From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ECFB1CCA47C for ; Tue, 14 Jun 2022 14:35:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343664AbiFNOfR (ORCPT ); Tue, 14 Jun 2022 10:35:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355789AbiFNOeO (ORCPT ); Tue, 14 Jun 2022 10:34:14 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C41951FA51 for ; Tue, 14 Jun 2022 07:34:12 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-2eb7d137101so26877307b3.12 for ; Tue, 14 Jun 2022 07:34:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=RhxA7eRgAfXCkykh9Mqke3rmlCOtyFU0Irt1epvp7hw=; b=GLjcD5Dx33HCbsoWEkqU+neIygwWnlhBDLV2vzAwLmDz8x5q82nfJom16BkE93u/PK hspUdyCTqgVsnGxFdzeO5+D4K6rzB3TOgcohdxOodk2l0hhBFzS3hSKzwR+uRNqflmP+ w7qStg224/xe3rky8A1vFJ2as88HVYqhbgTuIJcGhoTpjcW0rTHT8xVaOLwraPFGxvFW NPJ7yLaBgPfavu3063eucMRS730PQ3OflSLL0j4EZhowwrnC48rqarnfIPxoRPaGoMHf ffxw+WkWbqF/XQXM86FoXasPo2as2buUgyNc2GyL1oUe+IWM36/8TJEw7C3JshxZ+Xu+ i8CQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=RhxA7eRgAfXCkykh9Mqke3rmlCOtyFU0Irt1epvp7hw=; b=uME3QOwKvDuhYqv1JrIsuNWYnw3svtLm1l2hSgFhuNdJri7+ofripZR8w3GIOstxUd zyFfXEVWAXYSxaJY5ZrogBpCojWdTYR8JXAw4qLrwbqSDO/Cfdu/MJOxeKS1VEnlu2Ll kCzP+cDmajI2V5y1MDR7zwZrdikkfZ4rPEppWRZWxlnMrex40N8W6LFhkgaTcvUhEmCn N0FiY7FiEMH07rWLvAZH10+RHXIotEOYu1OBOYpCacNlpRu+fhHZo/rWfBbG1TRU7YtU pa11lDPRHIOqc6BxXbfa2ephuKZfH1ekdy7N6gOZVB37o8bzc+hzs8ceqBA9tEnm2jvt ++/A== X-Gm-Message-State: AJIora859nwGAPaSbQsDEVg38TqcPIUnfTg5iNbbPhXeAHlUf7IhcUgJ 5KmqvT8HhtmDdZ3+w4Nk8gzyT1OChWRk X-Google-Smtp-Source: AGRyM1t1Ygr0jc8VIJfd7IOc2+oMNdhp6qPa2VuDhBtAwkK9kLSXnT7iPkQCmX1L3JPff2GK64cCWAczPWx4 X-Received: from irogers.svl.corp.google.com ([2620:15c:2cd:202:b55a:aaa7:a:1b17]) (user=irogers job=sendgmr) by 2002:a81:2d0b:0:b0:313:34ae:77b9 with SMTP id t11-20020a812d0b000000b0031334ae77b9mr6077081ywt.233.1655217251575; Tue, 14 Jun 2022 07:34:11 -0700 (PDT) Date: Tue, 14 Jun 2022 07:33:52 -0700 In-Reply-To: <20220614143353.1559597-1-irogers@google.com> Message-Id: <20220614143353.1559597-6-irogers@google.com> Mime-Version: 1.0 References: <20220614143353.1559597-1-irogers@google.com> X-Mailer: git-send-email 2.36.1.476.g0c4daa206d-goog Subject: [PATCH v2 5/6] perf events: Prefer union over variable length array From: Ian Rogers To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , James Clark , Kees Cook , "Gustavo A. R. Silva" , Adrian Hunter , Riccardo Mancini , German Gomez , Colin Ian King , Song Liu , Dave Marchevsky , Athira Rajeev , Alexey Bayduraev , Leo Yan , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Stephane Eranian , Ian Rogers Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org It is possible for casts to introduce alignment issues, prefer a union for perf_record_event_update. Signed-off-by: Ian Rogers --- tools/lib/perf/include/perf/event.h | 11 ++++++++++- tools/perf/tests/event_update.c | 14 ++++---------- tools/perf/util/header.c | 24 ++++++++---------------- tools/perf/util/synthetic-events.c | 12 +++++------- 4 files changed, 27 insertions(+), 34 deletions(-) diff --git a/tools/lib/perf/include/perf/event.h b/tools/lib/perf/include/perf/event.h index d2d32589758a..21170f5afb61 100644 --- a/tools/lib/perf/include/perf/event.h +++ b/tools/lib/perf/include/perf/event.h @@ -221,7 +221,16 @@ 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 78db4d704e76..d093a9b878d1 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 53332da100e8..108c8da5d2e3 100644 --- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -4264,8 +4264,6 @@ 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; @@ -4273,20 +4271,18 @@ 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 @@ -4343,8 +4339,6 @@ 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; @@ -4361,19 +4355,17 @@ 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 4fa7d0d7dbcf..ec54ac1ed96f 100644 --- a/tools/perf/util/synthetic-events.c +++ b/tools/perf/util/synthetic-events.c @@ -1848,7 +1848,7 @@ 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; @@ -1865,8 +1865,7 @@ 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; @@ -1883,7 +1882,7 @@ 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; @@ -1892,7 +1891,7 @@ 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; @@ -1909,8 +1908,7 @@ 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); -- 2.36.1.476.g0c4daa206d-goog