perf, x86: Fix silly bug in intel_pmu_pebs_{enable,disable}

We need to use the actual cpuc->pebs_enabled value, not a local copy for
the changes to take effect.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: paulus@samba.org
Cc: eranian@google.com
Cc: robert.richter@amd.com
Cc: fweisbec@gmail.com
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/cpu/perf_event_intel_ds.c

@@ -333,11 +333,10 @@ static void intel_pmu_pebs_enable(struct perf_event *event)
 {
 	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 	struct hw_perf_event *hwc = &event->hw;
-	u64 val = cpuc->pebs_enabled;
 
 	hwc->config &= ~ARCH_PERFMON_EVENTSEL_INT;
 
-	val |= 1ULL << hwc->idx;
+	cpuc->pebs_enabled |= 1ULL << hwc->idx;
 	WARN_ON_ONCE(cpuc->enabled);
 
 	if (x86_pmu.intel_cap.pebs_trap)
@@ -348,11 +347,10 @@ static void intel_pmu_pebs_disable(struct perf_event *event)
 {
 	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 	struct hw_perf_event *hwc = &event->hw;
-	u64 val = cpuc->pebs_enabled;
 
-	val &= ~(1ULL << hwc->idx);
+	cpuc->pebs_enabled &= ~(1ULL << hwc->idx);
 	if (cpuc->enabled)
-		wrmsrl(MSR_IA32_PEBS_ENABLE, val);
+		wrmsrl(MSR_IA32_PEBS_ENABLE, cpuc->pebs_enabled);
 
 	hwc->config |= ARCH_PERFMON_EVENTSEL_INT;