perf/x86/intel/ds: Extract code of event update in short period

The drain_pebs() could be called twice in a short period for auto-reload
event in pmu::read(). The intel_pmu_save_and_restart_reload() should be
called to update the event->count.

This case should also be handled on Icelake. Extract the code for
later reuse.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: acme@kernel.org
Cc: jolsa@kernel.org
Link: https://lkml.kernel.org/r/20190402194509.2832-5-kan.liang@linux.intel.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/events/intel/ds.c

@@ -1491,6 +1491,25 @@ static void intel_pmu_drain_pebs_core(struct pt_regs *iregs)
 	__intel_pmu_pebs_event(event, iregs, at, top, 0, n);
 }
 
+static void intel_pmu_pebs_event_update_no_drain(struct cpu_hw_events *cpuc, int size)
+{
+	struct perf_event *event;
+	int bit;
+
+	/*
+	 * The drain_pebs() could be called twice in a short period
+	 * for auto-reload event in pmu::read(). There are no
+	 * overflows have happened in between.
+	 * It needs to call intel_pmu_save_and_restart_reload() to
+	 * update the event->count for this case.
+	 */
+	for_each_set_bit(bit, (unsigned long *)&cpuc->pebs_enabled, size) {
+		event = cpuc->events[bit];
+		if (event->hw.flags & PERF_X86_EVENT_AUTO_RELOAD)
+			intel_pmu_save_and_restart_reload(event, 0);
+	}
+}
+
 static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
 {
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
@@ -1518,19 +1537,7 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
 	}
 
 	if (unlikely(base >= top)) {
-		/*
-		 * The drain_pebs() could be called twice in a short period
-		 * for auto-reload event in pmu::read(). There are no
-		 * overflows have happened in between.
-		 * It needs to call intel_pmu_save_and_restart_reload() to
-		 * update the event->count for this case.
-		 */
-		for_each_set_bit(bit, (unsigned long *)&cpuc->pebs_enabled,
-				 size) {
-			event = cpuc->events[bit];
-			if (event->hw.flags & PERF_X86_EVENT_AUTO_RELOAD)
-				intel_pmu_save_and_restart_reload(event, 0);
-		}
+		intel_pmu_pebs_event_update_no_drain(cpuc, size);
 		return;
 	}