Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fixes from Thomas Gleixner: "Two fixes for the perf subsystem: - Fix an inconsistency of RDPMC mm struct tagging across exec() which causes RDPMC to fault. - Correct the timestamp mechanics across IOC_DISABLE/ENABLE which causes incorrect timestamps and total time calculations" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf/core: Fix time on IOC_ENABLE perf/x86: Fix RDPMC vs. mm_struct tracking

Linus Torvalds committed 9 years ago

Commit e46db8d2 parents 9dae41a 9b231d93 files · +48 −19Browse files

Unified · Split

3 files

arch/x86/events/core.c +7 −9
include/linux/perf_event.h +2 −2
kernel/events/core.c +39 −8

arch/x86/events/core.c+7−9

 	load_mm_cr4(this_cpu_read(cpu_tlbstate.loaded_mm));
 }
-static void x86_pmu_event_mapped(struct perf_event *event)
+static void x86_pmu_event_mapped(struct perf_event *event, struct mm_struct *mm)
 {
 	if (!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED))
 		return;
 	 * 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);
+	lockdep_assert_held_exclusive(&mm->mmap_sem);
-	if (atomic_inc_return(&current->mm->context.perf_rdpmc_allowed) == 1)
+	if (atomic_inc_return(&mm->context.perf_rdpmc_allowed) == 1)
-		on_each_cpu_mask(mm_cpumask(current->mm), refresh_pce, NULL, 1);
+		on_each_cpu_mask(mm_cpumask(mm), refresh_pce, NULL, 1);
 }
-static void x86_pmu_event_unmapped(struct perf_event *event)
+static void x86_pmu_event_unmapped(struct perf_event *event, struct mm_struct *mm)
 {
-	if (!current->mm)
-		return;
 	if (!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED))
 		return;
-	if (atomic_dec_and_test(&current->mm->context.perf_rdpmc_allowed))
+	if (atomic_dec_and_test(&mm->context.perf_rdpmc_allowed))
-		on_each_cpu_mask(mm_cpumask(current->mm), refresh_pce, NULL, 1);
+		on_each_cpu_mask(mm_cpumask(mm), refresh_pce, NULL, 1);
 }
 static int x86_pmu_event_idx(struct perf_event *event)

include/linux/perf_event.h+2−2

@@ -310,8 +310,8 @@ struct pmu { · 309 unmodified lines
310	* Notification that the event was mapped or unmapped. Called	310	* Notification that the event was mapped or unmapped. Called
311	* in the context of the mapping task.	311	* in the context of the mapping task.
312	*/	312	*/
313	void (event_mapped) (struct perf_event event); /optional/	313	void (event_mapped) (struct perf_event event, struct mm_struct mm); / optional */
314	void (event_unmapped) (struct perf_event event); /optional/	314	void (event_unmapped) (struct perf_event event, struct mm_struct mm); / optional */
315		315
316	/*	316	/*
317	* Flags for ->add()/->del()/ ->start()/->stop(). There are	317	* Flags for ->add()/->del()/ ->start()/->stop(). There are

kernel/events/core.c+39−8

 	return can_add_hw;
 }
+/*
+ * Complement to update_event_times(). This computes the tstamp_* values to
+ * continue 'enabled' state from @now, and effectively discards the time
+ * between the prior tstamp_stopped and now (as we were in the OFF state, or
+ * just switched (context) time base).
+ *
+ * This further assumes '@event->state == INACTIVE' (we just came from OFF) and
+ * cannot have been scheduled in yet. And going into INACTIVE state means
+ * '@event->tstamp_stopped = @now'.
+ *
+ * Thus given the rules of update_event_times():
+ *
+ *   total_time_enabled = tstamp_stopped - tstamp_enabled
+ *   total_time_running = tstamp_stopped - tstamp_running
+ *
+ * We can insert 'tstamp_stopped == now' and reverse them to compute new
+ * tstamp_* values.
+ */
+static void __perf_event_enable_time(struct perf_event *event, u64 now)
+{
+	WARN_ON_ONCE(event->state != PERF_EVENT_STATE_INACTIVE);
+	event->tstamp_stopped = now;
+	event->tstamp_enabled = now - event->total_time_enabled;
+	event->tstamp_running = now - event->total_time_running;
+}
 static void add_event_to_ctx(struct perf_event *event,
 			       struct perf_event_context *ctx)
 {
 	list_add_event(event, ctx);
 	perf_group_attach(event);
-	event->tstamp_enabled = tstamp;
+	/*
-	event->tstamp_running = tstamp;
+	 * We can be called with event->state == STATE_OFF when we create with
-	event->tstamp_stopped = tstamp;
+	 * .disabled = 1. In that case the IOC_ENABLE will call this function.
+	 */
+	if (event->state == PERF_EVENT_STATE_INACTIVE)
+		__perf_event_enable_time(event, tstamp);
 }
 static void ctx_sched_out(struct perf_event_context *ctx,
 	u64 tstamp = perf_event_time(event);
 	event->state = PERF_EVENT_STATE_INACTIVE;
-	event->tstamp_enabled = tstamp - event->total_time_enabled;
+	__perf_event_enable_time(event, tstamp);
 	list_for_each_entry(sub, &event->sibling_list, group_entry) {
+		/* XXX should not be > INACTIVE if event isn't */
 		if (sub->state >= PERF_EVENT_STATE_INACTIVE)
-			sub->tstamp_enabled = tstamp - sub->total_time_enabled;
+			__perf_event_enable_time(sub, tstamp);
 	}
 }
 		atomic_inc(&event->rb->aux_mmap_count);
 	if (event->pmu->event_mapped)
-		event->pmu->event_mapped(event);
+		event->pmu->event_mapped(event, vma->vm_mm);
 }
 static void perf_pmu_output_stop(struct perf_event *event);
 	unsigned long size = perf_data_size(rb);
 	if (event->pmu->event_unmapped)
-		event->pmu->event_unmapped(event);
+		event->pmu->event_unmapped(event, vma->vm_mm);
 	/*
 	 * rb->aux_mmap_count will always drop before rb->mmap_count and
 	vma->vm_ops = &perf_mmap_vmops;
 	if (event->pmu->event_mapped)
-		event->pmu->event_mapped(event);
+		event->pmu->event_mapped(event, vma->vm_mm);
 	return ret;
 }