[PATCH 3/4] perf/x86: introduce read function for x86_pmu

[kan . liang]

From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>

Large PEBS need to be specially handled in event count read.

Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
---
 arch/x86/events/core.c       | 3 +++
 arch/x86/events/perf_event.h | 1 +
 2 files changed, 4 insertions(+)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index f74e21d..c781497 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1899,6 +1899,9 @@ early_initcall(init_hw_perf_events);
 
 static inline void x86_pmu_read(struct perf_event *event)
 {
+	if (x86_pmu.read)
+		return x86_pmu.read(event);
+
 	x86_perf_event_update(event, 0, 0);
 }
 
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index fabb8b3..3a7a2e7 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -534,6 +534,7 @@ struct x86_pmu {
 	void		(*disable)(struct perf_event *);
 	void		(*add)(struct perf_event *);
 	void		(*del)(struct perf_event *);
+	void		(*read)(struct perf_event *event);
 	int		(*hw_config)(struct perf_event *event);
 	int		(*schedule_events)(struct cpu_hw_events *cpuc, int n, int *assign);
 	unsigned	eventsel;
-- 
2.7.4