[PATCH v7 14/23] perf inject: Don't pass evsel with sample

Ian Rogers
2026-04-08T07:26:39Z

The sample contains the evsel and so it is unnecessary to pass the
evsel as well. Clean up handling of sample and mmap_evsel when
synthesizing build id events and mmap2 events with build ids. For
callchain walking and things that expect the evsel to match sample,
the sample->evsel shouldn't change. The mmap_evsel should be used when
making mmap2 events.

Add space for sample identifiers in
perf_event__synthesize_mmap2_build_id to avoid Sashiko caught
potential buffer overrun. Also add a NULL check to avoid an unlikely
SEGV.

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/builtin-inject.c | 52 ++++++++++++++-------------
tools/perf/util/synthetic-events.c | 57 ++++++++++++++++++++++--------
tools/perf/util/synthetic-events.h | 2 --
3 files changed, 70 insertions(+), 41 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 6955eca145d8..2297d5e08638 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -146,14 +146,12 @@ struct event_entry {
static int tool__inject_build_id(const struct perf_tool *tool,
struct perf_sample *sample,
struct machine *machine,
- const struct evsel *evsel,
__u16 misc,
const char *filename,
struct dso *dso, u32 flags);
static int tool__inject_mmap2_build_id(const struct perf_tool *tool,
struct perf_sample *sample,
struct machine *machine,
- const struct evsel *evsel,
__u16 misc,
__u32 pid, __u32 tid,
__u64 start, __u64 len, __u64 pgoff,
@@ -357,7 +355,6 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
typedef int (*inject_handler)(const struct perf_tool *tool,
union perf_event *event,
struct perf_sample *sample,
- struct evsel *evsel,
struct machine *machine);

static int perf_event__repipe_sample(const struct perf_tool *tool,
@@ -370,7 +367,7 @@ static int perf_event__repipe_sample(const struct perf_tool *tool,

if (evsel && evsel->handler) {
inject_handler f = evsel->handler;
- return f(tool, event, sample, evsel, machine);
+ return f(tool, event, sample, machine);
}

build_id__mark_dso_hit(tool, event, sample, machine);
@@ -584,11 +581,12 @@ static int perf_event__repipe_common_mmap(const struct perf_tool *tool,
}

if (dso && !dso__hit(dso)) {
- struct evsel *evsel = evlist__event2evsel(inject->session->evlist, event);
+ if (!sample->evsel)
+ sample->evsel = evlist__event2evsel(inject->session->evlist, event);

- if (evsel) {
+ if (sample->evsel) {
dso__set_hit(dso);
- tool__inject_build_id(tool, sample, machine, evsel,
+ tool__inject_build_id(tool, sample, machine,
/*misc=*/sample->cpumode,
filename, dso, flags);
}
@@ -615,23 +613,26 @@ static int perf_event__repipe_common_mmap(const struct perf_tool *tool,
}
if ((inject->build_id_style == BID_RWS__MMAP2_BUILDID_ALL) &&
!(event->header.misc & PERF_RECORD_MISC_MMAP_BUILD_ID)) {
- struct evsel *evsel = evlist__event2evsel(inject->session->evlist, event);
+ struct evsel *saved_evsel = sample->evsel;

- if (evsel && !dso_sought) {
+ sample->evsel = evlist__event2evsel(inject->session->evlist, event);
+ if (sample->evsel && !dso_sought) {
dso = findnew_dso(pid, tid, filename, dso_id, machine);
dso_sought = true;
}
- if (evsel && dso &&
- !tool__inject_mmap2_build_id(tool, sample, machine, evsel,
+ if (sample->evsel && dso &&
+ !tool__inject_mmap2_build_id(tool, sample, machine,
sample->cpumode | PERF_RECORD_MISC_MMAP_BUILD_ID,
pid, tid, start, len, pgoff,
dso,
prot, flags,
filename)) {
/* Injected mmap2 so no need to repipe. */
+ sample->evsel = saved_evsel;
dso__put(dso);
return 0;
}
+ sample->evsel = saved_evsel;
}
dso__put(dso);
if (inject->build_id_style == BID_RWS__MMAP2_BUILDID_LAZY)
@@ -836,7 +837,6 @@ static bool perf_inject__lookup_known_build_id(struct perf_inject *inject,
static int tool__inject_build_id(const struct perf_tool *tool,
struct perf_sample *sample,
struct machine *machine,
- const struct evsel *evsel,
__u16 misc,
const char *filename,
struct dso *dso, u32 flags)
@@ -860,7 +860,7 @@ static int tool__inject_build_id(const struct perf_tool *tool,

err = perf_event__synthesize_build_id(tool, sample, machine,
perf_event__repipe,
- evsel, misc, dso__bid(dso),
+ misc, dso__bid(dso),
filename);
if (err) {
pr_err("Can't synthesize build_id event for %s\n", filename);
@@ -873,7 +873,6 @@ static int tool__inject_build_id(const struct perf_tool *tool,
static int tool__inject_mmap2_build_id(const struct perf_tool *tool,
struct perf_sample *sample,
struct machine *machine,
- const struct evsel *evsel,
__u16 misc,
__u32 pid, __u32 tid,
__u64 start, __u64 len, __u64 pgoff,
@@ -896,7 +895,6 @@ static int tool__inject_mmap2_build_id(const struct perf_tool *tool,

err = perf_event__synthesize_mmap2_build_id(tool, sample, machine,
perf_event__repipe,
- evsel,
misc, pid, tid,
start, len, pgoff,
dso__bid(dso),
@@ -913,7 +911,7 @@ static int mark_dso_hit(const struct perf_inject *inject,
const struct perf_tool *tool,
struct perf_sample *sample,
struct machine *machine,
- const struct evsel *mmap_evsel,
+ struct evsel *mmap_evsel,
struct map *map, bool sample_in_dso)
{
struct dso *dso;
@@ -941,9 +939,13 @@ static int mark_dso_hit(const struct perf_inject *inject,
dso = map__dso(map);
if (inject->build_id_style == BID_RWS__INJECT_HEADER_LAZY) {
if (dso && !dso__hit(dso)) {
+ /*
+ * The sample is just read for identifiers which we want
+ * to match the for the event of the sample.
+ */
dso__set_hit(dso);
tool__inject_build_id(tool, sample, machine,
- mmap_evsel, misc, dso__long_name(dso), dso,
+ misc, dso__long_name(dso), dso,
map__flags(map));
}
} else if (inject->build_id_style == BID_RWS__MMAP2_BUILDID_LAZY) {
@@ -951,11 +953,13 @@ static int mark_dso_hit(const struct perf_inject *inject,
const struct build_id null_bid = { .size = 0 };
const struct build_id *bid = dso ? dso__bid(dso) : &null_bid;
const char *filename = dso ? dso__long_name(dso) : "";
+ struct evsel *saved_evsel = sample->evsel;

map__set_hit(map);
+ /* Creating a new mmap2 event which has an evsel for the mmap event. */
+ sample->evsel = mmap_evsel;
perf_event__synthesize_mmap2_build_id(tool, sample, machine,
perf_event__repipe,
- mmap_evsel,
misc,
sample->pid, sample->tid,
map__start(map),
@@ -965,6 +969,7 @@ static int mark_dso_hit(const struct perf_inject *inject,
map__prot(map),
map__flags(map),
filename);
+ sample->evsel = saved_evsel;
}
}
return 0;
@@ -975,7 +980,7 @@ struct mark_dso_hit_args {
const struct perf_tool *tool;
struct perf_sample *sample;
struct machine *machine;
- const struct evsel *mmap_evsel;
+ struct evsel *mmap_evsel;
};

static int mark_dso_hit_callback(struct callchain_cursor_node *node, void *data)
@@ -1030,7 +1035,6 @@ static int perf_event__inject_buildid(const struct perf_tool *tool, union perf_e
static int perf_inject__sched_process_exit(const struct perf_tool *tool,
union perf_event *event __maybe_unused,
struct perf_sample *sample,
- struct evsel *evsel __maybe_unused,
struct machine *machine __maybe_unused)
{
struct perf_inject *inject = container_of(tool, struct perf_inject, tool);
@@ -1050,13 +1054,12 @@ static int perf_inject__sched_process_exit(const struct perf_tool *tool,
static int perf_inject__sched_switch(const struct perf_tool *tool,
union perf_event *event,
struct perf_sample *sample,
- struct evsel *evsel,
struct machine *machine)
{
struct perf_inject *inject = container_of(tool, struct perf_inject, tool);
struct event_entry *ent;

- perf_inject__sched_process_exit(tool, event, sample, evsel, machine);
+ perf_inject__sched_process_exit(tool, event, sample, machine);

ent = malloc(event->header.size + sizeof(struct event_entry));
if (ent == NULL) {
@@ -1075,13 +1078,13 @@ static int perf_inject__sched_switch(const struct perf_tool *tool,
static int perf_inject__sched_stat(const struct perf_tool *tool,
union perf_event *event __maybe_unused,
struct perf_sample *sample,
- struct evsel *evsel,
struct machine *machine)
{
struct event_entry *ent;
union perf_event *event_sw;
struct perf_sample sample_sw;
struct perf_inject *inject = container_of(tool, struct perf_inject, tool);
+ struct evsel *evsel = sample->evsel;
u32 pid = perf_sample__intval(sample, "pid");
int ret;

@@ -1446,7 +1449,7 @@ static int synthesize_build_id(struct perf_inject *inject, struct dso *dso, pid_
dso__set_hit(dso);

return perf_event__synthesize_build_id(&inject->tool, &synth_sample, machine,
- process_build_id, inject__mmap_evsel(inject),
+ process_build_id,
/*misc=*/synth_sample.cpumode,
dso__bid(dso), dso__long_name(dso));
}
@@ -2008,7 +2011,6 @@ static int evsel__check_stype(struct evsel *evsel, u64 sample_type, const char *
static int drop_sample(const struct perf_tool *tool __maybe_unused,
union perf_event *event __maybe_unused,
struct perf_sample *sample __maybe_unused,
- struct evsel *evsel __maybe_unused,
struct machine *machine __maybe_unused)
{
return 0;
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 85bee747f4cd..502b1f847c91 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1802,7 +1802,12 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo
return 0;
}

-int perf_event__synthesize_id_sample(__u64 *array, u64 type, const struct perf_sample *sample)
+static int __perf_event__synthesize_id_sample(__u64 *array, u64 type,
+ __u32 pid, __u32 tid,
+ __u64 sample_time,
+ __u64 sample_id,
+ __u64 stream_id,
+ __u32 cpu)
{
__u64 *start = array;

@@ -1813,42 +1818,52 @@ int perf_event__synthesize_id_sample(__u64 *array, u64 type, const struct perf_s
union u64_swap u;

if (type & PERF_SAMPLE_TID) {
- u.val32[0] = sample->pid;
- u.val32[1] = sample->tid;
+ u.val32[0] = pid;
+ u.val32[1] = tid;
*array = u.val64;
array++;
}

if (type & PERF_SAMPLE_TIME) {
- *array = sample->time;
+ *array = sample_time;
array++;
}

if (type & PERF_SAMPLE_ID) {
- *array = sample->id;
+ *array = sample_id;
array++;
}

if (type & PERF_SAMPLE_STREAM_ID) {
- *array = sample->stream_id;
+ *array = stream_id;
array++;
}

if (type & PERF_SAMPLE_CPU) {
- u.val32[0] = sample->cpu;
+ u.val32[0] = cpu;
u.val32[1] = 0;
*array = u.val64;
array++;
}

if (type & PERF_SAMPLE_IDENTIFIER) {
- *array = sample->id;
+ *array = sample_id;
array++;
}

return (void *)array - (void *)start;
}

+int perf_event__synthesize_id_sample(__u64 *array, u64 type, const struct perf_sample *sample)
+{
+ return __perf_event__synthesize_id_sample(array, type,
+ sample->pid, sample->tid,
+ sample->time,
+ sample->id,
+ sample->stream_id,
+ sample->cpu);
+}
+
int __perf_event__synthesize_id_index(const struct perf_tool *tool, perf_event__handler_t process,
struct evlist *evlist, struct machine *machine, size_t from)
{
@@ -2252,7 +2267,6 @@ int perf_event__synthesize_build_id(const struct perf_tool *tool,
struct perf_sample *sample,
struct machine *machine,
perf_event__handler_t process,
- const struct evsel *evsel,
__u16 misc,
const struct build_id *bid,
const char *filename)
@@ -2275,12 +2289,13 @@ int perf_event__synthesize_build_id(const struct perf_tool *tool,
ev.build_id.header.size = len;
strcpy(ev.build_id.filename, filename);

- if (evsel) {
+ if (sample->evsel) {
void *array = &ev;
int ret;

array += ev.header.size;
- ret = perf_event__synthesize_id_sample(array, evsel->core.attr.sample_type, sample);
+ ret = perf_event__synthesize_id_sample(array, sample->evsel->core.attr.sample_type,
+ sample);
if (ret < 0)
return ret;

@@ -2299,7 +2314,6 @@ int perf_event__synthesize_mmap2_build_id(const struct perf_tool *tool,
struct perf_sample *sample,
struct machine *machine,
perf_event__handler_t process,
- const struct evsel *evsel,
__u16 misc,
__u32 pid, __u32 tid,
__u64 start, __u64 len, __u64 pgoff,
@@ -2308,13 +2322,23 @@ int perf_event__synthesize_mmap2_build_id(const struct perf_tool *tool,
const char *filename)
{
union perf_event ev;
+ size_t filename_len = strlen(filename);
size_t ev_len;
void *array;
int ret;

- ev_len = sizeof(ev.mmap2) - sizeof(ev.mmap2.filename) + strlen(filename) + 1;
+ if (!sample->evsel)
+ return -EINVAL; /* Evsel is needed for sample_type data. */
+
+ if (filename_len >= sizeof(ev.mmap2.filename))
+ return -EINVAL;
+
+ ev_len = sizeof(ev.mmap2) - sizeof(ev.mmap2.filename) + filename_len + 1;
ev_len = PERF_ALIGN(ev_len, sizeof(u64));

+ if (ev_len + MAX_ID_HDR_ENTRIES * sizeof(__u64) > sizeof(ev))
+ return -E2BIG;
+
memset(&ev, 0, ev_len);

ev.mmap2.header.type = PERF_RECORD_MMAP2;
@@ -2339,7 +2363,12 @@ int perf_event__synthesize_mmap2_build_id(const struct perf_tool *tool,

array = &ev;
array += ev.header.size;
- ret = perf_event__synthesize_id_sample(array, evsel->core.attr.sample_type, sample);
+ ret = __perf_event__synthesize_id_sample(array, sample->evsel->core.attr.sample_type,
+ pid, tid,
+ sample->time,
+ sample->id,
+ sample->stream_id,
+ sample->cpu);
if (ret < 0)
return ret;

diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
index b0edad0c3100..473a43a78993 100644
--- a/tools/perf/util/synthetic-events.h
+++ b/tools/perf/util/synthetic-events.h
@@ -50,7 +50,6 @@ int perf_event__synthesize_build_id(const struct perf_tool *tool,
struct perf_sample *sample,
struct machine *machine,
perf_event__handler_t process,
- const struct evsel *evsel,
__u16 misc,
const struct build_id *bid,
const char *filename);
@@ -58,7 +57,6 @@ int perf_event__synthesize_mmap2_build_id(const struct perf_tool *tool,
struct perf_sample *sample,
struct machine *machine,
perf_event__handler_t process,
- const struct evsel *evsel,
__u16 misc,
__u32 pid, __u32 tid,
__u64 start, __u64 len, __u64 pgoff,
--
2.53.0.1213.gd9a14994de-goog