From: Ian Rogers Date: Tue, 14 Jun 2022 14:33:52 +0000 (-0700) Subject: perf events: Prefer union over variable length array X-Git-Tag: v6.1-rc5~199^2~112 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d773c999b8d22ad3ffd42eca373ebae4cb6512fd;p=platform%2Fkernel%2Flinux-starfive.git 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: Ian Rogers Acked-by: Jiri Olsa Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Alexey Bayduraev Cc: Athira Jajeev Cc: Colin Ian King Cc: Dave Marchevsky Cc: German Gomez Cc: Gustavo A. R. Silva Cc: Ingo Molnar Cc: James Clark Cc: Kees Kook Cc: Leo Yan Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Riccardo Mancini Cc: Song Liu Cc: Stephane Eranian Link: https://lore.kernel.org/r/20220614143353.1559597-6-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- diff --git a/tools/lib/perf/include/perf/event.h b/tools/lib/perf/include/perf/event.h index d8ae4e9..e147e61 100644 --- a/tools/lib/perf/include/perf/event.h +++ b/tools/lib/perf/include/perf/event.h @@ -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 diff --git a/tools/perf/tests/event_update.c b/tools/perf/tests/event_update.c index 78db4d7..d093a9b 100644 --- a/tools/perf/tests/event_update.c +++ b/tools/perf/tests/event_update.c @@ -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); diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c index c30c29c..98dfaf8 100644 --- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -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; diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c index 5387907..851d11a 100644 --- a/tools/perf/util/synthetic-events.c +++ b/tools/perf/util/synthetic-events.c @@ -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);