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perf event: Fix size of synthesized sample with branch stacks

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Synthesizing branch stacks for Intel-PT highlighted 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 by passing the branch_sample_type into the sample size
and synthesis functions. Also update hardware tracers (Intel PT,
ARM SPE, CS-ETM) to retrieve and pass their branch_sample_type
dynamically to prevent payload misalignment.

Fixes: d3f85437ad ("perf evsel: Support PERF_SAMPLE_BRANCH_HW_INDEX")
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Dapeng Mi <dapeng1.mi@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linux.dev>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Thomas Falcon <thomas.falcon@intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Ian Rogers 2026-05-18 15:43:24 -07:00 committed by Arnaldo Carvalho de Melo
parent 017bca78e4
commit 059e9100d8
10 changed files with 118 additions and 33 deletions
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9
tools/perf/bench/inject-buildid.c
View File

@ -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);
}

12
tools/perf/builtin-inject.c
View File

@ -465,8 +465,13 @@ 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, 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);
}
@ -1102,7 +1107,8 @@ 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);

8
tools/perf/tests/dlfilter-test.c
View File

@ -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);

5
tools/perf/tests/sample-parsing.c
View File

@ -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);

28
tools/perf/util/arm-spe.c
View File

@ -487,10 +487,30 @@ static void arm_spe__prep_branch_stack(struct arm_spe_queue *speq)
bstack->hw_idx = -1ULL;
}
static int arm_spe__inject_event(union perf_event *event, struct perf_sample *sample, u64 type)
static int arm_spe__inject_event(struct arm_spe *spe, 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);
struct evsel *evsel = sample->evsel;
u64 branch_sample_type = 0;
size_t sz;
if (!evsel && spe->session && spe->session->evlist)
evsel = evlist__id2evsel(spe->session->evlist, sample->id);
if (evsel)
branch_sample_type = evsel->core.attr.branch_sample_type;
event->header.type = PERF_RECORD_SAMPLE;
sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
branch_sample_type);
if (sz >= PERF_SAMPLE_MAX_SIZE) {
pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
return -EFAULT;
}
event->header.size = sz;
return perf_event__synthesize_sample(event, type, /*read_format=*/0,
branch_sample_type, sample);
}
static inline int
@ -502,7 +522,7 @@ arm_spe_deliver_synth_event(struct arm_spe *spe,
int ret;
if (spe->synth_opts.inject) {
ret = arm_spe__inject_event(event, sample, spe->sample_type);
ret = arm_spe__inject_event(spe, event, sample, spe->sample_type);
if (ret)
return ret;
}

28
tools/perf/util/cs-etm.c
View File

@ -1422,11 +1422,29 @@ static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq,
bs->nr += 1;
}
static int cs_etm__inject_event(union perf_event *event,
static int cs_etm__inject_event(struct cs_etm_auxtrace *etm, 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);
struct evsel *evsel = sample->evsel;
u64 branch_sample_type = 0;
size_t sz;
if (!evsel && etm->session && etm->session->evlist)
evsel = evlist__id2evsel(etm->session->evlist, sample->id);
if (evsel)
branch_sample_type = evsel->core.attr.branch_sample_type;
sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
branch_sample_type);
if (sz >= PERF_SAMPLE_MAX_SIZE) {
pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
return -EFAULT;
}
event->header.size = sz;
return perf_event__synthesize_sample(event, type, /*read_format=*/0,
branch_sample_type, sample);
}
@ -1592,7 +1610,7 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
sample.branch_stack = tidq->last_branch;
if (etm->synth_opts.inject) {
ret = cs_etm__inject_event(event, &sample,
ret = cs_etm__inject_event(etm, event, &sample,
etm->instructions_sample_type);
if (ret)
return ret;
@ -1667,7 +1685,7 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq,
}
if (etm->synth_opts.inject) {
ret = cs_etm__inject_event(event, &sample,
ret = cs_etm__inject_event(etm, event, &sample,
etm->branches_sample_type);
if (ret)
return ret;

3
tools/perf/util/intel-bts.c
View File

@ -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;
}

27
tools/perf/util/intel-pt.c
View File

@ -1728,11 +1728,30 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
event->sample.header.misc = sample->cpumode;
}
static int intel_pt_inject_event(union perf_event *event,
static int intel_pt_inject_event(struct intel_pt *pt, 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);
struct evsel *evsel = sample->evsel;
u64 branch_sample_type = 0;
size_t sz;
if (!evsel && pt->session && pt->session->evlist)
evsel = evlist__id2evsel(pt->session->evlist, sample->id);
if (evsel)
branch_sample_type = evsel->core.attr.branch_sample_type;
event->header.type = PERF_RECORD_SAMPLE;
sz = perf_event__sample_event_size(sample, type, /*read_format=*/0,
branch_sample_type);
if (sz >= PERF_SAMPLE_MAX_SIZE) {
pr_err("Sample size %zu exceeds max size %d\n", sz, PERF_SAMPLE_MAX_SIZE);
return -EFAULT;
}
event->header.size = sz;
return perf_event__synthesize_sample(event, type, /*read_format=*/0,
branch_sample_type, sample);
}
static inline int intel_pt_opt_inject(struct intel_pt *pt,
@ -1742,7 +1761,7 @@ static inline int intel_pt_opt_inject(struct intel_pt *pt,
if (!pt->synth_opts.inject)
return 0;
return intel_pt_inject_event(event, sample, type);
return intel_pt_inject_event(pt, event, sample, type);
}
static int intel_pt_deliver_synth_event(struct intel_pt *pt,

25
tools/perf/util/synthetic-events.c
View File

@ -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;
}

6
tools/perf/util/synthetic-events.h
View File

@ -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,