From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 905E83264F4; Tue, 28 Apr 2026 23:19:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777418369; cv=none; b=htXIPFtL+7CXhntDZW4i9d6gFWoMjdtXx+cuMJPFOA7Wyu0Shx/X4uefBP5Ly+cP/l01zIxPveKQErpcUvNclMwqAPWdqIErFq6NGeg+XolucrDcC8B3KYV5PjWaiUKjrduyj05VwwJKAt9WbNnW7GRq+oo/oxiINaDT50Uutwo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777418369; c=relaxed/simple; bh=+aonKUnaiY8pSgSFFphj0LQC/12BFnhuYoBKfBWt3go=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Ms2xQbqbT5iG3l0YupwVmn/QwOTXei/HGtbDF1Z7yKvUfEkVWVt5H8+5hI0DWXxFDcNgQOvpaYRmZpYDIkkB22ToUGBPghp6k/useAXZ0iC3kD/29NtDeL0SRWiZa9rC1bxg081Gs7/tS4qrpiLSZweaywlfz7oRurm1+CHjDDc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tCRtAZsn; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tCRtAZsn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B5472C2BCAF; Tue, 28 Apr 2026 23:19:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777418369; bh=+aonKUnaiY8pSgSFFphj0LQC/12BFnhuYoBKfBWt3go=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tCRtAZsnaK1M+6v7vr9wYC/P0MW37Pl6txrQuTg8ei0ugnF6s49177PiqNNY9eOf1 sCDkwGtuKsQbLeDobFp4MJJksUmnJMqA+5kBAzlSM6mblV+StmXjTJhRlMnK1qfplZ mYmm0mH2s+4KZLKc6CFTxZ1eusDSfmPbrnFYOnJ8GRqiSejvgm85QHZBA7ftkdxNj5 1T/j+1c0E4u1egYuP7zVPf/SjzMUcaQVE+b8xGjfJqeOT0elmf0ZXwKyGt41w4FZVg Zl/yOlsuKbgYTqd7APAdhQL5qTFU6vlmBp5x692VZcZYAnHpgewCYmva/B3huYku4a 37nslFEK58eEw== Date: Tue, 28 Apr 2026 16:19:27 -0700 From: Namhyung Kim To: Ian Rogers Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Adrian Hunter , James Clark , Leo Yan , Ravi Bangoria , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, thomas.falcon@intel.com, dapeng1.mi@linux.intel.com Subject: Re: [PATCH v1 1/2] perf event: Fix size of synthesized sample with branch stacks Message-ID: References: <20260428070328.1880314-1-irogers@google.com> <20260428070328.1880314-2-irogers@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260428070328.1880314-2-irogers@google.com> On Tue, Apr 28, 2026 at 12:03:27AM -0700, Ian Rogers wrote: > Synthesizing branch stacks for Intel-PT highlighed an issue where > PERF_SAMPLE_BRANCH_HW_INDEX was assumed to always be set in the > perf_event_attr branch_sample_type. This caused an incorrect size > calculation. > > Fix the writing of the nr and hw_idx values during sample event > synthesis. > > Assisted-by: Gemini:gemini-3.1-pro-preview > Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Thanks, Namhyung > --- > tools/perf/bench/inject-buildid.c | 9 ++++++--- > tools/perf/builtin-inject.c | 12 +++++++++--- > tools/perf/tests/dlfilter-test.c | 8 ++++++-- > tools/perf/tests/sample-parsing.c | 5 +++-- > tools/perf/util/arm-spe.c | 7 +++++-- > tools/perf/util/cs-etm.c | 6 ++++-- > tools/perf/util/intel-bts.c | 3 ++- > tools/perf/util/intel-pt.c | 7 +++++-- > tools/perf/util/synthetic-events.c | 25 ++++++++++++++++++------- > tools/perf/util/synthetic-events.h | 6 ++++-- > 10 files changed, 62 insertions(+), 26 deletions(-) > > diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c > index aad572a78d7f..bfd2c5ec9488 100644 > --- a/tools/perf/bench/inject-buildid.c > +++ b/tools/perf/bench/inject-buildid.c > @@ -228,9 +228,12 @@ static ssize_t synthesize_sample(struct bench_data *data, struct bench_dso *dso, > > event.header.type = PERF_RECORD_SAMPLE; > event.header.misc = PERF_RECORD_MISC_USER; > - event.header.size = perf_event__sample_event_size(&sample, bench_sample_type, 0); > - > - perf_event__synthesize_sample(&event, bench_sample_type, 0, &sample); > + event.header.size = perf_event__sample_event_size(&sample, bench_sample_type, > + /*read_format=*/0, > + /*branch_sample_type=*/0); > + perf_event__synthesize_sample(&event, bench_sample_type, > + /*read_format=*/0, > + /*branch_sample_type=*/0, &sample); > > return writen(data->input_pipe[1], &event, event.header.size); > } > diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c > index f174bc69cec4..0c51cb4250d1 100644 > --- a/tools/perf/builtin-inject.c > +++ b/tools/perf/builtin-inject.c > @@ -463,8 +463,13 @@ static int perf_event__convert_sample_callchain(const struct perf_tool *tool, > /* remove sample_type {STACK,REGS}_USER for synthesize */ > sample_type &= ~(PERF_SAMPLE_STACK_USER | PERF_SAMPLE_REGS_USER); > > - perf_event__synthesize_sample(event_copy, sample_type, > - evsel->core.attr.read_format, sample); > + ret = perf_event__synthesize_sample(event_copy, evsel->core.attr.sample_type, > + evsel->core.attr.read_format, > + evsel->core.attr.branch_sample_type, sample); > + if (ret) { > + pr_err("Failed to synthesize sample\n"); > + return ret; > + } > return perf_event__repipe_synth(tool, event_copy); > } > > @@ -1100,7 +1105,8 @@ static int perf_inject__sched_stat(const struct perf_tool *tool, > sample_sw.period = sample->period; > sample_sw.time = sample->time; > perf_event__synthesize_sample(event_sw, evsel->core.attr.sample_type, > - evsel->core.attr.read_format, &sample_sw); > + evsel->core.attr.read_format, > + evsel->core.attr.branch_sample_type, &sample_sw); > build_id__mark_dso_hit(tool, event_sw, &sample_sw, evsel, machine); > ret = perf_event__repipe(tool, event_sw, &sample_sw, machine); > perf_sample__exit(&sample_sw); > diff --git a/tools/perf/tests/dlfilter-test.c b/tools/perf/tests/dlfilter-test.c > index e63790c61d53..204663571943 100644 > --- a/tools/perf/tests/dlfilter-test.c > +++ b/tools/perf/tests/dlfilter-test.c > @@ -188,8 +188,12 @@ static int write_sample(struct test_data *td, u64 sample_type, u64 id, pid_t pid > > event->header.type = PERF_RECORD_SAMPLE; > event->header.misc = PERF_RECORD_MISC_USER; > - event->header.size = perf_event__sample_event_size(&sample, sample_type, 0); > - err = perf_event__synthesize_sample(event, sample_type, 0, &sample); > + event->header.size = perf_event__sample_event_size(&sample, sample_type, > + /*read_format=*/0, > + /*branch_sample_type=*/0); > + err = perf_event__synthesize_sample(event, sample_type, > + /*read_format=*/0, > + /*branch_sample_type=*/0, &sample); > if (err) > return test_result("perf_event__synthesize_sample() failed", TEST_FAIL); > > diff --git a/tools/perf/tests/sample-parsing.c b/tools/perf/tests/sample-parsing.c > index a7327c942ca2..55f0b73ca20e 100644 > --- a/tools/perf/tests/sample-parsing.c > +++ b/tools/perf/tests/sample-parsing.c > @@ -310,7 +310,8 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format) > sample.read.one.lost = 1; > } > > - sz = perf_event__sample_event_size(&sample, sample_type, read_format); > + sz = perf_event__sample_event_size(&sample, sample_type, read_format, > + evsel.core.attr.branch_sample_type); > bufsz = sz + 4096; /* Add a bit for overrun checking */ > event = malloc(bufsz); > if (!event) { > @@ -324,7 +325,7 @@ static int do_test(u64 sample_type, u64 sample_regs, u64 read_format) > event->header.size = sz; > > err = perf_event__synthesize_sample(event, sample_type, read_format, > - &sample); > + evsel.core.attr.branch_sample_type, &sample); > if (err) { > pr_debug("%s failed for sample_type %#"PRIx64", error %d\n", > "perf_event__synthesize_sample", sample_type, err); > diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c > index e5835042acdf..c4ed9f10e731 100644 > --- a/tools/perf/util/arm-spe.c > +++ b/tools/perf/util/arm-spe.c > @@ -484,8 +484,11 @@ static void arm_spe__prep_branch_stack(struct arm_spe_queue *speq) > > static int arm_spe__inject_event(union perf_event *event, struct perf_sample *sample, u64 type) > { > - event->header.size = perf_event__sample_event_size(sample, type, 0); > - return perf_event__synthesize_sample(event, type, 0, sample); > + event->header.type = PERF_RECORD_SAMPLE; > + event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0, > + /*branch_sample_type=*/0); > + return perf_event__synthesize_sample(event, type, /*read_format=*/0, > + /*branch_sample_type=*/0, sample); > } > > static inline int > diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c > index 8a639d2e51a4..1ebc1a6a5e75 100644 > --- a/tools/perf/util/cs-etm.c > +++ b/tools/perf/util/cs-etm.c > @@ -1425,8 +1425,10 @@ static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq, > static int cs_etm__inject_event(union perf_event *event, > struct perf_sample *sample, u64 type) > { > - event->header.size = perf_event__sample_event_size(sample, type, 0); > - return perf_event__synthesize_sample(event, type, 0, sample); > + event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0, > + /*branch_sample_type=*/0); > + return perf_event__synthesize_sample(event, type, /*read_format=*/0, > + /*branch_sample_type=*/0, sample); > } > > > diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c > index 382255393fb3..0b18ebd13f7c 100644 > --- a/tools/perf/util/intel-bts.c > +++ b/tools/perf/util/intel-bts.c > @@ -303,7 +303,8 @@ static int intel_bts_synth_branch_sample(struct intel_bts_queue *btsq, > event.sample.header.size = bts->branches_event_size; > ret = perf_event__synthesize_sample(&event, > bts->branches_sample_type, > - 0, &sample); > + /*read_format=*/0, /*branch_sample_type=*/0, > + &sample); > if (ret) > return ret; > } > diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c > index fc9eec8b54b8..5142983e3243 100644 > --- a/tools/perf/util/intel-pt.c > +++ b/tools/perf/util/intel-pt.c > @@ -1731,8 +1731,11 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt, > static int intel_pt_inject_event(union perf_event *event, > struct perf_sample *sample, u64 type) > { > - event->header.size = perf_event__sample_event_size(sample, type, 0); > - return perf_event__synthesize_sample(event, type, 0, sample); > + event->header.size = perf_event__sample_event_size(sample, type, /*read_format=*/0, > + /*branch_sample_type=*/0); > + > + return perf_event__synthesize_sample(event, type, /*read_format=*/0, > + /*branch_sample_type=*/0, sample); > } > > static inline int intel_pt_opt_inject(struct intel_pt *pt, > diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c > index 85bee747f4cd..2461f25a4d7d 100644 > --- a/tools/perf/util/synthetic-events.c > +++ b/tools/perf/util/synthetic-events.c > @@ -1455,7 +1455,8 @@ int perf_event__synthesize_stat_round(const struct perf_tool *tool, > return process(tool, (union perf_event *) &event, NULL, machine); > } > > -size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format) > +size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format, > + u64 branch_sample_type) > { > size_t sz, result = sizeof(struct perf_record_sample); > > @@ -1515,8 +1516,10 @@ size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, > > if (type & PERF_SAMPLE_BRANCH_STACK) { > sz = sample->branch_stack->nr * sizeof(struct branch_entry); > - /* nr, hw_idx */ > - sz += 2 * sizeof(u64); > + /* nr */ > + sz += sizeof(u64); > + if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX) > + sz += sizeof(u64); > result += sz; > } > > @@ -1605,7 +1608,7 @@ static __u64 *copy_read_group_values(__u64 *array, __u64 read_format, > } > > int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format, > - const struct perf_sample *sample) > + u64 branch_sample_type, const struct perf_sample *sample) > { > __u64 *array; > size_t sz; > @@ -1719,9 +1722,17 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo > > if (type & PERF_SAMPLE_BRANCH_STACK) { > sz = sample->branch_stack->nr * sizeof(struct branch_entry); > - /* nr, hw_idx */ > - sz += 2 * sizeof(u64); > - memcpy(array, sample->branch_stack, sz); > + > + *array++ = sample->branch_stack->nr; > + > + if (branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX) { > + if (sample->no_hw_idx) > + *array++ = 0; > + else > + *array++ = sample->branch_stack->hw_idx; > + } > + > + memcpy(array, perf_sample__branch_entries((struct perf_sample *)sample), sz); > array = (void *)array + sz; > } > > diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h > index b0edad0c3100..8c7f49f9ccf5 100644 > --- a/tools/perf/util/synthetic-events.h > +++ b/tools/perf/util/synthetic-events.h > @@ -81,7 +81,8 @@ int perf_event__synthesize_mmap_events(const struct perf_tool *tool, union perf_ > int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine); > int perf_event__synthesize_namespaces(const struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine); > int perf_event__synthesize_cgroups(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine); > -int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format, const struct perf_sample *sample); > +int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format, > + u64 branch_sample_type, const struct perf_sample *sample); > int perf_event__synthesize_stat_config(const struct perf_tool *tool, struct perf_stat_config *config, perf_event__handler_t process, struct machine *machine); > int perf_event__synthesize_stat_events(struct perf_stat_config *config, const struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process, bool attrs); > int perf_event__synthesize_stat_round(const struct perf_tool *tool, u64 time, u64 type, perf_event__handler_t process, struct machine *machine); > @@ -97,7 +98,8 @@ void perf_event__synthesize_final_bpf_metadata(struct perf_session *session, > > int perf_tool__process_synth_event(const struct perf_tool *tool, union perf_event *event, struct machine *machine, perf_event__handler_t process); > > -size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format); > +size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, > + u64 read_format, u64 branch_sample_type); > > int __machine__synthesize_threads(struct machine *machine, const struct perf_tool *tool, > struct target *target, struct perf_thread_map *threads, > -- > 2.54.0.545.g6539524ca2-goog >