Merge branch 'perf/urgent' into perf/core, to pick up fixes

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

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 349d4d17aa7fbd3a6268be3bd6e7bea909e76ccf..2aa1ad194db21a541f65c30b65fe20f2806fdff3 100644 (file)
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2101,8 +2101,8 @@ static int x86_pmu_event_init(struct perf_event *event)
 
 static void refresh_pce(void *ignored)
 {
-       if (current->mm)
-               load_mm_cr4(current->mm);
+       if (current->active_mm)
+               load_mm_cr4(current->active_mm);
 }
 
 static void x86_pmu_event_mapped(struct perf_event *event)
@@ -2110,6 +2110,18 @@ static void x86_pmu_event_mapped(struct perf_event *event)
        if (!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED))
                return;
 
+       /*
+        * This function relies on not being called concurrently in two
+        * tasks in the same mm.  Otherwise one task could observe
+        * perf_rdpmc_allowed > 1 and return all the way back to
+        * userspace with CR4.PCE clear while another task is still
+        * doing on_each_cpu_mask() to propagate CR4.PCE.
+        *
+        * For now, this can't happen because all callers hold mmap_sem
+        * for write.  If this changes, we'll need a different solution.
+        */
+       lockdep_assert_held_exclusive(&current->mm->mmap_sem);
+
        if (atomic_inc_return(&current->mm->context.perf_rdpmc_allowed) == 1)
                on_each_cpu_mask(mm_cpumask(current->mm), refresh_pce, NULL, 1);
 }

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 2d7990d4e9884ce9cf0b2e51676c96b362097afc..6e75a5c9412dee17daabc1cb131bb517ad431207 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4261,7 +4261,7 @@ int perf_event_release_kernel(struct perf_event *event)
 
        raw_spin_lock_irq(&ctx->lock);
        /*
-        * Mark this even as STATE_DEAD, there is no external reference to it
+        * Mark this event as STATE_DEAD, there is no external reference to it
         * anymore.
         *
         * Anybody acquiring event->child_mutex after the below loop _must_
@@ -10556,21 +10556,22 @@ void perf_event_free_task(struct task_struct *task)
                        continue;
 
                mutex_lock(&ctx->mutex);
-again:
-               list_for_each_entry_safe(event, tmp, &ctx->pinned_groups,
-                               group_entry)
-                       perf_free_event(event, ctx);
+               raw_spin_lock_irq(&ctx->lock);
+               /*
+                * Destroy the task <-> ctx relation and mark the context dead.
+                *
+                * This is important because even though the task hasn't been
+                * exposed yet the context has been (through child_list).
+                */
+               RCU_INIT_POINTER(task->perf_event_ctxp[ctxn], NULL);
+               WRITE_ONCE(ctx->task, TASK_TOMBSTONE);
+               put_task_struct(task); /* cannot be last */
+               raw_spin_unlock_irq(&ctx->lock);
 
-               list_for_each_entry_safe(event, tmp, &ctx->flexible_groups,
-                               group_entry)
+               list_for_each_entry_safe(event, tmp, &ctx->event_list, event_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);
        }
 }
@@ -10608,7 +10609,12 @@ const struct perf_event_attr *perf_event_attrs(struct perf_event *event)
 }
 
 /*
- * inherit a event from parent task to child task:
+ * Inherit a event from parent task to child task.
+ *
+ * Returns:
+ *  - valid pointer on success
+ *  - NULL for orphaned events
+ *  - IS_ERR() on error
  */
 static struct perf_event *
 inherit_event(struct perf_event *parent_event,
@@ -10702,6 +10708,16 @@ inherit_event(struct perf_event *parent_event,
        return child_event;
 }
 
+/*
+ * Inherits an event group.
+ *
+ * This will quietly suppress orphaned events; !inherit_event() is not an error.
+ * This matches with perf_event_release_kernel() removing all child events.
+ *
+ * Returns:
+ *  - 0 on success
+ *  - <0 on error
+ */
 static int inherit_group(struct perf_event *parent_event,
              struct task_struct *parent,
              struct perf_event_context *parent_ctx,
@@ -10716,6 +10732,11 @@ static int inherit_group(struct perf_event *parent_event,
                                 child, NULL, child_ctx);
        if (IS_ERR(leader))
                return PTR_ERR(leader);
+       /*
+        * @leader can be NULL here because of is_orphaned_event(). In this
+        * case inherit_event() will create individual events, similar to what
+        * perf_group_detach() would do anyway.
+        */
        list_for_each_entry(sub, &parent_event->sibling_list, group_entry) {
                child_ctr = inherit_event(sub, parent, parent_ctx,
                                            child, leader, child_ctx);
@@ -10725,6 +10746,17 @@ static int inherit_group(struct perf_event *parent_event,
        return 0;
 }
 
+/*
+ * Creates the child task context and tries to inherit the event-group.
+ *
+ * Clears @inherited_all on !attr.inherited or error. Note that we'll leave
+ * inherited_all set when we 'fail' to inherit an orphaned event; this is
+ * consistent with perf_event_release_kernel() removing all child events.
+ *
+ * Returns:
+ *  - 0 on success
+ *  - <0 on error
+ */
 static int
 inherit_task_group(struct perf_event *event, struct task_struct *parent,
                   struct perf_event_context *parent_ctx,
@@ -10747,7 +10779,6 @@ inherit_task_group(struct perf_event *event, struct task_struct *parent,
                 * First allocate and initialize a context for the
                 * child.
                 */
-
                child_ctx = alloc_perf_context(parent_ctx->pmu, child);
                if (!child_ctx)
                        return -ENOMEM;
@@ -10809,7 +10840,7 @@ static int perf_event_init_context(struct task_struct *child, int ctxn)
                ret = inherit_task_group(event, parent, parent_ctx,
                                         child, ctxn, &inherited_all);
                if (ret)
-                       break;
+                       goto out_unlock;
        }
 
        /*
@@ -10825,7 +10856,7 @@ static int perf_event_init_context(struct task_struct *child, int ctxn)
                ret = inherit_task_group(event, parent, parent_ctx,
                                         child, ctxn, &inherited_all);
                if (ret)
-                       break;
+                       goto out_unlock;
        }
 
        raw_spin_lock_irqsave(&parent_ctx->lock, flags);
@@ -10853,6 +10884,7 @@ static int perf_event_init_context(struct task_struct *child, int ctxn)
        }
 
        raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
+out_unlock:
        mutex_unlock(&parent_ctx->mutex);
 
        perf_unpin_context(parent_ctx);

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 70e389bc4af71aa8f18ae67507fb65b5093a7f98..9b4d8ba22fed85f1f2bef6f5d47dc88cbb4df5d1 100644 (file)
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -202,7 +202,7 @@ void symbols__fixup_end(struct rb_root *symbols)
 
        /* Last entry */
        if (curr->end == curr->start)
-               curr->end = roundup(curr->start, 4096);
+               curr->end = roundup(curr->start, 4096) + 4096;
 }
 
 void __map_groups__fixup_end(struct map_groups *mg, enum map_type type)