Commit d773c999 authored by Ian Rogers's avatar Ian Rogers Committed by Arnaldo Carvalho de Melo
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perf events: Prefer union over variable length array 



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

Signed-off-by: default avatarIan Rogers <irogers@google.com>
Acked-by: default avatarJiri 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 3657ad4b

tools/lib/perf/include/perf/event.h

+10 −1
Original line number Diff line number Diff line
@@ -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

tools/perf/tests/event_update.c

+4 −10
Original line number Diff line number Diff line
@@ -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);

tools/perf/util/header.c

+8 −16
Original line number Diff line number Diff line
@@ -4295,8 +4295,6 @@ int perf_event__process_feature(struct perf_session *session, 
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;

tools/perf/util/synthetic-events.c

+5 −7
Original line number Diff line number Diff line
@@ -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);