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| author | Alexander Shishkin <alexander.shishkin@linux.intel.com> | 2019-12-10 12:51:01 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2019-12-17 13:32:46 +0100 |
| commit | 92ca7da4bdc24d63bb0bcd241c11441ddb63b80a (patch) | |
| tree | 149940e4c77a558df00df7038a6aa6f6eb48942f /arch | |
| parent | ff61541cc6c1962957758ba433c574b76f588d23 (diff) | |
| download | linux-92ca7da4bdc24d63bb0bcd241c11441ddb63b80a.tar.gz linux-92ca7da4bdc24d63bb0bcd241c11441ddb63b80a.tar.bz2 linux-92ca7da4bdc24d63bb0bcd241c11441ddb63b80a.zip | |
perf/x86/intel: Fix PT PMI handling
Commit:
ccbebba4c6bf ("perf/x86/intel/pt: Bypass PT vs. LBR exclusivity if the core supports it")
skips the PT/LBR exclusivity check on CPUs where PT and LBRs coexist, but
also inadvertently skips the active_events bump for PT in that case, which
is a bug. If there aren't any hardware events at the same time as PT, the
PMI handler will ignore PT PMIs, as active_events reads zero in that case,
resulting in the "Uhhuh" spurious NMI warning and PT data loss.
Fix this by always increasing active_events for PT events.
Fixes: ccbebba4c6bf ("perf/x86/intel/pt: Bypass PT vs. LBR exclusivity if the core supports it")
Reported-by: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lkml.kernel.org/r/20191210105101.77210-1-alexander.shishkin@linux.intel.com
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/events/core.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 84fe1becbe26..f118af9f0718 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -376,7 +376,7 @@ int x86_add_exclusive(unsigned int what) * LBR and BTS are still mutually exclusive. */ if (x86_pmu.lbr_pt_coexist && what == x86_lbr_exclusive_pt) - return 0; + goto out; if (!atomic_inc_not_zero(&x86_pmu.lbr_exclusive[what])) { mutex_lock(&pmc_reserve_mutex); @@ -388,6 +388,7 @@ int x86_add_exclusive(unsigned int what) mutex_unlock(&pmc_reserve_mutex); } +out: atomic_inc(&active_events); return 0; @@ -398,11 +399,15 @@ fail_unlock: void x86_del_exclusive(unsigned int what) { + atomic_dec(&active_events); + + /* + * See the comment in x86_add_exclusive(). + */ if (x86_pmu.lbr_pt_coexist && what == x86_lbr_exclusive_pt) return; atomic_dec(&x86_pmu.lbr_exclusive[what]); - atomic_dec(&active_events); } int x86_setup_perfctr(struct perf_event *event) |