diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/events/intel/core.c | 30 |
1 files changed, 21 insertions, 9 deletions
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index cb8522290e6a..86138267b68a 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -2110,6 +2110,27 @@ again: GLOBAL_STATUS_LBRS_FROZEN); if (!status) goto done; + /* + * In case multiple PEBS events are sampled at the same time, + * it is possible to have GLOBAL_STATUS bit 62 set indicating + * PEBS buffer overflow and also seeing at most 3 PEBS counters + * having their bits set in the status register. This is a sign + * that there was at least one PEBS record pending at the time + * of the PMU interrupt. PEBS counters must only be processed + * via the drain_pebs() calls and not via the regular sample + * processing loop coming after that the function, otherwise + * phony regular samples may be generated in the sampling buffer + * not marked with the EXACT tag. Another possibility is to have + * one PEBS event and at least one non-PEBS event whic hoverflows + * while PEBS has armed. In this case, bit 62 of GLOBAL_STATUS will + * not be set, yet the overflow status bit for the PEBS counter will + * be on Skylake. + * + * To avoid this problem, we systematically ignore the PEBS-enabled + * counters from the GLOBAL_STATUS mask and we always process PEBS + * events via drain_pebs(). + */ + status &= ~cpuc->pebs_enabled; /* * PEBS overflow sets bit 62 in the global status register @@ -2117,15 +2138,6 @@ again: if (__test_and_clear_bit(62, (unsigned long *)&status)) { handled++; x86_pmu.drain_pebs(regs); - /* - * There are cases where, even though, the PEBS ovfl bit is set - * in GLOBAL_OVF_STATUS, the PEBS events may also have their - * overflow bits set for their counters. We must clear them - * here because they have been processed as exact samples in - * the drain_pebs() routine. They must not be processed again - * in the for_each_bit_set() loop for regular samples below. - */ - status &= ~cpuc->pebs_enabled; status &= x86_pmu.intel_ctrl | GLOBAL_STATUS_TRACE_TOPAPMI; } |