2 files changed, 14 insertions, 1 deletions

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index cae4a9481777..9fc9b0d31442 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -272,6 +272,11 @@ struct pmu {
          */
         size_t                          task_ctx_size;
 
+
+        /*
+         * Return the count value for a counter.
+         */
+        u64 (*count)                    (struct perf_event *event); /*optional*/
 };
 
 /**
@@ -770,6 +775,11 @@ static inline void perf_event_task_sched_out(struct task_struct *prev,
                 __perf_event_task_sched_out(prev, next);
 }
 
+static inline u64 __perf_event_count(struct perf_event *event)
+{
+        return local64_read(&event->count) + atomic64_read(&event->child_count);
+}
+
 extern void perf_event_mmap(struct vm_area_struct *vma);
 extern struct perf_guest_info_callbacks *perf_guest_cbs;
 extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 072de3143244..4e8dc596f101 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3194,7 +3194,10 @@ static void __perf_event_read(void *info)
 
 static inline u64 perf_event_count(struct perf_event *event)
 {
-        return local64_read(&event->count) + atomic64_read(&event->child_count);
+        if (event->pmu->count)
+                return event->pmu->count(event);
+
+        return __perf_event_count(event);
 }
 
 static u64 perf_event_read(struct perf_event *event)