inline void perf_put_cgroup(struct perf_event *event)
+{
+        css_put(&event->cgrp->css);
+}
+
+static inline void perf_detach_cgroup(struct perf_event *event)
+{
+        perf_put_cgroup(event);
+        event->cgrp = NULL;
+}
+
+static inline int is_cgroup_event(struct perf_event *event)
+{
+        return event->cgrp != NULL;
+}
+
+static inline u64 perf_cgroup_event_time(struct perf_event *event)
+{
+        struct perf_cgroup_info *t;
+
+        t = per_cpu_ptr(event->cgrp->info, event->cpu);
+        return t->time;
+}
+
+static inline void __update_cgrp_time(struct perf_cgroup *cgrp)
+{
+        struct perf_cgroup_info *info;
+        u64 now;
+
+        now = perf_clock();
+
+        info = this_cpu_ptr(cgrp->info);
+
+        info->time += now - info->timestamp;
+        info->timestamp = now;
+}
+
+static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx)
+{
+        struct perf_cgroup *cgrp_out = cpuctx->cgrp;
+        if (cgrp_out)
+                __update_cgrp_time(cgrp_out);
+}
+
+static inline void update_cgrp_time_from_event(struct perf_event *event)
+{
+        struct perf_cgroup *cgrp;
+
+        /*
+         * ensure we access cgroup data only when needed and
+         * when we know the cgroup is pinned (css_get)
+         */
+        if (!is_cgroup_event(event))
+                return;
+
+        cgrp = perf_cgroup_from_task(current);
+        /*
+         * Do not update time when cgroup is not active
+         */
+        if (cgrp == event->cgrp)
+                __update_cgrp_time(event->cgrp);
+}
+
+static inline void
+perf_cgroup_set_timestamp(struct task_struct *task,
+                          struct perf_event_context *ctx)
+{
+        struct perf_cgroup *cgrp;
+        struct perf_cgroup_info *info;
+
+        /*
+         * ctx->lock held by caller
+         * ensure we do not access cgroup data
+         * unless we have the cgroup pinned (css_get)
+         */
+        if (!task || !ctx->nr_cgroups)
+                return;
+
+        cgrp = perf_cgroup_from_task(task);
+        info = this_cpu_ptr(cgrp->info);
+        info->timestamp = ctx->timestamp;
+}
+
+#define PERF_CGROUP_SWOUT       0x1 /* cgroup switch out every event */
+#define PERF_CGROUP_SWIN        0x2 /* cgroup switch in events based on task */
+
+/*
+ * reschedule events based on the cgroup constraint of task.
+ *
+ * mode SWOUT : schedule out everything
+ * mode SWIN : schedule in based on cgroup for next
+ */
+void perf_cgroup_switch(struct task_struct *task, int mode)
+{
+        struct perf_cpu_context *cpuctx;
+        struct pmu *pmu;
+        unsigned long flags;
+
+        /*
+         * disable interrupts to avoid geting nr_cgroup
+         * changes via __perf_event_disable(). Also
+         * avoids preemption.
+         */
+        local_irq_save(flags);
+
+        /*
+         * we reschedule only in the presence of cgroup
+         * constrained events.
+         */
+        rcu_read_lock();
+
+        list_for_each_entry_rcu(pmu, &pmus, entry) {
+
+                cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+
+                perf_pmu_disable(cpuctx->ctx.pmu);
+
+                /*
+                 * perf_cgroup_events says at least one
+                 * context on this CPU has cgroup events.
+                 *
+                 * ctx->nr_cgroups reports the number of cgroup
+                 * events for a context.
+                 */
+                if (cpuctx->ctx.nr_cgroups > 0) {
+
+                        if (mode & PERF_CGROUP_SWOUT) {
+                                cpu_ctx_sched_out(cpuctx, EVENT_ALL);
+                                /*
+                                 * must not be done before ctxswout due
+                                 * to event_filter_match() in event_sched_out()
+                                 */
+                                cpuctx->cgrp = NULL;
+                        }
+
+                        if (mode & PERF_CGROUP_SWIN) {
+                                WARN_ON_ONCE(cpuctx->cgrp);
+                                /* set cgrp before ctxsw in to
+                                 * allow event_filter_match() to not
+                                 * have to pass task around
+                                 */
+                                cpuctx->cgrp = perf_cgroup_from_task(task);
+                                cpu_ctx_sched_in(cpuctx, EVENT_ALL, task);
+                        }
+                }
+
+                perf_pmu_enable(cpuctx->ctx.pmu);
+        }
+
+        rcu_read_unlock();
+
+        local_irq_restore(flags);
+}
+
+static inline void perf_cgroup_sched_out(struct task_struct *task)
+{
+        perf_cgroup_switch(task, PERF_CGROUP_SWOUT);
+}
+
+static inline void perf_cgroup_sched_in(struct task_struct *task)
+{
+        perf_cgroup_switch(task, PERF_CGROUP_SWIN);
+}
+
+static inline int perf_cgroup_connect(int fd, struct perf_event *event,
+                                      struct perf_event_attr *attr,
+                                      struct perf_event *group_leader)
+{
+        struct perf_cgroup *cgrp;
+        struct cgroup_subsys_state *css;
+        struct file *file;
+        int ret = 0, fput_needed;
+
+        file = fget_light(fd, &fput_needed);
+        if (!file)
+                return -EBADF;
+
+        css = cgroup_css_from_dir(file, perf_subsys_id);
+        if (IS_ERR(css)) {
+                ret = PTR_ERR(css);
+                goto out;
+        }
+
+        cgrp = container_of(css, struct perf_cgroup, css);
+        event->cgrp = cgrp;
+
+        /* must be done before we fput() the file */
+        perf_get_cgroup(event);
+
+        /*
+         * all events in a group must monitor
+         * the same cgroup because a task belongs
+         * to only one perf cgroup at a time
+         */
+        if (group_leader && group_leader->cgrp != cgrp) {
+                perf_detach_cgroup(event);
+                ret = -EINVAL;
+        }
+out:
+        fput_light(file, fput_needed);
+        return ret;
+}
+
+static inline void
+perf_cgroup_set_shadow_time(struct perf_event *event, u64 now)
+{
+        struct perf_cgroup_info *t;
+        t = per_cpu_ptr(event->cgrp->info, event->cpu);
+        event->shadow_ctx_time = now - t->timestamp;
+}
+
+static inline void
+perf_cgroup_defer_enabled(struct perf_event *event)
+{
+        /*
+         * when the current task's perf cgroup does not match
+         * the event's, we need to remember to call the
+         * perf_mark_enable() function the first time a task with
+         * a matching perf cgroup is scheduled in.
+         */
+        if (is_cgroup_event(event) && !perf_cgroup_match(event))
+                event->cgrp_defer_enabled = 1;
+}
+
+static inline void
+perf_cgroup_mark_enabled(struct perf_event *event,
+                         struct perf_event_context *ctx)
+{
+        struct perf_event *sub;
+        u64 tstamp = perf_event_time(event);
+
+        if (!event->cgrp_defer_enabled)
+                return;
+
+        event->cgrp_defer_enabled = 0;
+
+        event->tstamp_enabled = tstamp - event->total_time_enabled;
+        list_for_each_entry(sub, &event->sibling_list, group_entry) {
+                if (sub->state >= PERF_EVENT_STATE_INACTIVE) {
+                        sub->tstamp_enabled = tstamp - sub->total_time_enabled;
+                        sub->cgrp_defer_enabled = 0;
+                }
+        }
+}
+#else /* !CONFIG_CGROUP_PERF */
+
+static inline bool
+perf_cgroup_match(struct perf_event *event)
+{
+        return true;
+}
+
+static inline void perf_detach_cgroup(struct perf_event *event)
+{}
+
+static inline int is_cgroup_event(struct perf_event *event)
+{
+        return 0;
+}
+
+static inline u64 perf_cgroup_event_cgrp_time(struct perf_event *event)
+{
+        return 0;
+}
+
+static inline void update_cgrp_time_from_event(struct perf_event *event)
+{
+}
+
+static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx)
+{
+}
+
+static inline void perf_cgroup_sched_out(struct task_struct *task)
+{
+}
+
+static inline void perf_cgroup_sched_in(struct task_struct *task)
+{
+}
+
+static inline int perf_cgroup_connect(pid_t pid, struct perf_event *event,
+                                      struct perf_event_attr *attr,
+                                      struct perf_event *group_leader)
+{
+        return -EINVAL;
+}
+
+static inline void
+perf_cgroup_set_timestamp(struct task_struct *task,
+                          struct perf_event_context *ctx)
+{
+}
+
+void
+perf_cgroup_switch(struct task_struct *task, struct task_struct *next)
+{
+}
+
+static inline void
+perf_cgroup_set_shadow_time(struct perf_event *event, u64 now)
+{
+}
+
+static inline u64 perf_cgroup_event_time(struct perf_event *event)
+{
+        return 0;
+}
+
+static inline void
+perf_cgroup_defer_enabled(struct perf_event *event)
+{
+}
+
+static inline void
+perf_cgroup_mark_enabled(struct perf_event *event,
+                         struct perf_event_context *ctx)
+{
+}
+#endif
+
+void perf_pmu_disable(struct pmu *pmu)
+{
+        int *count = this_cpu_ptr(pmu->pmu_disable_count);
+        if (!(*count)++)
+                pmu->pmu_disable(pmu);
+}
+
+void perf_pmu_enable(struct pmu *pmu)
+{
+        int *count = this_cpu_ptr(pmu->pmu_disable_count);
+        if (!--(*count))
+                pmu->pmu_enable(pmu);
+}
+
+static DEFINE_PER_CPU(struct list_head, rotation_list);
+
+/*
+ * perf_pmu_rotate_start() and perf_rotate_context() are fully serialized
+ * because they're strictly cpu affine and rotate_start is called with IRQs
+ * disabled, while rotate_context is called from IRQ context.
+ */
+static void perf_pmu_rotate_start(struct pmu *pmu)
+{
+        struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+        struct list_head *head = &__get_cpu_var(rotation_list);
+
+        WARN_ON(!irqs_disabled());
+
+        if (list_empty(&cpuctx->rotation_list))
+                list_add(&cpuctx->rotation_list, head);
+}
+
+static void get_ctx(struct perf_event_context *ctx)
+{
+        WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
+}
+
+static void put_ctx(struct perf_event_context *ctx)
+{
+        if (atomic_dec_and_test(&ctx->refcount)) {
+                if (ctx->parent_ctx)
+                        put_ctx(ctx->parent_ctx);
+                if (ctx->task)
+                        put_task_struct(ctx->task);
+                kfree_rcu(ctx, rcu_head);
+        }
+}
+
+static void unclone_ctx(struct perf_event_context *ctx)
+{
+        if (ctx->parent_ctx) {
+                put_ctx(ctx->parent_ctx);
+                ctx->parent_ctx = NULL;
+        }
+}
+
+static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
+{
+        /*
+         * only top level events have the pid namespace they were created in
+         */
+        if (event->parent)
+                event = event->parent;
+
+        return task_tgid_nr_ns(p, event->ns);
+}
+
+static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
+{
+        /*
+         * only top level events have the pid namespace they were created in
+         */
+        if (event->parent)
+                event = event->parent;
+
+        return task_pid_nr_ns(p, event->ns);
+}
+
+/*
+ * If we inherit events we want to return the parent event id
+ * to userspace.
+ */
+static u64 primary_event_id(struct perf_event *event)
+{
+        u64 id = event->id;
+
+        if (event->parent)
+                id = event->parent->id;
+
+        return id;
+}
+
+/*
+ * Get the perf_event_context for a task and lock it.
+ * This has to cope with with the fact that until it is locked,
+ * the context could get moved to another task.
+ */
+static struct perf_event_context *
+perf_lock_task_context(struct task_struct *task, int ctxn, unsigned long *flags)
+{
+        struct perf_event_context *ctx;
+
+        rcu_read_lock();
+retry:
+        ctx = rcu_dereference(task->perf_event_ctxp[ctxn]);
+        if (ctx) {
+                /*
+                 * If this context is a clone of another, it might
+                 * get swapped for another underneath us by
+                 * perf_event_task_sched_out, though the
+                 * rcu_read_lock() protects us from any context
+                 * getting freed.  Lock the context and check if it
+                 * got swapped before we could get the lock, and retry
+                 * if so.  If we locked the right context, then it
+                 * can't get swapped on us any more.
+                 */
+                raw_spin_lock_irqsave(&ctx->lock, *flags);
+                if (ctx != rcu_dereference(task->perf_event_ctxp[ctxn])) {
+                        raw_spin_unlock_irqrestore(&ctx->lock, *flags);
+                        goto retry;
+                }
+
+                if (!atomic_inc_not_zero(&ctx->refcount)) {
+                        raw_spin_unlock_irqrestore(&ctx->lock, *flags);
+                        ctx = NULL;
+                }
+        }
+        rcu_read_unlock();
+        return ctx;
+}
+
+/*
+ * Get the context for a task and increment its pin_count so it
+ * can't get swapped to another task.  This also increments its
+ * reference count so that the context can't get freed.
+ */
+static struct perf_event_context *
+perf_pin_task_context(struct task_struct *task, int ctxn)
+{
+        struct perf_event_context *ctx;
+        unsigned long flags;
+
+        ctx = perf_lock_task_context(task, ctxn, &flags);
+        if (ctx) {
+                ++ctx->pin_count;
+                raw_spin_unlock_irqrestore(&ctx->lock, flags);
+        }
+        return ctx;
+}
+
+static void perf_unpin_context(struct perf_event_context *ctx)
+{
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&ctx->lock, flags);
+        --ctx->pin_count;
+        raw_spin_unlock_irqrestore(&ctx->lock, flags);
+}
+
+/*
+ * Update the record of the current time in a context.
+ */
+static void update_context_time(struct perf_event_context *ctx)
+{
+        u64 now = perf_clock();
+
+        ctx->time += now - ctx->timestamp;
+        ctx->timestamp = now;
+}
+
+static u64 perf_event_time(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+
+        if (is_cgroup_event(event))
+                return perf_cgroup_event_time(event);
+
+        return ctx ? ctx->time : 0;
+}
+
+/*
+ * Update the total_time_enabled and total_time_running fields for a event.
+ */
+static void update_event_times(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+        u64 run_end;
+
+        if (event->state < PERF_EVENT_STATE_INACTIVE ||
+            event->group_leader->state < PERF_EVENT_STATE_INACTIVE)
+                return;
+        /*
+         * in cgroup mode, time_enabled represents
+         * the time the event was enabled AND active
+         * tasks were in the monitored cgroup. This is
+         * independent of the activity of the context as
+         * there may be a mix of cgroup and non-cgroup events.
+         *
+         * That is why we treat cgroup events differently
+         * here.
+         */
+        if (is_cgroup_event(event))
+                run_end = perf_event_time(event);
+        else if (ctx->is_active)
+                run_end = ctx->time;
+        else
+                run_end = event->tstamp_stopped;
+
+        event->total_time_enabled = run_end - event->tstamp_enabled;
+
+        if (event->state == PERF_EVENT_STATE_INACTIVE)
+                run_end = event->tstamp_stopped;
+        else
+                run_end = perf_event_time(event);
+
+        event->total_time_running = run_end - event->tstamp_running;
+
+}
+
+/*
+ * Update total_time_enabled and total_time_running for all events in a group.
+ */
+static void update_group_times(struct perf_event *leader)
+{
+        struct perf_event *event;
+
+        update_event_times(leader);
+        list_for_each_entry(event, &leader->sibling_list, group_entry)
+                update_event_times(event);
+}
+
+static struct list_head *
+ctx_group_list(struct perf_event *event, struct perf_event_context *ctx)
+{
+        if (event->attr.pinned)
+                return &ctx->pinned_groups;
+        else
+                return &ctx->flexible_groups;
+}
+
+/*
+ * Add a event from the lists for its context.
+ * Must be called with ctx->mutex and ctx->lock held.
+ */
+static void
+list_add_event(struct perf_event *event, struct perf_event_context *ctx)
+{
+        WARN_ON_ONCE(event->attach_state & PERF_ATTACH_CONTEXT);
+        event->attach_state |= PERF_ATTACH_CONTEXT;
+
+        /*
+         * If we're a stand alone event or group leader, we go to the context
+         * list, group events are kept attached to the group so that
+         * perf_group_detach can, at all times, locate all siblings.
+         */
+        if (event->group_leader == event) {
+                struct list_head *list;
+
+                if (is_software_event(event))
+                        event->group_flags |= PERF_GROUP_SOFTWARE;
+
+                list = ctx_group_list(event, ctx);
+                list_add_tail(&event->group_entry, list);
+        }
+
+        if (is_cgroup_event(event))
+                ctx->nr_cgroups++;
+
+        list_add_rcu(&event->event_entry, &ctx->event_list);
+        if (!ctx->nr_events)
+                perf_pmu_rotate_start(ctx->pmu);
+        ctx->nr_events++;
+        if (event->attr.inherit_stat)
+                ctx->nr_stat++;
+}
+
+/*
+ * Called at perf_event creation and when events are attached/detached from a
+ * group.
+ */
+static void perf_event__read_size(struct perf_event *event)
+{
+        int entry = sizeof(u64); /* value */
+        int size = 0;
+        int nr = 1;
+
+        if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+                size += sizeof(u64);
+
+        if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+                size += sizeof(u64);
+
+        if (event->attr.read_format & PERF_FORMAT_ID)
+                entry += sizeof(u64);
+
+        if (event->attr.read_format & PERF_FORMAT_GROUP) {
+                nr += event->group_leader->nr_siblings;
+                size += sizeof(u64);
+        }
+
+        size += entry * nr;
+        event->read_size = size;
+}
+
+static void perf_event__header_size(struct perf_event *event)
+{
+        struct perf_sample_data *data;
+        u64 sample_type = event->attr.sample_type;
+        u16 size = 0;
+
+        perf_event__read_size(event);
+
+        if (sample_type & PERF_SAMPLE_IP)
+                size += sizeof(data->ip);
+
+        if (sample_type & PERF_SAMPLE_ADDR)
+                size += sizeof(data->addr);
+
+        if (sample_type & PERF_SAMPLE_PERIOD)
+                size += sizeof(data->period);
+
+        if (sample_type & PERF_SAMPLE_READ)
+                size += event->read_size;
+
+        event->header_size = size;
+}
+
+static void perf_event__id_header_size(struct perf_event *event)
+{
+        struct perf_sample_data *data;
+        u64 sample_type = event->attr.sample_type;
+        u16 size = 0;
+
+        if (sample_type & PERF_SAMPLE_TID)
+                size += sizeof(data->tid_entry);
+
+        if (sample_type & PERF_SAMPLE_TIME)
+                size += sizeof(data->time);
+
+        if (sample_type & PERF_SAMPLE_ID)
+                size += sizeof(data->id);
+
+        if (sample_type & PERF_SAMPLE_STREAM_ID)
+                size += sizeof(data->stream_id);
+
+        if (sample_type & PERF_SAMPLE_CPU)
+                size += sizeof(data->cpu_entry);
+
+        event->id_header_size = size;
+}
+
+static void perf_group_attach(struct perf_event *event)
+{
+        struct perf_event *group_leader = event->group_leader, *pos;
+
+        /*
+         * We can have double attach due to group movement in perf_event_open.
+         */
+        if (event->attach_state & PERF_ATTACH_GROUP)
+                return;
+
+        event->attach_state |= PERF_ATTACH_GROUP;
+
+        if (group_leader == event)
+                return;
+
+        if (group_leader->group_flags & PERF_GROUP_SOFTWARE &&
+                        !is_software_event(event))
+                group_leader->group_flags &= ~PERF_GROUP_SOFTWARE;
+
+        list_add_tail(&event->group_entry, &group_leader->sibling_list);
+        group_leader->nr_siblings++;
+
+        perf_event__header_size(group_leader);
+
+        list_for_each_entry(pos, &group_leader->sibling_list, group_entry)
+                perf_event__header_size(pos);
+}
+
+/*
+ * Remove a event from the lists for its context.
+ * Must be called with ctx->mutex and ctx->lock held.
+ */
+static void
+list_del_event(struct perf_event *event, struct perf_event_context *ctx)
+{
+        struct perf_cpu_context *cpuctx;
+        /*
+         * We can have double detach due to exit/hot-unplug + close.
+         */
+        if (!(event->attach_state & PERF_ATTACH_CONTEXT))
+                return;
+
+        event->attach_state &= ~PERF_ATTACH_CONTEXT;
+
+        if (is_cgroup_event(event)) {
+                ctx->nr_cgroups--;
+                cpuctx = __get_cpu_context(ctx);
+                /*
+                 * if there are no more cgroup events
+                 * then cler cgrp to avoid stale pointer
+                 * in update_cgrp_time_from_cpuctx()
+                 */
+                if (!ctx->nr_cgroups)
+                        cpuctx->cgrp = NULL;
+        }
+
+        ctx->nr_events--;
+        if (event->attr.inherit_stat)
+                ctx->nr_stat--;
+
+        list_del_rcu(&event->event_entry);
+
+        if (event->group_leader == event)
+                list_del_init(&event->group_entry);
+
+        update_group_times(event);
+
+        /*
+         * If event was in error state, then keep it
+         * that way, otherwise bogus counts will be
+         * returned on read(). The only way to get out
+         * of error state is by explicit re-enabling
+         * of the event
+         */
+        if (event->state > PERF_EVENT_STATE_OFF)
+                event->state = PERF_EVENT_STATE_OFF;
+}
+
+static void perf_group_detach(struct perf_event *event)
+{
+        struct perf_event *sibling, *tmp;
+        struct list_head *list = NULL;
+
+        /*
+         * We can have double detach due to exit/hot-unplug + close.
+         */
+        if (!(event->attach_state & PERF_ATTACH_GROUP))
+                return;
+
+        event->attach_state &= ~PERF_ATTACH_GROUP;
+
+        /*
+         * If this is a sibling, remove it from its group.
+         */
+        if (event->group_leader != event) {
+                list_del_init(&event->group_entry);
+                event->group_leader->nr_siblings--;
+                goto out;
+        }
+
+        if (!list_empty(&event->group_entry))
+                list = &event->group_entry;
+
+        /*
+         * If this was a group event with sibling events then
+         * upgrade the siblings to singleton events by adding them
+         * to whatever list we are on.
+         */
+        list_for_each_entry_safe(sibling, tmp, &event->sibling_list, group_entry) {
+                if (list)
+                        list_move_tail(&sibling->group_entry, list);
+                sibling->group_leader = sibling;
+
+                /* Inherit group flags from the previous leader */
+                sibling->group_flags = event->group_flags;
+        }
+
+out:
+        perf_event__header_size(event->group_leader);
+
+        list_for_each_entry(tmp, &event->group_leader->sibling_list, group_entry)
+                perf_event__header_size(tmp);
+}
+
+static inline int
+event_filter_match(struct perf_event *event)
+{
+        return (event->cpu == -1 || event->cpu == smp_processor_id())
+            && perf_cgroup_match(event);
+}
+
+static void
+event_sched_out(struct perf_event *event,
+                  struct perf_cpu_context *cpuctx,
+                  struct perf_event_context *ctx)
+{
+        u64 tstamp = perf_event_time(event);
+        u64 delta;
+        /*
+         * An event which could not be activated because of
+         * filter mismatch still needs to have its timings
+         * maintained, otherwise bogus information is return
+         * via read() for time_enabled, time_running:
+         */
+        if (event->state == PERF_EVENT_STATE_INACTIVE
+            && !event_filter_match(event)) {
+                delta = tstamp - event->tstamp_stopped;
+                event->tstamp_running += delta;
+                event->tstamp_stopped = tstamp;
+        }
+
+        if (event->state != PERF_EVENT_STATE_ACTIVE)
+                return;
+
+        event->state = PERF_EVENT_STATE_INACTIVE;
+        if (event->pending_disable) {
+                event->pending_disable = 0;
+                event->state = PERF_EVENT_STATE_OFF;
+        }
+        event->tstamp_stopped = tstamp;
+        event->pmu->del(event, 0);
+        event->oncpu = -1;
+
+        if (!is_software_event(event))
+                cpuctx->active_oncpu--;
+        ctx->nr_active--;
+        if (event->attr.exclusive || !cpuctx->active_oncpu)
+                cpuctx->exclusive = 0;
+}
+
+static void
+group_sched_out(struct perf_event *group_event,
+                struct perf_cpu_context *cpuctx,
+                struct perf_event_context *ctx)
+{
+        struct perf_event *event;
+        int state = group_event->state;
+
+        event_sched_out(group_event, cpuctx, ctx);
+
+        /*
+         * Schedule out siblings (if any):
+         */
+        list_for_each_entry(event, &group_event->sibling_list, group_entry)
+                event_sched_out(event, cpuctx, ctx);
+
+        if (state == PERF_EVENT_STATE_ACTIVE && group_event->attr.exclusive)
+                cpuctx->exclusive = 0;
+}
+
+/*
+ * Cross CPU call to remove a performance event
+ *
+ * We disable the event on the hardware level first. After that we
+ * remove it from the context list.
+ */
+static int __perf_remove_from_context(void *info)
+{
+        struct perf_event *event = info;
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+
+        raw_spin_lock(&ctx->lock);
+        event_sched_out(event, cpuctx, ctx);
+        list_del_event(event, ctx);
+        raw_spin_unlock(&ctx->lock);
+
+        return 0;
+}
+
+
+/*
+ * Remove the event from a task's (or a CPU's) list of events.
+ *
+ * CPU events are removed with a smp call. For task events we only
+ * call when the task is on a CPU.
+ *
+ * If event->ctx is a cloned context, callers must make sure that
+ * every task struct that event->ctx->task could possibly point to
+ * remains valid.  This is OK when called from perf_release since
+ * that only calls us on the top-level context, which can't be a clone.
+ * When called from perf_event_exit_task, it's OK because the
+ * context has been detached from its task.
+ */
+static void perf_remove_from_context(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+        struct task_struct *task = ctx->task;
+
+        lockdep_assert_held(&ctx->mutex);
+
+        if (!task) {
+                /*
+                 * Per cpu events are removed via an smp call and
+                 * the removal is always successful.
+                 */
+                cpu_function_call(event->cpu, __perf_remove_from_context, event);
+                return;
+        }
+
+retry:
+        if (!task_function_call(task, __perf_remove_from_context, event))
+                return;
+
+        raw_spin_lock_irq(&ctx->lock);
+        /*
+         * If we failed to find a running task, but find the context active now
+         * that we've acquired the ctx->lock, retry.
+         */
+        if (ctx->is_active) {
+                raw_spin_unlock_irq(&ctx->lock);
+                goto retry;
+        }
+
+        /*
+         * Since the task isn't running, its safe to remove the event, us
+         * holding the ctx->lock ensures the task won't get scheduled in.
+         */
+        list_del_event(event, ctx);
+        raw_spin_unlock_irq(&ctx->lock);
+}
+
+/*
+ * Cross CPU call to disable a performance event
+ */
+static int __perf_event_disable(void *info)
+{
+        struct perf_event *event = info;
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+
+        /*
+         * If this is a per-task event, need to check whether this
+         * event's task is the current task on this cpu.
+         *
+         * Can trigger due to concurrent perf_event_context_sched_out()
+         * flipping contexts around.
+         */
+        if (ctx->task && cpuctx->task_ctx != ctx)
+                return -EINVAL;
+
+        raw_spin_lock(&ctx->lock);
+
+        /*
+         * If the event is on, turn it off.
+         * If it is in error state, leave it in error state.
+         */
+        if (event->state >= PERF_EVENT_STATE_INACTIVE) {
+                update_context_time(ctx);
+                update_cgrp_time_from_event(event);
+                update_group_times(event);
+                if (event == event->group_leader)
+                        group_sched_out(event, cpuctx, ctx);
+                else
+                        event_sched_out(event, cpuctx, ctx);
+                event->state = PERF_EVENT_STATE_OFF;
+        }
+
+        raw_spin_unlock(&ctx->lock);
+
+        return 0;
+}
+
+/*
+ * Disable a event.
+ *
+ * If event->ctx is a cloned context, callers must make sure that
+ * every task struct that event->ctx->task could possibly point to
+ * remains valid.  This condition is satisifed when called through
+ * perf_event_for_each_child or perf_event_for_each because they
+ * hold the top-level event's child_mutex, so any descendant that
+ * goes to exit will block in sync_child_event.
+ * When called from perf_pending_event it's OK because event->ctx
+ * is the current context on this CPU and preemption is disabled,
+ * hence we can't get into perf_event_task_sched_out for this context.
+ */
+void perf_event_disable(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+        struct task_struct *task = ctx->task;
+
+        if (!task) {
+                /*
+                 * Disable the event on the cpu that it's on
+                 */
+                cpu_function_call(event->cpu, __perf_event_disable, event);
+                return;
+        }
+
+retry:
+        if (!task_function_call(task, __perf_event_disable, event))
+                return;
+
+        raw_spin_lock_irq(&ctx->lock);
+        /*
+         * If the event is still active, we need to retry the cross-call.
+         */
+        if (event->state == PERF_EVENT_STATE_ACTIVE) {
+                raw_spin_unlock_irq(&ctx->lock);
+                /*
+                 * Reload the task pointer, it might have been changed by
+                 * a concurrent perf_event_context_sched_out().
+                 */
+                task = ctx->task;
+                goto retry;
+        }
+
+        /*
+         * Since we have the lock this context can't be scheduled
+         * in, so we can change the state safely.
+         */
+        if (event->state == PERF_EVENT_STATE_INACTIVE) {
+                update_group_times(event);
+                event->state = PERF_EVENT_STATE_OFF;
+        }
+        raw_spin_unlock_irq(&ctx->lock);
+}
+
+static void perf_set_shadow_time(struct perf_event *event,
+                                 struct perf_event_context *ctx,
+                                 u64 tstamp)
+{
+        /*
+         * use the correct time source for the time snapshot
+         *
+         * We could get by without this by leveraging the
+         * fact that to get to this function, the caller
+         * has most likely already called update_context_time()
+         * and update_cgrp_time_xx() and thus both timestamp
+         * are identical (or very close). Given that tstamp is,
+         * already adjusted for cgroup, we could say that:
+         *    tstamp - ctx->timestamp
+         * is equivalent to
+         *    tstamp - cgrp->timestamp.
+         *
+         * Then, in perf_output_read(), the calculation would
+         * work with no changes because:
+         * - event is guaranteed scheduled in
+         * - no scheduled out in between
+         * - thus the timestamp would be the same
+         *
+         * But this is a bit hairy.
+         *
+         * So instead, we have an explicit cgroup call to remain
+         * within the time time source all along. We believe it
+         * is cleaner and simpler to understand.
+         */
+        if (is_cgroup_event(event))
+                perf_cgroup_set_shadow_time(event, tstamp);
+        else
+                event->shadow_ctx_time = tstamp - ctx->timestamp;
+}
+
+#define MAX_INTERRUPTS (~0ULL)
+
+static void perf_log_throttle(struct perf_event *event, int enable);
+
+static int
+event_sched_in(struct perf_event *event,
+                 struct perf_cpu_context *cpuctx,
+                 struct perf_event_context *ctx)
+{
+        u64 tstamp = perf_event_time(event);
+
+        if (event->state <= PERF_EVENT_STATE_OFF)
+                return 0;
+
+        event->state = PERF_EVENT_STATE_ACTIVE;
+        event->oncpu = smp_processor_id();
+
+        /*
+         * Unthrottle events, since we scheduled we might have missed several
+         * ticks already, also for a heavily scheduling task there is little
+         * guarantee it'll get a tick in a timely manner.
+         */
+        if (unlikely(event->hw.interrupts == MAX_INTERRUPTS)) {
+                perf_log_throttle(event, 1);
+                event->hw.interrupts = 0;
+        }
+
+        /*
+         * The new state must be visible before we turn it on in the hardware:
+         */
+        smp_wmb();
+
+        if (event->pmu->add(event, PERF_EF_START)) {
+                event->state = PERF_EVENT_STATE_INACTIVE;
+                event->oncpu = -1;
+                return -EAGAIN;
+        }
+
+        event->tstamp_running += tstamp - event->tstamp_stopped;
+
+        perf_set_shadow_time(event, ctx, tstamp);
+
+        if (!is_software_event(event))
+                cpuctx->active_oncpu++;
+        ctx->nr_active++;
+
+        if (event->attr.exclusive)
+                cpuctx->exclusive = 1;
+
+        return 0;
+}
+
+static int
+group_sched_in(struct perf_event *group_event,
+               struct perf_cpu_context *cpuctx,
+               struct perf_event_context *ctx)
+{
+        struct perf_event *event, *partial_group = NULL;
+        struct pmu *pmu = group_event->pmu;
+        u64 now = ctx->time;
+        bool simulate = false;
+
+        if (group_event->state == PERF_EVENT_STATE_OFF)
+                return 0;
+
+        pmu->start_txn(pmu);
+
+        if (event_sched_in(group_event, cpuctx, ctx)) {
+                pmu->cancel_txn(pmu);
+                return -EAGAIN;
+        }
+
+        /*
+         * Schedule in siblings as one group (if any):
+         */
+        list_for_each_entry(event, &group_event->sibling_list, group_entry) {
+                if (event_sched_in(event, cpuctx, ctx)) {
+                        partial_group = event;
+                        goto group_error;
+                }
+        }
+
+        if (!pmu->commit_txn(pmu))
+                return 0;
+
+group_error:
+        /*
+         * Groups can be scheduled in as one unit only, so undo any
+         * partial group before returning:
+         * The events up to the failed event are scheduled out normally,
+         * tstamp_stopped will be updated.
+         *
+         * The failed events and the remaining siblings need to have
+         * their timings updated as if they had gone thru event_sched_in()
+         * and event_sched_out(). This is required to get consistent timings
+         * across the group. This also takes care of the case where the group
+         * could never be scheduled by ensuring tstamp_stopped is set to mark
+         * the time the event was actually stopped, such that time delta
+         * calculation in update_event_times() is correct.
+         */
+        list_for_each_entry(event, &group_event->sibling_list, group_entry) {
+                if (event == partial_group)
+                        simulate = true;
+
+                if (simulate) {
+                        event->tstamp_running += now - event->tstamp_stopped;
+                        event->tstamp_stopped = now;
+                } else {
+                        event_sched_out(event, cpuctx, ctx);
+                }
+        }
+        event_sched_out(group_event, cpuctx, ctx);
+
+        pmu->cancel_txn(pmu);
+
+        return -EAGAIN;
+}
+
+/*
+ * Work out whether we can put this event group on the CPU now.
+ */
+static int group_can_go_on(struct perf_event *event,
+                           struct perf_cpu_context *cpuctx,
+                           int can_add_hw)
+{
+        /*
+         * Groups consisting entirely of software events can always go on.
+         */
+        if (event->group_flags & PERF_GROUP_SOFTWARE)
+                return 1;
+        /*
+         * If an exclusive group is already on, no other hardware
+         * events can go on.
+         */
+        if (cpuctx->exclusive)
+                return 0;
+        /*
+         * If this group is exclusive and there are already
+         * events on the CPU, it can't go on.
+         */
+        if (event->attr.exclusive && cpuctx->active_oncpu)
+                return 0;
+        /*
+         * Otherwise, try to add it if all previous groups were able
+         * to go on.
+         */
+        return can_add_hw;
+}
+
+static void add_event_to_ctx(struct perf_event *event,
+                               struct perf_event_context *ctx)
+{
+        u64 tstamp = perf_event_time(event);
+
+        list_add_event(event, ctx);
+        perf_group_attach(event);
+        event->tstamp_enabled = tstamp;
+        event->tstamp_running = tstamp;
+        event->tstamp_stopped = tstamp;
+}
+
+static void perf_event_context_sched_in(struct perf_event_context *ctx,
+                                        struct task_struct *tsk);
+
+/*
+ * Cross CPU call to install and enable a performance event
+ *
+ * Must be called with ctx->mutex held
+ */
+static int  __perf_install_in_context(void *info)
+{
+        struct perf_event *event = info;
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_event *leader = event->group_leader;
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+        int err;
+
+        /*
+         * In case we're installing a new context to an already running task,
+         * could also happen before perf_event_task_sched_in() on architectures
+         * which do context switches with IRQs enabled.
+         */
+        if (ctx->task && !cpuctx->task_ctx)
+                perf_event_context_sched_in(ctx, ctx->task);
+
+        raw_spin_lock(&ctx->lock);
+        ctx->is_active = 1;
+        update_context_time(ctx);
+        /*
+         * update cgrp time only if current cgrp
+         * matches event->cgrp. Must be done before
+         * calling add_event_to_ctx()
+         */
+        update_cgrp_time_from_event(event);
+
+        add_event_to_ctx(event, ctx);
+
+        if (!event_filter_match(event))
+                goto unlock;
+
+        /*
+         * Don't put the event on if it is disabled or if
+         * it is in a group and the group isn't on.
+         */
+        if (event->state != PERF_EVENT_STATE_INACTIVE ||
+            (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE))
+                goto unlock;
+
+        /*
+         * An exclusive event can't go on if there are already active
+         * hardware events, and no hardware event can go on if there
+         * is already an exclusive event on.
+         */
+        if (!group_can_go_on(event, cpuctx, 1))
+                err = -EEXIST;
+        else
+                err = event_sched_in(event, cpuctx, ctx);
+
+        if (err) {
+                /*
+                 * This event couldn't go on.  If it is in a group
+                 * then we have to pull the whole group off.
+                 * If the event group is pinned then put it in error state.
+                 */
+                if (leader != event)
+                        group_sched_out(leader, cpuctx, ctx);
+                if (leader->attr.pinned) {
+                        update_group_times(leader);
+                        leader->state = PERF_EVENT_STATE_ERROR;
+                }
+        }
+
+unlock:
+        raw_spin_unlock(&ctx->lock);
+
+        return 0;
+}
+
+/*
+ * Attach a performance event to a context
+ *
+ * First we add the event to the list with the hardware enable bit
+ * in event->hw_config cleared.
+ *
+ * If the event is attached to a task which is on a CPU we use a smp
+ * call to enable it in the task context. The task might have been
+ * scheduled away, but we check this in the smp call again.
+ */
+static void
+perf_install_in_context(struct perf_event_context *ctx,
+                        struct perf_event *event,
+                        int cpu)
+{
+        struct task_struct *task = ctx->task;
+
+        lockdep_assert_held(&ctx->mutex);
+
+        event->ctx = ctx;
+
+        if (!task) {
+                /*
+                 * Per cpu events are installed via an smp call and
+                 * the install is always successful.
+                 */
+                cpu_function_call(cpu, __perf_install_in_context, event);
+                return;
+        }
+
+retry:
+        if (!task_function_call(task, __perf_install_in_context, event))
+                return;
+
+        raw_spin_lock_irq(&ctx->lock);
+        /*
+         * If we failed to find a running task, but find the context active now
+         * that we've acquired the ctx->lock, retry.
+         */
+        if (ctx->is_active) {
+                raw_spin_unlock_irq(&ctx->lock);
+                goto retry;
+        }
+
+        /*
+         * Since the task isn't running, its safe to add the event, us holding
+         * the ctx->lock ensures the task won't get scheduled in.
+         */
+        add_event_to_ctx(event, ctx);
+        raw_spin_unlock_irq(&ctx->lock);
+}
+
+/*
+ * Put a event into inactive state and update time fields.
+ * Enabling the leader of a group effectively enables all
+ * the group members that aren't explicitly disabled, so we
+ * have to update their ->tstamp_enabled also.
+ * Note: this works for group members as well as group leaders
+ * since the non-leader members' sibling_lists will be empty.
+ */
+static void __perf_event_mark_enabled(struct perf_event *event,
+                                        struct perf_event_context *ctx)
+{
+        struct perf_event *sub;
+        u64 tstamp = perf_event_time(event);
+
+        event->state = PERF_EVENT_STATE_INACTIVE;
+        event->tstamp_enabled = tstamp - event->total_time_enabled;
+        list_for_each_entry(sub, &event->sibling_list, group_entry) {
+                if (sub->state >= PERF_EVENT_STATE_INACTIVE)
+                        sub->tstamp_enabled = tstamp - sub->total_time_enabled;
+        }
+}
+
+/*
+ * Cross CPU call to enable a performance event
+ */
+static int __perf_event_enable(void *info)
+{
+        struct perf_event *event = info;
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_event *leader = event->group_leader;
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+        int err;
+
+        if (WARN_ON_ONCE(!ctx->is_active))
+                return -EINVAL;
+
+        raw_spin_lock(&ctx->lock);
+        update_context_time(ctx);
+
+        if (event->state >= PERF_EVENT_STATE_INACTIVE)
+                goto unlock;
+
+        /*
+         * set current task's cgroup time reference point
+         */
+        perf_cgroup_set_timestamp(current, ctx);
+
+        __perf_event_mark_enabled(event, ctx);
+
+        if (!event_filter_match(event)) {
+                if (is_cgroup_event(event))
+                        perf_cgroup_defer_enabled(event);
+                goto unlock;
+        }
+
+        /*
+         * If the event is in a group and isn't the group leader,
+         * then don't put it on unless the group is on.
+         */
+        if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE)
+                goto unlock;
+
+        if (!group_can_go_on(event, cpuctx, 1)) {
+                err = -EEXIST;
+        } else {
+                if (event == leader)
+                        err = group_sched_in(event, cpuctx, ctx);
+                else
+                        err = event_sched_in(event, cpuctx, ctx);
+        }
+
+        if (err) {
+                /*
+                 * If this event can't go on and it's part of a
+                 * group, then the whole group has to come off.
+                 */
+                if (leader != event)
+                        group_sched_out(leader, cpuctx, ctx);
+                if (leader->attr.pinned) {
+                        update_group_times(leader);
+                        leader->state = PERF_EVENT_STATE_ERROR;
+                }
+        }
+
+unlock:
+        raw_spin_unlock(&ctx->lock);
+
+        return 0;
+}
+
+/*
+ * Enable a event.
+ *
+ * If event->ctx is a cloned context, callers must make sure that
+ * every task struct that event->ctx->task could possibly point to
+ * remains valid.  This condition is satisfied when called through
+ * perf_event_for_each_child or perf_event_for_each as described
+ * for perf_event_disable.
+ */
+void perf_event_enable(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+        struct task_struct *task = ctx->task;
+
+        if (!task) {
+                /*
+                 * Enable the event on the cpu that it's on
+                 */
+                cpu_function_call(event->cpu, __perf_event_enable, event);
+                return;
+        }
+
+        raw_spin_lock_irq(&ctx->lock);
+        if (event->state >= PERF_EVENT_STATE_INACTIVE)
+                goto out;
+
+        /*
+         * If the event is in error state, clear that first.
+         * That way, if we see the event in error state below, we
+         * know that it has gone back into error state, as distinct
+         * from the task having been scheduled away before the
+         * cross-call arrived.
+         */
+        if (event->state == PERF_EVENT_STATE_ERROR)
+                event->state = PERF_EVENT_STATE_OFF;
+
+retry:
+        if (!ctx->is_active) {
+                __perf_event_mark_enabled(event, ctx);
+                goto out;
+        }
+
+        raw_spin_unlock_irq(&ctx->lock);
+
+        if (!task_function_call(task, __perf_event_enable, event))
+                return;
+
+        raw_spin_lock_irq(&ctx->lock);
+
+        /*
+         * If the context is active and the event is still off,
+         * we need to retry the cross-call.
+         */
+        if (ctx->is_active && event->state == PERF_EVENT_STATE_OFF) {
+                /*
+                 * task could have been flipped by a concurrent
+                 * perf_event_context_sched_out()
+                 */
+                task = ctx->task;
+                goto retry;
+        }
+
+out:
+        raw_spin_unlock_irq(&ctx->lock);
+}
+
+static int perf_event_refresh(struct perf_event *event, int refresh)
+{
+        /*
+         * not supported on inherited events
+         */
+        if (event->attr.inherit || !is_sampling_event(event))
+                return -EINVAL;
+
+        atomic_add(refresh, &event->event_limit);
+        perf_event_enable(event);
+
+        return 0;
+}
+
+static void ctx_sched_out(struct perf_event_context *ctx,
+                          struct perf_cpu_context *cpuctx,
+                          enum event_type_t event_type)
+{
+        struct perf_event *event;
+
+        raw_spin_lock(&ctx->lock);
+        perf_pmu_disable(ctx->pmu);
+        ctx->is_active = 0;
+        if (likely(!ctx->nr_events))
+                goto out;
+        update_context_time(ctx);
+        update_cgrp_time_from_cpuctx(cpuctx);
+
+        if (!ctx->nr_active)
+                goto out;
+
+        if (event_type & EVENT_PINNED) {
+                list_for_each_entry(event, &ctx->pinned_groups, group_entry)
+                        group_sched_out(event, cpuctx, ctx);
+        }
+
+        if (event_type & EVENT_FLEXIBLE) {
+                list_for_each_entry(event, &ctx->flexible_groups, group_entry)
+                        group_sched_out(event, cpuctx, ctx);
+        }
+out:
+        perf_pmu_enable(ctx->pmu);
+        raw_spin_unlock(&ctx->lock);
+}
+
+/*
+ * Test whether two contexts are equivalent, i.e. whether they
+ * have both been cloned from the same version of the same context
+ * and they both have the same number of enabled events.
+ * If the number of enabled events is the same, then the set
+ * of enabled events should be the same, because these are both
+ * inherited contexts, therefore we can't access individual events
+ * in them directly with an fd; we can only enable/disable all
+ * events via prctl, or enable/disable all events in a family
+ * via ioctl, which will have the same effect on both contexts.
+ */
+static int context_equiv(struct perf_event_context *ctx1,
+                         struct perf_event_context *ctx2)
+{
+        return ctx1->parent_ctx && ctx1->parent_ctx == ctx2->parent_ctx
+                && ctx1->parent_gen == ctx2->parent_gen
+                && !ctx1->pin_count && !ctx2->pin_count;
+}
+
+static void __perf_event_sync_stat(struct perf_event *event,
+                                     struct perf_event *next_event)
+{
+        u64 value;
+
+        if (!event->attr.inherit_stat)
+                return;
+
+        /*
+         * Update the event value, we cannot use perf_event_read()
+         * because we're in the middle of a context switch and have IRQs
+         * disabled, which upsets smp_call_function_single(), however
+         * we know the event must be on the current CPU, therefore we
+         * don't need to use it.
+         */
+        switch (event->state) {
+        case PERF_EVENT_STATE_ACTIVE:
+                event->pmu->read(event);
+                /* fall-through */
+
+        case PERF_EVENT_STATE_INACTIVE:
+                update_event_times(event);
+                break;
+
+        default:
+                break;
+        }
+
+        /*
+         * In order to keep per-task stats reliable we need to flip the event
+         * values when we flip the contexts.
+         */
+        value = local64_read(&next_event->count);
+        value = local64_xchg(&event->count, value);
+        local64_set(&next_event->count, value);
+
+        swap(event->total_time_enabled, next_event->total_time_enabled);
+        swap(event->total_time_running, next_event->total_time_running);
+
+        /*
+         * Since we swizzled the values, update the user visible data too.
+         */
+        perf_event_update_userpage(event);
+        perf_event_update_userpage(next_event);
+}
+
+#define list_next_entry(pos, member) \
+        list_entry(pos->member.next, typeof(*pos), member)
+
+static void perf_event_sync_stat(struct perf_event_context *ctx,
+                                   struct perf_event_context *next_ctx)
+{
+        struct perf_event *event, *next_event;
+
+        if (!ctx->nr_stat)
+                return;
+
+        update_context_time(ctx);
+
+        event = list_first_entry(&ctx->event_list,
+                                   struct perf_event, event_entry);
+
+        next_event = list_first_entry(&next_ctx->event_list,
+                                        struct perf_event, event_entry);
+
+        while (&event->event_entry != &ctx->event_list &&
+               &next_event->event_entry != &next_ctx->event_list) {
+
+                __perf_event_sync_stat(event, next_event);
+
+                event = list_next_entry(event, event_entry);
+                next_event = list_next_entry(next_event, event_entry);
+        }
+}
+
+static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
+                                         struct task_struct *next)
+{
+        struct perf_event_context *ctx = task->perf_event_ctxp[ctxn];
+        struct perf_event_context *next_ctx;
+        struct perf_event_context *parent;
+        struct perf_cpu_context *cpuctx;
+        int do_switch = 1;
+
+        if (likely(!ctx))
+                return;
+
+        cpuctx = __get_cpu_context(ctx);
+        if (!cpuctx->task_ctx)
+                return;
+
+        rcu_read_lock();
+        parent = rcu_dereference(ctx->parent_ctx);
+        next_ctx = next->perf_event_ctxp[ctxn];
+        if (parent && next_ctx &&
+            rcu_dereference(next_ctx->parent_ctx) == parent) {
+                /*
+                 * Looks like the two contexts are clones, so we might be
+                 * able to optimize the context switch.  We lock both
+                 * contexts and check that they are clones under the
+                 * lock (including re-checking that neither has been
+                 * uncloned in the meantime).  It doesn't matter which
+                 * order we take the locks because no other cpu could
+                 * be trying to lock both of these tasks.
+                 */
+                raw_spin_lock(&ctx->lock);
+                raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
+                if (context_equiv(ctx, next_ctx)) {
+                        /*
+                         * XXX do we need a memory barrier of sorts
+                         * wrt to rcu_dereference() of perf_event_ctxp
+                         */
+                        task->perf_event_ctxp[ctxn] = next_ctx;
+                        next->perf_event_ctxp[ctxn] = ctx;
+                        ctx->task = next;
+                        next_ctx->task = task;
+                        do_switch = 0;
+
+                        perf_event_sync_stat(ctx, next_ctx);
+                }
+                raw_spin_unlock(&next_ctx->lock);
+                raw_spin_unlock(&ctx->lock);
+        }
+        rcu_read_unlock();
+
+        if (do_switch) {
+                ctx_sched_out(ctx, cpuctx, EVENT_ALL);
+                cpuctx->task_ctx = NULL;
+        }
+}
+
+#define for_each_task_context_nr(ctxn)                                  \
+        for ((ctxn) = 0; (ctxn) < perf_nr_task_contexts; (ctxn)++)
+
+/*
+ * Called from scheduler to remove the events of the current task,
+ * with interrupts disabled.
+ *
+ * We stop each event and update the event value in event->count.
+ *
+ * This does not protect us against NMI, but disable()
+ * sets the disabled bit in the control field of event _before_
+ * accessing the event control register. If a NMI hits, then it will
+ * not restart the event.
+ */
+void __perf_event_task_sched_out(struct task_struct *task,
+                                 struct task_struct *next)
+{
+        int ctxn;
+
+        for_each_task_context_nr(ctxn)
+                perf_event_context_sched_out(task, ctxn, next);
+
+        /*
+         * if cgroup events exist on this CPU, then we need
+         * to check if we have to switch out PMU state.
+         * cgroup event are system-wide mode only
+         */
+        if (atomic_read(&__get_cpu_var(perf_cgroup_events)))
+                perf_cgroup_sched_out(task);
+}
+
+static void task_ctx_sched_out(struct perf_event_context *ctx,
+                               enum event_type_t event_type)
+{
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+
+        if (!cpuctx->task_ctx)
+                return;
+
+        if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
+                return;
+
+        ctx_sched_out(ctx, cpuctx, event_type);
+        cpuctx->task_ctx = NULL;
+}
+
+/*
+ * Called with IRQs disabled
+ */
+static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
+                              enum event_type_t event_type)
+{
+        ctx_sched_out(&cpuctx->ctx, cpuctx, event_type);
+}
+
+static void
+ctx_pinned_sched_in(struct perf_event_context *ctx,
+                    struct perf_cpu_context *cpuctx)
+{
+        struct perf_event *event;
+
+        list_for_each_entry(event, &ctx->pinned_groups, group_entry) {
+                if (event->state <= PERF_EVENT_STATE_OFF)
+                        continue;
+                if (!event_filter_match(event))
+                        continue;
+
+                /* may need to reset tstamp_enabled */
+                if (is_cgroup_event(event))
+                        perf_cgroup_mark_enabled(event, ctx);
+
+                if (group_can_go_on(event, cpuctx, 1))
+                        group_sched_in(event, cpuctx, ctx);
+
+                /*
+                 * If this pinned group hasn't been scheduled,
+                 * put it in error state.
+                 */
+                if (event->state == PERF_EVENT_STATE_INACTIVE) {
+                        update_group_times(event);
+                        event->state = PERF_EVENT_STATE_ERROR;
+                }
+        }
+}
+
+static void
+ctx_flexible_sched_in(struct perf_event_context *ctx,
+                      struct perf_cpu_context *cpuctx)
+{
+        struct perf_event *event;
+        int can_add_hw = 1;
+
+        list_for_each_entry(event, &ctx->flexible_groups, group_entry) {
+                /* Ignore events in OFF or ERROR state */
+                if (event->state <= PERF_EVENT_STATE_OFF)
+                        continue;
+                /*
+                 * Listen to the 'cpu' scheduling filter constraint
+                 * of events:
+                 */
+                if (!event_filter_match(event))
+                        continue;
+
+                /* may need to reset tstamp_enabled */
+                if (is_cgroup_event(event))
+                        perf_cgroup_mark_enabled(event, ctx);
+
+                if (group_can_go_on(event, cpuctx, can_add_hw)) {
+                        if (group_sched_in(event, cpuctx, ctx))
+                                can_add_hw = 0;
+                }
+        }
+}
+
+static void
+ctx_sched_in(struct perf_event_context *ctx,
+             struct perf_cpu_context *cpuctx,
+             enum event_type_t event_type,
+             struct task_struct *task)
+{
+        u64 now;
+
+        raw_spin_lock(&ctx->lock);
+        ctx->is_active = 1;
+        if (likely(!ctx->nr_events))
+                goto out;
+
+        now = perf_clock();
+        ctx->timestamp = now;
+        perf_cgroup_set_timestamp(task, ctx);
+        /*
+         * First go through the list and put on any pinned groups
+         * in order to give them the best chance of going on.
+         */
+        if (event_type & EVENT_PINNED)
+                ctx_pinned_sched_in(ctx, cpuctx);
+
+        /* Then walk through the lower prio flexible groups */
+        if (event_type & EVENT_FLEXIBLE)
+                ctx_flexible_sched_in(ctx, cpuctx);
+
+out:
+        raw_spin_unlock(&ctx->lock);
+}
+
+static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
+                             enum event_type_t event_type,
+                             struct task_struct *task)
+{
+        struct perf_event_context *ctx = &cpuctx->ctx;
+
+        ctx_sched_in(ctx, cpuctx, event_type, task);
+}
+
+static void task_ctx_sched_in(struct perf_event_context *ctx,
+                              enum event_type_t event_type)
+{
+        struct perf_cpu_context *cpuctx;
+
+        cpuctx = __get_cpu_context(ctx);
+        if (cpuctx->task_ctx == ctx)
+                return;
+
+        ctx_sched_in(ctx, cpuctx, event_type, NULL);
+        cpuctx->task_ctx = ctx;
+}
+
+static void perf_event_context_sched_in(struct perf_event_context *ctx,
+                                        struct task_struct *task)
+{
+        struct perf_cpu_context *cpuctx;
+
+        cpuctx = __get_cpu_context(ctx);
+        if (cpuctx->task_ctx == ctx)
+                return;
+
+        perf_pmu_disable(ctx->pmu);
+        /*
+         * We want to keep the following priority order:
+         * cpu pinned (that don't need to move), task pinned,
+         * cpu flexible, task flexible.
+         */
+        cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
+
+        ctx_sched_in(ctx, cpuctx, EVENT_PINNED, task);
+        cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE, task);
+        ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE, task);
+
+        cpuctx->task_ctx = ctx;
+
+        /*
+         * Since these rotations are per-cpu, we need to ensure the
+         * cpu-context we got scheduled on is actually rotating.
+         */
+        perf_pmu_rotate_start(ctx->pmu);
+        perf_pmu_enable(ctx->pmu);
+}
+
+/*
+ * Called from scheduler to add the events of the current task
+ * with interrupts disabled.
+ *
+ * We restore the event value and then enable it.
+ *
+ * This does not protect us against NMI, but enable()
+ * sets the enabled bit in the control field of event _before_
+ * accessing the event control register. If a NMI hits, then it will
+ * keep the event running.
+ */
+void __perf_event_task_sched_in(struct task_struct *task)
+{
+        struct perf_event_context *ctx;
+        int ctxn;
+
+        for_each_task_context_nr(ctxn) {
+                ctx = task->perf_event_ctxp[ctxn];
+                if (likely(!ctx))
+                        continue;
+
+                perf_event_context_sched_in(ctx, task);
+        }
+        /*
+         * if cgroup events exist on this CPU, then we need
+         * to check if we have to switch in PMU state.
+         * cgroup event are system-wide mode only
+         */
+        if (atomic_read(&__get_cpu_var(perf_cgroup_events)))
+                perf_cgroup_sched_in(task);
+}
+
+static u64 perf_calculate_period(struct perf_event *event, u64 nsec, u64 count)
+{
+        u64 frequency = event->attr.sample_freq;
+        u64 sec = NSEC_PER_SEC;
+        u64 divisor, dividend;
+
+        int count_fls, nsec_fls, frequency_fls, sec_fls;
+
+        count_fls = fls64(count);
+        nsec_fls = fls64(nsec);
+        frequency_fls = fls64(frequency);
+        sec_fls = 30;
+
+        /*
+         * We got @count in @nsec, with a target of sample_freq HZ
+         * the target period becomes:
+         *
+         *             @count * 10^9
+         * period = -------------------
+         *          @nsec * sample_freq
+         *
+         */
+
+        /*
+         * Reduce accuracy by one bit such that @a and @b converge
+         * to a similar magnitude.
+         */
+#define REDUCE_FLS(a, b)                \
+do {                                    \
+        if (a##_fls > b##_fls) {        \
+                a >>= 1;                \
+                a##_fls--;              \
+        } else {                        \
+                b >>= 1;                \
+                b##_fls--;              \
+        }                               \
+} while (0)
+
+        /*
+         * Reduce accuracy until either term fits in a u64, then proceed with
+         * the other, so that finally we can do a u64/u64 division.
+         */
+        while (count_fls + sec_fls > 64 && nsec_fls + frequency_fls > 64) {
+                REDUCE_FLS(nsec, frequency);
+                REDUCE_FLS(sec, count);
+        }
+
+        if (count_fls + sec_fls > 64) {
+                divisor = nsec * frequency;
+
+                while (count_fls + sec_fls > 64) {
+                        REDUCE_FLS(count, sec);
+                        divisor >>= 1;
+                }
+
+                dividend = count * sec;
+        } else {
+                dividend = count * sec;
+
+                while (nsec_fls + frequency_fls > 64) {
+                        REDUCE_FLS(nsec, frequency);
+                        dividend >>= 1;
+                }
+
+                divisor = nsec * frequency;
+        }
+
+        if (!divisor)
+                return dividend;
+
+        return div64_u64(dividend, divisor);
+}
+
+static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count)
+{
+        struct hw_perf_event *hwc = &event->hw;
+        s64 period, sample_period;
+        s64 delta;
+
+        period = perf_calculate_period(event, nsec, count);
+
+        delta = (s64)(period - hwc->sample_period);
+        delta = (delta + 7) / 8; /* low pass filter */
+
+        sample_period = hwc->sample_period + delta;
+
+        if (!sample_period)
+                sample_period = 1;
+
+        hwc->sample_period = sample_period;
+
+        if (local64_read(&hwc->period_left) > 8*sample_period) {
+                event->pmu->stop(event, PERF_EF_UPDATE);
+                local64_set(&hwc->period_left, 0);
+                event->pmu->start(event, PERF_EF_RELOAD);
+        }
+}
+
+static void perf_ctx_adjust_freq(struct perf_event_context *ctx, u64 period)
+{
+        struct perf_event *event;
+        struct hw_perf_event *hwc;
+        u64 interrupts, now;
+        s64 delta;
+
+        raw_spin_lock(&ctx->lock);
+        list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+                if (event->state != PERF_EVENT_STATE_ACTIVE)
+                        continue;
+
+                if (!event_filter_match(event))
+                        continue;
+
+                hwc = &event->hw;
+
+                interrupts = hwc->interrupts;
+                hwc->interrupts = 0;
+
+                /*
+                 * unthrottle events on the tick
+                 */
+                if (interrupts == MAX_INTERRUPTS) {
+                        perf_log_throttle(event, 1);
+                        event->pmu->start(event, 0);
+                }
+
+                if (!event->attr.freq || !event->attr.sample_freq)
+                        continue;
+
+                event->pmu->read(event);
+                now = local64_read(&event->count);
+                delta = now - hwc->freq_count_stamp;
+                hwc->freq_count_stamp = now;
+
+                if (delta > 0)
+                        perf_adjust_period(event, period, delta);
+        }
+        raw_spin_unlock(&ctx->lock);
+}
+
+/*
+ * Round-robin a context's events:
+ */
+static void rotate_ctx(struct perf_event_context *ctx)
+{
+        raw_spin_lock(&ctx->lock);
+
+        /*
+         * Rotate the first entry last of non-pinned groups. Rotation might be
+         * disabled by the inheritance code.
+         */
+        if (!ctx->rotate_disable)
+                list_rotate_left(&ctx->flexible_groups);
+
+        raw_spin_unlock(&ctx->lock);
+}
+
+/*
+ * perf_pmu_rotate_start() and perf_rotate_context() are fully serialized
+ * because they're strictly cpu affine and rotate_start is called with IRQs
+ * disabled, while rotate_context is called from IRQ context.
+ */
+static void perf_rotate_context(struct perf_cpu_context *cpuctx)
+{
+        u64 interval = (u64)cpuctx->jiffies_interval * TICK_NSEC;
+        struct perf_event_context *ctx = NULL;
+        int rotate = 0, remove = 1;
+
+        if (cpuctx->ctx.nr_events) {
+                remove = 0;
+                if (cpuctx->ctx.nr_events != cpuctx->ctx.nr_active)
+                        rotate = 1;
+        }
+
+        ctx = cpuctx->task_ctx;
+        if (ctx && ctx->nr_events) {
+                remove = 0;
+                if (ctx->nr_events != ctx->nr_active)
+                        rotate = 1;
+        }
+
+        perf_pmu_disable(cpuctx->ctx.pmu);
+        perf_ctx_adjust_freq(&cpuctx->ctx, interval);
+        if (ctx)
+                perf_ctx_adjust_freq(ctx, interval);
+
+        if (!rotate)
+                goto done;
+
+        cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
+        if (ctx)
+                task_ctx_sched_out(ctx, EVENT_FLEXIBLE);
+
+        rotate_ctx(&cpuctx->ctx);
+        if (ctx)
+                rotate_ctx(ctx);
+
+        cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE, current);
+        if (ctx)
+                task_ctx_sched_in(ctx, EVENT_FLEXIBLE);
+
+done:
+        if (remove)
+                list_del_init(&cpuctx->rotation_list);
+
+        perf_pmu_enable(cpuctx->ctx.pmu);
+}
+
+void perf_event_task_tick(void)
+{
+        struct list_head *head = &__get_cpu_var(rotation_list);
+        struct perf_cpu_context *cpuctx, *tmp;
+
+        WARN_ON(!irqs_disabled());
+
+        list_for_each_entry_safe(cpuctx, tmp, head, rotation_list) {
+                if (cpuctx->jiffies_interval == 1 ||
+                                !(jiffies % cpuctx->jiffies_interval))
+                        perf_rotate_context(cpuctx);
+        }
+}
+
+static int event_enable_on_exec(struct perf_event *event,
+                                struct perf_event_context *ctx)
+{
+        if (!event->attr.enable_on_exec)
+                return 0;
+
+        event->attr.enable_on_exec = 0;
+        if (event->state >= PERF_EVENT_STATE_INACTIVE)
+                return 0;
+
+        __perf_event_mark_enabled(event, ctx);
+
+        return 1;
+}
+
+/*
+ * Enable all of a task's events that have been marked enable-on-exec.
+ * This expects task == current.
+ */
+static void perf_event_enable_on_exec(struct perf_event_context *ctx)
+{
+        struct perf_event *event;
+        unsigned long flags;
+        int enabled = 0;
+        int ret;
+
+        local_irq_save(flags);
+        if (!ctx || !ctx->nr_events)
+                goto out;
+
+        /*
+         * We must ctxsw out cgroup events to avoid conflict
+         * when invoking perf_task_event_sched_in() later on
+         * in this function. Otherwise we end up trying to
+         * ctxswin cgroup events which are already scheduled
+         * in.
+         */
+        perf_cgroup_sched_out(current);
+        task_ctx_sched_out(ctx, EVENT_ALL);
+
+        raw_spin_lock(&ctx->lock);
+
+        list_for_each_entry(event, &ctx->pinned_groups, group_entry) {
+                ret = event_enable_on_exec(event, ctx);
+                if (ret)
+                        enabled = 1;
+        }
+
+        list_for_each_entry(event, &ctx->flexible_groups, group_entry) {
+                ret = event_enable_on_exec(event, ctx);
+                if (ret)
+                        enabled = 1;
+        }
+
+        /*
+         * Unclone this context if we enabled any event.
+         */
+        if (enabled)
+                unclone_ctx(ctx);
+
+        raw_spin_unlock(&ctx->lock);
+
+        /*
+         * Also calls ctxswin for cgroup events, if any:
+         */
+        perf_event_context_sched_in(ctx, ctx->task);
+out:
+        local_irq_restore(flags);
+}
+
+/*
+ * Cross CPU call to read the hardware event
+ */
+static void __perf_event_read(void *info)
+{
+        struct perf_event *event = info;
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+
+        /*
+         * If this is a task context, we need to check whether it is
+         * the current task context of this cpu.  If not it has been
+         * scheduled out before the smp call arrived.  In that case
+         * event->count would have been updated to a recent sample
+         * when the event was scheduled out.
+         */
+        if (ctx->task && cpuctx->task_ctx != ctx)
+                return;
+
+        raw_spin_lock(&ctx->lock);
+        if (ctx->is_active) {
+                update_context_time(ctx);
+                update_cgrp_time_from_event(event);
+        }
+        update_event_times(event);
+        if (event->state == PERF_EVENT_STATE_ACTIVE)
+                event->pmu->read(event);
+        raw_spin_unlock(&ctx->lock);
+}
+
+static inline u64 perf_event_count(struct perf_event *event)
+{
+        return local64_read(&event->count) + atomic64_read(&event->child_count);
+}
+
+static u64 perf_event_read(struct perf_event *event)
+{
+        /*
+         * If event is enabled and currently active on a CPU, update the
+         * value in the event structure:
+         */
+        if (event->state == PERF_EVENT_STATE_ACTIVE) {
+                smp_call_function_single(event->oncpu,
+                                         __perf_event_read, event, 1);
+        } else if (event->state == PERF_EVENT_STATE_INACTIVE) {
+                struct perf_event_context *ctx = event->ctx;
+                unsigned long flags;
+
+                raw_spin_lock_irqsave(&ctx->lock, flags);
+                /*
+                 * may read while context is not active
+                 * (e.g., thread is blocked), in that case
+                 * we cannot update context time
+                 */
+                if (ctx->is_active) {
+                        update_context_time(ctx);
+                        update_cgrp_time_from_event(event);
+                }
+                update_event_times(event);
+                raw_spin_unlock_irqrestore(&ctx->lock, flags);
+        }
+
+        return perf_event_count(event);
+}
+
+/*
+ * Callchain support
+ */
+
+struct callchain_cpus_entries {
+        struct rcu_head                 rcu_head;
+        struct perf_callchain_entry     *cpu_entries[0];
+};
+
+static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
+static atomic_t nr_callchain_events;
+static DEFINE_MUTEX(callchain_mutex);
+struct callchain_cpus_entries *callchain_cpus_entries;
+
+
+__weak void perf_callchain_kernel(struct perf_callchain_entry *entry,
+                                  struct pt_regs *regs)
+{
+}
+
+__weak void perf_callchain_user(struct perf_callchain_entry *entry,
+                                struct pt_regs *regs)
+{
+}
+
+static void release_callchain_buffers_rcu(struct rcu_head *head)
+{
+        struct callchain_cpus_entries *entries;
+        int cpu;
+
+        entries = container_of(head, struct callchain_cpus_entries, rcu_head);
+
+        for_each_possible_cpu(cpu)
+                kfree(entries->cpu_entries[cpu]);
+
+        kfree(entries);
+}
+
+static void release_callchain_buffers(void)
+{
+        struct callchain_cpus_entries *entries;
+
+        entries = callchain_cpus_entries;
+        rcu_assign_pointer(callchain_cpus_entries, NULL);
+        call_rcu(&entries->rcu_head, release_callchain_buffers_rcu);
+}
+
+static int alloc_callchain_buffers(void)
+{
+        int cpu;
+        int size;
+        struct callchain_cpus_entries *entries;
+
+        /*
+         * We can't use the percpu allocation API for data that can be
+         * accessed from NMI. Use a temporary manual per cpu allocation
+         * until that gets sorted out.
+         */
+        size = offsetof(struct callchain_cpus_entries, cpu_entries[nr_cpu_ids]);
+
+        entries = kzalloc(size, GFP_KERNEL);
+        if (!entries)
+                return -ENOMEM;
+
+        size = sizeof(struct perf_callchain_entry) * PERF_NR_CONTEXTS;
+
+        for_each_possible_cpu(cpu) {
+                entries->cpu_entries[cpu] = kmalloc_node(size, GFP_KERNEL,
+                                                         cpu_to_node(cpu));
+                if (!entries->cpu_entries[cpu])
+                        goto fail;
+        }
+
+        rcu_assign_pointer(callchain_cpus_entries, entries);
+
+        return 0;
+
+fail:
+        for_each_possible_cpu(cpu)
+                kfree(entries->cpu_entries[cpu]);
+        kfree(entries);
+
+        return -ENOMEM;
+}
+
+static int get_callchain_buffers(void)
+{
+        int err = 0;
+        int count;
+
+        mutex_lock(&callchain_mutex);
+
+        count = atomic_inc_return(&nr_callchain_events);
+        if (WARN_ON_ONCE(count < 1)) {
+                err = -EINVAL;
+                goto exit;
+        }
+
+        if (count > 1) {
+                /* If the allocation failed, give up */
+                if (!callchain_cpus_entries)
+                        err = -ENOMEM;
+                goto exit;
+        }
+
+        err = alloc_callchain_buffers();
+        if (err)
+                release_callchain_buffers();
+exit:
+        mutex_unlock(&callchain_mutex);
+
+        return err;
+}
+
+static void put_callchain_buffers(void)
+{
+        if (atomic_dec_and_mutex_lock(&nr_callchain_events, &callchain_mutex)) {
+                release_callchain_buffers();
+                mutex_unlock(&callchain_mutex);
+        }
+}
+
+static int get_recursion_context(int *recursion)
+{
+        int rctx;
+
+        if (in_nmi())
+                rctx = 3;
+        else if (in_irq())
+                rctx = 2;
+        else if (in_softirq())
+                rctx = 1;
+        else
+                rctx = 0;
+
+        if (recursion[rctx])
+                return -1;
+
+        recursion[rctx]++;
+        barrier();
+
+        return rctx;
+}
+
+static inline void put_recursion_context(int *recursion, int rctx)
+{
+        barrier();
+        recursion[rctx]--;
+}
+
+static struct perf_callchain_entry *get_callchain_entry(int *rctx)
+{
+        int cpu;
+        struct callchain_cpus_entries *entries;
+
+        *rctx = get_recursion_context(__get_cpu_var(callchain_recursion));
+        if (*rctx == -1)
+                return NULL;
+
+        entries = rcu_dereference(callchain_cpus_entries);
+        if (!entries)
+                return NULL;
+
+        cpu = smp_processor_id();
+
+        return &entries->cpu_entries[cpu][*rctx];
+}
+
+static void
+put_callchain_entry(int rctx)
+{
+        put_recursion_context(__get_cpu_var(callchain_recursion), rctx);
+}
+
+static struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
+{
+        int rctx;
+        struct perf_callchain_entry *entry;
+
+
+        entry = get_callchain_entry(&rctx);
+        if (rctx == -1)
+                return NULL;
+
+        if (!entry)
+                goto exit_put;
+
+        entry->nr = 0;
+
+        if (!user_mode(regs)) {
+                perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
+                perf_callchain_kernel(entry, regs);
+                if (current->mm)
+                        regs = task_pt_regs(current);
+                else
+                        regs = NULL;
+        }
+
+        if (regs) {
+                perf_callchain_store(entry, PERF_CONTEXT_USER);
+                perf_callchain_user(entry, regs);
+        }
+
+exit_put:
+        put_callchain_entry(rctx);
+
+        return entry;
+}
+
+/*
+ * Initialize the perf_event context in a task_struct:
+ */
+static void __perf_event_init_context(struct perf_event_context *ctx)
+{
+        raw_spin_lock_init(&ctx->lock);
+        mutex_init(&ctx->mutex);
+        INIT_LIST_HEAD(&ctx->pinned_groups);
+        INIT_LIST_HEAD(&ctx->flexible_groups);
+        INIT_LIST_HEAD(&ctx->event_list);
+        atomic_set(&ctx->refcount, 1);
+}
+
+static struct perf_event_context *
+alloc_perf_context(struct pmu *pmu, struct task_struct *task)
+{
+        struct perf_event_context *ctx;
+
+        ctx = kzalloc(sizeof(struct perf_event_context), GFP_KERNEL);
+        if (!ctx)
+                return NULL;
+
+        __perf_event_init_context(ctx);
+        if (task) {
+                ctx->task = task;
+                get_task_struct(task);
+        }
+        ctx->pmu = pmu;
+
+        return ctx;
+}
+
+static struct task_struct *
+find_lively_task_by_vpid(pid_t vpid)
+{
+        struct task_struct *task;
+        int err;
+
+        rcu_read_lock();
+        if (!vpid)
+                task = current;
+        else
+                task = find_task_by_vpid(vpid);
+        if (task)
+                get_task_struct(task);
+        rcu_read_unlock();
+
+        if (!task)
+                return ERR_PTR(-ESRCH);
+
+        /* Reuse ptrace permission checks for now. */
+        err = -EACCES;
+        if (!ptrace_may_access(task, PTRACE_MODE_READ))
+                goto errout;
+
+        return task;
+errout:
+        put_task_struct(task);
+        return ERR_PTR(err);
+
+}
+
+/*
+ * Returns a matching context with refcount and pincount.
+ */
+static struct perf_event_context *
+find_get_context(struct pmu *pmu, struct task_struct *task, int cpu)
+{
+        struct perf_event_context *ctx;
+        struct perf_cpu_context *cpuctx;
+        unsigned long flags;
+        int ctxn, err;
+
+        if (!task) {
+                /* Must be root to operate on a CPU event: */
+                if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
+                        return ERR_PTR(-EACCES);
+
+                /*
+                 * We could be clever and allow to attach a event to an
+                 * offline CPU and activate it when the CPU comes up, but
+                 * that's for later.
+                 */
+                if (!cpu_online(cpu))
+                        return ERR_PTR(-ENODEV);
+
+                cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+                ctx = &cpuctx->ctx;
+                get_ctx(ctx);
+                ++ctx->pin_count;
+
+                return ctx;
+        }
+
+        err = -EINVAL;
+        ctxn = pmu->task_ctx_nr;
+        if (ctxn < 0)
+                goto errout;
+
+retry:
+        ctx = perf_lock_task_context(task, ctxn, &flags);
+        if (ctx) {
+                unclone_ctx(ctx);
+                ++ctx->pin_count;
+                raw_spin_unlock_irqrestore(&ctx->lock, flags);
+        }
+
+        if (!ctx) {
+                ctx = alloc_perf_context(pmu, task);
+                err = -ENOMEM;
+                if (!ctx)
+                        goto errout;
+
+                get_ctx(ctx);
+
+                err = 0;
+                mutex_lock(&task->perf_event_mutex);
+                /*
+                 * If it has already passed perf_event_exit_task().
+                 * we must see PF_EXITING, it takes this mutex too.
+                 */
+                if (task->flags & PF_EXITING)
+                        err = -ESRCH;
+                else if (task->perf_event_ctxp[ctxn])
+                        err = -EAGAIN;
+                else {
+                        ++ctx->pin_count;
+                        rcu_assign_pointer(task->perf_event_ctxp[ctxn], ctx);
+                }
+                mutex_unlock(&task->perf_event_mutex);
+
+                if (unlikely(err)) {
+                        put_task_struct(task);
+                        kfree(ctx);
+
+                        if (err == -EAGAIN)
+                                goto retry;
+                        goto errout;
+                }
+        }
+
+        return ctx;
+
+errout:
+        return ERR_PTR(err);
+}
+
+static void perf_event_free_filter(struct perf_event *event);
+
+static void free_event_rcu(struct rcu_head *head)
+{
+        struct perf_event *event;
+
+        event = container_of(head, struct perf_event, rcu_head);
+        if (event->ns)
+                put_pid_ns(event->ns);
+        perf_event_free_filter(event);
+        kfree(event);
+}
+
+static void perf_buffer_put(struct perf_buffer *buffer);
+
+static void free_event(struct perf_event *event)
+{
+        irq_work_sync(&event->pending);
+
+        if (!event->parent) {
+                if (event->attach_state & PERF_ATTACH_TASK)
+                        jump_label_dec(&perf_sched_events);
+                if (event->attr.mmap || event->attr.mmap_data)
+                        atomic_dec(&nr_mmap_events);
+                if (event->attr.comm)
+                        atomic_dec(&nr_comm_events);
+                if (event->attr.task)
+                        atomic_dec(&nr_task_events);
+                if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
+                        put_callchain_buffers();
+                if (is_cgroup_event(event)) {
+                        atomic_dec(&per_cpu(perf_cgroup_events, event->cpu));
+                        jump_label_dec(&perf_sched_events);
+                }
+        }
+
+        if (event->buffer) {
+                perf_buffer_put(event->buffer);
+                event->buffer = NULL;
+        }
+
+        if (is_cgroup_event(event))
+                perf_detach_cgroup(event);
+
+        if (event->destroy)
+                event->destroy(event);
+
+        if (event->ctx)
+                put_ctx(event->ctx);
+
+        call_rcu(&event->rcu_head, free_event_rcu);
+}
+
+int perf_event_release_kernel(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+
+        /*
+         * Remove from the PMU, can't get re-enabled since we got
+         * here because the last ref went.
+         */
+        perf_event_disable(event);
+
+        WARN_ON_ONCE(ctx->parent_ctx);
+        /*
+         * There are two ways this annotation is useful:
+         *
+         *  1) there is a lock recursion from perf_event_exit_task
+         *     see the comment there.
+         *
+         *  2) there is a lock-inversion with mmap_sem through
+         *     perf_event_read_group(), which takes faults while
+         *     holding ctx->mutex, however this is called after
+         *     the last filedesc died, so there is no possibility
+         *     to trigger the AB-BA case.
+         */
+        mutex_lock_nested(&ctx->mutex, SINGLE_DEPTH_NESTING);
+        raw_spin_lock_irq(&ctx->lock);
+        perf_group_detach(event);
+        list_del_event(event, ctx);
+        raw_spin_unlock_irq(&ctx->lock);
+        mutex_unlock(&ctx->mutex);
+
+        free_event(event);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(perf_event_release_kernel);
+
+/*
+ * Called when the last reference to the file is gone.
+ */
+static int perf_release(struct inode *inode, struct file *file)
+{
+        struct perf_event *event = file->private_data;
+        struct task_struct *owner;
+
+        file->private_data = NULL;
+
+        rcu_read_lock();
+        owner = ACCESS_ONCE(event->owner);
+        /*
+         * Matches the smp_wmb() in perf_event_exit_task(). If we observe
+         * !owner it means the list deletion is complete and we can indeed
+         * free this event, otherwise we need to serialize on
+         * owner->perf_event_mutex.
+         */
+        smp_read_barrier_depends();
+        if (owner) {
+                /*
+                 * Since delayed_put_task_struct() also drops the last
+                 * task reference we can safely take a new reference
+                 * while holding the rcu_read_lock().
+                 */
+                get_task_struct(owner);
+        }
+        rcu_read_unlock();
+
+        if (owner) {
+                mutex_lock(&owner->perf_event_mutex);
+                /*
+                 * We have to re-check the event->owner field, if it is cleared
+                 * we raced with perf_event_exit_task(), acquiring the mutex
+                 * ensured they're done, and we can proceed with freeing the
+                 * event.
+                 */
+                if (event->owner)
+                        list_del_init(&event->owner_entry);
+                mutex_unlock(&owner->perf_event_mutex);
+                put_task_struct(owner);
+        }
+
+        return perf_event_release_kernel(event);
+}
+
+u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
+{
+        struct perf_event *child;
+        u64 total = 0;
+
+        *enabled = 0;
+        *running = 0;
+
+        mutex_lock(&event->child_mutex);
+        total += perf_event_read(event);
+        *enabled += event->total_time_enabled +
+                        atomic64_read(&event->child_total_time_enabled);
+        *running += event->total_time_running +
+                        atomic64_read(&event->child_total_time_running);
+
+        list_for_each_entry(child, &event->child_list, child_list) {
+                total += perf_event_read(child);
+                *enabled += child->total_time_enabled;
+                *running += child->total_time_running;
+        }
+        mutex_unlock(&event->child_mutex);
+
+        return total;
+}
+EXPORT_SYMBOL_GPL(perf_event_read_value);
+
+static int perf_event_read_group(struct perf_event *event,
+                                   u64 read_format, char __user *buf)
+{
+        struct perf_event *leader = event->group_leader, *sub;
+        int n = 0, size = 0, ret = -EFAULT;
+        struct perf_event_context *ctx = leader->ctx;
+        u64 values[5];
+        u64 count, enabled, running;
+
+        mutex_lock(&ctx->mutex);
+        count = perf_event_read_value(leader, &enabled, &running);
+
+        values[n++] = 1 + leader->nr_siblings;
+        if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+                values[n++] = enabled;
+        if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+                values[n++] = running;
+        values[n++] = count;
+        if (read_format & PERF_FORMAT_ID)
+                values[n++] = primary_event_id(leader);
+
+        size = n * sizeof(u64);
+
+        if (copy_to_user(buf, values, size))
+                goto unlock;
+
+        ret = size;
+
+        list_for_each_entry(sub, &leader->sibling_list, group_entry) {
+                n = 0;
+
+                values[n++] = perf_event_read_value(sub, &enabled, &running);
+                if (read_format & PERF_FORMAT_ID)
+                        values[n++] = primary_event_id(sub);
+
+                size = n * sizeof(u64);
+
+                if (copy_to_user(buf + ret, values, size)) {
+                        ret = -EFAULT;
+                        goto unlock;
+                }
+
+                ret += size;
+        }
+unlock:
+        mutex_unlock(&ctx->mutex);
+
+        return ret;
+}
+
+static int perf_event_read_one(struct perf_event *event,
+                                 u64 read_format, char __user *buf)
+{
+        u64 enabled, running;
+        u64 values[4];
+        int n = 0;
+
+        values[n++] = perf_event_read_value(event, &enabled, &running);
+        if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+                values[n++] = enabled;
+        if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+                values[n++] = running;
+        if (read_format & PERF_FORMAT_ID)
+                values[n++] = primary_event_id(event);
+
+        if (copy_to_user(buf, values, n * sizeof(u64)))
+                return -EFAULT;
+
+        return n * sizeof(u64);
+}
+
+/*
+ * Read the performance event - simple non blocking version for now
+ */
+static ssize_t
+perf_read_hw(struct perf_event *event, char __user *buf, size_t count)
+{
+        u64 read_format = event->attr.read_format;
+        int ret;
+
+        /*
+         * Return end-of-file for a read on a event that is in
+         * error state (i.e. because it was pinned but it couldn't be
+         * scheduled on to the CPU at some point).
+         */
+        if (event->state == PERF_EVENT_STATE_ERROR)
+                return 0;
+
+        if (count < event->read_size)
+                return -ENOSPC;
+
+        WARN_ON_ONCE(event->ctx->parent_ctx);
+        if (read_format & PERF_FORMAT_GROUP)
+                ret = perf_event_read_group(event, read_format, buf);
+        else
+                ret = perf_event_read_one(event, read_format, buf);
+
+        return ret;
+}
+
+static ssize_t
+perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+        struct perf_event *event = file->private_data;
+
+        return perf_read_hw(event, buf, count);
+}
+
+static unsigned int perf_poll(struct file *file, poll_table *wait)
+{
+        struct perf_event *event = file->private_data;
+        struct perf_buffer *buffer;
+        unsigned int events = POLL_HUP;
+
+        rcu_read_lock();
+        buffer = rcu_dereference(event->buffer);
+        if (buffer)
+                events = atomic_xchg(&buffer->poll, 0);
+        rcu_read_unlock();
+
+        poll_wait(file, &event->waitq, wait);
+
+        return events;
+}
+
+static void perf_event_reset(struct perf_event *event)
+{
+        (void)perf_event_read(event);
+        local64_set(&event->count, 0);
+        perf_event_update_userpage(event);
+}
+
+/*
+ * Holding the top-level event's child_mutex means that any
+ * descendant process that has inherited this event will block
+ * in sync_child_event if it goes to exit, thus satisfying the
+ * task existence requirements of perf_event_enable/disable.
+ */
+static void perf_event_for_each_child(struct perf_event *event,
+                                        void (*func)(struct perf_event *))
+{
+        struct perf_event *child;
+
+        WARN_ON_ONCE(event->ctx->parent_ctx);
+        mutex_lock(&event->child_mutex);
+        func(event);
+        list_for_each_entry(child, &event->child_list, child_list)
+                func(child);
+        mutex_unlock(&event->child_mutex);
+}
+
+static void perf_event_for_each(struct perf_event *event,
+                                  void (*func)(struct perf_event *))
+{
+        struct perf_event_context *ctx = event->ctx;
+        struct perf_event *sibling;
+
+        WARN_ON_ONCE(ctx->parent_ctx);
+        mutex_lock(&ctx->mutex);
+        event = event->group_leader;
+
+        perf_event_for_each_child(event, func);
+        func(event);
+        list_for_each_entry(sibling, &event->sibling_list, group_entry)
+                perf_event_for_each_child(event, func);
+        mutex_unlock(&ctx->mutex);
+}
+
+static int perf_event_period(struct perf_event *event, u64 __user *arg)
+{
+        struct perf_event_context *ctx = event->ctx;
+        int ret = 0;
+        u64 value;
+
+        if (!is_sampling_event(event))
+                return -EINVAL;
+
+        if (copy_from_user(&value, arg, sizeof(value)))
+                return -EFAULT;
+
+        if (!value)
+                return -EINVAL;
+
+        raw_spin_lock_irq(&ctx->lock);
+        if (event->attr.freq) {
+                if (value > sysctl_perf_event_sample_rate) {
+                        ret = -EINVAL;
+                        goto unlock;
+                }
+
+                event->attr.sample_freq = value;
+        } else {
+                event->attr.sample_period = value;
+                event->hw.sample_period = value;
+        }
+unlock:
+        raw_spin_unlock_irq(&ctx->lock);
+
+        return ret;
+}
+
+static const struct file_operations perf_fops;
+
+static struct perf_event *perf_fget_light(int fd, int *fput_needed)
+{
+        struct file *file;
+
+        file = fget_light(fd, fput_needed);
+        if (!file)
+                return ERR_PTR(-EBADF);
+
+        if (file->f_op != &perf_fops) {
+                fput_light(file, *fput_needed);
+                *fput_needed = 0;
+                return ERR_PTR(-EBADF);
+        }
+
+        return file->private_data;
+}
+
+static int perf_event_set_output(struct perf_event *event,
+                                 struct perf_event *output_event);
+static int perf_event_set_filter(struct perf_event *event, void __user *arg);
+
+static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+        struct perf_event *event = file->private_data;
+        void (*func)(struct perf_event *);
+        u32 flags = arg;
+
+        switch (cmd) {
+        case PERF_EVENT_IOC_ENABLE:
+                func = perf_event_enable;
+                break;
+        case PERF_EVENT_IOC_DISABLE:
+                func = perf_event_disable;
+                break;
+        case PERF_EVENT_IOC_RESET:
+                func = perf_event_reset;
+                break;
+
+        case PERF_EVENT_IOC_REFRESH:
+                return perf_event_refresh(event, arg);
+
+        case PERF_EVENT_IOC_PERIOD:
+                return perf_event_period(event, (u64 __user *)arg);
+
+        case PERF_EVENT_IOC_SET_OUTPUT:
+        {
+                struct perf_event *output_event = NULL;
+                int fput_needed = 0;
+                int ret;
+
+                if (arg != -1) {
+                        output_event = perf_fget_light(arg, &fput_needed);
+                        if (IS_ERR(output_event))
+                                return PTR_ERR(output_event);
+                }
+
+                ret = perf_event_set_output(event, output_event);
+                if (output_event)
+                        fput_light(output_event->filp, fput_needed);
+
+                return ret;
+        }
+
+        case PERF_EVENT_IOC_SET_FILTER:
+                return perf_event_set_filter(event, (void __user *)arg);
+
+        default:
+                return -ENOTTY;
+        }
+
+        if (flags & PERF_IOC_FLAG_GROUP)
+                perf_event_for_each(event, func);
+        else
+                perf_event_for_each_child(event, func);
+
+        return 0;
+}
+
+int perf_event_task_enable(void)
+{
+        struct perf_event *event;
+
+        mutex_lock(&current->perf_event_mutex);
+        list_for_each_entry(event, &current->perf_event_list, owner_entry)
+                perf_event_for_each_child(event, perf_event_enable);
+        mutex_unlock(&current->perf_event_mutex);
+
+        return 0;
+}
+
+int perf_event_task_disable(void)
+{
+        struct perf_event *event;
+
+        mutex_lock(&current->perf_event_mutex);
+        list_for_each_entry(event, &current->perf_event_list, owner_entry)
+                perf_event_for_each_child(event, perf_event_disable);
+        mutex_unlock(&current->perf_event_mutex);
+
+        return 0;
+}
+
+#ifndef PERF_EVENT_INDEX_OFFSET
+# define PERF_EVENT_INDEX_OFFSET 0
+#endif
+
+static int perf_event_index(struct perf_event *event)
+{
+        if (event->hw.state & PERF_HES_STOPPED)
+                return 0;
+
+        if (event->state != PERF_EVENT_STATE_ACTIVE)
+                return 0;
+
+        return event->hw.idx + 1 - PERF_EVENT_INDEX_OFFSET;
+}
+
+/*
+ * Callers need to ensure there can be no nesting of this function, otherwise
+ * the seqlock logic goes bad. We can not serialize this because the arch
+ * code calls this from NMI context.
+ */
+void perf_event_update_userpage(struct perf_event *event)
+{
+        struct perf_event_mmap_page *userpg;
+        struct perf_buffer *buffer;
+
+        rcu_read_lock();
+        buffer = rcu_dereference(event->buffer);
+        if (!buffer)
+                goto unlock;
+
+        userpg = buffer->user_page;
+
+        /*
+         * Disable preemption so as to not let the corresponding user-space
+         * spin too long if we get preempted.
+         */
+        preempt_disable();
+        ++userpg->lock;
+        barrier();
+        userpg->index = perf_event_index(event);
+        userpg->offset = perf_event_count(event);
+        if (event->state == PERF_EVENT_STATE_ACTIVE)
+                userpg->offset -= local64_read(&event->hw.prev_count);
+
+        userpg->time_enabled = event->total_time_enabled +
+                        atomic64_read(&event->child_total_time_enabled);
+
+        userpg->time_running = event->total_time_running +
+                        atomic64_read(&event->child_total_time_running);
+
+        barrier();
+        ++userpg->lock;
+        preempt_enable();
+unlock:
+        rcu_read_unlock();
+}
+
+static unsigned long perf_data_size(struct perf_buffer *buffer);
+
+static void
+perf_buffer_init(struct perf_buffer *buffer, long watermark, int flags)
+{
+        long max_size = perf_data_size(buffer);
+
+        if (watermark)
+                buffer->watermark = min(max_size, watermark);
+
+        if (!buffer->watermark)
+                buffer->watermark = max_size / 2;
+
+        if (flags & PERF_BUFFER_WRITABLE)
+                buffer->writable = 1;
+
+        atomic_set(&buffer->refcount, 1);
+}
+
+#ifndef CONFIG_PERF_USE_VMALLOC
+
+/*
+ * Back perf_mmap() with regular GFP_KERNEL-0 pages.
+ */
+
+static struct page *
+perf_mmap_to_page(struct perf_buffer *buffer, unsigned long pgoff)
+{
+        if (pgoff > buffer->nr_pages)
+                return NULL;
+
+        if (pgoff == 0)
+                return virt_to_page(buffer->user_page);
+
+        return virt_to_page(buffer->data_pages[pgoff - 1]);
+}
+
+static void *perf_mmap_alloc_page(int cpu)
+{
+        struct page *page;
+        int node;
+
+        node = (cpu == -1) ? cpu : cpu_to_node(cpu);
+        page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
+        if (!page)
+                return NULL;
+
+        return page_address(page);
+}
+
+static struct perf_buffer *
+perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags)
+{
+        struct perf_buffer *buffer;
+        unsigned long size;
+        int i;
+
+        size = sizeof(struct perf_buffer);
+        size += nr_pages * sizeof(void *);
+
+        buffer = kzalloc(size, GFP_KERNEL);
+        if (!buffer)
+                goto fail;
+
+        buffer->user_page = perf_mmap_alloc_page(cpu);
+        if (!buffer->user_page)
+                goto fail_user_page;
+
+        for (i = 0; i < nr_pages; i++) {
+                buffer->data_pages[i] = perf_mmap_alloc_page(cpu);
+                if (!buffer->data_pages[i])
+                        goto fail_data_pages;
+        }
+
+        buffer->nr_pages = nr_pages;
+
+        perf_buffer_init(buffer, watermark, flags);
+
+        return buffer;
+
+fail_data_pages:
+        for (i--; i >= 0; i--)
+                free_page((unsigned long)buffer->data_pages[i]);
+
+        free_page((unsigned long)buffer->user_page);
+
+fail_user_page:
+        kfree(buffer);
+
+fail:
+        return NULL;
+}
+
+static void perf_mmap_free_page(unsigned long addr)
+{
+        struct page *page = virt_to_page((void *)addr);
+
+        page->mapping = NULL;
+        __free_page(page);
+}
+
+static void perf_buffer_free(struct perf_buffer *buffer)
+{
+        int i;
+
+        perf_mmap_free_page((unsigned long)buffer->user_page);
+        for (i = 0; i < buffer->nr_pages; i++)
+                perf_mmap_free_page((unsigned long)buffer->data_pages[i]);
+        kfree(buffer);
+}
+
+static inline int page_order(struct perf_buffer *buffer)
+{
+        return 0;
+}
+
+#else
+
+/*
+ * Back perf_mmap() with vmalloc memory.
+ *
+ * Required for architectures that have d-cache aliasing issues.
+ */
+
+static inline int page_order(struct perf_buffer *buffer)
+{
+        return buffer->page_order;
+}
+
+static struct page *
+perf_mmap_to_page(struct perf_buffer *buffer, unsigned long pgoff)
+{
+        if (pgoff > (1UL << page_order(buffer)))
+                return NULL;
+
+        return vmalloc_to_page((void *)buffer->user_page + pgoff * PAGE_SIZE);
+}
+
+static void perf_mmap_unmark_page(void *addr)
+{
+        struct page *page = vmalloc_to_page(addr);
+
+        page->mapping = NULL;
+}
+
+static void perf_buffer_free_work(struct work_struct *work)
+{
+        struct perf_buffer *buffer;
+        void *base;
+        int i, nr;
+
+        buffer = container_of(work, struct perf_buffer, work);
+        nr = 1 << page_order(buffer);
+
+        base = buffer->user_page;
+        for (i = 0; i < nr + 1; i++)
+                perf_mmap_unmark_page(base + (i * PAGE_SIZE));
+
+        vfree(base);
+        kfree(buffer);
+}
+
+static void perf_buffer_free(struct perf_buffer *buffer)
+{
+        schedule_work(&buffer->work);
+}
+
+static struct perf_buffer *
+perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags)
+{
+        struct perf_buffer *buffer;
+        unsigned long size;
+        void *all_buf;
+
+        size = sizeof(struct perf_buffer);
+        size += sizeof(void *);
+
+        buffer = kzalloc(size, GFP_KERNEL);
+        if (!buffer)
+                goto fail;
+
+        INIT_WORK(&buffer->work, perf_buffer_free_work);
+
+        all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
+        if (!all_buf)
+                goto fail_all_buf;
+
+        buffer->user_page = all_buf;
+        buffer->data_pages[0] = all_buf + PAGE_SIZE;
+        buffer->page_order = ilog2(nr_pages);
+        buffer->nr_pages = 1;
+
+        perf_buffer_init(buffer, watermark, flags);
+
+        return buffer;
+
+fail_all_buf:
+        kfree(buffer);
+
+fail:
+        return NULL;
+}
+
+#endif
+
+static unsigned long perf_data_size(struct perf_buffer *buffer)
+{
+        return buffer->nr_pages << (PAGE_SHIFT + page_order(buffer));
+}
+
+static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+        struct perf_event *event = vma->vm_file->private_data;
+        struct perf_buffer *buffer;
+        int ret = VM_FAULT_SIGBUS;
+
+        if (vmf->flags & FAULT_FLAG_MKWRITE) {
+                if (vmf->pgoff == 0)
+                        ret = 0;
+                return ret;
+        }
+
+        rcu_read_lock();
+        buffer = rcu_dereference(event->buffer);
+        if (!buffer)
+                goto unlock;
+
+        if (vmf->pgoff && (vmf->flags & FAULT_FLAG_WRITE))
+                goto unlock;
+
+        vmf->page = perf_mmap_to_page(buffer, vmf->pgoff);
+        if (!vmf->page)
+                goto unlock;
+
+        get_page(vmf->page);
+        vmf->page->mapping = vma->vm_file->f_mapping;
+        vmf->page->index   = vmf->pgoff;
+
+        ret = 0;
+unlock:
+        rcu_read_unlock();
+
+        return ret;
+}
+
+static void perf_buffer_free_rcu(struct rcu_head *rcu_head)
+{
+        struct perf_buffer *buffer;
+
+        buffer = container_of(rcu_head, struct perf_buffer, rcu_head);
+        perf_buffer_free(buffer);
+}
+
+static struct perf_buffer *perf_buffer_get(struct perf_event *event)
+{
+        struct perf_buffer *buffer;
+
+        rcu_read_lock();
+        buffer = rcu_dereference(event->buffer);
+        if (buffer) {
+                if (!atomic_inc_not_zero(&buffer->refcount))
+                        buffer = NULL;
+        }
+        rcu_read_unlock();
+
+        return buffer;
+}
+
+static void perf_buffer_put(struct perf_buffer *buffer)
+{
+        if (!atomic_dec_and_test(&buffer->refcount))
+                return;
+
+        call_rcu(&buffer->rcu_head, perf_buffer_free_rcu);
+}
+
+static void perf_mmap_open(struct vm_area_struct *vma)
+{
+        struct perf_event *event = vma->vm_file->private_data;
+
+        atomic_inc(&event->mmap_count);
+}
+
+static void perf_mmap_close(struct vm_area_struct *vma)
+{
+        struct perf_event *event = vma->vm_file->private_data;
+
+        if (atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) {
+                unsigned long size = perf_data_size(event->buffer);
+                struct user_struct *user = event->mmap_user;
+                struct perf_buffer *buffer = event->buffer;
+
+                atomic_long_sub((size >> PAGE_SHIFT) + 1, &user->locked_vm);
+                vma->vm_mm->locked_vm -= event->mmap_locked;
+                rcu_assign_pointer(event->buffer, NULL);
+                mutex_unlock(&event->mmap_mutex);
+
+                perf_buffer_put(buffer);
+                free_uid(user);
+        }
+}
+
+static const struct vm_operations_struct perf_mmap_vmops = {
+        .open           = perf_mmap_open,
+        .close          = perf_mmap_close,
+        .fault          = perf_mmap_fault,
+        .page_mkwrite   = perf_mmap_fault,
+};
+
+static int perf_mmap(struct file *file, struct vm_area_struct *vma)
+{
+        struct perf_event *event = file->private_data;
+        unsigned long user_locked, user_lock_limit;
+        struct user_struct *user = current_user();
+        unsigned long locked, lock_limit;
+        struct perf_buffer *buffer;
+        unsigned long vma_size;
+        unsigned long nr_pages;
+        long user_extra, extra;
+        int ret = 0, flags = 0;
+
+        /*
+         * Don't allow mmap() of inherited per-task counters. This would
+         * create a performance issue due to all children writing to the
+         * same buffer.
+         */
+        if (event->cpu == -1 && event->attr.inherit)
+                return -EINVAL;
+
+        if (!(vma->vm_flags & VM_SHARED))
+                return -EINVAL;
+
+        vma_size = vma->vm_end - vma->vm_start;
+        nr_pages = (vma_size / PAGE_SIZE) - 1;
+
+        /*
+         * If we have buffer pages ensure they're a power-of-two number, so we
+         * can do bitmasks instead of modulo.
+         */
+        if (nr_pages != 0 && !is_power_of_2(nr_pages))
+                return -EINVAL;
+
+        if (vma_size != PAGE_SIZE * (1 + nr_pages))
+                return -EINVAL;
+
+        if (vma->vm_pgoff != 0)
+                return -EINVAL;
+
+        WARN_ON_ONCE(event->ctx->parent_ctx);
+        mutex_lock(&event->mmap_mutex);
+        if (event->buffer) {
+                if (event->buffer->nr_pages == nr_pages)
+                        atomic_inc(&event->buffer->refcount);
+                else
+                        ret = -EINVAL;
+                goto unlock;
+        }
+
+        user_extra = nr_pages + 1;
+        user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10);
+
+        /*
+         * Increase the limit linearly with more CPUs:
+         */
+        user_lock_limit *= num_online_cpus();
+
+        user_locked = atomic_long_read(&user->locked_vm) + user_extra;
+
+        extra = 0;
+        if (user_locked > user_lock_limit)
+                extra = user_locked - user_lock_limit;
+
+        lock_limit = rlimit(RLIMIT_MEMLOCK);
+        lock_limit >>= PAGE_SHIFT;
+        locked = vma->vm_mm->locked_vm + extra;
+
+        if ((locked > lock_limit) && perf_paranoid_tracepoint_raw() &&
+                !capable(CAP_IPC_LOCK)) {
+                ret = -EPERM;
+                goto unlock;
+        }
+
+        WARN_ON(event->buffer);
+
+        if (vma->vm_flags & VM_WRITE)
+                flags |= PERF_BUFFER_WRITABLE;
+
+        buffer = perf_buffer_alloc(nr_pages, event->attr.wakeup_watermark,
+                                   event->cpu, flags);
+        if (!buffer) {
+                ret = -ENOMEM;
+                goto unlock;
+        }
+        rcu_assign_pointer(event->buffer, buffer);
+
+        atomic_long_add(user_extra, &user->locked_vm);
+        event->mmap_locked = extra;
+        event->mmap_user = get_current_user();
+        vma->vm_mm->locked_vm += event->mmap_locked;
+
+unlock:
+        if (!ret)
+                atomic_inc(&event->mmap_count);
+        mutex_unlock(&event->mmap_mutex);
+
+        vma->vm_flags |= VM_RESERVED;
+        vma->vm_ops = &perf_mmap_vmops;
+
+        return ret;
+}
+
+static int perf_fasync(int fd, struct file *filp, int on)
+{
+        struct inode *inode = filp->f_path.dentry->d_inode;
+        struct perf_event *event = filp->private_data;
+        int retval;
+
+        mutex_lock(&inode->i_mutex);
+        retval = fasync_helper(fd, filp, on, &event->fasync);
+        mutex_unlock(&inode->i_mutex);
+
+        if (retval < 0)
+                return retval;
+
+        return 0;
+}
+
+static const struct file_operations perf_fops = {
+        .llseek                 = no_llseek,
+        .release                = perf_release,
+        .read                   = perf_read,
+        .poll                   = perf_poll,
+        .unlocked_ioctl         = perf_ioctl,
+        .compat_ioctl           = perf_ioctl,
+        .mmap                   = perf_mmap,
+        .fasync                 = perf_fasync,
+};
+
+/*
+ * Perf event wakeup
+ *
+ * If there's data, ensure we set the poll() state and publish everything
+ * to user-space before waking everybody up.
+ */
+
+void perf_event_wakeup(struct perf_event *event)
+{
+        wake_up_all(&event->waitq);
+
+        if (event->pending_kill) {
+                kill_fasync(&event->fasync, SIGIO, event->pending_kill);
+                event->pending_kill = 0;
+        }
+}
+
+static void perf_pending_event(struct irq_work *entry)
+{
+        struct perf_event *event = container_of(entry,
+                        struct perf_event, pending);
+
+        if (event->pending_disable) {
+                event->pending_disable = 0;
+                __perf_event_disable(event);
+        }
+
+        if (event->pending_wakeup) {
+                event->pending_wakeup = 0;
+                perf_event_wakeup(event);
+        }
+}
+
+/*
+ * We assume there is only KVM supporting the callbacks.
+ * Later on, we might change it to a list if there is
+ * another virtualization implementation supporting the callbacks.
+ */
+struct perf_guest_info_callbacks *perf_guest_cbs;
+
+int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+        perf_guest_cbs = cbs;
+        return 0;
+}
+EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
+
+int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+        perf_guest_cbs = NULL;
+        return 0;
+}
+EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
+
+/*
+ * Output
+ */
+static bool perf_output_space(struct perf_buffer *buffer, unsigned long tail,
+                              unsigned long offset, unsigned long head)
+{
+        unsigned long mask;
+
+        if (!buffer->writable)
+                return true;
+
+        mask = perf_data_size(buffer) - 1;
+
+        offset = (offset - tail) & mask;
+        head   = (head   - tail) & mask;
+
+        if ((int)(head - offset) < 0)
+                return false;
+
+        return true;
+}
+
+static void perf_output_wakeup(struct perf_output_handle *handle)
+{
+        atomic_set(&handle->buffer->poll, POLL_IN);
+
+        if (handle->nmi) {
+                handle->event->pending_wakeup = 1;
+                irq_work_queue(&handle->event->pending);
+        } else
+                perf_event_wakeup(handle->event);
+}
+
+/*
+ * We need to ensure a later event_id doesn't publish a head when a former
+ * event isn't done writing. However since we need to deal with NMIs we
+ * cannot fully serialize things.
+ *
+ * We only publish the head (and generate a wakeup) when the outer-most
+ * event completes.
+ */
+static void perf_output_get_handle(struct perf_output_handle *handle)
+{
+        struct perf_buffer *buffer = handle->buffer;
+
+        preempt_disable();
+        local_inc(&buffer->nest);
+        handle->wakeup = local_read(&buffer->wakeup);
+}
+
+static void perf_output_put_handle(struct perf_output_handle *handle)
+{
+        struct perf_buffer *buffer = handle->buffer;
+        unsigned long head;
+
+again:
+        head = local_read(&buffer->head);
+
+        /*
+         * IRQ/NMI can happen here, which means we can miss a head update.
+         */
+
+        if (!local_dec_and_test(&buffer->nest))
+                goto out;
+
+        /*
+         * Publish the known good head. Rely on the full barrier implied
+         * by atomic_dec_and_test() order the buffer->head read and this
+         * write.
+         */
+        buffer->user_page->data_head = head;
+
+        /*
+         * Now check if we missed an update, rely on the (compiler)
+         * barrier in atomic_dec_and_test() to re-read buffer->head.
+         */
+        if (unlikely(head != local_read(&buffer->head))) {
+                local_inc(&buffer->nest);
+                goto again;
+        }
+
+        if (handle->wakeup != local_read(&buffer->wakeup))
+                perf_output_wakeup(handle);
+
+out:
+        preempt_enable();
+}
+
+__always_inline void perf_output_copy(struct perf_output_handle *handle,
+                      const void *buf, unsigned int len)
+{
+        do {
+                unsigned long size = min_t(unsigned long, handle->size, len);
+
+                memcpy(handle->addr, buf, size);
+
+                len -= size;
+                handle->addr += size;
+                buf += size;
+                handle->size -= size;
+                if (!handle->size) {
+                        struct perf_buffer *buffer = handle->buffer;
+
+                        handle->page++;
+                        handle->page &= buffer->nr_pages - 1;
+                        handle->addr = buffer->data_pages[handle->page];
+                        handle->size = PAGE_SIZE << page_order(buffer);
+                }
+        } while (len);
+}
+
+static void __perf_event_header__init_id(struct perf_event_header *header,
+                                         struct perf_sample_data *data,
+                                         struct perf_event *event)
+{
+        u64 sample_type = event->attr.sample_type;
+
+        data->type = sample_type;
+        header->size += event->id_header_size;
+
+        if (sample_type & PERF_SAMPLE_TID) {
+                /* namespace issues */
+                data->tid_entry.pid = perf_event_pid(event, current);
+                data->tid_entry.tid = perf_event_tid(event, current);
+        }
+
+        if (sample_type & PERF_SAMPLE_TIME)
+                data->time = perf_clock();
+
+        if (sample_type & PERF_SAMPLE_ID)
+                data->id = primary_event_id(event);
+
+        if (sample_type & PERF_SAMPLE_STREAM_ID)
+                data->stream_id = event->id;
+
+        if (sample_type & PERF_SAMPLE_CPU) {
+                data->cpu_entry.cpu      = raw_smp_processor_id();
+                data->cpu_entry.reserved = 0;
+        }
+}
+
+static void perf_event_header__init_id(struct perf_event_header *header,
+                                       struct perf_sample_data *data,
+                                       struct perf_event *event)
+{
+        if (event->attr.sample_id_all)
+                __perf_event_header__init_id(header, data, event);
+}
+
+static void __perf_event__output_id_sample(struct perf_output_handle *handle,
+                                           struct perf_sample_data *data)
+{
+        u64 sample_type = data->type;
+
+        if (sample_type & PERF_SAMPLE_TID)
+                perf_output_put(handle, data->tid_entry);
+
+        if (sample_type & PERF_SAMPLE_TIME)
+                perf_output_put(handle, data->time);
+
+        if (sample_type & PERF_SAMPLE_ID)
+                perf_output_put(handle, data->id);
+
+        if (sample_type & PERF_SAMPLE_STREAM_ID)
+                perf_output_put(handle, data->stream_id);
+
+        if (sample_type & PERF_SAMPLE_CPU)
+                perf_output_put(handle, data->cpu_entry);
+}
+
+static void perf_event__output_id_sample(struct perf_event *event,
+                                         struct perf_output_handle *handle,
+                                         struct perf_sample_data *sample)
+{
+        if (event->attr.sample_id_all)
+                __perf_event__output_id_sample(handle, sample);
+}
+
+int perf_output_begin(struct perf_output_handle *handle,
+                      struct perf_event *event, unsigned int size,
+                      int nmi, int sample)
+{
+        struct perf_buffer *buffer;
+        unsigned long tail, offset, head;
+        int have_lost;
+        struct perf_sample_data sample_data;
+        struct {
+                struct perf_event_header header;
+                u64                      id;
+                u64                      lost;
+        } lost_event;
+
+        rcu_read_lock();
+        /*
+         * For inherited events we send all the output towards the parent.
+         */
+        if (event->parent)
+                event = event->parent;
+
+        buffer = rcu_dereference(event->buffer);
+        if (!buffer)
+                goto out;
+
+        handle->buffer  = buffer;
+        handle->event   = event;
+        handle->nmi     = nmi;
+        handle->sample  = sample;
+
+        if (!buffer->nr_pages)
+                goto out;
+
+        have_lost = local_read(&buffer->lost);
+        if (have_lost) {
+                lost_event.header.size = sizeof(lost_event);
+                perf_event_header__init_id(&lost_event.header, &sample_data,
+                                           event);
+                size += lost_event.header.size;
+        }
+
+        perf_output_get_handle(handle);
+
+        do {
+                /*
+                 * Userspace could choose to issue a mb() before updating the
+                 * tail pointer. So that all reads will be completed before the
+                 * write is issued.
+                 */
+                tail = ACCESS_ONCE(buffer->user_page->data_tail);
+                smp_rmb();
+                offset = head = local_read(&buffer->head);
+                head += size;
+                if (unlikely(!perf_output_space(buffer, tail, offset, head)))
+                        goto fail;
+        } while (local_cmpxchg(&buffer->head, offset, head) != offset);
+
+        if (head - local_read(&buffer->wakeup) > buffer->watermark)
+                local_add(buffer->watermark, &buffer->wakeup);
+
+        handle->page = offset >> (PAGE_SHIFT + page_order(buffer));
+        handle->page &= buffer->nr_pages - 1;
+        handle->size = offset & ((PAGE_SIZE << page_order(buffer)) - 1);
+        handle->addr = buffer->data_pages[handle->page];
+        handle->addr += handle->size;
+        handle->size = (PAGE_SIZE << page_order(buffer)) - handle->size;
+
+        if (have_lost) {
+                lost_event.header.type = PERF_RECORD_LOST;
+                lost_event.header.misc = 0;
+                lost_event.id          = event->id;
+                lost_event.lost        = local_xchg(&buffer->lost, 0);
+
+                perf_output_put(handle, lost_event);
+                perf_event__output_id_sample(event, handle, &sample_data);
+        }
+
+        return 0;
+
+fail:
+        local_inc(&buffer->lost);
+        perf_output_put_handle(handle);
+out:
+        rcu_read_unlock();
+
+        return -ENOSPC;
+}
+
+void perf_output_end(struct perf_output_handle *handle)
+{
+        struct perf_event *event = handle->event;
+        struct perf_buffer *buffer = handle->buffer;
+
+        int wakeup_events = event->attr.wakeup_events;
+
+        if (handle->sample && wakeup_events) {
+                int events = local_inc_return(&buffer->events);
+                if (events >= wakeup_events) {
+                        local_sub(wakeup_events, &buffer->events);
+                        local_inc(&buffer->wakeup);
+                }
+        }
+
+        perf_output_put_handle(handle);
+        rcu_read_unlock();
+}
+
+static void perf_output_read_one(struct perf_output_handle *handle,
+                                 struct perf_event *event,
+                                 u64 enabled, u64 running)
+{
+        u64 read_format = event->attr.read_format;
+        u64 values[4];
+        int n = 0;
+
+        values[n++] = perf_event_count(event);
+        if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
+                values[n++] = enabled +
+                        atomic64_read(&event->child_total_time_enabled);
+        }
+        if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
+                values[n++] = running +
+                        atomic64_read(&event->child_total_time_running);
+        }
+        if (read_format & PERF_FORMAT_ID)
+                values[n++] = primary_event_id(event);
+
+        perf_output_copy(handle, values, n * sizeof(u64));
+}
+
+/*
+ * XXX PERF_FORMAT_GROUP vs inherited events seems difficult.
+ */
+static void perf_output_read_group(struct perf_output_handle *handle,
+                            struct perf_event *event,
+                            u64 enabled, u64 running)
+{
+        struct perf_event *leader = event->group_leader, *sub;
+        u64 read_format = event->attr.read_format;
+        u64 values[5];
+        int n = 0;
+
+        values[n++] = 1 + leader->nr_siblings;
+
+        if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+                values[n++] = enabled;
+
+        if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+                values[n++] = running;
+
+        if (leader != event)
+                leader->pmu->read(leader);
+
+        values[n++] = perf_event_count(leader);
+        if (read_format & PERF_FORMAT_ID)
+                values[n++] = primary_event_id(leader);
+
+        perf_output_copy(handle, values, n * sizeof(u64));
+
+        list_for_each_entry(sub, &leader->sibling_list, group_entry) {
+                n = 0;
+
+                if (sub != event)
+                        sub->pmu->read(sub);
+
+                values[n++] = perf_event_count(sub);
+                if (read_format & PERF_FORMAT_ID)
+                        values[n++] = primary_event_id(sub);
+
+                perf_output_copy(handle, values, n * sizeof(u64));
+        }
+}
+
+#define PERF_FORMAT_TOTAL_TIMES (PERF_FORMAT_TOTAL_TIME_ENABLED|\
+                                 PERF_FORMAT_TOTAL_TIME_RUNNING)
+
+static void perf_output_read(struct perf_output_handle *handle,
+                             struct perf_event *event)
+{
+        u64 enabled = 0, running = 0, now, ctx_time;
+        u64 read_format = event->attr.read_format;
+
+        /*
+         * compute total_time_enabled, total_time_running
+         * based on snapshot values taken when the event
+         * was last scheduled in.
+         *
+         * we cannot simply called update_context_time()
+         * because of locking issue as we are called in
+         * NMI context
+         */
+        if (read_format & PERF_FORMAT_TOTAL_TIMES) {
+                now = perf_clock();
+                ctx_time = event->shadow_ctx_time + now;
+                enabled = ctx_time - event->tstamp_enabled;
+                running = ctx_time - event->tstamp_running;
+        }
+
+        if (event->attr.read_format & PERF_FORMAT_GROUP)
+                perf_output_read_group(handle, event, enabled, running);
+        else
+                perf_output_read_one(handle, event, enabled, running);
+}
+
+void perf_output_sample(struct perf_output_handle *handle,
+                        struct perf_event_header *header,
+                        struct perf_sample_data *data,
+                        struct perf_event *event)
+{
+        u64 sample_type = data->type;
+
+        perf_output_put(handle, *header);
+
+        if (sample_type & PERF_SAMPLE_IP)
+                perf_output_put(handle, data->ip);
+
+        if (sample_type & PERF_SAMPLE_TID)
+                perf_output_put(handle, data->tid_entry);
+
+        if (sample_type & PERF_SAMPLE_TIME)
+                perf_output_put(handle, data->time);
+
+        if (sample_type & PERF_SAMPLE_ADDR)
+                perf_output_put(handle, data->addr);
+
+        if (sample_type & PERF_SAMPLE_ID)
+                perf_output_put(handle, data->id);
+
+        if (sample_type & PERF_SAMPLE_STREAM_ID)
+                perf_output_put(handle, data->stream_id);
+
+        if (sample_type & PERF_SAMPLE_CPU)
+                perf_output_put(handle, data->cpu_entry);
+
+        if (sample_type & PERF_SAMPLE_PERIOD)
+                perf_output_put(handle, data->period);
+
+        if (sample_type & PERF_SAMPLE_READ)
+                perf_output_read(handle, event);
+
+        if (sample_type & PERF_SAMPLE_CALLCHAIN) {
+                if (data->callchain) {
+                        int size = 1;
+
+                        if (data->callchain)
+                                size += data->callchain->nr;
+
+                        size *= sizeof(u64);
+
+                        perf_output_copy(handle, data->callchain, size);
+                } else {
+                        u64 nr = 0;
+                        perf_output_put(handle, nr);
+                }
+        }
+
+        if (sample_type & PERF_SAMPLE_RAW) {
+                if (data->raw) {
+                        perf_output_put(handle, data->raw->size);
+                        perf_output_copy(handle, data->raw->data,
+                                         data->raw->size);
+                } else {
+                        struct {
+                                u32     size;
+                                u32     data;
+                        } raw = {
+                                .size = sizeof(u32),
+                                .data = 0,
+                        };
+                        perf_output_put(handle, raw);
+                }
+        }
+}
+
+void perf_prepare_sample(struct perf_event_header *header,
+                         struct perf_sample_data *data,
+                         struct perf_event *event,
+                         struct pt_regs *regs)
+{
+        u64 sample_type = event->attr.sample_type;
+
+        header->type = PERF_RECORD_SAMPLE;
+        header->size = sizeof(*header) + event->header_size;
+
+        header->misc = 0;
+        header->misc |= perf_misc_flags(regs);
+
+        __perf_event_header__init_id(header, data, event);
+
+        if (sample_type & PERF_SAMPLE_IP)
+                data->ip = perf_instruction_pointer(regs);
+
+        if (sample_type & PERF_SAMPLE_CALLCHAIN) {
+                int size = 1;
+
+                data->callchain = perf_callchain(regs);
+
+                if (data->callchain)
+                        size += data->callchain->nr;
+
+                header->size += size * sizeof(u64);
+        }
+
+        if (sample_type & PERF_SAMPLE_RAW) {
+                int size = sizeof(u32);
+
+                if (data->raw)
+                        size += data->raw->size;
+                else
+                        size += sizeof(u32);
+
+                WARN_ON_ONCE(size & (sizeof(u64)-1));
+                header->size += size;
+        }
+}
+
+static void perf_event_output(struct perf_event *event, int nmi,
+                                struct perf_sample_data *data,
+                                struct pt_regs *regs)
+{
+        struct perf_output_handle handle;
+        struct perf_event_header header;
+
+        /* protect the callchain buffers */
+        rcu_read_lock();
+
+        perf_prepare_sample(&header, data, event, regs);
+
+        if (perf_output_begin(&handle, event, header.size, nmi, 1))
+                goto exit;
+
+        perf_output_sample(&handle, &header, data, event);
+
+        perf_output_end(&handle);
+
+exit:
+        rcu_read_unlock();
+}
+
+/*
+ * read event_id
+ */
+
+struct perf_read_event {
+        struct perf_event_header        header;
+
+        u32                             pid;
+        u32                             tid;
+};
+
+static void
+perf_event_read_event(struct perf_event *event,
+                        struct task_struct *task)
+{
+        struct perf_output_handle handle;
+        struct perf_sample_data sample;
+        struct perf_read_event read_event = {
+                .header = {
+                        .type = PERF_RECORD_READ,
+                        .misc = 0,
+                        .size = sizeof(read_event) + event->read_size,
+                },
+                .pid = perf_event_pid(event, task),
+                .tid = perf_event_tid(event, task),
+        };
+        int ret;
+
+        perf_event_header__init_id(&read_event.header, &sample, event);
+        ret = perf_output_begin(&handle, event, read_event.header.size, 0, 0);
+        if (ret)
+                return;
+
+        perf_output_put(&handle, read_event);
+        perf_output_read(&handle, event);
+        perf_event__output_id_sample(event, &handle, &sample);
+
+        perf_output_end(&handle);
+}
+
+/*
+ * task tracking -- fork/exit
+ *
+ * enabled by: attr.comm | attr.mmap | attr.mmap_data | attr.task
+ */
+
+struct perf_task_event {
+        struct task_struct              *task;
+        struct perf_event_context       *task_ctx;
+
+        struct {
+                struct perf_event_header        header;
+
+                u32                             pid;
+                u32                             ppid;
+                u32                             tid;
+                u32                             ptid;
+                u64                             time;
+        } event_id;
+};
+
+static void perf_event_task_output(struct perf_event *event,
+                                     struct perf_task_event *task_event)
+{
+        struct perf_output_handle handle;
+        struct perf_sample_data sample;
+        struct task_struct *task = task_event->task;
+        int ret, size = task_event->event_id.header.size;
+
+        perf_event_header__init_id(&task_event->event_id.header, &sample, event);
+
+        ret = perf_output_begin(&handle, event,
+                                task_event->event_id.header.size, 0, 0);
+        if (ret)
+                goto out;
+
+        task_event->event_id.pid = perf_event_pid(event, task);
+        task_event->event_id.ppid = perf_event_pid(event, current);
+
+        task_event->event_id.tid = perf_event_tid(event, task);
+        task_event->event_id.ptid = perf_event_tid(event, current);
+
+        perf_output_put(&handle, task_event->event_id);
+
+        perf_event__output_id_sample(event, &handle, &sample);
+
+        perf_output_end(&handle);
+out:
+        task_event->event_id.header.size = size;
+}
+
+static int perf_event_task_match(struct perf_event *event)
+{
+        if (event->state < PERF_EVENT_STATE_INACTIVE)
+                return 0;
+
+        if (!event_filter_match(event))
+                return 0;
+
+        if (event->attr.comm || event->attr.mmap ||
+            event->attr.mmap_data || event->attr.task)
+                return 1;
+
+        return 0;
+}
+
+static void perf_event_task_ctx(struct perf_event_context *ctx,
+                                  struct perf_task_event *task_event)
+{
+        struct perf_event *event;
+
+        list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+                if (perf_event_task_match(event))
+                        perf_event_task_output(event, task_event);
+        }
+}
+
+static void perf_event_task_event(struct perf_task_event *task_event)
+{
+        struct perf_cpu_context *cpuctx;
+        struct perf_event_context *ctx;
+        struct pmu *pmu;
+        int ctxn;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(pmu, &pmus, entry) {
+                cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
+                if (cpuctx->active_pmu != pmu)
+                        goto next;
+                perf_event_task_ctx(&cpuctx->ctx, task_event);
+
+                ctx = task_event->task_ctx;
+                if (!ctx) {
+                        ctxn = pmu->task_ctx_nr;
+                        if (ctxn < 0)
+                                goto next;
+                        ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
+                }
+                if (ctx)
+                        perf_event_task_ctx(ctx, task_event);
+next:
+                put_cpu_ptr(pmu->pmu_cpu_context);
+        }
+        rcu_read_unlock();
+}
+
+static void perf_event_task(struct task_struct *task,
+                              struct perf_event_context *task_ctx,
+                              int new)
+{
+        struct perf_task_event task_event;
+
+        if (!atomic_read(&nr_comm_events) &&
+            !atomic_read(&nr_mmap_events) &&
+            !atomic_read(&nr_task_events))
+                return;
+
+        task_event = (struct perf_task_event){
+                .task     = task,
+                .task_ctx = task_ctx,
+                .event_id    = {
+                        .header = {
+                                .type = new ? PERF_RECORD_FORK : PERF_RECORD_EXIT,
+                                .misc = 0,
+                                .size = sizeof(task_event.event_id),
+                        },
+                        /* .pid  */
+                        /* .ppid */
+                        /* .tid  */
+                        /* .ptid */
+                        .time = perf_clock(),
+                },
+        };
+
+        perf_event_task_event(&task_event);
+}
+
+void perf_event_fork(struct task_struct *task)
+{
+        perf_event_task(task, NULL, 1);
+}
+
+/*
+ * comm tracking
+ */
+
+struct perf_comm_event {
+        struct task_struct      *task;
+        char                    *comm;
+        int                     comm_size;
+
+        struct {
+                struct perf_event_header        header;
+
+                u32                             pid;
+                u32                             tid;
+        } event_id;
+};
+
+static void perf_event_comm_output(struct perf_event *event,
+                                     struct perf_comm_event *comm_event)
+{
+        struct perf_output_handle handle;
+        struct perf_sample_data sample;
+        int size = comm_event->event_id.header.size;
+        int ret;
+
+        perf_event_header__init_id(&comm_event->event_id.header, &sample, event);
+        ret = perf_output_begin(&handle, event,
+                                comm_event->event_id.header.size, 0, 0);
+
+        if (ret)
+                goto out;
+
+        comm_event->event_id.pid = perf_event_pid(event, comm_event->task);
+        comm_event->event_id.tid = perf_event_tid(event, comm_event->task);
+
+        perf_output_put(&handle, comm_event->event_id);
+        perf_output_copy(&handle, comm_event->comm,
+                                   comm_event->comm_size);
+
+        perf_event__output_id_sample(event, &handle, &sample);
+
+        perf_output_end(&handle);
+out:
+        comm_event->event_id.header.size = size;
+}
+
+static int perf_event_comm_match(struct perf_event *event)
+{
+        if (event->state < PERF_EVENT_STATE_INACTIVE)
+                return 0;
+
+        if (!event_filter_match(event))
+                return 0;
+
+        if (event->attr.comm)
+                return 1;
+
+        return 0;
+}
+
+static void perf_event_comm_ctx(struct perf_event_context *ctx,
+                                  struct perf_comm_event *comm_event)
+{
+        struct perf_event *event;
+
+        list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+                if (perf_event_comm_match(event))
+                        perf_event_comm_output(event, comm_event);
+        }
+}
+
+static void perf_event_comm_event(struct perf_comm_event *comm_event)
+{
+        struct perf_cpu_context *cpuctx;
+        struct perf_event_context *ctx;
+        char comm[TASK_COMM_LEN];
+        unsigned int size;
+        struct pmu *pmu;
+        int ctxn;
+
+        memset(comm, 0, sizeof(comm));
+        strlcpy(comm, comm_event->task->comm, sizeof(comm));
+        size = ALIGN(strlen(comm)+1, sizeof(u64));
+
+        comm_event->comm = comm;
+        comm_event->comm_size = size;
+
+        comm_event->event_id.header.size = sizeof(comm_event->event_id) + size;
+        rcu_read_lock();
+        list_for_each_entry_rcu(pmu, &pmus, entry) {
+                cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
+                if (cpuctx->active_pmu != pmu)
+                        goto next;
+                perf_event_comm_ctx(&cpuctx->ctx, comm_event);
+
+                ctxn = pmu->task_ctx_nr;
+                if (ctxn < 0)
+                        goto next;
+
+                ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
+                if (ctx)
+                        perf_event_comm_ctx(ctx, comm_event);
+next:
+                put_cpu_ptr(pmu->pmu_cpu_context);
+        }
+        rcu_read_unlock();
+}
+
+void perf_event_comm(struct task_struct *task)
+{
+        struct perf_comm_event comm_event;
+        struct perf_event_context *ctx;
+        int ctxn;
+
+        for_each_task_context_nr(ctxn) {
+                ctx = task->perf_event_ctxp[ctxn];
+                if (!ctx)
+                        continue;
+
+                perf_event_enable_on_exec(ctx);
+        }
+
+        if (!atomic_read(&nr_comm_events))
+                return;
+
+        comm_event = (struct perf_comm_event){
+                .task   = task,
+                /* .comm      */
+                /* .comm_size */
+                .event_id  = {
+                        .header = {
+                                .type = PERF_RECORD_COMM,
+                                .misc = 0,
+                                /* .size */
+                        },
+                        /* .pid */
+                        /* .tid */
+                },
+        };
+
+        perf_event_comm_event(&comm_event);
+}
+
+/*
+ * mmap tracking
+ */
+
+struct perf_mmap_event {
+        struct vm_area_struct   *vma;
+
+        const char              *file_name;
+        int                     file_size;
+
+        struct {
+                struct perf_event_header        header;
+
+                u32                             pid;
+                u32                             tid;
+                u64                             start;
+                u64                             len;
+                u64                             pgoff;
+        } event_id;
+};
+
+static void perf_event_mmap_output(struct perf_event *event,
+                                     struct perf_mmap_event *mmap_event)
+{
+        struct perf_output_handle handle;
+        struct perf_sample_data sample;
+        int size = mmap_event->event_id.header.size;
+        int ret;
+
+        perf_event_header__init_id(&mmap_event->event_id.header, &sample, event);
+        ret = perf_output_begin(&handle, event,
+                                mmap_event->event_id.header.size, 0, 0);
+        if (ret)
+                goto out;
+
+        mmap_event->event_id.pid = perf_event_pid(event, current);
+        mmap_event->event_id.tid = perf_event_tid(event, current);
+
+        perf_output_put(&handle, mmap_event->event_id);
+        perf_output_copy(&handle, mmap_event->file_name,
+                                   mmap_event->file_size);
+
+        perf_event__output_id_sample(event, &handle, &sample);
+
+        perf_output_end(&handle);
+out:
+        mmap_event->event_id.header.size = size;
+}
+
+static int perf_event_mmap_match(struct perf_event *event,
+                                   struct perf_mmap_event *mmap_event,
+                                   int executable)
+{
+        if (event->state < PERF_EVENT_STATE_INACTIVE)
+                return 0;
+
+        if (!event_filter_match(event))
+                return 0;
+
+        if ((!executable && event->attr.mmap_data) ||
+            (executable && event->attr.mmap))
+                return 1;
+
+        return 0;
+}
+
+static void perf_event_mmap_ctx(struct perf_event_context *ctx,
+                                  struct perf_mmap_event *mmap_event,
+                                  int executable)
+{
+        struct perf_event *event;
+
+        list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+                if (perf_event_mmap_match(event, mmap_event, executable))
+                        perf_event_mmap_output(event, mmap_event);
+        }
+}
+
+static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
+{
+        struct perf_cpu_context *cpuctx;
+        struct perf_event_context *ctx;
+        struct vm_area_struct *vma = mmap_event->vma;
+        struct file *file = vma->vm_file;
+        unsigned int size;
+        char tmp[16];
+        char *buf = NULL;
+        const char *name;
+        struct pmu *pmu;
+        int ctxn;
+
+        memset(tmp, 0, sizeof(tmp));
+
+        if (file) {
+                /*
+                 * d_path works from the end of the buffer backwards, so we
+                 * need to add enough zero bytes after the string to handle
+                 * the 64bit alignment we do later.
+                 */
+                buf = kzalloc(PATH_MAX + sizeof(u64), GFP_KERNEL);
+                if (!buf) {
+                        name = strncpy(tmp, "//enomem", sizeof(tmp));
+                        goto got_name;
+                }
+                name = d_path(&file->f_path, buf, PATH_MAX);
+                if (IS_ERR(name)) {
+                        name = strncpy(tmp, "//toolong", sizeof(tmp));
+                        goto got_name;
+                }
+        } else {
+                if (arch_vma_name(mmap_event->vma)) {
+                        name = strncpy(tmp, arch_vma_name(mmap_event->vma),
+                                       sizeof(tmp));
+                        goto got_name;
+                }
+
+                if (!vma->vm_mm) {
+                        name = strncpy(tmp, "[vdso]", sizeof(tmp));
+                        goto got_name;
+                } else if (vma->vm_start <= vma->vm_mm->start_brk &&
+                                vma->vm_end >= vma->vm_mm->brk) {
+                        name = strncpy(tmp, "[heap]", sizeof(tmp));
+                        goto got_name;
+                } else if (vma->vm_start <= vma->vm_mm->start_stack &&
+                                vma->vm_end >= vma->vm_mm->start_stack) {
+                        name = strncpy(tmp, "[stack]", sizeof(tmp));
+                        goto got_name;
+                }
+
+                name = strncpy(tmp, "//anon", sizeof(tmp));
+                goto got_name;
+        }
+
+got_name:
+        size = ALIGN(strlen(name)+1, sizeof(u64));
+
+        mmap_event->file_name = name;
+        mmap_event->file_size = size;
+
+        mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(pmu, &pmus, entry) {
+                cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
+                if (cpuctx->active_pmu != pmu)
+                        goto next;
+                perf_event_mmap_ctx(&cpuctx->ctx, mmap_event,
+                                        vma->vm_flags & VM_EXEC);
+
+                ctxn = pmu->task_ctx_nr;
+                if (ctxn < 0)
+                        goto next;
+
+                ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
+                if (ctx) {
+                        perf_event_mmap_ctx(ctx, mmap_event,
+                                        vma->vm_flags & VM_EXEC);
+                }
+next:
+                put_cpu_ptr(pmu->pmu_cpu_context);
+        }
+        rcu_read_unlock();
+
+        kfree(buf);
+}
+
+void perf_event_mmap(struct vm_area_struct *vma)
+{
+        struct perf_mmap_event mmap_event;
+
+        if (!atomic_read(&nr_mmap_events))
+                return;
+
+        mmap_event = (struct perf_mmap_event){
+                .vma    = vma,
+                /* .file_name */
+                /* .file_size */
+                .event_id  = {
+                        .header = {
+                                .type = PERF_RECORD_MMAP,
+                                .misc = PERF_RECORD_MISC_USER,
+                                /* .size */
+                        },
+                        /* .pid */
+                        /* .tid */
+                        .start  = vma->vm_start,
+                        .len    = vma->vm_end - vma->vm_start,
+                        .pgoff  = (u64)vma->vm_pgoff << PAGE_SHIFT,
+                },
+        };
+
+        perf_event_mmap_event(&mmap_event);
+}
+
+/*
+ * IRQ throttle logging
+ */
+
+static void perf_log_throttle(struct perf_event *event, int enable)
+{
+        struct perf_output_handle handle;
+        struct perf_sample_data sample;
+        int ret;
+
+        struct {
+                struct perf_event_header        header;
+                u64                             time;
+                u64                             id;
+                u64                             stream_id;
+        } throttle_event = {
+                .header = {
+                        .type = PERF_RECORD_THROTTLE,
+                        .misc = 0,
+                        .size = sizeof(throttle_event),
+                },
+                .time           = perf_clock(),
+                .id             = primary_event_id(event),
+                .stream_id      = event->id,
+        };
+
+        if (enable)
+                throttle_event.header.type = PERF_RECORD_UNTHROTTLE;
+
+        perf_event_header__init_id(&throttle_event.header, &sample, event);
+
+        ret = perf_output_begin(&handle, event,
+                                throttle_event.header.size, 1, 0);
+        if (ret)
+                return;
+
+        perf_output_put(&handle, throttle_event);
+        perf_event__output_id_sample(event, &handle, &sample);
+        perf_output_end(&handle);
+}
+
+/*
+ * Generic event overflow handling, sampling.
+ */
+
+static int __perf_event_overflow(struct perf_event *event, int nmi,
+                                   int throttle, struct perf_sample_data *data,
+                                   struct pt_regs *regs)
+{
+        int events = atomic_read(&event->event_limit);
+        struct hw_perf_event *hwc = &event->hw;
+        int ret = 0;
+
+        /*
+         * Non-sampling counters might still use the PMI to fold short
+         * hardware counters, ignore those.
+         */
+        if (unlikely(!is_sampling_event(event)))
+                return 0;
+
+        if (unlikely(hwc->interrupts >= max_samples_per_tick)) {
+                if (throttle) {
+                        hwc->interrupts = MAX_INTERRUPTS;
+                        perf_log_throttle(event, 0);
+                        ret = 1;
+                }
+        } else
+                hwc->interrupts++;
+
+        if (event->attr.freq) {
+                u64 now = perf_clock();
+                s64 delta = now - hwc->freq_time_stamp;
+
+                hwc->freq_time_stamp = now;
+
+                if (delta > 0 && delta < 2*TICK_NSEC)
+                        perf_adjust_period(event, delta, hwc->last_period);
+        }
+
+        /*
+         * XXX event_limit might not quite work as expected on inherited
+         * events
+         */
+
+        event->pending_kill = POLL_IN;
+        if (events && atomic_dec_and_test(&event->event_limit)) {
+                ret = 1;
+                event->pending_kill = POLL_HUP;
+                if (nmi) {
+                        event->pending_disable = 1;
+                        irq_work_queue(&event->pending);
+                } else
+                        perf_event_disable(event);
+        }
+
+        if (event->overflow_handler)
+                event->overflow_handler(event, nmi, data, regs);
+        else
+                perf_event_output(event, nmi, data, regs);
+
+        return ret;
+}
+
+int perf_event_overflow(struct perf_event *event, int nmi,
+                          struct perf_sample_data *data,
+                          struct pt_regs *regs)
+{
+        return __perf_event_overflow(event, nmi, 1, data, regs);
+}
+
+/*
+ * Generic software event infrastructure
+ */
+
+struct swevent_htable {
+        struct swevent_hlist            *swevent_hlist;
+        struct mutex                    hlist_mutex;
+        int                             hlist_refcount;
+
+        /* Recursion avoidance in each contexts */
+        int                             recursion[PERF_NR_CONTEXTS];
+};
+
+static DEFINE_PER_CPU(struct swevent_htable, swevent_htable);
+
+/*
+ * We directly increment event->count and keep a second value in
+ * event->hw.period_left to count intervals. This period event
+ * is kept in the range [-sample_period, 0] so that we can use the
+ * sign as trigger.
+ */
+
+static u64 perf_swevent_set_period(struct perf_event *event)
+{
+        struct hw_perf_event *hwc = &event->hw;
+        u64 period = hwc->last_period;
+        u64 nr, offset;
+        s64 old, val;
+
+        hwc->last_period = hwc->sample_period;
+
+again:
+        old = val = local64_read(&hwc->period_left);
+        if (val < 0)
+                return 0;
+
+        nr = div64_u64(period + val, period);
+        offset = nr * period;
+        val -= offset;
+        if (local64_cmpxchg(&hwc->period_left, old, val) != old)
+                goto again;
+
+        return nr;
+}
+
+static void perf_swevent_overflow(struct perf_event *event, u64 overflow,
+                                    int nmi, struct perf_sample_data *data,
+                                    struct pt_regs *regs)
+{
+        struct hw_perf_event *hwc = &event->hw;
+        int throttle = 0;
+
+        data->period = event->hw.last_period;
+        if (!overflow)
+                overflow = perf_swevent_set_period(event);
+
+        if (hwc->interrupts == MAX_INTERRUPTS)
+                return;
+
+        for (; overflow; overflow--) {
+                if (__perf_event_overflow(event, nmi, throttle,
+                                            data, regs)) {
+                        /*
+                         * We inhibit the overflow from happening when
+                         * hwc->interrupts == MAX_INTERRUPTS.
+                         */
+                        break;
+                }
+                throttle = 1;
+        }
+}
+
+static void perf_swevent_event(struct perf_event *event, u64 nr,
+                               int nmi, struct perf_sample_data *data,
+                               struct pt_regs *regs)
+{
+        struct hw_perf_event *hwc = &event->hw;
+
+        local64_add(nr, &event->count);
+
+        if (!regs)
+                return;
+
+        if (!is_sampling_event(event))
+                return;
+
+        if (nr == 1 && hwc->sample_period == 1 && !event->attr.freq)
+                return perf_swevent_overflow(event, 1, nmi, data, regs);
+
+        if (local64_add_negative(nr, &hwc->period_left))
+                return;
+
+        perf_swevent_overflow(event, 0, nmi, data, regs);
+}
+
+static int perf_exclude_event(struct perf_event *event,
+                              struct pt_regs *regs)
+{
+        if (event->hw.state & PERF_HES_STOPPED)
+                return 1;
+
+        if (regs) {
+                if (event->attr.exclude_user && user_mode(regs))
+                        return 1;
+
+                if (event->attr.exclude_kernel && !user_mode(regs))
+                        return 1;
+        }
+
+        return 0;
+}
+
+static int perf_swevent_match(struct perf_event *event,
+                                enum perf_type_id type,
+                                u32 event_id,
+                                struct perf_sample_data *data,
+                                struct pt_regs *regs)
+{
+        if (event->attr.type != type)
+                return 0;
+
+        if (event->attr.config != event_id)
+                return 0;
+
+        if (perf_exclude_event(event, regs))
+                return 0;
+
+        return 1;
+}
+
+static inline u64 swevent_hash(u64 type, u32 event_id)
+{
+        u64 val = event_id | (type << 32);
+
+        return hash_64(val, SWEVENT_HLIST_BITS);
+}
+
+static inline struct hlist_head *
+__find_swevent_head(struct swevent_hlist *hlist, u64 type, u32 event_id)
+{
+        u64 hash = swevent_hash(type, event_id);
+
+        return &hlist->heads[hash];
+}
+
+/* For the read side: events when they trigger */
+static inline struct hlist_head *
+find_swevent_head_rcu(struct swevent_htable *swhash, u64 type, u32 event_id)
+{
+        struct swevent_hlist *hlist;
+
+        hlist = rcu_dereference(swhash->swevent_hlist);
+        if (!hlist)
+                return NULL;
+
+        return __find_swevent_head(hlist, type, event_id);
+}
+
+/* For the event head insertion and removal in the hlist */
+static inline struct hlist_head *
+find_swevent_head(struct swevent_htable *swhash, struct perf_event *event)
+{
+        struct swevent_hlist *hlist;
+        u32 event_id = event->attr.config;
+        u64 type = event->attr.type;
+
+        /*
+         * Event scheduling is always serialized against hlist allocation
+         * and release. Which makes the protected version suitable here.
+         * The context lock guarantees that.
+         */
+        hlist = rcu_dereference_protected(swhash->swevent_hlist,
+                                          lockdep_is_held(&event->ctx->lock));
+        if (!hlist)
+                return NULL;
+
+        return __find_swevent_head(hlist, type, event_id);
+}
+
+static void do_perf_sw_event(enum perf_type_id type, u32 event_id,
+                                    u64 nr, int nmi,
+                                    struct perf_sample_data *data,
+                                    struct pt_regs *regs)
+{
+        struct swevent_htable *swhash = &__get_cpu_var(swevent_htable);
+        struct perf_event *event;
+        struct hlist_node *node;
+        struct hlist_head *head;
+
+        rcu_read_lock();
+        head = find_swevent_head_rcu(swhash, type, event_id);
+        if (!head)
+                goto end;
+
+        hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
+                if (perf_swevent_match(event, type, event_id, data, regs))
+                        perf_swevent_event(event, nr, nmi, data, regs);
+        }
+end:
+        rcu_read_unlock();
+}
+
+int perf_swevent_get_recursion_context(void)
+{
+        struct swevent_htable *swhash = &__get_cpu_var(swevent_htable);
+
+        return get_recursion_context(swhash->recursion);
+}
+EXPORT_SYMBOL_GPL(perf_swevent_get_recursion_context);
+
+inline void perf_swevent_put_recursion_context(int rctx)
+{
+        struct swevent_htable *swhash = &__get_cpu_var(swevent_htable);
+
+        put_recursion_context(swhash->recursion, rctx);
+}
+
+void __perf_sw_event(u32 event_id, u64 nr, int nmi,
+                            struct pt_regs *regs, u64 addr)
+{
+        struct perf_sample_data data;
+        int rctx;
+
+        preempt_disable_notrace();
+        rctx = perf_swevent_get_recursion_context();
+        if (rctx < 0)
+                return;
+
+        perf_sample_data_init(&data, addr);
+
+        do_perf_sw_event(PERF_TYPE_SOFTWARE, event_id, nr, nmi, &data, regs);
+
+        perf_swevent_put_recursion_context(rctx);
+        preempt_enable_notrace();
+}
+
+static void perf_swevent_read(struct perf_event *event)
+{
+}
+
+static int perf_swevent_add(struct perf_event *event, int flags)
+{
+        struct swevent_htable *swhash = &__get_cpu_var(swevent_htable);
+        struct hw_perf_event *hwc = &event->hw;
+        struct hlist_head *head;
+
+        if (is_sampling_event(event)) {
+                hwc->last_period = hwc->sample_period;
+                perf_swevent_set_period(event);
+        }
+
+        hwc->state = !(flags & PERF_EF_START);
+
+        head = find_swevent_head(swhash, event);
+        if (WARN_ON_ONCE(!head))
+                return -EINVAL;
+
+        hlist_add_head_rcu(&event->hlist_entry, head);
+
+        return 0;
+}
+
+static void perf_swevent_del(struct perf_event *event, int flags)
+{
+        hlist_del_rcu(&event->hlist_entry);
+}
+
+static void perf_swevent_start(struct perf_event *event, int flags)
+{
+        event->hw.state = 0;
+}
+
+static void perf_swevent_stop(struct perf_event *event, int flags)
+{
+        event->hw.state = PERF_HES_STOPPED;
+}
+
+/* Deref the hlist from the update side */
+static inline struct swevent_hlist *
+swevent_hlist_deref(struct swevent_htable *swhash)
+{
+        return rcu_dereference_protected(swhash->swevent_hlist,
+                                         lockdep_is_held(&swhash->hlist_mutex));
+}
+
+static void swevent_hlist_release(struct swevent_htable *swhash)
+{
+        struct swevent_hlist *hlist = swevent_hlist_deref(swhash);
+
+        if (!hlist)
+                return;
+
+        rcu_assign_pointer(swhash->swevent_hlist, NULL);
+        kfree_rcu(hlist, rcu_head);
+}
+
+static void swevent_hlist_put_cpu(struct perf_event *event, int cpu)
+{
+        struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
+
+        mutex_lock(&swhash->hlist_mutex);
+
+        if (!--swhash->hlist_refcount)
+                swevent_hlist_release(swhash);
+
+        mutex_unlock(&swhash->hlist_mutex);
+}
+
+static void swevent_hlist_put(struct perf_event *event)
+{
+        int cpu;
+
+        if (event->cpu != -1) {
+                swevent_hlist_put_cpu(event, event->cpu);
+                return;
+        }
+
+        for_each_possible_cpu(cpu)
+                swevent_hlist_put_cpu(event, cpu);
+}
+
+static int swevent_hlist_get_cpu(struct perf_event *event, int cpu)
+{
+        struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
+        int err = 0;
+
+        mutex_lock(&swhash->hlist_mutex);
+
+        if (!swevent_hlist_deref(swhash) && cpu_online(cpu)) {
+                struct swevent_hlist *hlist;
+
+                hlist = kzalloc(sizeof(*hlist), GFP_KERNEL);
+                if (!hlist) {
+                        err = -ENOMEM;
+                        goto exit;
+                }
+                rcu_assign_pointer(swhash->swevent_hlist, hlist);
+        }
+        swhash->hlist_refcount++;
+exit:
+        mutex_unlock(&swhash->hlist_mutex);
+
+        return err;
+}
+
+static int swevent_hlist_get(struct perf_event *event)
+{
+        int err;
+        int cpu, failed_cpu;
+
+        if (event->cpu != -1)
+                return swevent_hlist_get_cpu(event, event->cpu);
+
+        get_online_cpus();
+        for_each_possible_cpu(cpu) {
+                err = swevent_hlist_get_cpu(event, cpu);
+                if (err) {
+                        failed_cpu = cpu;
+                        goto fail;
+                }
+        }
+        put_online_cpus();
+
+        return 0;
+fail:
+        for_each_possible_cpu(cpu) {
+                if (cpu == failed_cpu)
+                        break;
+                swevent_hlist_put_cpu(event, cpu);
+        }
+
+        put_online_cpus();
+        return err;
+}
+
+struct jump_label_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
+
+static void sw_perf_event_destroy(struct perf_event *event)
+{
+        u64 event_id = event->attr.config;
+
+        WARN_ON(event->parent);
+
+        jump_label_dec(&perf_swevent_enabled[event_id]);
+        swevent_hlist_put(event);
+}
+
+static int perf_swevent_init(struct perf_event *event)
+{
+        int event_id = event->attr.config;
+
+        if (event->attr.type != PERF_TYPE_SOFTWARE)
+                return -ENOENT;
+
+        switch (event_id) {
+        case PERF_COUNT_SW_CPU_CLOCK:
+        case PERF_COUNT_SW_TASK_CLOCK:
+                return -ENOENT;
+
+        default:
+                break;
+        }
+
+        if (event_id >= PERF_COUNT_SW_MAX)
+                return -ENOENT;
+
+        if (!event->parent) {
+                int err;
+
+                err = swevent_hlist_get(event);
+                if (err)
+                        return err;
+
+                jump_label_inc(&perf_swevent_enabled[event_id]);
+                event->destroy = sw_perf_event_destroy;
+        }
+
+        return 0;
+}
+
+static struct pmu perf_swevent = {
+        .task_ctx_nr    = perf_sw_context,
+
+        .event_init     = perf_swevent_init,
+        .add            = perf_swevent_add,
+        .del            = perf_swevent_del,
+        .start          = perf_swevent_start,
+        .stop           = perf_swevent_stop,
+        .read           = perf_swevent_read,
+};
+
+#ifdef CONFIG_EVENT_TRACING
+
+static int perf_tp_filter_match(struct perf_event *event,
+                                struct perf_sample_data *data)
+{
+        void *record = data->raw->data;
+
+        if (likely(!event->filter) || filter_match_preds(event->filter, record))
+                return 1;
+        return 0;
+}
+
+static int perf_tp_event_match(struct perf_event *event,
+                                struct perf_sample_data *data,
+                                struct pt_regs *regs)
+{
+        if (event->hw.state & PERF_HES_STOPPED)
+                return 0;
+        /*
+         * All tracepoints are from kernel-space.
+         */
+        if (event->attr.exclude_kernel)
+                return 0;
+
+        if (!perf_tp_filter_match(event, data))
+                return 0;
+
+        return 1;
+}
+
+void perf_tp_event(u64 addr, u64 count, void *record, int entry_size,
+                   struct pt_regs *regs, struct hlist_head *head, int rctx)
+{
+        struct perf_sample_data data;
+        struct perf_event *event;
+        struct hlist_node *node;
+
+        struct perf_raw_record raw = {
+                .size = entry_size,
+                .data = record,
+        };
+
+        perf_sample_data_init(&data, addr);
+        data.raw = &raw;
+
+        hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
+                if (perf_tp_event_match(event, &data, regs))
+                        perf_swevent_event(event, count, 1, &data, regs);
+        }
+
+        perf_swevent_put_recursion_context(rctx);
+}
+EXPORT_SYMBOL_GPL(perf_tp_event);
+
+static void tp_perf_event_destroy(struct perf_event *event)
+{
+        perf_trace_destroy(event);
+}
+
+static int perf_tp_event_init(struct perf_event *event)
+{
+        int err;
+
+        if (event->attr.type != PERF_TYPE_TRACEPOINT)
+                return -ENOENT;
+
+        err = perf_trace_init(event);
+        if (err)
+                return err;
+
+        event->destroy = tp_perf_event_destroy;
+
+        return 0;
+}
+
+static struct pmu perf_tracepoint = {
+        .task_ctx_nr    = perf_sw_context,
+
+        .event_init     = perf_tp_event_init,
+        .add            = perf_trace_add,
+        .del            = perf_trace_del,
+        .start          = perf_swevent_start,
+        .stop           = perf_swevent_stop,
+        .read           = perf_swevent_read,
+};
+
+static inline void perf_tp_register(void)
+{
+        perf_pmu_register(&perf_tracepoint, "tracepoint", PERF_TYPE_TRACEPOINT);
+}
+
+static int perf_event_set_filter(struct perf_event *event, void __user *arg)
+{
+        char *filter_str;
+        int ret;
+
+        if (event->attr.type != PERF_TYPE_TRACEPOINT)
+                return -EINVAL;
+
+        filter_str = strndup_user(arg, PAGE_SIZE);
+        if (IS_ERR(filter_str))
+                return PTR_ERR(filter_str);
+
+        ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
+
+        kfree(filter_str);
+        return ret;
+}
+
+static void perf_event_free_filter(struct perf_event *event)
+{
+        ftrace_profile_free_filter(event);
+}
+
+#else
+
+static inline void perf_tp_register(void)
+{
+}
+
+static int perf_event_set_filter(struct perf_event *event, void __user *arg)
+{
+        return -ENOENT;
+}
+
+static void perf_event_free_filter(struct perf_event *event)
+{
+}
+
+#endif /* CONFIG_EVENT_TRACING */
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+void perf_bp_event(struct perf_event *bp, void *data)
+{
+        struct perf_sample_data sample;
+        struct pt_regs *regs = data;
+
+        perf_sample_data_init(&sample, bp->attr.bp_addr);
+
+        if (!bp->hw.state && !perf_exclude_event(bp, regs))
+                perf_swevent_event(bp, 1, 1, &sample, regs);
+}
+#endif
+
+/*
+ * hrtimer based swevent callback
+ */
+
+static enum hrtimer_restart perf_swevent_hrtimer(struct hrtimer *hrtimer)
+{
+        enum hrtimer_restart ret = HRTIMER_RESTART;
+        struct perf_sample_data data;
+        struct pt_regs *regs;
+        struct perf_event *event;
+        u64 period;
+
+        event = container_of(hrtimer, struct perf_event, hw.hrtimer);
+
+        if (event->state != PERF_EVENT_STATE_ACTIVE)
+                return HRTIMER_NORESTART;
+
+        event->pmu->read(event);
+
+        perf_sample_data_init(&data, 0);
+        data.period = event->hw.last_period;
+        regs = get_irq_regs();
+
+        if (regs && !perf_exclude_event(event, regs)) {
+                if (!(event->attr.exclude_idle && current->pid == 0))
+                        if (perf_event_overflow(event, 0, &data, regs))
+                                ret = HRTIMER_NORESTART;
+        }
+
+        period = max_t(u64, 10000, event->hw.sample_period);
+        hrtimer_forward_now(hrtimer, ns_to_ktime(period));
+
+        return ret;
+}
+
+static void perf_swevent_start_hrtimer(struct perf_event *event)
+{
+        struct hw_perf_event *hwc = &event->hw;
+        s64 period;
+
+        if (!is_sampling_event(event))
+                return;
+
+        period = local64_read(&hwc->period_left);
+        if (period) {
+                if (period < 0)
+                        period = 10000;
+
+                local64_set(&hwc->period_left, 0);
+        } else {
+                period = max_t(u64, 10000, hwc->sample_period);
+        }
+        __hrtimer_start_range_ns(&hwc->hrtimer,
+                                ns_to_ktime(period), 0,
+                                HRTIMER_MODE_REL_PINNED, 0);
+}
+
+static void perf_swevent_cancel_hrtimer(struct perf_event *event)
+{
+        struct hw_perf_event *hwc = &event->hw;
+
+        if (is_sampling_event(event)) {
+                ktime_t remaining = hrtimer_get_remaining(&hwc->hrtimer);
+                local64_set(&hwc->period_left, ktime_to_ns(remaining));
+
+                hrtimer_cancel(&hwc->hrtimer);
+        }
+}
+
+static void perf_swevent_init_hrtimer(struct perf_event *event)
+{
+        struct hw_perf_event *hwc = &event->hw;
+
+        if (!is_sampling_event(event))
+                return;
+
+        hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+        hwc->hrtimer.function = perf_swevent_hrtimer;
+
+        /*
+         * Since hrtimers have a fixed rate, we can do a static freq->period
+         * mapping and avoid the whole period adjust feedback stuff.
+         */
+        if (event->attr.freq) {
+                long freq = event->attr.sample_freq;
+
+                event->attr.sample_period = NSEC_PER_SEC / freq;
+                hwc->sample_period = event->attr.sample_period;
+                local64_set(&hwc->period_left, hwc->sample_period);
+                event->attr.freq = 0;
+        }
+}
+
+/*
+ * Software event: cpu wall time clock
+ */
+
+static void cpu_clock_event_update(struct perf_event *event)
+{
+        s64 prev;
+        u64 now;
+
+        now = local_clock();
+        prev = local64_xchg(&event->hw.prev_count, now);
+        local64_add(now - prev, &event->count);
+}
+
+static void cpu_clock_event_start(struct perf_event *event, int flags)
+{
+        local64_set(&event->hw.prev_count, local_clock());
+        perf_swevent_start_hrtimer(event);
+}
+
+static void cpu_clock_event_stop(struct perf_event *event, int flags)
+{
+        perf_swevent_cancel_hrtimer(event);
+        cpu_clock_event_update(event);
+}
+
+static int cpu_clock_event_add(struct perf_event *event, int flags)
+{
+        if (flags & PERF_EF_START)
+                cpu_clock_event_start(event, flags);
+
+        return 0;
+}
+
+static void cpu_clock_event_del(struct perf_event *event, int flags)
+{
+        cpu_clock_event_stop(event, flags);
+}
+
+static void cpu_clock_event_read(struct perf_event *event)
+{
+        cpu_clock_event_update(event);
+}
+
+static int cpu_clock_event_init(struct perf_event *event)
+{
+        if (event->attr.type != PERF_TYPE_SOFTWARE)
+                return -ENOENT;
+
+        if (event->attr.config != PERF_COUNT_SW_CPU_CLOCK)
+                return -ENOENT;
+
+        perf_swevent_init_hrtimer(event);
+
+        return 0;
+}
+
+static struct pmu perf_cpu_clock = {
+        .task_ctx_nr    = perf_sw_context,
+
+        .event_init     = cpu_clock_event_init,
+        .add            = cpu_clock_event_add,
+        .del            = cpu_clock_event_del,
+        .start          = cpu_clock_event_start,
+        .stop           = cpu_clock_event_stop,
+        .read           = cpu_clock_event_read,
+};
+
+/*
+ * Software event: task time clock
+ */
+
+static void task_clock_event_update(struct perf_event *event, u64 now)
+{
+        u64 prev;
+        s64 delta;
+
+        prev = local64_xchg(&event->hw.prev_count, now);
+        delta = now - prev;
+        local64_add(delta, &event->count);
+}
+
+static void task_clock_event_start(struct perf_event *event, int flags)
+{
+        local64_set(&event->hw.prev_count, event->ctx->time);
+        perf_swevent_start_hrtimer(event);
+}
+
+static void task_clock_event_stop(struct perf_event *event, int flags)
+{
+        perf_swevent_cancel_hrtimer(event);
+        task_clock_event_update(event, event->ctx->time);
+}
+
+static int task_clock_event_add(struct perf_event *event, int flags)
+{
+        if (flags & PERF_EF_START)
+                task_clock_event_start(event, flags);
+
+        return 0;
+}
+
+static void task_clock_event_del(struct perf_event *event, int flags)
+{
+        task_clock_event_stop(event, PERF_EF_UPDATE);
+}
+
+static void task_clock_event_read(struct perf_event *event)
+{
+        u64 now = perf_clock();
+        u64 delta = now - event->ctx->timestamp;
+        u64 time = event->ctx->time + delta;
+
+        task_clock_event_update(event, time);
+}
+
+static int task_clock_event_init(struct perf_event *event)
+{
+        if (event->attr.type != PERF_TYPE_SOFTWARE)
+                return -ENOENT;
+
+        if (event->attr.config != PERF_COUNT_SW_TASK_CLOCK)
+                return -ENOENT;
+
+        perf_swevent_init_hrtimer(event);
+
+        return 0;
+}
+
+static struct pmu perf_task_clock = {
+        .task_ctx_nr    = perf_sw_context,
+
+        .event_init     = task_clock_event_init,
+        .add            = task_clock_event_add,
+        .del            = task_clock_event_del,
+        .start          = task_clock_event_start,
+        .stop           = task_clock_event_stop,
+        .read           = task_clock_event_read,
+};
+
+static void perf_pmu_nop_void(struct pmu *pmu)
+{
+}
+
+static int perf_pmu_nop_int(struct pmu *pmu)
+{
+        return 0;
+}
+
+static void perf_pmu_start_txn(struct pmu *pmu)
+{
+        perf_pmu_disable(pmu);
+}
+
+static int perf_pmu_commit_txn(struct pmu *pmu)
+{
+        perf_pmu_enable(pmu);
+        return 0;
+}
+
+static void perf_pmu_cancel_txn(struct pmu *pmu)
+{
+        perf_pmu_enable(pmu);
+}
+
+/*
+ * Ensures all contexts with the same task_ctx_nr have the same
+ * pmu_cpu_context too.
+ */
+static void *find_pmu_context(int ctxn)
+{
+        struct pmu *pmu;
+
+        if (ctxn < 0)
+                return NULL;
+
+        list_for_each_entry(pmu, &pmus, entry) {
+                if (pmu->task_ctx_nr == ctxn)
+                        return pmu->pmu_cpu_context;
+        }
+
+        return NULL;
+}
+
+static void update_pmu_context(struct pmu *pmu, struct pmu *old_pmu)
+{
+        int cpu;
+
+        for_each_possible_cpu(cpu) {
+                struct perf_cpu_context *cpuctx;
+
+                cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+
+                if (cpuctx->active_pmu == old_pmu)
+                        cpuctx->active_pmu = pmu;
+        }
+}
+
+static void free_pmu_context(struct pmu *pmu)
+{
+        struct pmu *i;
+
+        mutex_lock(&pmus_lock);
+        /*
+         * Like a real lame refcount.
+         */
+        list_for_each_entry(i, &pmus, entry) {
+                if (i->pmu_cpu_context == pmu->pmu_cpu_context) {
+                        update_pmu_context(i, pmu);
+                        goto out;
+                }
+        }
+
+        free_percpu(pmu->pmu_cpu_context);
+out:
+        mutex_unlock(&pmus_lock);
+}
+static struct idr pmu_idr;
+
+static ssize_t
+type_show(struct device *dev, struct device_attribute *attr, char *page)
+{
+        struct pmu *pmu = dev_get_drvdata(dev);
+
+        return snprintf(page, PAGE_SIZE-1, "%d\n", pmu->type);
+}
+
+static struct device_attribute pmu_dev_attrs[] = {
+       __ATTR_RO(type),
+       __ATTR_NULL,
+};
+
+static int pmu_bus_running;
+static struct bus_type pmu_bus = {
+        .name           = "event_source",
+        .dev_attrs      = pmu_dev_attrs,
+};
+
+static void pmu_dev_release(struct device *dev)
+{
+        kfree(dev);
+}
+
+static int pmu_dev_alloc(struct pmu *pmu)
+{
+        int ret = -ENOMEM;
+
+        pmu->dev = kzalloc(sizeof(struct device), GFP_KERNEL);
+        if (!pmu->dev)
+                goto out;
+
+        device_initialize(pmu->dev);
+        ret = dev_set_name(pmu->dev, "%s", pmu->name);
+        if (ret)
+                goto free_dev;
+
+        dev_set_drvdata(pmu->dev, pmu);
+        pmu->dev->bus = &pmu_bus;
+        pmu->dev->release = pmu_dev_release;
+        ret = device_add(pmu->dev);
+        if (ret)
+                goto free_dev;
+
+out:
+        return ret;
+
+free_dev:
+        put_device(pmu->dev);
+        goto out;
+}
+
+static struct lock_class_key cpuctx_mutex;
+
+int perf_pmu_register(struct pmu *pmu, char *name, int type)
+{
+        int cpu, ret;
+
+        mutex_lock(&pmus_lock);
+        ret = -ENOMEM;
+        pmu->pmu_disable_count = alloc_percpu(int);
+        if (!pmu->pmu_disable_count)
+                goto unlock;
+
+        pmu->type = -1;
+        if (!name)
+                goto skip_type;
+        pmu->name = name;
+
+        if (type < 0) {
+                int err = idr_pre_get(&pmu_idr, GFP_KERNEL);
+                if (!err)
+                        goto free_pdc;
+
+                err = idr_get_new_above(&pmu_idr, pmu, PERF_TYPE_MAX, &type);
+                if (err) {
+                        ret = err;
+                        goto free_pdc;
+                }
+        }
+        pmu->type = type;
+
+        if (pmu_bus_running) {
+                ret = pmu_dev_alloc(pmu);
+                if (ret)
+                        goto free_idr;
+        }
+
+skip_type:
+        pmu->pmu_cpu_context = find_pmu_context(pmu->task_ctx_nr);
+        if (pmu->pmu_cpu_context)
+                goto got_cpu_context;
+
+        pmu->pmu_cpu_context = alloc_percpu(struct perf_cpu_context);
+        if (!pmu->pmu_cpu_context)
+                goto free_dev;
+
+        for_each_possible_cpu(cpu) {
+                struct perf_cpu_context *cpuctx;
+
+                cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+                __perf_event_init_context(&cpuctx->ctx);
+                lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex);
+                cpuctx->ctx.type = cpu_context;
+                cpuctx->ctx.pmu = pmu;
+                cpuctx->jiffies_interval = 1;
+                INIT_LIST_HEAD(&cpuctx->rotation_list);
+                cpuctx->active_pmu = pmu;
+        }
+
+got_cpu_context:
+        if (!pmu->start_txn) {
+                if (pmu->pmu_enable) {
+                        /*
+                         * If we have pmu_enable/pmu_disable calls, install
+                         * transaction stubs that use that to try and batch
+                         * hardware accesses.
+                         */
+                        pmu->start_txn  = perf_pmu_start_txn;
+                        pmu->commit_txn = perf_pmu_commit_txn;
+                        pmu->cancel_txn = perf_pmu_cancel_txn;
+                } else {
+                        pmu->start_txn  = perf_pmu_nop_void;
+                        pmu->commit_txn = perf_pmu_nop_int;
+                        pmu->cancel_txn = perf_pmu_nop_void;
+                }
+        }
+
+        if (!pmu->pmu_enable) {
+                pmu->pmu_enable  = perf_pmu_nop_void;
+                pmu->pmu_disable = perf_pmu_nop_void;
+        }
+
+        list_add_rcu(&pmu->entry, &pmus);
+        ret = 0;
+unlock:
+        mutex_unlock(&pmus_lock);
+
+        return ret;
+
+free_dev:
+        device_del(pmu->dev);
+        put_device(pmu->dev);
+
+free_idr:
+        if (pmu->type >= PERF_TYPE_MAX)
+                idr_remove(&pmu_idr, pmu->type);
+
+free_pdc:
+        free_percpu(pmu->pmu_disable_count);
+        goto unlock;
+}
+
+void perf_pmu_unregister(struct pmu *pmu)
+{
+        mutex_lock(&pmus_lock);
+        list_del_rcu(&pmu->entry);
+        mutex_unlock(&pmus_lock);
+
+        /*
+         * We dereference the pmu list under both SRCU and regular RCU, so
+         * synchronize against both of those.
+         */
+        synchronize_srcu(&pmus_srcu);
+        synchronize_rcu();
+
+        free_percpu(pmu->pmu_disable_count);
+        if (pmu->type >= PERF_TYPE_MAX)
+                idr_remove(&pmu_idr, pmu->type);
+        device_del(pmu->dev);
+        put_device(pmu->dev);
+        free_pmu_context(pmu);
+}
+
+struct pmu *perf_init_event(struct perf_event *event)
+{
+        struct pmu *pmu = NULL;
+        int idx;
+        int ret;
+
+        idx = srcu_read_lock(&pmus_srcu);
+
+        rcu_read_lock();
+        pmu = idr_find(&pmu_idr, event->attr.type);
+        rcu_read_unlock();
+        if (pmu) {
+                ret = pmu->event_init(event);
+                if (ret)
+                        pmu = ERR_PTR(ret);
+                goto unlock;
+        }
+
+        list_for_each_entry_rcu(pmu, &pmus, entry) {
+                ret = pmu->event_init(event);
+                if (!ret)
+                        goto unlock;
+
+                if (ret != -ENOENT) {
+                        pmu = ERR_PTR(ret);
+                        goto unlock;
+                }
+        }
+        pmu = ERR_PTR(-ENOENT);
+unlock:
+        srcu_read_unlock(&pmus_srcu, idx);
+
+        return pmu;
+}
+
+/*
+ * Allocate and initialize a event structure
+ */
+static struct perf_event *
+perf_event_alloc(struct perf_event_attr *attr, int cpu,
+                 struct task_struct *task,
+                 struct perf_event *group_leader,
+                 struct perf_event *parent_event,
+                 perf_overflow_handler_t overflow_handler)
+{
+        struct pmu *pmu;
+        struct perf_event *event;
+        struct hw_perf_event *hwc;
+        long err;
+
+        if ((unsigned)cpu >= nr_cpu_ids) {
+                if (!task || cpu != -1)
+                        return ERR_PTR(-EINVAL);
+        }
+
+        event = kzalloc(sizeof(*event), GFP_KERNEL);
+        if (!event)
+                return ERR_PTR(-ENOMEM);
+
+        /*
+         * Single events are their own group leaders, with an
+         * empty sibling list:
+         */
+        if (!group_leader)
+                group_leader = event;
+
+        mutex_init(&event->child_mutex);
+        INIT_LIST_HEAD(&event->child_list);
+
+        INIT_LIST_HEAD(&event->group_entry);
+        INIT_LIST_HEAD(&event->event_entry);
+        INIT_LIST_HEAD(&event->sibling_list);
+        init_waitqueue_head(&event->waitq);
+        init_irq_work(&event->pending, perf_pending_event);
+
+        mutex_init(&event->mmap_mutex);
+
+        event->cpu              = cpu;
+        event->attr             = *attr;
+        event->group_leader     = group_leader;
+        event->pmu              = NULL;
+        event->oncpu            = -1;
+
+        event->parent           = parent_event;
+
+        event->ns               = get_pid_ns(current->nsproxy->pid_ns);
+        event->id               = atomic64_inc_return(&perf_event_id);
+
+        event->state            = PERF_EVENT_STATE_INACTIVE;
+
+        if (task) {
+                event->attach_state = PERF_ATTACH_TASK;
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+                /*
+                 * hw_breakpoint is a bit difficult here..
+                 */
+                if (attr->type == PERF_TYPE_BREAKPOINT)
+                        event->hw.bp_target = task;
+#endif
+        }
+
+        if (!overflow_handler && parent_event)
+                overflow_handler = parent_event->overflow_handler;
+
+        event->overflow_handler = overflow_handler;
+
+        if (attr->disabled)
+                event->state = PERF_EVENT_STATE_OFF;
+
+        pmu = NULL;
+
+        hwc = &event->hw;
+        hwc->sample_period = attr->sample_period;
+        if (attr->freq && attr->sample_freq)
+                hwc->sample_period = 1;
+        hwc->last_period = hwc->sample_period;
+
+        local64_set(&hwc->period_left, hwc->sample_period);
+
+        /*
+         * we currently do not support PERF_FORMAT_GROUP on inherited events
+         */
+        if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP))
+                goto done;
+
+        pmu = perf_init_event(event);
+
+done:
+        err = 0;
+        if (!pmu)
+                err = -EINVAL;
+        else if (IS_ERR(pmu))
+                err = PTR_ERR(pmu);
+
+        if (err) {
+                if (event->ns)
+                        put_pid_ns(event->ns);
+                kfree(event);
+                return ERR_PTR(err);
+        }
+
+        event->pmu = pmu;
+
+        if (!event->parent) {
+                if (event->attach_state & PERF_ATTACH_TASK)
+                        jump_label_inc(&perf_sched_events);
+                if (event->attr.mmap || event->attr.mmap_data)
+                        atomic_inc(&nr_mmap_events);
+                if (event->attr.comm)
+                        atomic_inc(&nr_comm_events);
+                if (event->attr.task)
+                        atomic_inc(&nr_task_events);
+                if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) {
+                        err = get_callchain_buffers();
+                        if (err) {
+                                free_event(event);
+                                return ERR_PTR(err);
+                        }
+                }
+        }
+
+        return event;
+}
+
+static int perf_copy_attr(struct perf_event_attr __user *uattr,
+                          struct perf_event_attr *attr)
+{
+        u32 size;
+        int ret;
+
+        if (!access_ok(VERIFY_WRITE, uattr, PERF_ATTR_SIZE_VER0))
+                return -EFAULT;
+
+        /*
+         * zero the full structure, so that a short copy will be nice.
+         */
+        memset(attr, 0, sizeof(*attr));
+
+        ret = get_user(size, &uattr->size);
+        if (ret)
+                return ret;
+
+        if (size > PAGE_SIZE)   /* silly large */
+                goto err_size;
+
+        if (!size)              /* abi compat */
+                size = PERF_ATTR_SIZE_VER0;
+
+        if (size < PERF_ATTR_SIZE_VER0)
+                goto err_size;
+
+        /*
+         * If we're handed a bigger struct than we know of,
+         * ensure all the unknown bits are 0 - i.e. new
+         * user-space does not rely on any kernel feature
+         * extensions we dont know about yet.
+         */
+        if (size > sizeof(*attr)) {
+                unsigned char __user *addr;
+                unsigned char __user *end;
+                unsigned char val;
+
+                addr = (void __user *)uattr + sizeof(*attr);
+                end  = (void __user *)uattr + size;
+
+                for (; addr < end; addr++) {
+                        ret = get_user(val, addr);
+                        if (ret)
+                                return ret;
+                        if (val)
+                                goto err_size;
+                }
+                size = sizeof(*attr);
+        }
+
+        ret = copy_from_user(attr, uattr, size);
+        if (ret)
+                return -EFAULT;
+
+        /*
+         * If the type exists, the corresponding creation will verify
+         * the attr->config.
+         */
+        if (attr->type >= PERF_TYPE_MAX)
+                return -EINVAL;
+
+        if (attr->__reserved_1)
+                return -EINVAL;
+
+        if (attr->sample_type & ~(PERF_SAMPLE_MAX-1))
+                return -EINVAL;
+
+        if (attr->read_format & ~(PERF_FORMAT_MAX-1))
+                return -EINVAL;
+
+out:
+        return ret;
+
+err_size:
+        put_user(sizeof(*attr), &uattr->size);
+        ret = -E2BIG;
+        goto out;
+}
+
+static int
+perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
+{
+        struct perf_buffer *buffer = NULL, *old_buffer = NULL;
+        int ret = -EINVAL;
+
+        if (!output_event)
+                goto set;
+
+        /* don't allow circular references */
+        if (event == output_event)
+                goto out;
+
+        /*
+         * Don't allow cross-cpu buffers
+         */
+        if (output_event->cpu != event->cpu)
+                goto out;
+
+        /*
+         * If its not a per-cpu buffer, it must be the same task.
+         */
+        if (output_event->cpu == -1 && output_event->ctx != event->ctx)
+                goto out;
+
+set:
+        mutex_lock(&event->mmap_mutex);
+        /* Can't redirect output if we've got an active mmap() */
+        if (atomic_read(&event->mmap_count))
+                goto unlock;
+
+        if (output_event) {
+                /* get the buffer we want to redirect to */
+                buffer = perf_buffer_get(output_event);
+                if (!buffer)
+                        goto unlock;
+        }
+
+        old_buffer = event->buffer;
+        rcu_assign_pointer(event->buffer, buffer);
+        ret = 0;
+unlock:
+        mutex_unlock(&event->mmap_mutex);
+
+        if (old_buffer)
+                perf_buffer_put(old_buffer);
+out:
+        return ret;
+}
+
+/**
+ * sys_perf_event_open - open a performance event, associate it to a task/cpu
+ *
+ * @attr_uptr:  event_id type attributes for monitoring/sampling
+ * @pid:                target pid
+ * @cpu:                target cpu
+ * @group_fd:           group leader event fd
+ */
+SYSCALL_DEFINE5(perf_event_open,
+                struct perf_event_attr __user *, attr_uptr,
+                pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
+{
+        struct perf_event *group_leader = NULL, *output_event = NULL;
+        struct perf_event *event, *sibling;
+        struct perf_event_attr attr;
+        struct perf_event_context *ctx;
+        struct file *event_file = NULL;
+        struct file *group_file = NULL;
+        struct task_struct *task = NULL;
+        struct pmu *pmu;
+        int event_fd;
+        int move_group = 0;
+        int fput_needed = 0;
+        int err;
+
+        /* for future expandability... */
+        if (flags & ~PERF_FLAG_ALL)
+                return -EINVAL;
+
+        err = perf_copy_attr(attr_uptr, &attr);
+        if (err)
+                return err;
+
+        if (!attr.exclude_kernel) {
+                if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
+                        return -EACCES;
+        }
+
+        if (attr.freq) {
+                if (attr.sample_freq > sysctl_perf_event_sample_rate)
+                        return -EINVAL;
+        }
+
+        /*
+         * In cgroup mode, the pid argument is used to pass the fd
+         * opened to the cgroup directory in cgroupfs. The cpu argument
+         * designates the cpu on which to monitor threads from that
+         * cgroup.
+         */
+        if ((flags & PERF_FLAG_PID_CGROUP) && (pid == -1 || cpu == -1))
+                return -EINVAL;
+
+        event_fd = get_unused_fd_flags(O_RDWR);
+        if (event_fd < 0)
+                return event_fd;
+
+        if (group_fd != -1) {
+                group_leader = perf_fget_light(group_fd, &fput_needed);
+                if (IS_ERR(group_leader)) {
+                        err = PTR_ERR(group_leader);
+                        goto err_fd;
+                }
+                group_file = group_leader->filp;
+                if (flags & PERF_FLAG_FD_OUTPUT)
+                        output_event = group_leader;
+                if (flags & PERF_FLAG_FD_NO_GROUP)
+                        group_leader = NULL;
+        }
+
+        if (pid != -1 && !(flags & PERF_FLAG_PID_CGROUP)) {
+                task = find_lively_task_by_vpid(pid);
+                if (IS_ERR(task)) {
+                        err = PTR_ERR(task);
+                        goto err_group_fd;
+                }
+        }
+
+        event = perf_event_alloc(&attr, cpu, task, group_leader, NULL, NULL);
+        if (IS_ERR(event)) {
+                err = PTR_ERR(event);
+                goto err_task;
+        }
+
+        if (flags & PERF_FLAG_PID_CGROUP) {
+                err = perf_cgroup_connect(pid, event, &attr, group_leader);
+                if (err)
+                        goto err_alloc;
+                /*
+                 * one more event:
+                 * - that has cgroup constraint on event->cpu
+                 * - that may need work on context switch
+                 */
+                atomic_inc(&per_cpu(perf_cgroup_events, event->cpu));
+                jump_label_inc(&perf_sched_events);
+        }
+
+        /*
+         * Special case software events and allow them to be part of
+         * any hardware group.
+         */
+        pmu = event->pmu;
+
+        if (group_leader &&
+            (is_software_event(event) != is_software_event(group_leader))) {
+                if (is_software_event(event)) {
+                        /*
+                         * If event and group_leader are not both a software
+                         * event, and event is, then group leader is not.
+                         *
+                         * Allow the addition of software events to !software
+                         * groups, this is safe because software events never
+                         * fail to schedule.
+                         */
+                        pmu = group_leader->pmu;
+                } else if (is_software_event(group_leader) &&
+                           (group_leader->group_flags & PERF_GROUP_SOFTWARE)) {
+                        /*
+                         * In case the group is a pure software group, and we
+                         * try to add a hardware event, move the whole group to
+                         * the hardware context.
+                         */
+                        move_group = 1;
+                }
+        }
+
+        /*
+         * Get the target context (task or percpu):
+         */
+        ctx = find_get_context(pmu, task, cpu);
+        if (IS_ERR(ctx)) {
+                err = PTR_ERR(ctx);
+                goto err_alloc;
+        }
+
+        if (task) {
+                put_task_struct(task);
+                task = NULL;
+        }
+
+        /*
+         * Look up the group leader (we will attach this event to it):
+         */
+        if (group_leader) {
+                err = -EINVAL;
+
+                /*
+                 * Do not allow a recursive hierarchy (this new sibling
+                 * becoming part of another group-sibling):
+                 */
+                if (group_leader->group_leader != group_leader)
+                        goto err_context;
+                /*
+                 * Do not allow to attach to a group in a different
+                 * task or CPU context:
+                 */
+                if (move_group) {
+                        if (group_leader->ctx->type != ctx->type)
+                                goto err_context;
+                } else {
+                        if (group_leader->ctx != ctx)
+                                goto err_context;
+                }
+
+                /*
+                 * Only a group leader can be exclusive or pinned
+                 */
+                if (attr.exclusive || attr.pinned)
+                        goto err_context;
+        }
+
+        if (output_event) {
+                err = perf_event_set_output(event, output_event);
+                if (err)
+                        goto err_context;
+        }
+
+        event_file = anon_inode_getfile("[perf_event]", &perf_fops, event, O_RDWR);
+        if (IS_ERR(event_file)) {
+                err = PTR_ERR(event_file);
+                goto err_context;
+        }
+
+        if (move_group) {
+                struct perf_event_context *gctx = group_leader->ctx;
+
+                mutex_lock(&gctx->mutex);
+                perf_remove_from_context(group_leader);
+                list_for_each_entry(sibling, &group_leader->sibling_list,
+                                    group_entry) {
+                        perf_remove_from_context(sibling);
+                        put_ctx(gctx);
+                }
+                mutex_unlock(&gctx->mutex);
+                put_ctx(gctx);
+        }
+
+        event->filp = event_file;
+        WARN_ON_ONCE(ctx->parent_ctx);
+        mutex_lock(&ctx->mutex);
+
+        if (move_group) {
+                perf_install_in_context(ctx, group_leader, cpu);
+                get_ctx(ctx);
+                list_for_each_entry(sibling, &group_leader->sibling_list,
+                                    group_entry) {
+                        perf_install_in_context(ctx, sibling, cpu);
+                        get_ctx(ctx);
+                }
+        }
+
+        perf_install_in_context(ctx, event, cpu);
+        ++ctx->generation;
+        perf_unpin_context(ctx);
+        mutex_unlock(&ctx->mutex);
+
+        event->owner = current;
+
+        mutex_lock(&current->perf_event_mutex);
+        list_add_tail(&event->owner_entry, &current->perf_event_list);
+        mutex_unlock(&current->perf_event_mutex);
+
+        /*
+         * Precalculate sample_data sizes
+         */
+        perf_event__header_size(event);
+        perf_event__id_header_size(event);
+
+        /*
+         * Drop the reference on the group_event after placing the
+         * new event on the sibling_list. This ensures destruction
+         * of the group leader will find the pointer to itself in
+         * perf_group_detach().
+         */
+        fput_light(group_file, fput_needed);
+        fd_install(event_fd, event_file);
+        return event_fd;
+
+err_context:
+        perf_unpin_context(ctx);
+        put_ctx(ctx);
+err_alloc:
+        free_event(event);
+err_task:
+        if (task)
+                put_task_struct(task);
+err_group_fd:
+        fput_light(group_file, fput_needed);
+err_fd:
+        put_unused_fd(event_fd);
+        return err;
+}
+
+/**
+ * perf_event_create_kernel_counter
+ *
+ * @attr: attributes of the counter to create
+ * @cpu: cpu in which the counter is bound
+ * @task: task to profile (NULL for percpu)
+ */
+struct perf_event *
+perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
+                                 struct task_struct *task,
+                                 perf_overflow_handler_t overflow_handler)
+{
+        struct perf_event_context *ctx;
+        struct perf_event *event;
+        int err;
+
+        /*
+         * Get the target context (task or percpu):
+         */
+
+        event = perf_event_alloc(attr, cpu, task, NULL, NULL, overflow_handler);
+        if (IS_ERR(event)) {
+                err = PTR_ERR(event);
+                goto err;
+        }
+
+        ctx = find_get_context(event->pmu, task, cpu);
+        if (IS_ERR(ctx)) {
+                err = PTR_ERR(ctx);
+                goto err_free;
+        }
+
+        event->filp = NULL;
+        WARN_ON_ONCE(ctx->parent_ctx);
+        mutex_lock(&ctx->mutex);
+        perf_install_in_context(ctx, event, cpu);
+        ++ctx->generation;
+        perf_unpin_context(ctx);
+        mutex_unlock(&ctx->mutex);
+
+        return event;
+
+err_free:
+        free_event(event);
+err:
+        return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
+
+static void sync_child_event(struct perf_event *child_event,
+                               struct task_struct *child)
+{
+        struct perf_event *parent_event = child_event->parent;
+        u64 child_val;
+
+        if (child_event->attr.inherit_stat)
+                perf_event_read_event(child_event, child);
+
+        child_val = perf_event_count(child_event);
+
+        /*
+         * Add back the child's count to the parent's count:
+         */
+        atomic64_add(child_val, &parent_event->child_count);
+        atomic64_add(child_event->total_time_enabled,
+                     &parent_event->child_total_time_enabled);
+        atomic64_add(child_event->total_time_running,
+                     &parent_event->child_total_time_running);
+
+        /*
+         * Remove this event from the parent's list
+         */
+        WARN_ON_ONCE(parent_event->ctx->parent_ctx);
+        mutex_lock(&parent_event->child_mutex);
+        list_del_init(&child_event->child_list);
+        mutex_unlock(&parent_event->child_mutex);
+
+        /*
+         * Release the parent event, if this was the last
+         * reference to it.
+         */
+        fput(parent_event->filp);
+}
+
+static void
+__perf_event_exit_task(struct perf_event *child_event,
+                         struct perf_event_context *child_ctx,
+                         struct task_struct *child)
+{
+        if (child_event->parent) {
+                raw_spin_lock_irq(&child_ctx->lock);
+                perf_group_detach(child_event);
+                raw_spin_unlock_irq(&child_ctx->lock);
+        }
+
+        perf_remove_from_context(child_event);
+
+        /*
+         * It can happen that the parent exits first, and has events
+         * that are still around due to the child reference. These
+         * events need to be zapped.
+         */
+        if (child_event->parent) {
+                sync_child_event(child_event, child);
+                free_event(child_event);
+        }
+}
+
+static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
+{
+        struct perf_event *child_event, *tmp;
+        struct perf_event_context *child_ctx;
+        unsigned long flags;
+
+        if (likely(!child->perf_event_ctxp[ctxn])) {
+                perf_event_task(child, NULL, 0);
+                return;
+        }
+
+        local_irq_save(flags);
+        /*
+         * We can't reschedule here because interrupts are disabled,
+         * and either child is current or it is a task that can't be
+         * scheduled, so we are now safe from rescheduling changing
+         * our context.
+         */
+        child_ctx = rcu_dereference_raw(child->perf_event_ctxp[ctxn]);
+        task_ctx_sched_out(child_ctx, EVENT_ALL);
+
+        /*
+         * Take the context lock here so that if find_get_context is
+         * reading child->perf_event_ctxp, we wait until it has
+         * incremented the context's refcount before we do put_ctx below.
+         */
+        raw_spin_lock(&child_ctx->lock);
+        child->perf_event_ctxp[ctxn] = NULL;
+        /*
+         * If this context is a clone; unclone it so it can't get
+         * swapped to another process while we're removing all
+         * the events from it.
+         */
+        unclone_ctx(child_ctx);
+        update_context_time(child_ctx);
+        raw_spin_unlock_irqrestore(&child_ctx->lock, flags);
+
+        /*
+         * Report the task dead after unscheduling the events so that we
+         * won't get any samples after PERF_RECORD_EXIT. We can however still
+         * get a few PERF_RECORD_READ events.
+         */
+        perf_event_task(child, child_ctx, 0);
+
+        /*
+         * We can recurse on the same lock type through:
+         *
+         *   __perf_event_exit_task()
+         *     sync_child_event()
+         *       fput(parent_event->filp)
+         *         perf_release()
+         *           mutex_lock(&ctx->mutex)
+         *
+         * But since its the parent context it won't be the same instance.
+         */
+        mutex_lock(&child_ctx->mutex);
+
+again:
+        list_for_each_entry_safe(child_event, tmp, &child_ctx->pinned_groups,
+                                 group_entry)
+                __perf_event_exit_task(child_event, child_ctx, child);
+
+        list_for_each_entry_safe(child_event, tmp, &child_ctx->flexible_groups,
+                                 group_entry)
+                __perf_event_exit_task(child_event, child_ctx, child);
+
+        /*
+         * If the last event was a group event, it will have appended all
+         * its siblings to the list, but we obtained 'tmp' before that which
+         * will still point to the list head terminating the iteration.
+         */
+        if (!list_empty(&child_ctx->pinned_groups) ||
+            !list_empty(&child_ctx->flexible_groups))
+                goto again;
+
+        mutex_unlock(&child_ctx->mutex);
+
+        put_ctx(child_ctx);
+}
+
+/*
+ * When a child task exits, feed back event values to parent events.
+ */
+void perf_event_exit_task(struct task_struct *child)
+{
+        struct perf_event *event, *tmp;
+        int ctxn;
+
+        mutex_lock(&child->perf_event_mutex);
+        list_for_each_entry_safe(event, tmp, &child->perf_event_list,
+                                 owner_entry) {
+                list_del_init(&event->owner_entry);
+
+                /*
+                 * Ensure the list deletion is visible before we clear
+                 * the owner, closes a race against perf_release() where
+                 * we need to serialize on the owner->perf_event_mutex.
+                 */
+                smp_wmb();
+                event->owner = NULL;
+        }
+        mutex_unlock(&child->perf_event_mutex);
+
+        for_each_task_context_nr(ctxn)
+                perf_event_exit_task_context(child, ctxn);
+}
+
+static void perf_free_event(struct perf_event *event,
+                            struct perf_event_context *ctx)
+{
+        struct perf_event *parent = event->parent;
+
+        if (WARN_ON_ONCE(!parent))
+                return;
+
+        mutex_lock(&parent->child_mutex);
+        list_del_init(&event->child_list);
+        mutex_unlock(&parent->child_mutex);
+
+        fput(parent->filp);
+
+        perf_group_detach(event);
+        list_del_event(event, ctx);
+        free_event(event);
+}
+
+/*
+ * free an unexposed, unused context as created by inheritance by
+ * perf_event_init_task below, used by fork() in case of fail.
+ */
+void perf_event_free_task(struct task_struct *task)
+{
+        struct perf_event_context *ctx;
+        struct perf_event *event, *tmp;
+        int ctxn;
+
+        for_each_task_context_nr(ctxn) {
+                ctx = task->perf_event_ctxp[ctxn];
+                if (!ctx)
+                        continue;
+
+                mutex_lock(&ctx->mutex);
+again:
+                list_for_each_entry_safe(event, tmp, &ctx->pinned_groups,
+                                group_entry)
+                        perf_free_event(event, ctx);
+
+                list_for_each_entry_safe(event, tmp, &ctx->flexible_groups,
+                                group_entry)
+                        perf_free_event(event, ctx);
+
+                if (!list_empty(&ctx->pinned_groups) ||
+                                !list_empty(&ctx->flexible_groups))
+                        goto again;
+
+                mutex_unlock(&ctx->mutex);
+
+                put_ctx(ctx);
+        }
+}
+
+void perf_event_delayed_put(struct task_struct *task)
+{
+        int ctxn;
+
+        for_each_task_context_nr(ctxn)
+                WARN_ON_ONCE(task->perf_event_ctxp[ctxn]);
+}
+
+/*
+ * inherit a event from parent task to child task:
+ */
+static struct perf_event *
+inherit_event(struct perf_event *parent_event,
+              struct task_struct *parent,
+              struct perf_event_context *parent_ctx,
+              struct task_struct *child,
+              struct perf_event *group_leader,
+              struct perf_event_context *child_ctx)
+{
+        struct perf_event *child_event;
+        unsigned long flags;
+
+        /*
+         * Instead of creating recursive hierarchies of events,
+         * we link inherited events back to the original parent,
+         * which has a filp for sure, which we use as the reference
+         * count:
+         */
+        if (parent_event->parent)
+                parent_event = parent_event->parent;
+
+        child_event = perf_event_alloc(&parent_event->attr,
+                                           parent_event->cpu,
+                                           child,
+                                           group_leader, parent_event,
+                                           NULL);
+        if (IS_ERR(child_event))
+                return child_event;
+        get_ctx(child_ctx);
+
+        /*
+         * Make the child state follow the state of the parent event,
+         * not its attr.disabled bit.  We hold the parent's mutex,
+         * so we won't race with perf_event_{en, dis}able_family.
+         */
+        if (parent_event->state >= PERF_EVENT_STATE_INACTIVE)
+                child_event->state = PERF_EVENT_STATE_INACTIVE;
+        else
+                child_event->state = PERF_EVENT_STATE_OFF;
+
+        if (parent_event->attr.freq) {
+                u64 sample_period = parent_event->hw.sample_period;
+                struct hw_perf_event *hwc = &child_event->hw;
+
+                hwc->sample_period = sample_period;
+                hwc->last_period   = sample_period;
+
+                local64_set(&hwc->period_left, sample_period);
+        }
+
+        child_event->ctx = child_ctx;
+        child_event->overflow_handler = parent_event->overflow_handler;
+
+        /*
+         * Precalculate sample_data sizes
+         */
+        perf_event__header_size(child_event);
+        perf_event__id_header_size(child_event);
+
+        /*
+         * Link it up in the child's context:
+         */
+        raw_spin_lock_irqsave(&child_ctx->lock, flags);
+        add_event_to_ctx(child_event, child_ctx);
+        raw_spin_unlock_irqrestore(&child_ctx->lock, flags);
+
+        /*
+         * Get a reference to the parent filp - we will fput it
+         * when the child event exits. This is safe to do because
+         * we are in the parent and we know that the filp still
+         * exists and has a nonzero count:
+         */
+        atomic_long_inc(&parent_event->filp->f_count);
+
+        /*
+         * Link this into the parent event's child list
+         */
+        WARN_ON_ONCE(parent_event->ctx->parent_ctx);
+        mutex_lock(&parent_event->child_mutex);
+        list_add_tail(&child_event->child_list, &parent_event->child_list);
+        mutex_unlock(&parent_event->child_mutex);
+
+        return child_event;
+}
+
+static int inherit_group(struct perf_event *parent_event,
+              struct task_struct *parent,
+              struct perf_event_context *parent_ctx,
+              struct task_struct *child,
+              struct perf_event_context *child_ctx)
+{
+        struct perf_event *leader;
+        struct perf_event *sub;
+        struct perf_event *child_ctr;
+
+        leader = inherit_event(parent_event, parent, parent_ctx,
+                                 child, NULL, child_ctx);
+        if (IS_ERR(leader))
+                return PTR_ERR(leader);
+        list_for_each_entry(sub, &parent_event->sibling_list, group_entry) {
+                child_ctr = inherit_event(sub, parent, parent_ctx,
+                                            child, leader, child_ctx);
+                if (IS_ERR(child_ctr))
+                        return PTR_ERR(child_ctr);
+        }
+        return 0;
+}
+
+static int
+inherit_task_group(struct perf_event *event, struct task_struct *parent,
+                   struct perf_event_context *parent_ctx,
+                   struct task_struct *child, int ctxn,
+                   int *inherited_all)
+{
+        int ret;
+        struct perf_event_context *child_ctx;
+
+        if (!event->attr.inherit) {
+                *inherited_all = 0;
+                return 0;
+        }
+
+        child_ctx = child->perf_event_ctxp[ctxn];
+        if (!child_ctx) {
+                /*
+                 * This is executed from the parent task context, so
+                 * inherit events that have been marked for cloning.
+                 * First allocate and initialize a context for the
+                 * child.
+                 */
+
+                child_ctx = alloc_perf_context(event->pmu, child);
+                if (!child_ctx)
+                        return -ENOMEM;
+
+                child->perf_event_ctxp[ctxn] = child_ctx;
+        }
+
+        ret = inherit_group(event, parent, parent_ctx,
+                            child, child_ctx);
+
+        if (ret)
+                *inherited_all = 0;
+
+        return ret;
+}
+
+/*
+ * Initialize the perf_event context in task_struct
+ */
+int perf_event_init_context(struct task_struct *child, int ctxn)
+{
+        struct perf_event_context *child_ctx, *parent_ctx;
+        struct perf_event_context *cloned_ctx;
+        struct perf_event *event;
+        struct task_struct *parent = current;
+        int inherited_all = 1;
+        unsigned long flags;
+        int ret = 0;
+
+        if (likely(!parent->perf_event_ctxp[ctxn]))
+                return 0;
+
+        /*
+         * If the parent's context is a clone, pin it so it won't get
+         * swapped under us.
+         */
+        parent_ctx = perf_pin_task_context(parent, ctxn);
+
+        /*
+         * No need to check if parent_ctx != NULL here; since we saw
+         * it non-NULL earlier, the only reason for it to become NULL
+         * is if we exit, and since we're currently in the middle of
+         * a fork we can't be exiting at the same time.
+         */
+
+        /*
+         * Lock the parent list. No need to lock the child - not PID
+         * hashed yet and not running, so nobody can access it.
+         */
+        mutex_lock(&parent_ctx->mutex);
+
+        /*
+         * We dont have to disable NMIs - we are only looking at
+         * the list, not manipulating it:
+         */
+        list_for_each_entry(event, &parent_ctx->pinned_groups, group_entry) {
+                ret = inherit_task_group(event, parent, parent_ctx,
+                                         child, ctxn, &inherited_all);
+                if (ret)
+                        break;
+        }
+
+        /*
+         * We can't hold ctx->lock when iterating the ->flexible_group list due
+         * to allocations, but we need to prevent rotation because
+         * rotate_ctx() will change the list from interrupt context.
+         */
+        raw_spin_lock_irqsave(&parent_ctx->lock, flags);
+        parent_ctx->rotate_disable = 1;
+        raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
+
+        list_for_each_entry(event, &parent_ctx->flexible_groups, group_entry) {
+                ret = inherit_task_group(event, parent, parent_ctx,
+                                         child, ctxn, &inherited_all);
+                if (ret)
+                        break;
+        }
+
+        raw_spin_lock_irqsave(&parent_ctx->lock, flags);
+        parent_ctx->rotate_disable = 0;
+
+        child_ctx = child->perf_event_ctxp[ctxn];
+
+        if (child_ctx && inherited_all) {
+                /*
+                 * Mark the child context as a clone of the parent
+                 * context, or of whatever the parent is a clone of.
+                 *
+                 * Note that if the parent is a clone, the holding of
+                 * parent_ctx->lock avoids it from being uncloned.
+                 */
+                cloned_ctx = parent_ctx->parent_ctx;
+                if (cloned_ctx) {
+                        child_ctx->parent_ctx = cloned_ctx;
+                        child_ctx->parent_gen = parent_ctx->parent_gen;
+                } else {
+                        child_ctx->parent_ctx = parent_ctx;
+                        child_ctx->parent_gen = parent_ctx->generation;
+                }
+                get_ctx(child_ctx->parent_ctx);
+        }
+
+        raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
+        mutex_unlock(&parent_ctx->mutex);
+
+        perf_unpin_context(parent_ctx);
+        put_ctx(parent_ctx);
+
+        return ret;
+}
+
+/*
+ * Initialize the perf_event context in task_struct
+ */
+int perf_event_init_task(struct task_struct *child)
+{
+        int ctxn, ret;
+
+        memset(child->perf_event_ctxp, 0, sizeof(child->perf_event_ctxp));
+        mutex_init(&child->perf_event_mutex);
+        INIT_LIST_HEAD(&child->perf_event_list);
+
+        for_each_task_context_nr(ctxn) {
+                ret = perf_event_init_context(child, ctxn);
+                if (ret)
+                        return ret;
+        }
+
+        return 0;
+}
+
+static void __init perf_event_init_all_cpus(void)
+{
+        struct swevent_htable *swhash;
+        int cpu;
+
+        for_each_possible_cpu(cpu) {
+                swhash = &per_cpu(swevent_htable, cpu);
+                mutex_init(&swhash->hlist_mutex);
+                INIT_LIST_HEAD(&per_cpu(rotation_list, cpu));
+        }
+}
+
+static void __cpuinit perf_event_init_cpu(int cpu)
+{
+        struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
+
+        mutex_lock(&swhash->hlist_mutex);
+        if (swhash->hlist_refcount > 0) {
+                struct swevent_hlist *hlist;
+
+                hlist = kzalloc_node(sizeof(*hlist), GFP_KERNEL, cpu_to_node(cpu));
+                WARN_ON(!hlist);
+                rcu_assign_pointer(swhash->swevent_hlist, hlist);
+        }
+        mutex_unlock(&swhash->hlist_mutex);
+}
+
+#if defined CONFIG_HOTPLUG_CPU || defined CONFIG_KEXEC
+static void perf_pmu_rotate_stop(struct pmu *pmu)
+{
+        struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+
+        WARN_ON(!irqs_disabled());
+
+        list_del_init(&cpuctx->rotation_list);
+}
+
+static void __perf_event_exit_context(void *__info)
+{
+        struct perf_event_context *ctx = __info;
+        struct perf_event *event, *tmp;
+
+        perf_pmu_rotate_stop(ctx->pmu);
+
+        list_for_each_entry_safe(event, tmp, &ctx->pinned_groups, group_entry)
+                __perf_remove_from_context(event);
+        list_for_each_entry_safe(event, tmp, &ctx->flexible_groups, group_entry)
+                __perf_remove_from_context(event);
+}
+
+static void perf_event_exit_cpu_context(int cpu)
+{
+        struct perf_event_context *ctx;
+        struct pmu *pmu;
+        int idx;
+
+        idx = srcu_read_lock(&pmus_srcu);
+        list_for_each_entry_rcu(pmu, &pmus, entry) {
+                ctx = &per_cpu_ptr(pmu->pmu_cpu_context, cpu)->ctx;
+
+                mutex_lock(&ctx->mutex);
+                smp_call_function_single(cpu, __perf_event_exit_context, ctx, 1);
+                mutex_unlock(&ctx->mutex);
+        }
+        srcu_read_unlock(&pmus_srcu, idx);
+}
+
+static void perf_event_exit_cpu(int cpu)
+{
+        struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
+
+        mutex_lock(&swhash->hlist_mutex);
+        swevent_hlist_release(swhash);
+        mutex_unlock(&swhash->hlist_mutex);
+
+        perf_event_exit_cpu_context(cpu);
+}
+#else
+static inline void perf_event_exit_cpu(int cpu) { }
+#endif
+
+static int
+perf_reboot(struct notifier_block *notifier, unsigned long val, void *v)
+{
+        int cpu;
+
+        for_each_online_cpu(cpu)
+                perf_event_exit_cpu(cpu);
+
+        return NOTIFY_OK;
+}
+
+/*
+ * Run the perf reboot notifier at the very last possible moment so that
+ * the generic watchdog code runs as long as possible.
+ */
+static struct notifier_block perf_reboot_notifier = {
+        .notifier_call = perf_reboot,
+        .priority = INT_MIN,
+};
+
+static int __cpuinit
+perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
+{
+        unsigned int cpu = (long)hcpu;
+
+        switch (action & ~CPU_TASKS_FROZEN) {
+
+        case CPU_UP_PREPARE:
+        case CPU_DOWN_FAILED:
+                perf_event_init_cpu(cpu);
+                break;
+
+        case CPU_UP_CANCELED:
+        case CPU_DOWN_PREPARE:
+                perf_event_exit_cpu(cpu);
+                break;
+
+        default:
+                break;
+        }
+
+        return NOTIFY_OK;
+}
+
+void __init perf_event_init(void)
+{
+        int ret;
+
+        idr_init(&pmu_idr);
+
+        perf_event_init_all_cpus();
+        init_srcu_struct(&pmus_srcu);
+        perf_pmu_register(&perf_swevent, "software", PERF_TYPE_SOFTWARE);
+        perf_pmu_register(&perf_cpu_clock, NULL, -1);
+        perf_pmu_register(&perf_task_clock, NULL, -1);
+        perf_tp_register();
+        perf_cpu_notifier(perf_cpu_notify);
+        register_reboot_notifier(&perf_reboot_notifier);
+
+        ret = init_hw_breakpoint();
+        WARN(ret, "hw_breakpoint initialization failed with: %d", ret);
+}
+
+static int __init perf_event_sysfs_init(void)
+{
+        struct pmu *pmu;
+        int ret;
+
+        mutex_lock(&pmus_lock);
+
+        ret = bus_register(&pmu_bus);
+        if (ret)
+                goto unlock;
+
+        list_for_each_entry(pmu, &pmus, entry) {
+                if (!pmu->name || pmu->type < 0)
+                        continue;
+
+                ret = pmu_dev_alloc(pmu);
+                WARN(ret, "Failed to register pmu: %s, reason %d\n", pmu->name, ret);
+        }
+        pmu_bus_running = 1;
+        ret = 0;
+
+unlock:
+        mutex_unlock(&pmus_lock);
+
+        return ret;
+}
+device_initcall(perf_event_sysfs_init);
+
+#ifdef CONFIG_CGROUP_PERF
+static struct cgroup_subsys_state *perf_cgroup_create(
+        struct cgroup_subsys *ss, struct cgroup *cont)
+{
+        struct perf_cgroup *jc;
+
+        jc = kzalloc(sizeof(*jc), GFP_KERNEL);
+        if (!jc)
+                return ERR_PTR(-ENOMEM);
+
+        jc->info = alloc_percpu(struct perf_cgroup_info);
+        if (!jc->info) {
+                kfree(jc);
+                return ERR_PTR(-ENOMEM);
+        }
+
+        return &jc->css;
+}
+
+static void perf_cgroup_destroy(struct cgroup_subsys *ss,
+                                struct cgroup *cont)
+{
+        struct perf_cgroup *jc;
+        jc = container_of(cgroup_subsys_state(cont, perf_subsys_id),
+                          struct perf_cgroup, css);
+        free_percpu(jc->info);
+        kfree(jc);
+}
+
+static int __perf_cgroup_move(void *info)
+{
+        struct task_struct *task = info;
+        perf_cgroup_switch(task, PERF_CGROUP_SWOUT | PERF_CGROUP_SWIN);
+        return 0;
+}
+
+static void perf_cgroup_move(struct task_struct *task)
+{
+        task_function_call(task, __perf_cgroup_move, task);
+}
+
+static void perf_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
+                struct cgroup *old_cgrp, struct task_struct *task,
+                bool threadgroup)
+{
+        perf_cgroup_move(task);
+        if (threadgroup) {
+                struct task_struct *c;
+                rcu_read_lock();
+                list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
+                        perf_cgroup_move(c);
+                }
+                rcu_read_unlock();
+        }
+}
+
+static void perf_cgroup_exit(struct cgroup_subsys *ss, struct cgroup *cgrp,
+                struct cgroup *old_cgrp, struct task_struct *task)
+{
+        /*
+         * cgroup_exit() is called in the copy_process() failure path.
+         * Ignore this case since the task hasn't ran yet, this avoids
+         * trying to poke a half freed task state from generic code.
+         */
+        if (!(task->flags & PF_EXITING))
+                return;
+
+        perf_cgroup_move(task);
+}
+
+struct cgroup_subsys perf_subsys = {
+        .name           = "perf_event",
+        .subsys_id      = perf_subsys_id,
+        .create         = perf_cgroup_create,
+        .destroy        = perf_cgroup_destroy,
+        .exit           = perf_cgroup_exit,
+        .attach         = perf_cgroup_attach,
+};
+#endif /* CONFIG_CGROUP_PERF */
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
new file mode 100644
index 000000000000..086adf25a55e
--- /dev/null
+++ b/kernel/events/hw_breakpoint.c
@@ -0,0 +1,659 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) 2007 Alan Stern
+ * Copyright (C) IBM Corporation, 2009
+ * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com>
+ *
+ * Thanks to Ingo Molnar for his many suggestions.
+ *
+ * Authors: Alan Stern <stern@rowland.harvard.edu>
+ *          K.Prasad <prasad@linux.vnet.ibm.com>
+ *          Frederic Weisbecker <fweisbec@gmail.com>
+ */
+
+/*
+ * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
+ * using the CPU's debug registers.
+ * This file contains the arch-independent routines.
+ */
+
+#include <linux/irqflags.h>
+#include <linux/kallsyms.h>
+#include <linux/notifier.h>
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/percpu.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+
+#include <linux/hw_breakpoint.h>
+
+
+/*
+ * Constraints data
+ */
+
+/* Number of pinned cpu breakpoints in a cpu */
+static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned[TYPE_MAX]);
+
+/* Number of pinned task breakpoints in a cpu */
+static DEFINE_PER_CPU(unsigned int *, nr_task_bp_pinned[TYPE_MAX]);
+
+/* Number of non-pinned cpu/task breakpoints in a cpu */
+static DEFINE_PER_CPU(unsigned int, nr_bp_flexible[TYPE_MAX]);
+
+static int nr_slots[TYPE_MAX];
+
+/* Keep track of the breakpoints attached to tasks */
+static LIST_HEAD(bp_task_head);
+
+static int constraints_initialized;
+
+/* Gather the number of total pinned and un-pinned bp in a cpuset */
+struct bp_busy_slots {
+        unsigned int pinned;
+        unsigned int flexible;
+};
+
+/* Serialize accesses to the above constraints */
+static DEFINE_MUTEX(nr_bp_mutex);
+
+__weak int hw_breakpoint_weight(struct perf_event *bp)
+{
+        return 1;
+}
+
+static inline enum bp_type_idx find_slot_idx(struct perf_event *bp)
+{
+        if (bp->attr.bp_type & HW_BREAKPOINT_RW)
+                return TYPE_DATA;
+
+        return TYPE_INST;
+}
+
+/*
+ * Report the maximum number of pinned breakpoints a task
+ * have in this cpu
+ */
+static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type)
+{
+        int i;
+        unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu);
+
+        for (i = nr_slots[type] - 1; i >= 0; i--) {
+                if (tsk_pinned[i] > 0)
+                        return i + 1;
+        }
+
+        return 0;
+}
+
+/*
+ * Count the number of breakpoints of the same type and same task.
+ * The given event must be not on the list.
+ */
+static int task_bp_pinned(struct perf_event *bp, enum bp_type_idx type)
+{
+        struct task_struct *tsk = bp->hw.bp_target;
+        struct perf_event *iter;
+        int count = 0;
+
+        list_for_each_entry(iter, &bp_task_head, hw.bp_list) {
+                if (iter->hw.bp_target == tsk && find_slot_idx(iter) == type)
+                        count += hw_breakpoint_weight(iter);
+        }
+
+        return count;
+}
+
+/*
+ * Report the number of pinned/un-pinned breakpoints we have in
+ * a given cpu (cpu > -1) or in all of them (cpu = -1).
+ */
+static void
+fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp,
+                    enum bp_type_idx type)
+{
+        int cpu = bp->cpu;
+        struct task_struct *tsk = bp->hw.bp_target;
+
+        if (cpu >= 0) {
+                slots->pinned = per_cpu(nr_cpu_bp_pinned[type], cpu);
+                if (!tsk)
+                        slots->pinned += max_task_bp_pinned(cpu, type);
+                else
+                        slots->pinned += task_bp_pinned(bp, type);
+                slots->flexible = per_cpu(nr_bp_flexible[type], cpu);
+
+                return;
+        }
+
+        for_each_online_cpu(cpu) {
+                unsigned int nr;
+
+                nr = per_cpu(nr_cpu_bp_pinned[type], cpu);
+                if (!tsk)
+                        nr += max_task_bp_pinned(cpu, type);
+                else
+                        nr += task_bp_pinned(bp, type);
+
+                if (nr > slots->pinned)
+                        slots->pinned = nr;
+
+                nr = per_cpu(nr_bp_flexible[type], cpu);
+
+                if (nr > slots->flexible)
+                        slots->flexible = nr;
+        }
+}
+
+/*
+ * For now, continue to consider flexible as pinned, until we can
+ * ensure no flexible event can ever be scheduled before a pinned event
+ * in a same cpu.
+ */
+static void
+fetch_this_slot(struct bp_busy_slots *slots, int weight)
+{
+        slots->pinned += weight;
+}
+
+/*
+ * Add a pinned breakpoint for the given task in our constraint table
+ */
+static void toggle_bp_task_slot(struct perf_event *bp, int cpu, bool enable,
+                                enum bp_type_idx type, int weight)
+{
+        unsigned int *tsk_pinned;
+        int old_count = 0;
+        int old_idx = 0;
+        int idx = 0;
+
+        old_count = task_bp_pinned(bp, type);
+        old_idx = old_count - 1;
+        idx = old_idx + weight;
+
+        /* tsk_pinned[n] is the number of tasks having n breakpoints */
+        tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu);
+        if (enable) {
+                tsk_pinned[idx]++;
+                if (old_count > 0)
+                        tsk_pinned[old_idx]--;
+        } else {
+                tsk_pinned[idx]--;
+                if (old_count > 0)
+                        tsk_pinned[old_idx]++;
+        }
+}
+
+/*
+ * Add/remove the given breakpoint in our constraint table
+ */
+static void
+toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type,
+               int weight)
+{
+        int cpu = bp->cpu;
+        struct task_struct *tsk = bp->hw.bp_target;
+
+        /* Pinned counter cpu profiling */
+        if (!tsk) {
+
+                if (enable)
+                        per_cpu(nr_cpu_bp_pinned[type], bp->cpu) += weight;
+                else
+                        per_cpu(nr_cpu_bp_pinned[type], bp->cpu) -= weight;
+                return;
+        }
+
+        /* Pinned counter task profiling */
+
+        if (!enable)
+                list_del(&bp->hw.bp_list);
+
+        if (cpu >= 0) {
+                toggle_bp_task_slot(bp, cpu, enable, type, weight);
+        } else {
+                for_each_online_cpu(cpu)
+                        toggle_bp_task_slot(bp, cpu, enable, type, weight);
+        }
+
+        if (enable)
+                list_add_tail(&bp->hw.bp_list, &bp_task_head);
+}
+
+/*
+ * Function to perform processor-specific cleanup during unregistration
+ */
+__weak void arch_unregister_hw_breakpoint(struct perf_event *bp)
+{
+        /*
+         * A weak stub function here for those archs that don't define
+         * it inside arch/.../kernel/hw_breakpoint.c
+         */
+}
+
+/*
+ * Contraints to check before allowing this new breakpoint counter:
+ *
+ *  == Non-pinned counter == (Considered as pinned for now)
+ *
+ *   - If attached to a single cpu, check:
+ *
+ *       (per_cpu(nr_bp_flexible, cpu) || (per_cpu(nr_cpu_bp_pinned, cpu)
+ *           + max(per_cpu(nr_task_bp_pinned, cpu)))) < HBP_NUM
+ *
+ *       -> If there are already non-pinned counters in this cpu, it means
+ *          there is already a free slot for them.
+ *          Otherwise, we check that the maximum number of per task
+ *          breakpoints (for this cpu) plus the number of per cpu breakpoint
+ *          (for this cpu) doesn't cover every registers.
+ *
+ *   - If attached to every cpus, check:
+ *
+ *       (per_cpu(nr_bp_flexible, *) || (max(per_cpu(nr_cpu_bp_pinned, *))
+ *           + max(per_cpu(nr_task_bp_pinned, *)))) < HBP_NUM
+ *
+ *       -> This is roughly the same, except we check the number of per cpu
+ *          bp for every cpu and we keep the max one. Same for the per tasks
+ *          breakpoints.
+ *
+ *
+ * == Pinned counter ==
+ *
+ *   - If attached to a single cpu, check:
+ *
+ *       ((per_cpu(nr_bp_flexible, cpu) > 1) + per_cpu(nr_cpu_bp_pinned, cpu)
+ *            + max(per_cpu(nr_task_bp_pinned, cpu))) < HBP_NUM
+ *
+ *       -> Same checks as before. But now the nr_bp_flexible, if any, must keep
+ *          one register at least (or they will never be fed).
+ *
+ *   - If attached to every cpus, check:
+ *
+ *       ((per_cpu(nr_bp_flexible, *) > 1) + max(per_cpu(nr_cpu_bp_pinned, *))
+ *            + max(per_cpu(nr_task_bp_pinned, *))) < HBP_NUM
+ */
+static int __reserve_bp_slot(struct perf_event *bp)
+{
+        struct bp_busy_slots slots = {0};
+        enum bp_type_idx type;
+        int weight;
+
+        /* We couldn't initialize breakpoint constraints on boot */
+        if (!constraints_initialized)
+                return -ENOMEM;
+
+        /* Basic checks */
+        if (bp->attr.bp_type == HW_BREAKPOINT_EMPTY ||
+            bp->attr.bp_type == HW_BREAKPOINT_INVALID)
+                return -EINVAL;
+
+        type = find_slot_idx(bp);
+        weight = hw_breakpoint_weight(bp);
+
+        fetch_bp_busy_slots(&slots, bp, type);
+        /*
+         * Simulate the addition of this breakpoint to the constraints
+         * and see the result.
+         */
+        fetch_this_slot(&slots, weight);
+
+        /* Flexible counters need to keep at least one slot */
+        if (slots.pinned + (!!slots.flexible) > nr_slots[type])
+                return -ENOSPC;
+
+        toggle_bp_slot(bp, true, type, weight);
+
+        return 0;
+}
+
+int reserve_bp_slot(struct perf_event *bp)
+{
+        int ret;
+
+        mutex_lock(&nr_bp_mutex);
+
+        ret = __reserve_bp_slot(bp);
+
+        mutex_unlock(&nr_bp_mutex);
+
+        return ret;
+}
+
+static void __release_bp_slot(struct perf_event *bp)
+{
+        enum bp_type_idx type;
+        int weight;
+
+        type = find_slot_idx(bp);
+        weight = hw_breakpoint_weight(bp);
+        toggle_bp_slot(bp, false, type, weight);
+}
+
+void release_bp_slot(struct perf_event *bp)
+{
+        mutex_lock(&nr_bp_mutex);
+
+        arch_unregister_hw_breakpoint(bp);
+        __release_bp_slot(bp);
+
+        mutex_unlock(&nr_bp_mutex);
+}
+
+/*
+ * Allow the kernel debugger to reserve breakpoint slots without
+ * taking a lock using the dbg_* variant of for the reserve and
+ * release breakpoint slots.
+ */
+int dbg_reserve_bp_slot(struct perf_event *bp)
+{
+        if (mutex_is_locked(&nr_bp_mutex))
+                return -1;
+
+        return __reserve_bp_slot(bp);
+}
+
+int dbg_release_bp_slot(struct perf_event *bp)
+{
+        if (mutex_is_locked(&nr_bp_mutex))
+                return -1;
+
+        __release_bp_slot(bp);
+
+        return 0;
+}
+
+static int validate_hw_breakpoint(struct perf_event *bp)
+{
+        int ret;
+
+        ret = arch_validate_hwbkpt_settings(bp);
+        if (ret)
+                return ret;
+
+        if (arch_check_bp_in_kernelspace(bp)) {
+                if (bp->attr.exclude_kernel)
+                        return -EINVAL;
+                /*
+                 * Don't let unprivileged users set a breakpoint in the trap
+                 * path to avoid trap recursion attacks.
+                 */
+                if (!capable(CAP_SYS_ADMIN))
+                        return -EPERM;
+        }
+
+        return 0;
+}
+
+int register_perf_hw_breakpoint(struct perf_event *bp)
+{
+        int ret;
+
+        ret = reserve_bp_slot(bp);
+        if (ret)
+                return ret;
+
+        ret = validate_hw_breakpoint(bp);
+
+        /* if arch_validate_hwbkpt_settings() fails then release bp slot */
+        if (ret)
+                release_bp_slot(bp);
+
+        return ret;
+}
+
+/**
+ * register_user_hw_breakpoint - register a hardware breakpoint for user space
+ * @attr: breakpoint attributes
+ * @triggered: callback to trigger when we hit the breakpoint
+ * @tsk: pointer to 'task_struct' of the process to which the address belongs
+ */
+struct perf_event *
+register_user_hw_breakpoint(struct perf_event_attr *attr,
+                            perf_overflow_handler_t triggered,
+                            struct task_struct *tsk)
+{
+        return perf_event_create_kernel_counter(attr, -1, tsk, triggered);
+}
+EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
+
+/**
+ * modify_user_hw_breakpoint - modify a user-space hardware breakpoint
+ * @bp: the breakpoint structure to modify
+ * @attr: new breakpoint attributes
+ * @triggered: callback to trigger when we hit the breakpoint
+ * @tsk: pointer to 'task_struct' of the process to which the address belongs
+ */
+int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr)
+{
+        u64 old_addr = bp->attr.bp_addr;
+        u64 old_len = bp->attr.bp_len;
+        int old_type = bp->attr.bp_type;
+        int err = 0;
+
+        perf_event_disable(bp);
+
+        bp->attr.bp_addr = attr->bp_addr;
+        bp->attr.bp_type = attr->bp_type;
+        bp->attr.bp_len = attr->bp_len;
+
+        if (attr->disabled)
+                goto end;
+
+        err = validate_hw_breakpoint(bp);
+        if (!err)
+                perf_event_enable(bp);
+
+        if (err) {
+                bp->attr.bp_addr = old_addr;
+                bp->attr.bp_type = old_type;
+                bp->attr.bp_len = old_len;
+                if (!bp->attr.disabled)
+                        perf_event_enable(bp);
+
+                return err;
+        }
+
+end:
+        bp->attr.disabled = attr->disabled;
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);
+
+/**
+ * unregister_hw_breakpoint - unregister a user-space hardware breakpoint
+ * @bp: the breakpoint structure to unregister
+ */
+void unregister_hw_breakpoint(struct perf_event *bp)
+{
+        if (!bp)
+                return;
+        perf_event_release_kernel(bp);
+}
+EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
+
+/**
+ * register_wide_hw_breakpoint - register a wide breakpoint in the kernel
+ * @attr: breakpoint attributes
+ * @triggered: callback to trigger when we hit the breakpoint
+ *
+ * @return a set of per_cpu pointers to perf events
+ */
+struct perf_event * __percpu *
+register_wide_hw_breakpoint(struct perf_event_attr *attr,
+                            perf_overflow_handler_t triggered)
+{
+        struct perf_event * __percpu *cpu_events, **pevent, *bp;
+        long err;
+        int cpu;
+
+        cpu_events = alloc_percpu(typeof(*cpu_events));
+        if (!cpu_events)
+                return (void __percpu __force *)ERR_PTR(-ENOMEM);
+
+        get_online_cpus();
+        for_each_online_cpu(cpu) {
+                pevent = per_cpu_ptr(cpu_events, cpu);
+                bp = perf_event_create_kernel_counter(attr, cpu, NULL, triggered);
+
+                *pevent = bp;
+
+                if (IS_ERR(bp)) {
+                        err = PTR_ERR(bp);
+                        goto fail;
+                }
+        }
+        put_online_cpus();
+
+        return cpu_events;
+
+fail:
+        for_each_online_cpu(cpu) {
+                pevent = per_cpu_ptr(cpu_events, cpu);
+                if (IS_ERR(*pevent))
+                        break;
+                unregister_hw_breakpoint(*pevent);
+        }
+        put_online_cpus();
+
+        free_percpu(cpu_events);
+        return (void __percpu __force *)ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);
+
+/**
+ * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel
+ * @cpu_events: the per cpu set of events to unregister
+ */
+void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events)
+{
+        int cpu;
+        struct perf_event **pevent;
+
+        for_each_possible_cpu(cpu) {
+                pevent = per_cpu_ptr(cpu_events, cpu);
+                unregister_hw_breakpoint(*pevent);
+        }
+        free_percpu(cpu_events);
+}
+EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint);
+
+static struct notifier_block hw_breakpoint_exceptions_nb = {
+        .notifier_call = hw_breakpoint_exceptions_notify,
+        /* we need to be notified first */
+        .priority = 0x7fffffff
+};
+
+static void bp_perf_event_destroy(struct perf_event *event)
+{
+        release_bp_slot(event);
+}
+
+static int hw_breakpoint_event_init(struct perf_event *bp)
+{
+        int err;
+
+        if (bp->attr.type != PERF_TYPE_BREAKPOINT)
+                return -ENOENT;
+
+        err = register_perf_hw_breakpoint(bp);
+        if (err)
+                return err;
+
+        bp->destroy = bp_perf_event_destroy;
+
+        return 0;
+}
+
+static int hw_breakpoint_add(struct perf_event *bp, int flags)
+{
+        if (!(flags & PERF_EF_START))
+                bp->hw.state = PERF_HES_STOPPED;
+
+        return arch_install_hw_breakpoint(bp);
+}
+
+static void hw_breakpoint_del(struct perf_event *bp, int flags)
+{
+        arch_uninstall_hw_breakpoint(bp);
+}
+
+static void hw_breakpoint_start(struct perf_event *bp, int flags)
+{
+        bp->hw.state = 0;
+}
+
+static void hw_breakpoint_stop(struct perf_event *bp, int flags)
+{
+        bp->hw.state = PERF_HES_STOPPED;
+}
+
+static struct pmu perf_breakpoint = {
+        .task_ctx_nr    = perf_sw_context, /* could eventually get its own */
+
+        .event_init     = hw_breakpoint_event_init,
+        .add            = hw_breakpoint_add,
+        .del            = hw_breakpoint_del,
+        .start          = hw_breakpoint_start,
+        .stop           = hw_breakpoint_stop,
+        .read           = hw_breakpoint_pmu_read,
+};
+
+int __init init_hw_breakpoint(void)
+{
+        unsigned int **task_bp_pinned;
+        int cpu, err_cpu;
+        int i;
+
+        for (i = 0; i < TYPE_MAX; i++)
+                nr_slots[i] = hw_breakpoint_slots(i);
+
+        for_each_possible_cpu(cpu) {
+                for (i = 0; i < TYPE_MAX; i++) {
+                        task_bp_pinned = &per_cpu(nr_task_bp_pinned[i], cpu);
+                        *task_bp_pinned = kzalloc(sizeof(int) * nr_slots[i],
+                                                  GFP_KERNEL);
+                        if (!*task_bp_pinned)
+                                goto err_alloc;
+                }
+        }
+
+        constraints_initialized = 1;
+
+        perf_pmu_register(&perf_breakpoint, "breakpoint", PERF_TYPE_BREAKPOINT);
+
+        return register_die_notifier(&hw_breakpoint_exceptions_nb);
+
+ err_alloc:
+        for_each_possible_cpu(err_cpu) {
+                if (err_cpu == cpu)
+                        break;
+                for (i = 0; i < TYPE_MAX; i++)
+                        kfree(per_cpu(nr_task_bp_pinned[i], cpu));
+        }
+
+        return -ENOMEM;
+}
+
+