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authorAndi Kleen <ak@linux.intel.com>2015-12-04 00:22:20 +0300
committerIngo Molnar <mingo@kernel.org>2016-01-06 13:15:31 +0300
commit01330d7288e0050c5aaabc558059ff91589e67cd (patch)
treeee228a018d1a61ec4e5ecfb334c1753725fc1f72 /arch
parent957ea1fdbcdb909e1540f06f06f1a9ce6e696efa (diff)
downloadlinux-01330d7288e0050c5aaabc558059ff91589e67cd.tar.xz
perf/x86: Allow zero PEBS status with only single active event
Normally we drop PEBS events with a zero status field. But when there is only a single PEBS event active we can assume the PEBS record is for that event. The PEBS buffer is always flushed when PEBS events are disabled, so there is no risk of mishandling state PEBS records this way. Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> 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> Link: http://lkml.kernel.org/r/1449177740-5422-2-git-send-email-andi@firstfloor.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/perf_event_intel_ds.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 0e3a9c73187d..cd1993e46d19 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -1230,6 +1230,18 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
pebs_status = p->status & cpuc->pebs_enabled;
pebs_status &= (1ULL << x86_pmu.max_pebs_events) - 1;
+ /*
+ * On some CPUs the PEBS status can be zero when PEBS is
+ * racing with clearing of GLOBAL_STATUS.
+ *
+ * Normally we would drop that record, but in the
+ * case when there is only a single active PEBS event
+ * we can assume it's for that event.
+ */
+ if (!pebs_status && cpuc->pebs_enabled &&
+ !(cpuc->pebs_enabled & (cpuc->pebs_enabled-1)))
+ pebs_status = cpuc->pebs_enabled;
+
bit = find_first_bit((unsigned long *)&pebs_status,
x86_pmu.max_pebs_events);
if (bit >= x86_pmu.max_pebs_events)