mirror of https://gitee.com/openkylin/linux.git
perf/x86: Fix filter_events() bug with event mappings
This patch fixes a bug in the filter_events() function.
The patch fixes the bug whereby if some mappings did not
exist, e.g., STALLED_CYCLES_FRONTEND, then any event after it
in the attrs array would disappear from the published list of
events in /sys/devices/cpu/events. This could be verified
easily on any system post SNB (which do not publish
STALLED_CYCLES_FRONTEND):
$ ./perf stat -e cycles,ref-cycles true
Performance counter stats for 'true':
1,217,348 cycles
<not supported> ref-cycles
The problem is that in filter_events() there is an assumption
that the argument (attrs) is organized in increasing continuous
event indexes related to the event_map(). But if we remove the
non-supported events by shifing the position in the array, then
the lookup x86_pmu.event_map() needs to compensate for it, otherwise
we are looking up the wrong index. This patch corrects this problem
by compensating for the deleted events and with that ref-cycles
reappears (here shown on Haswell):
$ perf stat -e ref-cycles,cycles true
Performance counter stats for 'true':
4,525,910 ref-cycles
1,064,920 cycles
0.002943888 seconds time elapsed
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: jolsa@kernel.org
Cc: kan.liang@intel.com
Fixes: 8300daa267
("perf/x86: Filter out undefined events from sysfs events attribute")
Link: http://lkml.kernel.org/r/1449516805-6637-1-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
parent
724697648e
commit
61b87cae63
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@ -1534,6 +1534,7 @@ static void __init filter_events(struct attribute **attrs)
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{
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struct device_attribute *d;
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struct perf_pmu_events_attr *pmu_attr;
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int offset = 0;
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int i, j;
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for (i = 0; attrs[i]; i++) {
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@ -1542,7 +1543,7 @@ static void __init filter_events(struct attribute **attrs)
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/* str trumps id */
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if (pmu_attr->event_str)
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continue;
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if (x86_pmu.event_map(i))
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if (x86_pmu.event_map(i + offset))
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continue;
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for (j = i; attrs[j]; j++)
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@ -1550,6 +1551,14 @@ static void __init filter_events(struct attribute **attrs)
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/* Check the shifted attr. */
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i--;
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/*
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* event_map() is index based, the attrs array is organized
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* by increasing event index. If we shift the events, then
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* we need to compensate for the event_map(), otherwise
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* we are looking up the wrong event in the map
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*/
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offset++;
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}
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}
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