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perf events: Prefer union over variable length array

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It is possible for casts to introduce alignment issues, prefer a union
for perf_record_event_update.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: Colin Ian King <colin.king@intel.com>
Cc: Dave Marchevsky <davemarchevsky@fb.com>
Cc: German Gomez <german.gomez@arm.com>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Kees Kook <keescook@chromium.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Riccardo Mancini <rickyman7@gmail.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20220614143353.1559597-6-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Ian Rogers 2022-06-14 07:33:52 -07:00 committed by Arnaldo Carvalho de Melo
parent 3657ad4b0f
commit d773c999b8
4 changed files with 27 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
tools/lib/perf/include/perf/event.h
View File

@ -233,7 +233,16 @@ struct perf_record_event_update {
struct perf_event_header header;
__u64 type;
__u64 id;
char data[];
union {
/* Used when type == PERF_EVENT_UPDATE__SCALE. */
struct perf_record_event_update_scale scale;
/* Used when type == PERF_EVENT_UPDATE__UNIT. */
char unit[0];
/* Used when type == PERF_EVENT_UPDATE__NAME. */
char name[0];
/* Used when type == PERF_EVENT_UPDATE__CPUS. */
struct perf_record_event_update_cpus cpus;
};
};
#define MAX_EVENT_NAME 64

14
tools/perf/tests/event_update.c
View File

@ -21,7 +21,7 @@ static int process_event_unit(struct perf_tool *tool __maybe_unused,
TEST_ASSERT_VAL("wrong id", ev->id == 123);
TEST_ASSERT_VAL("wrong id", ev->type == PERF_EVENT_UPDATE__UNIT);
TEST_ASSERT_VAL("wrong unit", !strcmp(ev->data, "KRAVA"));
TEST_ASSERT_VAL("wrong unit", !strcmp(ev->unit, "KRAVA"));
return 0;
}
@ -31,13 +31,10 @@ static int process_event_scale(struct perf_tool *tool __maybe_unused,
struct machine *machine __maybe_unused)
{
struct perf_record_event_update *ev = (struct perf_record_event_update *)event;
struct perf_record_event_update_scale *ev_data;
ev_data = (struct perf_record_event_update_scale *)ev->data;
TEST_ASSERT_VAL("wrong id", ev->id == 123);
TEST_ASSERT_VAL("wrong id", ev->type == PERF_EVENT_UPDATE__SCALE);
TEST_ASSERT_VAL("wrong scale", ev_data->scale == 0.123);
TEST_ASSERT_VAL("wrong scale", ev->scale.scale == 0.123);
return 0;
}
@ -56,7 +53,7 @@ static int process_event_name(struct perf_tool *tool,
TEST_ASSERT_VAL("wrong id", ev->id == 123);
TEST_ASSERT_VAL("wrong id", ev->type == PERF_EVENT_UPDATE__NAME);
TEST_ASSERT_VAL("wrong name", !strcmp(ev->data, tmp->name));
TEST_ASSERT_VAL("wrong name", !strcmp(ev->name, tmp->name));
return 0;
}
@ -66,12 +63,9 @@ static int process_event_cpus(struct perf_tool *tool __maybe_unused,
struct machine *machine __maybe_unused)
{
struct perf_record_event_update *ev = (struct perf_record_event_update *)event;
struct perf_record_event_update_cpus *ev_data;
struct perf_cpu_map *map;
ev_data = (struct perf_record_event_update_cpus *) ev->data;
map = cpu_map__new_data(&ev_data->cpus);
map = cpu_map__new_data(&ev->cpus.cpus);
TEST_ASSERT_VAL("wrong id", ev->id == 123);
TEST_ASSERT_VAL("wrong type", ev->type == PERF_EVENT_UPDATE__CPUS);

24
tools/perf/util/header.c
View File

@ -4295,8 +4295,6 @@ out:
size_t perf_event__fprintf_event_update(union perf_event *event, FILE *fp)
{
struct perf_record_event_update *ev = &event->event_update;
struct perf_record_event_update_scale *ev_scale;
struct perf_record_event_update_cpus *ev_cpus;
struct perf_cpu_map *map;
size_t ret;
@ -4304,20 +4302,18 @@ size_t perf_event__fprintf_event_update(union perf_event *event, FILE *fp)
switch (ev->type) {
case PERF_EVENT_UPDATE__SCALE:
ev_scale = (struct perf_record_event_update_scale *)ev->data;
ret += fprintf(fp, "... scale: %f\n", ev_scale->scale);
ret += fprintf(fp, "... scale: %f\n", ev->scale.scale);
break;
case PERF_EVENT_UPDATE__UNIT:
ret += fprintf(fp, "... unit: %s\n", ev->data);
ret += fprintf(fp, "... unit: %s\n", ev->unit);
break;
case PERF_EVENT_UPDATE__NAME:
ret += fprintf(fp, "... name: %s\n", ev->data);
ret += fprintf(fp, "... name: %s\n", ev->name);
break;
case PERF_EVENT_UPDATE__CPUS:
ev_cpus = (struct perf_record_event_update_cpus *)ev->data;
ret += fprintf(fp, "... ");
map = cpu_map__new_data(&ev_cpus->cpus);
map = cpu_map__new_data(&ev->cpus.cpus);
if (map)
ret += cpu_map__fprintf(map, fp);
else
@ -4374,8 +4370,6 @@ int perf_event__process_event_update(struct perf_tool *tool __maybe_unused,
struct evlist **pevlist)
{
struct perf_record_event_update *ev = &event->event_update;
struct perf_record_event_update_scale *ev_scale;
struct perf_record_event_update_cpus *ev_cpus;
struct evlist *evlist;
struct evsel *evsel;
struct perf_cpu_map *map;
@ -4395,19 +4389,17 @@ int perf_event__process_event_update(struct perf_tool *tool __maybe_unused,
switch (ev->type) {
case PERF_EVENT_UPDATE__UNIT:
free((char *)evsel->unit);
evsel->unit = strdup(ev->data);
evsel->unit = strdup(ev->unit);
break;
case PERF_EVENT_UPDATE__NAME:
free(evsel->name);
evsel->name = strdup(ev->data);
evsel->name = strdup(ev->name);
break;
case PERF_EVENT_UPDATE__SCALE:
ev_scale = (struct perf_record_event_update_scale *)ev->data;
evsel->scale = ev_scale->scale;
evsel->scale = ev->scale.scale;
break;
case PERF_EVENT_UPDATE__CPUS:
ev_cpus = (struct perf_record_event_update_cpus *)ev->data;
map = cpu_map__new_data(&ev_cpus->cpus);
map = cpu_map__new_data(&ev->cpus.cpus);
if (map) {
perf_cpu_map__put(evsel->core.own_cpus);
evsel->core.own_cpus = map;

12
tools/perf/util/synthetic-events.c
View File

@ -1955,7 +1955,7 @@ int perf_event__synthesize_event_update_unit(struct perf_tool *tool, struct evse
if (ev == NULL)
return -ENOMEM;
strlcpy(ev->data, evsel->unit, size + 1);
strlcpy(ev->unit, evsel->unit, size + 1);
err = process(tool, (union perf_event *)ev, NULL, NULL);
free(ev);
return err;
@ -1972,8 +1972,7 @@ int perf_event__synthesize_event_update_scale(struct perf_tool *tool, struct evs
if (ev == NULL)
return -ENOMEM;
ev_data = (struct perf_record_event_update_scale *)ev->data;
ev_data->scale = evsel->scale;
ev->scale.scale = evsel->scale;
err = process(tool, (union perf_event *)ev, NULL, NULL);
free(ev);
return err;
@ -1990,7 +1989,7 @@ int perf_event__synthesize_event_update_name(struct perf_tool *tool, struct evse
if (ev == NULL)
return -ENOMEM;
strlcpy(ev->data, evsel->name, len + 1);
strlcpy(ev->name, evsel->name, len + 1);
err = process(tool, (union perf_event *)ev, NULL, NULL);
free(ev);
return err;
@ -1999,7 +1998,7 @@ int perf_event__synthesize_event_update_name(struct perf_tool *tool, struct evse
int perf_event__synthesize_event_update_cpus(struct perf_tool *tool, struct evsel *evsel,
perf_event__handler_t process)
{
size_t size = sizeof(struct perf_record_event_update);
size_t size = sizeof(struct perf_event_header) + sizeof(u64) + sizeof(u64);
struct perf_record_event_update *ev;
int max, err;
u16 type;
@ -2016,8 +2015,7 @@ int perf_event__synthesize_event_update_cpus(struct perf_tool *tool, struct evse
ev->type = PERF_EVENT_UPDATE__CPUS;
ev->id = evsel->core.id[0];
cpu_map_data__synthesize((struct perf_record_cpu_map_data *)ev->data,
evsel->core.own_cpus, type, max);
cpu_map_data__synthesize(&ev->cpus.cpus, evsel->core.own_cpus, type, max);
err = process(tool, (union perf_event *)ev, NULL, NULL);
free(ev);