From: Stephane Eranian Date: Thu, 26 Nov 2020 11:09:22 +0000 (+0900) Subject: perf/x86/intel: Check PEBS status correctly X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=fc17db8aa4c53cbd2d5469bb0521ea0f0a6dbb27;p=linux.git perf/x86/intel: Check PEBS status correctly The kernel cannot disambiguate when 2+ PEBS counters overflow at the same time. This is what the comment for this code suggests. However, I see the comparison is done with the unfiltered p->status which is a copy of IA32_PERF_GLOBAL_STATUS at the time of the sample. This register contains more than the PEBS counter overflow bits. It also includes many other bits which could also be set. Signed-off-by: Namhyung Kim Signed-off-by: Stephane Eranian Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20201126110922.317681-2-namhyung@kernel.org --- diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c index 89dba588636ed..485c5066f8b8c 100644 --- a/arch/x86/events/intel/ds.c +++ b/arch/x86/events/intel/ds.c @@ -1916,7 +1916,7 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs, struct perf_sample_d * that caused the PEBS record. It's called collision. * If collision happened, the record will be dropped. */ - if (p->status != (1ULL << bit)) { + if (pebs_status != (1ULL << bit)) { for_each_set_bit(i, (unsigned long *)&pebs_status, size) error[i]++; continue;