perf, x86: Fix BTS condition
Currently the x86 backend incorrectly assumes that any BRANCH_INSN
with sample_period==1 is a BTS request. This is not true when we do
frequency driven profiling such as 'perf record -e branches'.
Solves this error:
$ perf record -e branches ./array
Error: sys_perf_event_open() syscall returned with 95 (Operation not supported).
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reported-by: Ingo Molnar <mingo@elte.hu>
Cc: "Metzger, Markus T" <markus.t.metzger@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-rd2y4ct71hjawzz6fpvsy9hg@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 632e5dc..fac0654 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -613,8 +613,8 @@
/*
* Branch tracing:
*/
- if ((attr->config == PERF_COUNT_HW_BRANCH_INSTRUCTIONS) &&
- (hwc->sample_period == 1)) {
+ if (attr->config == PERF_COUNT_HW_BRANCH_INSTRUCTIONS &&
+ !attr->freq && hwc->sample_period == 1) {
/* BTS is not supported by this architecture. */
if (!x86_pmu.bts_active)
return -EOPNOTSUPP;
diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 43fa20b..9194b06 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -998,6 +998,9 @@
struct hw_perf_event *hwc = &event->hw;
unsigned int hw_event, bts_event;
+ if (event->attr.freq)
+ return NULL;
+
hw_event = hwc->config & INTEL_ARCH_EVENT_MASK;
bts_event = x86_pmu.event_map(PERF_COUNT_HW_BRANCH_INSTRUCTIONS);