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| author | Kan Liang <kan.liang@linux.intel.com> | 2018-03-01 12:54:54 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-03-09 08:22:05 +0100 |
| commit | f605cfca8c39ffa2b98c06d2b9f30ba64f1e54e3 (patch) | |
| tree | 14fedd7100c8a1f4947beecbb6a05f92c804a6a2 /arch/x86/events/perf_event.h | |
| parent | 3f986eefc89c528bf2d398a6dc3637b743a7139e (diff) | |
| download | linux-stable-f605cfca8c39ffa2b98c06d2b9f30ba64f1e54e3.tar.gz linux-stable-f605cfca8c39ffa2b98c06d2b9f30ba64f1e54e3.tar.bz2 linux-stable-f605cfca8c39ffa2b98c06d2b9f30ba64f1e54e3.zip | |
perf/x86/intel: Fix large period handling on Broadwell CPUs
Large fixed period values could be truncated on Broadwell, for example:
perf record -e cycles -c 10000000000
Here the fixed period is 0x2540BE400, but the period which finally applied is
0x540BE400 - which is wrong.
The reason is that x86_pmu::limit_period() uses an u32 parameter, so the
high 32 bits of 'period' get truncated.
This bug was introduced in:
commit 294fe0f52a44 ("perf/x86/intel: Add INST_RETIRED.ALL workarounds")
It's safe to use u64 instead of u32:
- Although the 'left' is s64, the value of 'left' must be positive when
calling limit_period().
- bdw_limit_period() only modifies the lowest 6 bits, it doesn't touch
the higher 32 bits.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
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: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Fixes: 294fe0f52a44 ("perf/x86/intel: Add INST_RETIRED.ALL workarounds")
Link: http://lkml.kernel.org/r/1519926894-3520-1-git-send-email-kan.liang@linux.intel.com
[ Rewrote unacceptably bad changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/events/perf_event.h')
| -rw-r--r-- | arch/x86/events/perf_event.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h index 78f91ec1056e..6495ffd57e3e 100644 --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -557,7 +557,7 @@ struct x86_pmu { struct x86_pmu_quirk *quirks; int perfctr_second_write; bool late_ack; - unsigned (*limit_period)(struct perf_event *event, unsigned l); + u64 (*limit_period)(struct perf_event *event, u64 l); /* * sysfs attrs |