perf/x86/intel/lbr: Allow time stamp for free running PEBSv3

With PEBSv3 the PEBS record contains a time stamp. That means we can allow
free-running PEBS without a PMI even if the user program requested a time stamp.
This avoids the need to use -T to get free running PEBS, and also avoids
any problems with mis-identifying MMAPs later.

Move the free_running_flags state into a variable in x86_pmu and use it.
This only works when no explicit clock_id is set.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@kernel.org
Cc: eranian@google.com
Cc: jolsa@redhat.com
Cc: kan.liang@intel.com
Link: http://lkml.kernel.org/r/1432786398-23861-2-git-send-email-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 16 insertions, 1 deletions

diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
index 3474cf2..7378b10 100644
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -594,6 +594,7 @@ struct x86_pmu {
 	struct event_constraint *pebs_constraints;
 	void		(*pebs_aliases)(struct perf_event *event);
 	int 		max_pebs_events;
+	unsigned long	free_running_flags;
 
 	/*
 	 * Intel LBR
diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 71815cf..cb112bf 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -2257,6 +2257,15 @@ static void intel_pebs_aliases_snb(struct perf_event *event)
 	}
 }
 
+static unsigned long intel_pmu_free_running_flags(struct perf_event *event)
+{
+	unsigned long flags = x86_pmu.free_running_flags;
+
+	if (event->attr.use_clockid)
+		flags &= ~PERF_SAMPLE_TIME;
+	return flags;
+}
+
 static int intel_pmu_hw_config(struct perf_event *event)
 {
 	int ret = x86_pmu_hw_config(event);
@@ -2267,7 +2276,8 @@ static int intel_pmu_hw_config(struct perf_event *event)
 	if (event->attr.precise_ip) {
 		if (!event->attr.freq) {
 			event->hw.flags |= PERF_X86_EVENT_AUTO_RELOAD;
-			if (!(event->attr.sample_type & ~PEBS_FREERUNNING_FLAGS))
+			if (!(event->attr.sample_type &
+			      ~intel_pmu_free_running_flags(event)))
 				event->hw.flags |= PERF_X86_EVENT_FREERUNNING;
 		}
 		if (x86_pmu.pebs_aliases)
@@ -2689,6 +2699,8 @@ static __initconst const struct x86_pmu core_pmu = {
 	.event_map		= intel_pmu_event_map,
 	.max_events		= ARRAY_SIZE(intel_perfmon_event_map),
 	.apic			= 1,
+	.free_running_flags	= PEBS_FREERUNNING_FLAGS,
+
 	/*
 	 * Intel PMCs cannot be accessed sanely above 32-bit width,
 	 * so we install an artificial 1<<31 period regardless of
@@ -2727,6 +2739,7 @@ static __initconst const struct x86_pmu intel_pmu = {
 	.event_map		= intel_pmu_event_map,
 	.max_events		= ARRAY_SIZE(intel_perfmon_event_map),
 	.apic			= 1,
+	.free_running_flags	= PEBS_FREERUNNING_FLAGS,
 	/*
 	 * Intel PMCs cannot be accessed sanely above 32 bit width,
 	 * so we install an artificial 1<<31 period regardless of
diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 410270a..03773c2 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -1273,6 +1273,7 @@ void __init intel_ds_init(void)
 			x86_pmu.pebs_record_size =
 						sizeof(struct pebs_record_skl);
 			x86_pmu.drain_pebs = intel_pmu_drain_pebs_nhm;
+			x86_pmu.free_running_flags |= PERF_SAMPLE_TIME;
 			break;
 
 		default: