diff options
Diffstat (limited to 'arch/x86/events')
| -rw-r--r-- | arch/x86/events/intel/ds.c | 34 |
1 files changed, 24 insertions, 10 deletions
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c index da6780122786..8a10a045b57b 100644 --- a/arch/x86/events/intel/ds.c +++ b/arch/x86/events/intel/ds.c @@ -1153,7 +1153,6 @@ static void setup_pebs_sample_data(struct perf_event *event, if (pebs == NULL) return; - regs->flags &= ~PERF_EFLAGS_EXACT; sample_type = event->attr.sample_type; dsrc = sample_type & PERF_SAMPLE_DATA_SRC; @@ -1197,7 +1196,13 @@ static void setup_pebs_sample_data(struct perf_event *event, * and PMI. */ *regs = *iregs; - regs->flags = pebs->flags; + + /* + * Initialize regs_>flags from PEBS, + * Clear exact bit (which uses x86 EFLAGS Reserved bit 3), + * i.e., do not rely on it being zero: + */ + regs->flags = pebs->flags & ~PERF_EFLAGS_EXACT; if (sample_type & PERF_SAMPLE_REGS_INTR) { regs->ax = pebs->ax; @@ -1217,10 +1222,6 @@ static void setup_pebs_sample_data(struct perf_event *event, regs->sp = pebs->sp; } - /* - * Preserve PERF_EFLAGS_VM from set_linear_ip(). - */ - regs->flags = pebs->flags | (regs->flags & PERF_EFLAGS_VM); #ifndef CONFIG_X86_32 regs->r8 = pebs->r8; regs->r9 = pebs->r9; @@ -1234,20 +1235,33 @@ static void setup_pebs_sample_data(struct perf_event *event, } if (event->attr.precise_ip > 1) { - /* Haswell and later have the eventing IP, so use it: */ + /* + * Haswell and later processors have an 'eventing IP' + * (real IP) which fixes the off-by-1 skid in hardware. + * Use it when precise_ip >= 2 : + */ if (x86_pmu.intel_cap.pebs_format >= 2) { set_linear_ip(regs, pebs->real_ip); regs->flags |= PERF_EFLAGS_EXACT; } else { - /* Otherwise use PEBS off-by-1 IP: */ + /* Otherwise, use PEBS off-by-1 IP: */ set_linear_ip(regs, pebs->ip); - /* ... and try to fix it up using the LBR entries: */ + /* + * With precise_ip >= 2, try to fix up the off-by-1 IP + * using the LBR. If successful, the fixup function + * corrects regs->ip and calls set_linear_ip() on regs: + */ if (intel_pmu_pebs_fixup_ip(regs)) regs->flags |= PERF_EFLAGS_EXACT; } - } else + } else { + /* + * When precise_ip == 1, return the PEBS off-by-1 IP, + * no fixup attempted: + */ set_linear_ip(regs, pebs->ip); + } if ((sample_type & (PERF_SAMPLE_ADDR | PERF_SAMPLE_PHYS_ADDR)) && |