Merge branch 'perf/core' into perf/uprobes

Merge in latest upstream (and the latest perf development tree),
to prepare for tooling changes, and also to pick up v3.4 MM
changes that the uprobes code needs to take care of.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 205 insertions, 18 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 94afe5b91c6a..a6a9ec4cd8f5 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -118,6 +118,13 @@ static int cpu_function_call(int cpu, int (*func) (void *info), void *info)
                        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,
@@ -128,8 +135,9 @@ enum event_type_t {
  * perf_sched_events : >0 events exist
  * perf_cgroup_events: >0 per-cpu cgroup events exist on this cpu
  */
-struct jump_label_key_deferred perf_sched_events __read_mostly;
+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;
@@ -881,6 +889,9 @@ list_add_event(struct perf_event *event, struct perf_event_context *ctx)
         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);
@@ -1020,6 +1031,9 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx)
                         cpuctx->cgrp = NULL;
         }
 
+        if (has_branch_stack(event))
+                ctx->nr_branch_stack--;
+
         ctx->nr_events--;
         if (event->attr.inherit_stat)
                 ctx->nr_stat--;
@@ -2195,6 +2209,66 @@ static void perf_event_context_sched_in(struct perf_event_context *ctx,
 }
 
 /*
+ * 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.
  *
@@ -2225,6 +2299,10 @@ void __perf_event_task_sched_in(struct task_struct *prev,
          */
         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)
@@ -2778,7 +2856,7 @@ static void free_event(struct perf_event *event)
 
         if (!event->parent) {
                 if (event->attach_state & PERF_ATTACH_TASK)
-                        jump_label_dec_deferred(&perf_sched_events);
+                        static_key_slow_dec_deferred(&perf_sched_events);
                 if (event->attr.mmap || event->attr.mmap_data)
                         atomic_dec(&nr_mmap_events);
                 if (event->attr.comm)
@@ -2789,7 +2867,15 @@ static void free_event(struct perf_event *event)
                         put_callchain_buffers();
                 if (is_cgroup_event(event)) {
                         atomic_dec(&per_cpu(perf_cgroup_events, event->cpu));
-                        jump_label_dec_deferred(&perf_sched_events);
+                        static_key_slow_dec_deferred(&perf_sched_events);
+                }
+
+                if (has_branch_stack(event)) {
+                        static_key_slow_dec_deferred(&perf_sched_events);
+                        /* is system-wide event */
+                        if (!(event->attach_state & PERF_ATTACH_TASK))
+                                atomic_dec(&per_cpu(perf_branch_stack_events,
+                                                    event->cpu));
                 }
         }
 
@@ -3262,7 +3348,7 @@ static void calc_timer_values(struct perf_event *event,
         *running = ctx_time - event->tstamp_running;
 }
 
-void __weak perf_update_user_clock(struct perf_event_mmap_page *userpg, u64 now)
+void __weak arch_perf_update_userpage(struct perf_event_mmap_page *userpg, u64 now)
 {
 }
 
@@ -3312,7 +3398,7 @@ void perf_event_update_userpage(struct perf_event *event)
         userpg->time_running = running +
                         atomic64_read(&event->child_total_time_running);
 
-        perf_update_user_clock(userpg, now);
+        arch_perf_update_userpage(userpg, now);
 
         barrier();
         ++userpg->lock;
@@ -3907,6 +3993,24 @@ void perf_output_sample(struct perf_output_handle *handle,
                         }
                 }
         }
+
+        if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
+                if (data->br_stack) {
+                        size_t size;
+
+                        size = data->br_stack->nr
+                             * sizeof(struct perf_branch_entry);
+
+                        perf_output_put(handle, data->br_stack->nr);
+                        perf_output_copy(handle, data->br_stack->entries, size);
+                } else {
+                        /*
+                         * we always store at least the value of nr
+                         */
+                        u64 nr = 0;
+                        perf_output_put(handle, nr);
+                }
+        }
 }
 
 void perf_prepare_sample(struct perf_event_header *header,
@@ -3949,6 +4053,15 @@ void perf_prepare_sample(struct perf_event_header *header,
                 WARN_ON_ONCE(size & (sizeof(u64)-1));
                 header->size += size;
         }
+
+        if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
+                int size = sizeof(u64); /* nr */
+                if (data->br_stack) {
+                        size += data->br_stack->nr
+                              * sizeof(struct perf_branch_entry);
+                }
+                header->size += size;
+        }
 }
 
 static void perf_event_output(struct perf_event *event,
@@ -4991,7 +5104,7 @@ fail:
         return err;
 }
 
-struct jump_label_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
+struct static_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
 
 static void sw_perf_event_destroy(struct perf_event *event)
 {
@@ -4999,7 +5112,7 @@ static void sw_perf_event_destroy(struct perf_event *event)
 
         WARN_ON(event->parent);
 
-        jump_label_dec(&perf_swevent_enabled[event_id]);
+        static_key_slow_dec(&perf_swevent_enabled[event_id]);
         swevent_hlist_put(event);
 }
 
@@ -5010,6 +5123,12 @@ static int perf_swevent_init(struct perf_event *event)
         if (event->attr.type != PERF_TYPE_SOFTWARE)
                 return -ENOENT;
 
+        /*
+         * no branch sampling for software events
+         */
+        if (has_branch_stack(event))
+                return -EOPNOTSUPP;
+
         switch (event_id) {
         case PERF_COUNT_SW_CPU_CLOCK:
         case PERF_COUNT_SW_TASK_CLOCK:
@@ -5029,7 +5148,7 @@ static int perf_swevent_init(struct perf_event *event)
                 if (err)
                         return err;
 
-                jump_label_inc(&perf_swevent_enabled[event_id]);
+                static_key_slow_inc(&perf_swevent_enabled[event_id]);
                 event->destroy = sw_perf_event_destroy;
         }
 
@@ -5120,6 +5239,12 @@ static int perf_tp_event_init(struct perf_event *event)
         if (event->attr.type != PERF_TYPE_TRACEPOINT)
                 return -ENOENT;
 
+        /*
+         * no branch sampling for tracepoint events
+         */
+        if (has_branch_stack(event))
+                return -EOPNOTSUPP;
+
         err = perf_trace_init(event);
         if (err)
                 return err;
@@ -5345,6 +5470,12 @@ static int cpu_clock_event_init(struct perf_event *event)
         if (event->attr.config != PERF_COUNT_SW_CPU_CLOCK)
                 return -ENOENT;
 
+        /*
+         * no branch sampling for software events
+         */
+        if (has_branch_stack(event))
+                return -EOPNOTSUPP;
+
         perf_swevent_init_hrtimer(event);
 
         return 0;
@@ -5419,6 +5550,12 @@ static int task_clock_event_init(struct perf_event *event)
         if (event->attr.config != PERF_COUNT_SW_TASK_CLOCK)
                 return -ENOENT;
 
+        /*
+         * no branch sampling for software events
+         */
+        if (has_branch_stack(event))
+                return -EOPNOTSUPP;
+
         perf_swevent_init_hrtimer(event);
 
         return 0;
@@ -5852,7 +5989,7 @@ done:
 
         if (!event->parent) {
                 if (event->attach_state & PERF_ATTACH_TASK)
-                        jump_label_inc(&perf_sched_events.key);
+                        static_key_slow_inc(&perf_sched_events.key);
                 if (event->attr.mmap || event->attr.mmap_data)
                         atomic_inc(&nr_mmap_events);
                 if (event->attr.comm)
@@ -5866,6 +6003,12 @@ done:
                                 return ERR_PTR(err);
                         }
                 }
+                if (has_branch_stack(event)) {
+                        static_key_slow_inc(&perf_sched_events.key);
+                        if (!(event->attach_state & PERF_ATTACH_TASK))
+                                atomic_inc(&per_cpu(perf_branch_stack_events,
+                                                    event->cpu));
+                }
         }
 
         return event;
@@ -5935,6 +6078,40 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
         if (attr->read_format & ~(PERF_FORMAT_MAX-1))
                 return -EINVAL;
 
+        if (attr->sample_type & PERF_SAMPLE_BRANCH_STACK) {
+                u64 mask = attr->branch_sample_type;
+
+                /* only using defined bits */
+                if (mask & ~(PERF_SAMPLE_BRANCH_MAX-1))
+                        return -EINVAL;
+
+                /* at least one branch bit must be set */
+                if (!(mask & ~PERF_SAMPLE_BRANCH_PLM_ALL))
+                        return -EINVAL;
+
+                /* kernel level capture: check permissions */
+                if ((mask & PERF_SAMPLE_BRANCH_PERM_PLM)
+                    && perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
+                        return -EACCES;
+
+                /* propagate priv level, when not set for branch */
+                if (!(mask & PERF_SAMPLE_BRANCH_PLM_ALL)) {
+
+                        /* exclude_kernel checked on syscall entry */
+                        if (!attr->exclude_kernel)
+                                mask |= PERF_SAMPLE_BRANCH_KERNEL;
+
+                        if (!attr->exclude_user)
+                                mask |= PERF_SAMPLE_BRANCH_USER;
+
+                        if (!attr->exclude_hv)
+                                mask |= PERF_SAMPLE_BRANCH_HV;
+                        /*
+                         * adjust user setting (for HW filter setup)
+                         */
+                        attr->branch_sample_type = mask;
+                }
+        }
 out:
         return ret;
 
@@ -6090,7 +6267,7 @@ SYSCALL_DEFINE5(perf_event_open,
                  * - that may need work on context switch
                  */
                 atomic_inc(&per_cpu(perf_cgroup_events, event->cpu));
-                jump_label_inc(&perf_sched_events.key);
+                static_key_slow_inc(&perf_sched_events.key);
         }
 
         /*
@@ -6939,6 +7116,13 @@ void __init perf_event_init(void)
 
         /* do not patch jump label more than once per second */
         jump_label_rate_limit(&perf_sched_events, HZ);
+
+        /*
+         * Build time assertion that we keep the data_head at the intended
+         * location.  IOW, validation we got the __reserved[] size right.
+         */
+        BUILD_BUG_ON((offsetof(struct perf_event_mmap_page, data_head))
+                     != 1024);
 }
 
 static int __init perf_event_sysfs_init(void)
@@ -6970,8 +7154,7 @@ unlock:
 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)
+static struct cgroup_subsys_state *perf_cgroup_create(struct cgroup *cont)
 {
         struct perf_cgroup *jc;
 
@@ -6988,8 +7171,7 @@ static struct cgroup_subsys_state *perf_cgroup_create(
         return &jc->css;
 }
 
-static void perf_cgroup_destroy(struct cgroup_subsys *ss,
-                                struct cgroup *cont)
+static void perf_cgroup_destroy(struct cgroup *cont)
 {
         struct perf_cgroup *jc;
         jc = container_of(cgroup_subsys_state(cont, perf_subsys_id),
@@ -7005,8 +7187,7 @@ static int __perf_cgroup_move(void *info)
         return 0;
 }
 
-static void perf_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
-                               struct cgroup_taskset *tset)
+static void perf_cgroup_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 {
         struct task_struct *task;
 
@@ -7014,8 +7195,8 @@ static void perf_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
                 task_function_call(task, __perf_cgroup_move, task);
 }
 
-static void perf_cgroup_exit(struct cgroup_subsys *ss, struct cgroup *cgrp,
-                struct cgroup *old_cgrp, struct task_struct *task)
+static void perf_cgroup_exit(struct cgroup *cgrp, struct cgroup *old_cgrp,
+                             struct task_struct *task)
 {
         /*
          * cgroup_exit() is called in the copy_process() failure path.
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 3330022a7ac1..bb38c4d3ee12 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -581,6 +581,12 @@ static int hw_breakpoint_event_init(struct perf_event *bp)
         if (bp->attr.type != PERF_TYPE_BREAKPOINT)
                 return -ENOENT;
 
+        /*
+         * no branch sampling for breakpoint events
+         */
+        if (has_branch_stack(bp))
+                return -EOPNOTSUPP;
+
         err = register_perf_hw_breakpoint(bp);
         if (err)
                 return err;