From ab608344bcbde4f55ec4cd911b686b0ce3eae076 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 8 Apr 2010 23:03:20 +0200 Subject: [PATCH] perf, x86: Improve the PEBS ABI Rename perf_event_attr::precise to perf_event_attr::precise_ip and widen it to 2 bits. This new field describes the required precision of the PERF_SAMPLE_IP field: 0 - SAMPLE_IP can have arbitrary skid 1 - SAMPLE_IP must have constant skid 2 - SAMPLE_IP requested to have 0 skid 3 - SAMPLE_IP must have 0 skid And modify the Intel PEBS code accordingly. The PEBS implementation now supports up to precise_ip == 2, where we perform the IP fixup. Also s/PERF_RECORD_MISC_EXACT/&_IP/ to clarify its meaning, this bit should be set for each PERF_SAMPLE_IP field known to match the actual instruction triggering the event. This new scheme allows for a PEBS mode that uses the buffer for more than a single event. Signed-off-by: Peter Zijlstra Cc: Paul Mackerras Cc: Stephane Eranian LKML-Reference: Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event.c | 17 ++++++++++++++++- arch/x86/kernel/cpu/perf_event_intel.c | 4 ++-- arch/x86/kernel/cpu/perf_event_intel_ds.c | 12 ++++++------ include/linux/perf_event.h | 23 +++++++++++++++++++---- tools/perf/builtin-top.c | 2 +- tools/perf/util/parse-events.c | 25 ++++++++++++++++--------- 6 files changed, 60 insertions(+), 23 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 4a3f1f2..27fa9ee 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -488,6 +488,21 @@ static int x86_setup_perfctr(struct perf_event *event) static int x86_pmu_hw_config(struct perf_event *event) { + if (event->attr.precise_ip) { + int precise = 0; + + /* Support for constant skid */ + if (x86_pmu.pebs) + precise++; + + /* Support for IP fixup */ + if (x86_pmu.lbr_nr) + precise++; + + if (event->attr.precise_ip > precise) + return -EOPNOTSUPP; + } + /* * Generate PMC IRQs: * (keep 'enabled' bit clear for now) @@ -1780,7 +1795,7 @@ unsigned long perf_misc_flags(struct pt_regs *regs) } if (regs->flags & PERF_EFLAGS_EXACT) - misc |= PERF_RECORD_MISC_EXACT; + misc |= PERF_RECORD_MISC_EXACT_IP; return misc; } diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index a4b56ac..fdbc652 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -563,7 +563,7 @@ static void intel_pmu_disable_event(struct perf_event *event) x86_pmu_disable_event(event); - if (unlikely(event->attr.precise)) + if (unlikely(event->attr.precise_ip)) intel_pmu_pebs_disable(event); } @@ -615,7 +615,7 @@ static void intel_pmu_enable_event(struct perf_event *event) return; } - if (unlikely(event->attr.precise)) + if (unlikely(event->attr.precise_ip)) intel_pmu_pebs_enable(event); __x86_pmu_enable_event(hwc, ARCH_PERFMON_EVENTSEL_ENABLE); diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c index 35056f7..18018d1 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c @@ -307,7 +307,7 @@ intel_pebs_constraints(struct perf_event *event) { struct event_constraint *c; - if (!event->attr.precise) + if (!event->attr.precise_ip) return NULL; if (x86_pmu.pebs_constraints) { @@ -330,7 +330,7 @@ static void intel_pmu_pebs_enable(struct perf_event *event) cpuc->pebs_enabled |= 1ULL << hwc->idx; WARN_ON_ONCE(cpuc->enabled); - if (x86_pmu.intel_cap.pebs_trap) + if (x86_pmu.intel_cap.pebs_trap && event->attr.precise_ip > 1) intel_pmu_lbr_enable(event); } @@ -345,7 +345,7 @@ static void intel_pmu_pebs_disable(struct perf_event *event) hwc->config |= ARCH_PERFMON_EVENTSEL_INT; - if (x86_pmu.intel_cap.pebs_trap) + if (x86_pmu.intel_cap.pebs_trap && event->attr.precise_ip > 1) intel_pmu_lbr_disable(event); } @@ -485,7 +485,7 @@ static void __intel_pmu_pebs_event(struct perf_event *event, regs.bp = pebs->bp; regs.sp = pebs->sp; - if (intel_pmu_pebs_fixup_ip(regs)) + if (event->attr.precise_ip > 1 && intel_pmu_pebs_fixup_ip(®s)) regs.flags |= PERF_EFLAGS_EXACT; else regs.flags &= ~PERF_EFLAGS_EXACT; @@ -518,7 +518,7 @@ static void intel_pmu_drain_pebs_core(struct pt_regs *iregs) WARN_ON_ONCE(!event); - if (!event->attr.precise) + if (!event->attr.precise_ip) return; n = top - at; @@ -570,7 +570,7 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs) WARN_ON_ONCE(!event); - if (!event->attr.precise) + if (!event->attr.precise_ip) continue; if (__test_and_set_bit(bit, (unsigned long *)&status)) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 6be4a0f..23cd005 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -203,9 +203,19 @@ struct perf_event_attr { enable_on_exec : 1, /* next exec enables */ task : 1, /* trace fork/exit */ watermark : 1, /* wakeup_watermark */ - precise : 1, /* OoO invariant counter */ - - __reserved_1 : 48; + /* + * precise_ip: + * + * 0 - SAMPLE_IP can have arbitrary skid + * 1 - SAMPLE_IP must have constant skid + * 2 - SAMPLE_IP requested to have 0 skid + * 3 - SAMPLE_IP must have 0 skid + * + * See also PERF_RECORD_MISC_EXACT_IP + */ + precise_ip : 2, /* skid constraint */ + + __reserved_1 : 47; union { __u32 wakeup_events; /* wakeup every n events */ @@ -296,7 +306,12 @@ struct perf_event_mmap_page { #define PERF_RECORD_MISC_GUEST_KERNEL (4 << 0) #define PERF_RECORD_MISC_GUEST_USER (5 << 0) -#define PERF_RECORD_MISC_EXACT (1 << 14) +/* + * Indicates that the content of PERF_SAMPLE_IP points to + * the actual instruction that triggered the event. See also + * perf_event_attr::precise_ip. + */ +#define PERF_RECORD_MISC_EXACT_IP (1 << 14) /* * Reserve the last bit to indicate some extended misc field */ diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c index 3de3977..ed9b5b6 100644 --- a/tools/perf/builtin-top.c +++ b/tools/perf/builtin-top.c @@ -1021,7 +1021,7 @@ static void event__process_sample(const event_t *self, return; } - if (self->header.misc & PERF_RECORD_MISC_EXACT) + if (self->header.misc & PERF_RECORD_MISC_EXACT_IP) exact_samples++; if (event__preprocess_sample(self, session, &al, symbol_filter) < 0 || diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c index bc8b7e6..ae7f591 100644 --- a/tools/perf/util/parse-events.c +++ b/tools/perf/util/parse-events.c @@ -654,10 +654,6 @@ parse_raw_event(const char **strp, struct perf_event_attr *attr) return EVT_FAILED; n = hex2u64(str + 1, &config); if (n > 0) { - if (str[n+1] == 'p') { - attr->precise = 1; - n++; - } *strp = str + n + 1; attr->type = PERF_TYPE_RAW; attr->config = config; @@ -692,19 +688,29 @@ static enum event_result parse_event_modifier(const char **strp, struct perf_event_attr *attr) { const char *str = *strp; - int eu = 1, ek = 1, eh = 1; + int exclude = 0; + int eu = 0, ek = 0, eh = 0, precise = 0; if (*str++ != ':') return 0; while (*str) { - if (*str == 'u') + if (*str == 'u') { + if (!exclude) + exclude = eu = ek = eh = 1; eu = 0; - else if (*str == 'k') + } else if (*str == 'k') { + if (!exclude) + exclude = eu = ek = eh = 1; ek = 0; - else if (*str == 'h') + } else if (*str == 'h') { + if (!exclude) + exclude = eu = ek = eh = 1; eh = 0; - else + } else if (*str == 'p') { + precise++; + } else break; + ++str; } if (str >= *strp + 2) { @@ -712,6 +718,7 @@ parse_event_modifier(const char **strp, struct perf_event_attr *attr) attr->exclude_user = eu; attr->exclude_kernel = ek; attr->exclude_hv = eh; + attr->precise_ip = precise; return 1; } return 0; -- 1.8.2.3