perf/x86: Fix uncore PCI fixed counter handling
There was a bug in the handling of SNB-EP/IVB-EP uncore PCI
fixed counters, e.g., IMC.
It would cause erratic values to be returned for the IMC
clockticks event. This was due to a bogus hwc->config value
which was then written to PCI config space.
The erratic values can be seen via:
$ perf stat -a -C 0 -e uncore_imc_0/clockticks/ -I 1000 sleep 10
The fixed counter has most fields marked as reserved with
hw reset values of 0. Yet the kernel was defaulting to a
hwc->config = ~0 and that was causing the issues.
This patch sets the hwc->config values for fixed uncore event
to 0. Now, the values of IMC clockticks is correct.
Signed-off-by: Stephane Eranian <eranian@google.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: peterz@infradead.org
Cc: zheng.z.yan@intel.com
Link: http://lkml.kernel.org/r/20130909195350.GA17643@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
index fd8011e..8ed4458 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
@@ -2808,7 +2808,7 @@
return c;
}
- if (event->hw.config == ~0ULL)
+ if (event->attr.config == UNCORE_FIXED_EVENT)
return &constraint_fixed;
if (type->constraints) {
@@ -3112,7 +3112,9 @@
*/
if (pmu->type->single_fixed && pmu->pmu_idx > 0)
return -EINVAL;
- hwc->config = ~0ULL;
+
+ /* fixed counters have event field hardcoded to zero */
+ hwc->config = 0ULL;
} else {
hwc->config = event->attr.config & pmu->type->event_mask;
if (pmu->type->ops->hw_config) {