>From c3b53a5733fdea35807f4513255bca05e3aee5c5 Mon Sep 17 00:00:00 2001
From: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>
Date: Tue, 30 Oct 2012 23:05:05 -0700
Subject: [PATCH] perf: x86 filter_events() - use hw event id ?
The ->event_map() operation expects to index through the _hardware event id_.
But filter_events() function is calling ->event_map() with a loop index i.
Suppose a processor does not implement say PERF_COUNT_HW_BUS_CYCLES (6),
but implements, PERF_COUNT_HW_STALLED_CYCLES_FRONTEND (7).
->event_map() for "bus cycles" returns 0, we push the "stalled-cycles-frontend"
event up by one in the events_attr[].
The index of "stalled-cycles-frontend" in the events_attr[] is 6 which
is different from its hardware event id 7.
The next and subsequent calls to ->event_map() will use this index in the
modified events_attr[] table. All subsequent event ids appear unimplemented
because they continue to check the same index (6 in this case).
Should'nt we be checking the hardware event id instead ?
I have not tested this on x86 - only on my port of the sysfs events to Power.
---
arch/x86/kernel/cpu/perf_event.c | 11 ++++++++++-
1 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 0a55ab2..ae88512 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1325,12 +1325,21 @@ struct perf_pmu_events_attr {
* Remove all undefined events (x86_pmu.event_map(id) == 0)
* out of events_attr attributes.
*/
+#define PMU_ATTR(a) container_of((a), struct perf_pmu_events_attr, attr)
+#define DEV_ATTR(a) container_of((a), struct device_attribute, attr)
+
static void __init filter_events(struct attribute **attrs)
{
int i, j;
+ struct perf_pmu_events_attr *pmu_attr;
+ struct device_attribute *dev_attr;
+
for (i = 0; attrs[i]; i++) {
- if (x86_pmu.event_map(i))
+ dev_attr = DEV_ATTR(attrs[i]);
+ pmu_attr = PMU_ATTR(dev_attr);
+
+ if (x86_pmu.event_map(pmu_attr->id))
continue;
for (j = i; attrs[j]; j++)
--
1.7.1
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