/* * Performance events core code: * * Copyright (C) 2008 Thomas Gleixner * Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar * Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra * Copyright © 2009 Paul Mackerras, IBM Corp. * * For licensing details see kernel-base/COPYING */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "internal.h" #include 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) /* * branch priv levels that need permission checks */ #define PERF_SAMPLE_BRANCH_PERM_PLM \ (PERF_SAMPLE_BRANCH_KERNEL |\ PERF_SAMPLE_BRANCH_HV) 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 static_key_deferred perf_sched_events __read_mostly; static DEFINE_PER_CPU(atomic_t, perf_cgroup_events); static DEFINE_PER_CPU(atomic_t, perf_branch_stack_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); static void ring_buffer_attach(struct perf_event *event, struct ring_buffer *rb); 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); } static void perf_ctx_lock(struct perf_cpu_context *cpuctx, struct perf_event_context *ctx) { raw_spin_lock(&cpuctx->ctx.lock); if (ctx) raw_spin_lock(&ctx->lock); } static void perf_ctx_unlock(struct perf_cpu_context *cpuctx, struct perf_event_context *ctx) { if (ctx) raw_spin_unlock(&ctx->lock); raw_spin_unlock(&cpuctx->ctx.lock); } #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 bool perf_tryget_cgroup(struct perf_event *event) { return css_tryget(&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); if (cpuctx->unique_pmu != pmu) continue; /* ensure we process each cpuctx once */ /* * 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) { perf_ctx_lock(cpuctx, cpuctx->task_ctx); perf_pmu_disable(cpuctx->ctx.pmu); 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); perf_ctx_unlock(cpuctx, cpuctx->task_ctx); } } rcu_read_unlock(); local_irq_restore(flags); } static inline void perf_cgroup_sched_out(struct task_struct *task, struct task_struct *next) { struct perf_cgroup *cgrp1; struct perf_cgroup *cgrp2 = NULL; /* * we come here when we know perf_cgroup_events > 0 */ cgrp1 = perf_cgroup_from_task(task); /* * next is NULL when called from perf_event_enable_on_exec() * that will systematically cause a cgroup_switch() */ if (next) cgrp2 = perf_cgroup_from_task(next); /* * only schedule out current cgroup events if we know * that we are switching to a different cgroup. Otherwise, * do no touch the cgroup events. */ if (cgrp1 != cgrp2) perf_cgroup_switch(task, PERF_CGROUP_SWOUT); } static inline void perf_cgroup_sched_in(struct task_struct *prev, struct task_struct *task) { struct perf_cgroup *cgrp1; struct perf_cgroup *cgrp2 = NULL; /* * we come here when we know perf_cgroup_events > 0 */ cgrp1 = perf_cgroup_from_task(task); /* prev can never be NULL */ cgrp2 = perf_cgroup_from_task(prev); /* * only need to schedule in cgroup events if we are changing * cgroup during ctxsw. Cgroup events were not scheduled * out of ctxsw out if that was not the case. */ if (cgrp1 != cgrp2) 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 fd f = fdget(fd); int ret = 0; if (!f.file) return -EBADF; css = cgroup_css_from_dir(f.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 */ if (!perf_tryget_cgroup(event)) { event->cgrp = NULL; ret = -ENOENT; goto out; } /* * 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: fdput(f); 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, struct task_struct *next) { } static inline void perf_cgroup_sched_in(struct task_struct *prev, 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. * The caller of this function needs to hold the ctx->lock. */ 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_cgroup_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++; if (has_branch_stack(event)) ctx->nr_branch_stack++; 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++; } /* * Initialize event state based on the perf_event_attr::disabled. */ static inline void perf_event__state_init(struct perf_event *event) { event->state = event->attr.disabled ? PERF_EVENT_STATE_OFF : PERF_EVENT_STATE_INACTIVE; } /* * 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; } if (has_branch_stack(event)) ctx->nr_branch_stack--; 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.freq && event->attr.sample_freq) ctx->nr_freq--; 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); if (!ctx->nr_events && cpuctx->task_ctx == ctx) { ctx->is_active = 0; cpuctx->task_ctx = NULL; } 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 */ 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); } EXPORT_SYMBOL_GPL(perf_event_disable); 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.freq && event->attr.sample_freq) ctx->nr_freq++; 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 task_ctx_sched_out(struct perf_event_context *ctx); 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); static void perf_event_sched_in(struct perf_cpu_context *cpuctx, struct perf_event_context *ctx, struct task_struct *task) { cpu_ctx_sched_in(cpuctx, EVENT_PINNED, task); if (ctx) ctx_sched_in(ctx, cpuctx, EVENT_PINNED, task); cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE, task); if (ctx) ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE, task); } /* * 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_cpu_context *cpuctx = __get_cpu_context(ctx); struct perf_event_context *task_ctx = cpuctx->task_ctx; struct task_struct *task = current; perf_ctx_lock(cpuctx, task_ctx); perf_pmu_disable(cpuctx->ctx.pmu); /* * If there was an active task_ctx schedule it out. */ if (task_ctx) task_ctx_sched_out(task_ctx); /* * If the context we're installing events in is not the * active task_ctx, flip them. */ if (ctx->task && task_ctx != ctx) { if (task_ctx) raw_spin_unlock(&task_ctx->lock); raw_spin_lock(&ctx->lock); task_ctx = ctx; } if (task_ctx) { cpuctx->task_ctx = task_ctx; task = task_ctx->task; } cpu_ctx_sched_out(cpuctx, EVENT_ALL); 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); /* * Schedule everything back in */ perf_event_sched_in(cpuctx, task_ctx, task); perf_pmu_enable(cpuctx->ctx.pmu); perf_ctx_unlock(cpuctx, task_ctx); 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 (event->cpu != -1) event->cpu = cpu; 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 *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); 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); 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); } EXPORT_SYMBOL_GPL(perf_event_enable); 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; } EXPORT_SYMBOL_GPL(perf_event_refresh); 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; int is_active = ctx->is_active; ctx->is_active &= ~event_type; if (likely(!ctx->nr_events)) return; update_context_time(ctx); update_cgrp_time_from_cpuctx(cpuctx); if (!ctx->nr_active) return; perf_pmu_disable(ctx->pmu); if ((is_active & EVENT_PINNED) && (event_type & EVENT_PINNED)) { list_for_each_entry(event, &ctx->pinned_groups, group_entry) group_sched_out(event, cpuctx, ctx); } if ((is_active & EVENT_FLEXIBLE) && (event_type & EVENT_FLEXIBLE)) { list_for_each_entry(event, &ctx->flexible_groups, group_entry) group_sched_out(event, cpuctx, ctx); } perf_pmu_enable(ctx->pmu); } /* * 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) { raw_spin_lock(&ctx->lock); ctx_sched_out(ctx, cpuctx, EVENT_ALL); cpuctx->task_ctx = NULL; raw_spin_unlock(&ctx->lock); } } #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, next); } static void task_ctx_sched_out(struct perf_event_context *ctx) { 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_ALL); 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; int is_active = ctx->is_active; ctx->is_active |= event_type; if (likely(!ctx->nr_events)) return; 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 (!(is_active & EVENT_PINNED) && (event_type & EVENT_PINNED)) ctx_pinned_sched_in(ctx, cpuctx); /* Then walk through the lower prio flexible groups */ if (!(is_active & EVENT_FLEXIBLE) && (event_type & EVENT_FLEXIBLE)) ctx_flexible_sched_in(ctx, cpuctx); } 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 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_ctx_lock(cpuctx, ctx); 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); if (ctx->nr_events) cpuctx->task_ctx = ctx; perf_event_sched_in(cpuctx, cpuctx->task_ctx, task); perf_pmu_enable(ctx->pmu); perf_ctx_unlock(cpuctx, 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); } /* * When sampling the branck stack in system-wide, it may be necessary * to flush the stack on context switch. This happens when the branch * stack does not tag its entries with the pid of the current task. * Otherwise it becomes impossible to associate a branch entry with a * task. This ambiguity is more likely to appear when the branch stack * supports priv level filtering and the user sets it to monitor only * at the user level (which could be a useful measurement in system-wide * mode). In that case, the risk is high of having a branch stack with * branch from multiple tasks. Flushing may mean dropping the existing * entries or stashing them somewhere in the PMU specific code layer. * * This function provides the context switch callback to the lower code * layer. It is invoked ONLY when there is at least one system-wide context * with at least one active event using taken branch sampling. */ static void perf_branch_stack_sched_in(struct task_struct *prev, struct task_struct *task) { struct perf_cpu_context *cpuctx; struct pmu *pmu; unsigned long flags; /* no need to flush branch stack if not changing task */ if (prev == task) return; local_irq_save(flags); rcu_read_lock(); list_for_each_entry_rcu(pmu, &pmus, entry) { cpuctx = this_cpu_ptr(pmu->pmu_cpu_context); /* * check if the context has at least one * event using PERF_SAMPLE_BRANCH_STACK */ if (cpuctx->ctx.nr_branch_stack > 0 && pmu->flush_branch_stack) { pmu = cpuctx->ctx.pmu; perf_ctx_lock(cpuctx, cpuctx->task_ctx); perf_pmu_disable(pmu); pmu->flush_branch_stack(); perf_pmu_enable(pmu); perf_ctx_unlock(cpuctx, cpuctx->task_ctx); } } rcu_read_unlock(); local_irq_restore(flags); } /* * 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 *prev, 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(prev, task); /* check for system-wide branch_stack events */ if (atomic_read(&__get_cpu_var(perf_branch_stack_events))) perf_branch_stack_sched_in(prev, 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 DEFINE_PER_CPU(int, perf_throttled_count); static DEFINE_PER_CPU(u64, perf_throttled_seq); static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count, bool disable) { 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) { if (disable) event->pmu->stop(event, PERF_EF_UPDATE); local64_set(&hwc->period_left, 0); if (disable) event->pmu->start(event, PERF_EF_RELOAD); } } /* * combine freq adjustment with unthrottling to avoid two passes over the * events. At the same time, make sure, having freq events does not change * the rate of unthrottling as that would introduce bias. */ static void perf_adjust_freq_unthr_context(struct perf_event_context *ctx, int needs_unthr) { struct perf_event *event; struct hw_perf_event *hwc; u64 now, period = TICK_NSEC; s64 delta; /* * only need to iterate over all events iff: * - context have events in frequency mode (needs freq adjust) * - there are events to unthrottle on this cpu */ if (!(ctx->nr_freq || needs_unthr)) return; raw_spin_lock(&ctx->lock); perf_pmu_disable(ctx->pmu); 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; if (needs_unthr && hwc->interrupts == MAX_INTERRUPTS) { hwc->interrupts = 0; perf_log_throttle(event, 1); event->pmu->start(event, 0); } if (!event->attr.freq || !event->attr.sample_freq) continue; /* * stop the event and update event->count */ event->pmu->stop(event, PERF_EF_UPDATE); now = local64_read(&event->count); delta = now - hwc->freq_count_stamp; hwc->freq_count_stamp = now; /* * restart the event * reload only if value has changed * we have stopped the event so tell that * to perf_adjust_period() to avoid stopping it * twice. */ if (delta > 0) perf_adjust_period(event, period, delta, false); event->pmu->start(event, delta > 0 ? PERF_EF_RELOAD : 0); } perf_pmu_enable(ctx->pmu); raw_spin_unlock(&ctx->lock); } /* * Round-robin a context's events: */ static void rotate_ctx(struct perf_event_context *ctx) { /* * 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); } /* * 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) { 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; } if (!rotate) goto done; perf_ctx_lock(cpuctx, cpuctx->task_ctx); perf_pmu_disable(cpuctx->ctx.pmu); cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE); if (ctx) ctx_sched_out(ctx, cpuctx, EVENT_FLEXIBLE); rotate_ctx(&cpuctx->ctx); if (ctx) rotate_ctx(ctx); perf_event_sched_in(cpuctx, ctx, current); perf_pmu_enable(cpuctx->ctx.pmu); perf_ctx_unlock(cpuctx, cpuctx->task_ctx); done: if (remove) list_del_init(&cpuctx->rotation_list); } void perf_event_task_tick(void) { struct list_head *head = &__get_cpu_var(rotation_list); struct perf_cpu_context *cpuctx, *tmp; struct perf_event_context *ctx; int throttled; WARN_ON(!irqs_disabled()); __this_cpu_inc(perf_throttled_seq); throttled = __this_cpu_xchg(perf_throttled_count, 0); list_for_each_entry_safe(cpuctx, tmp, head, rotation_list) { ctx = &cpuctx->ctx; perf_adjust_freq_unthr_context(ctx, throttled); ctx = cpuctx->task_ctx; if (ctx) perf_adjust_freq_unthr_context(ctx, throttled); 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); 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 * wh