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charset="UTF-8" Extend perf_pmu__probe() with probe_sample_types() to test which enum perf_event_sample_format flags are supported by the PMU. First test a common bulk sample_type mask with a single perf_event_open() call to avoid per-bit syscall overhead when all standard sample flags are supported, and then probe any remaining PERF_SAMPLE_* bits individually (configuring required companion fields such as branch_sample_type, sample_regs_user, sample_regs_intr, and sample_stack_user). Populate probed.sample_types as well as convenience booleans for branch stack, callchain, data_src, and weight sampling. Signed-off-by: Ian Rogers --- tools/perf/util/pmu.c | 95 +++++++++++++++++++++++++++++++++++++++++++ tools/perf/util/pmu.h | 13 ++++++ 2 files changed, 108 insertions(+) diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c index 9033bada9f47..164ed926184e 100644 --- a/tools/perf/util/pmu.c +++ b/tools/perf/util/pmu.c @@ -3118,6 +3118,97 @@ static bool try_open_attr_variants(struct perf_event_attr *attr, return false; } +/* + * Probe which enum perf_event_sample_format flags are supported by @pmu, + * testing a common bulk mask first before probing individual flags. + */ +static void probe_sample_types(struct perf_pmu *pmu, + const struct perf_event_attr *base_attr, + pid_t pid, int cpu, unsigned long flags) +{ + u64 reg_bit = BIT_ULL(perf_arch_reg_ip(EM_HOST)) ?: 1ULL; + u64 bulk_mask = PERF_SAMPLE_IP | PERF_SAMPLE_TID | PERF_SAMPLE_TIME | + PERF_SAMPLE_ADDR | PERF_SAMPLE_READ | PERF_SAMPLE_CALLCHAIN | + PERF_SAMPLE_ID | PERF_SAMPLE_CPU | PERF_SAMPLE_PERIOD | + PERF_SAMPLE_STREAM_ID | PERF_SAMPLE_RAW | PERF_SAMPLE_REGS_USER | + PERF_SAMPLE_STACK_USER | PERF_SAMPLE_WEIGHT | PERF_SAMPLE_DATA_SRC | + PERF_SAMPLE_IDENTIFIER | PERF_SAMPLE_TRANSACTION | + PERF_SAMPLE_REGS_INTR | PERF_SAMPLE_CGROUP | + PERF_SAMPLE_DATA_PAGE_SIZE | PERF_SAMPLE_CODE_PAGE_SIZE; + struct perf_event_attr b_attr = *base_attr; + int b_fd; + + b_attr.disabled = 1; + b_attr.sample_period = base_attr->sample_period ?: 10000; + b_attr.sample_type = bulk_mask; + b_attr.sample_regs_user = reg_bit; + b_attr.sample_regs_intr = reg_bit; + b_attr.sample_stack_user = 64; + b_attr.exclude_callchain_kernel = b_attr.exclude_kernel; + b_attr.inherit = 0; + b_fd = sys_perf_event_open(&b_attr, pid, cpu, -1, flags); + if (b_fd >= 0) { + close(b_fd); + pmu->probed.sample_types |= bulk_mask; + } + + for (unsigned int shift = 0; (1ULL << shift) < PERF_SAMPLE_MAX; shift++) { + u64 bit = 1ULL << shift; + struct perf_event_attr attr = *base_attr; + int fd; + + if (pmu->probed.sample_types & bit) + continue; + + attr.disabled = 1; + attr.sample_period = base_attr->sample_period ?: 10000; + attr.sample_type = bit; + + switch (bit) { + case PERF_SAMPLE_BRANCH_STACK: + attr.branch_sample_type = PERF_SAMPLE_BRANCH_ANY | + (attr.exclude_kernel ? PERF_SAMPLE_BRANCH_USER : 0); + break; + case PERF_SAMPLE_CALLCHAIN: + attr.exclude_callchain_kernel = attr.exclude_kernel; + break; + case PERF_SAMPLE_REGS_USER: + attr.sample_regs_user = reg_bit; + break; + case PERF_SAMPLE_REGS_INTR: + attr.sample_regs_intr = reg_bit; + break; + case PERF_SAMPLE_STACK_USER: + attr.sample_stack_user = 64; + break; + case PERF_SAMPLE_READ: + attr.inherit = 0; + break; + default: + break; + } + + fd = sys_perf_event_open(&attr, pid, cpu, -1, flags); + if (fd < 0 && bit == PERF_SAMPLE_BRANCH_STACK) { + attr.branch_sample_type = PERF_SAMPLE_BRANCH_ANY; + fd = sys_perf_event_open(&attr, pid, cpu, -1, flags); + } + if (fd < 0 && bit != PERF_SAMPLE_IP) { + attr.sample_type = PERF_SAMPLE_IP | bit; + fd = sys_perf_event_open(&attr, pid, cpu, -1, flags); + } + if (fd >= 0) { + close(fd); + pmu->probed.sample_types |= bit; + } + } + + pmu->probed.can_branch_stack = !!(pmu->probed.sample_types & PERF_SAMPLE_BRANCH_STACK); + pmu->probed.can_callchain = !!(pmu->probed.sample_types & PERF_SAMPLE_CALLCHAIN); + pmu->probed.can_data_src = !!(pmu->probed.sample_types & PERF_SAMPLE_DATA_SRC); + pmu->probed.can_weight = !!(pmu->probed.sample_types & PERF_SAMPLE_WEIGHT); +} + static void __perf_pmu__probe(struct perf_pmu *pmu, int pmu_cpu) { struct probe_candidates cands = { .nr = 0 }; @@ -3358,6 +3449,10 @@ static void __perf_pmu__probe(struct perf_pmu *pmu, int pmu_cpu) pmu->probed.can_sample = true; } + /* 2. All enum perf_event_sample_format types */ + if (pmu->probed.can_sample) + probe_sample_types(pmu, &base_attr, pid, cpu, flags); + if (keepalive_fd >= 0) close(keepalive_fd); pmu->probed.checked = true; diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h index ddcd28b3cae5..658485faa05d 100644 --- a/tools/perf/util/pmu.h +++ b/tools/perf/util/pmu.h @@ -226,10 +226,23 @@ struct perf_pmu { bool can_count; /** @probed.can_sample: Supports interrupt-based sampling (sample_period > 0). */ bool can_sample; + /** @probed.can_branch_stack: Supports PERF_SAMPLE_BRANCH_STACK. */ + bool can_branch_stack; + /** @probed.can_callchain: Supports PERF_SAMPLE_CALLCHAIN. */ + bool can_callchain; + /** @probed.can_data_src: Supports PERF_SAMPLE_DATA_SRC. */ + bool can_data_src; + /** @probed.can_weight: Supports PERF_SAMPLE_WEIGHT. */ + bool can_weight; /** @probed.probe_event: Name of the event used to probe the PMU. */ char *probe_event; /** @probed.open_err: errno if open_supported is false. */ int open_err; + /** + * @probed.sample_types: Bitmask of supported + * enum perf_event_sample_format flags. + */ + u64 sample_types; } probed; }; -- 2.56.0.385.gac671c819a-goog