Commit-ID: dbc33f7016747bfce64f3d1e3af63f1251fcbf85
Gitweb: http://git.kernel.org/tip/dbc33f7016747bfce64f3d1e3af63f1251fcbf85
Author: Stephane Eranian <eranian@xxxxxxxxxx>
AuthorDate: Mon, 9 Sep 2013 12:53:50 -0700
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 12 Sep 2013 08:42:37 +0200
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@xxxxxxxxxx>
Reviewed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: peterz@xxxxxxxxxxxxx
Cc: zheng.z.yan@xxxxxxxxx
Link: http://lkml.kernel.org/r/20130909195350.GA17643@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/kernel/cpu/perf_event_intel_uncore.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
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 @@ uncore_get_event_constraint(struct intel_uncore_box *box, struct perf_event *eve
return c;
}
- if (event->hw.config == ~0ULL)
+ if (event->attr.config == UNCORE_FIXED_EVENT)
return &constraint_fixed;
if (type->constraints) {
@@ -3112,7 +3112,9 @@ static int uncore_pmu_event_init(struct perf_event *event)
*/
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) {
--
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