From nobody Wed Feb 11 13:10:13 2026 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 543F6C76188 for ; Mon, 3 Apr 2023 21:23:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233697AbjDCVXJ (ORCPT ); Mon, 3 Apr 2023 17:23:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39380 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233207AbjDCVWr (ORCPT ); Mon, 3 Apr 2023 17:22:47 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E46013C07 for ; Mon, 3 Apr 2023 14:22:45 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9B39762C43 for ; Mon, 3 Apr 2023 21:22:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 11F78C433EF; Mon, 3 Apr 2023 21:22:44 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.96) (envelope-from ) id 1pjRdT-000FRa-0Z; Mon, 03 Apr 2023 17:22:43 -0400 Message-ID: <20230403212242.984727709@goodmis.org> User-Agent: quilt/0.66 Date: Mon, 03 Apr 2023 17:21:31 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Andrew Morton , Douglas RAILLARD Subject: [for-linus][PATCH 6/6] tracing: Error if a trace event has an array for a __field() References: <20230403212125.244064799@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "Steven Rostedt (Google)" A __field() in the TRACE_EVENT() macro is used to set up the fields of the trace event data. It is for single storage units (word, char, int, pointer, etc) and not for complex structures or arrays. Unfortunately, there's nothing preventing the build from accepting: __field(int, arr[5]); from building. It will turn into a array value. This use to work fine, as the offset and size use to be determined by the macro using the field name, but things have changed and the offset and size are now determined by the type. So the above would only be size 4, and the next field will be located 4 bytes from it (instead of 20). The proper way to declare static arrays is to use the __array() macro. Instead of __field(int, arr[5]) it should be __array(int, arr, 5). Add some macro tricks to the building of a trace event from the TRACE_EVENT() macro such that __field(int, arr[5]) will fail to build. A comment by the failure will explain why the build failed. Link: https://lore.kernel.org/lkml/20230306122549.236561-1-douglas.raillard= @arm.com/ Link: https://lore.kernel.org/linux-trace-kernel/20230309221302.642e82d9@ga= ndalf.local.home Reported-by: Douglas RAILLARD Signed-off-by: Steven Rostedt (Google) Acked-by: Masami Hiramatsu (Google) --- include/trace/stages/stage5_get_offsets.h | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/include/trace/stages/stage5_get_offsets.h b/include/trace/stag= es/stage5_get_offsets.h index ac5c24d3beeb..e30a13be46ba 100644 --- a/include/trace/stages/stage5_get_offsets.h +++ b/include/trace/stages/stage5_get_offsets.h @@ -9,17 +9,30 @@ #undef __entry #define __entry entry =20 +/* + * Fields should never declare an array: i.e. __field(int, arr[5]) + * If they do, it will cause issues in parsing and possibly corrupt the + * events. To prevent that from happening, test the sizeof() a fictitious + * type called "struct _test_no_array_##item" which will fail if "item" + * contains array elements (like "arr[5]"). + * + * If you hit this, use __array(int, arr, 5) instead. + */ #undef __field -#define __field(type, item) +#define __field(type, item) \ + { (void)sizeof(struct _test_no_array_##item *); } =20 #undef __field_ext -#define __field_ext(type, item, filter_type) +#define __field_ext(type, item, filter_type) \ + { (void)sizeof(struct _test_no_array_##item *); } =20 #undef __field_struct -#define __field_struct(type, item) +#define __field_struct(type, item) \ + { (void)sizeof(struct _test_no_array_##item *); } =20 #undef __field_struct_ext -#define __field_struct_ext(type, item, filter_type) +#define __field_struct_ext(type, item, filter_type) \ + { (void)sizeof(struct _test_no_array_##item *); } =20 #undef __array #define __array(type, item, len) --=20 2.39.2