From patchwork Fri Feb 10 15:59:21 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yafang Shao X-Patchwork-Id: 13135970 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 B34A5C636CD for ; Fri, 10 Feb 2023 15:59:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232871AbjBJP7y (ORCPT ); Fri, 10 Feb 2023 10:59:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51688 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232940AbjBJP7s (ORCPT ); Fri, 10 Feb 2023 10:59:48 -0500 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8278578D6E; Fri, 10 Feb 2023 07:59:29 -0800 (PST) Received: by mail-pj1-x102a.google.com with SMTP id nn4-20020a17090b38c400b00233a6f118d0so3234339pjb.2; Fri, 10 Feb 2023 07:59:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=/2yZsou7AT3LrMXyTCd+FTdTvhKynWuAdyAqvzx2oio=; b=OE1gNB2U9IG5FxBDrs2PSL5SrsKcq92aM2lfBfMi6y3r9UMgvLxcfGC774dNfOlOX8 h9MdLawItbwCnmPZY/0HOc759mnKLI6SIThEtCxq9sVw0FcxumE8u2ZM9Y6wcG+gx0Ey I3c4vPBIia2ZMR/GzhShIYCMe/ASgdODKEVF8CsRnJkTvGFZfsiJh7prbg/bdu11fNrm A4oMZDa+1rJ6VT6FiVuf9qkf16ELu9Qi4ZxhNh4OSTtECoD3G1IlgslGXSfp+tlbUWu3 sQoZLdZVVjV2oe4oB5rEbHOudAdohCLLx/KlMicpz8oydiB6Fh8O7vP8ELQAvl8sWYmJ mYGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=/2yZsou7AT3LrMXyTCd+FTdTvhKynWuAdyAqvzx2oio=; b=0fv+W21vTe7XA3B7mqh/p9XNPnA4R3BIJtQDITPaIa8l2OKCb9fW6tMN8x8+7qHnpN dv28u9trlT9ff+IYwYBl5KjrDDw/s/7FJUlRg4yFmuiukdOqIS5++Ywrh4Ux02ycmLMq kRKiapzIb2jreVB881qV8R9vNG3e/gMJ2D9H6150YyNJY41l9lAQcxrnt6iyNjjRA0V3 UfvjsvEj5YACgRtBzctig+WRyDXTyEZKvYrruAyDjhe/cthSXHttiaJFwBAcqW2Kweex +nGA/kL59YriTGoHz398769PW9C021V4EY+BMzggjchoxo92mTM5QsMiVDRd114tnBGQ 0uCA== X-Gm-Message-State: AO0yUKUoDXVByFfq+2xx5+6jOgQqOzK8F8R1GsLcvP2lwF2g/CZekE43 lVFPIU7JzekLQhP/jFxkR98= X-Google-Smtp-Source: AK7set9iwZ3F0t4fKaGDqF1cHBT7zMho1KP7lsqsOEmvqebRDq8QmZUpT9aj84IEu1nrp4GaHLd6FA== X-Received: by 2002:a17:90a:1908:b0:230:7a2b:da9c with SMTP id 8-20020a17090a190800b002307a2bda9cmr17294693pjg.30.1676044766961; Fri, 10 Feb 2023 07:59:26 -0800 (PST) Received: from vultr.guest ([2001:19f0:7001:2f6a:5400:4ff:fe4c:e050]) by smtp.gmail.com with ESMTPSA id v13-20020a17090ac90d00b00232cd5171e1sm3252891pjt.52.2023.02.10.07.59.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Feb 2023 07:59:26 -0800 (PST) From: Yafang Shao To: rostedt@goodmis.org, mhiramat@kernel.org Cc: linux-trace-kernel@vger.kernel.org, Yafang Shao , John Stultz , Mathieu Desnoyers , Alexei Starovoitov , Kajetan Puchalski , stable@vger.kernel.org Subject: [PATCH -trace] trace: fix TASK_COMM_LEN in trace event format file Date: Fri, 10 Feb 2023 15:59:21 +0000 Message-Id: <20230210155921.4610-1-laoar.shao@gmail.com> X-Mailer: git-send-email 2.39.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org After commit 3087c61ed2c4 ("tools/testing/selftests/bpf: replace open-coded 16 with TASK_COMM_LEN"), the content of the format file under /sys/kernel/debug/tracing/events/task/task_newtask was changed from field:char comm[16]; offset:12; size:16; signed:0; to field:char comm[TASK_COMM_LEN]; offset:12; size:16; signed:0; John reported that this change breaks older versions of perfetto. Then Mathieu pointed out that this behavioral change was caused by the use of __stringify(_len), which happens to work on macros, but not on enum labels. And he also gave the suggestion on how to fix it: :One possible solution to make this more robust would be to extend :struct trace_event_fields with one more field that indicates the length :of an array as an actual integer, without storing it in its stringified :form in the type, and do the formatting in f_show where it belongs. The result as follows after this change, $ cat /sys/kernel/debug/tracing/events/task/task_newtask/format field:char comm[16]; offset:12; size:16; signed:0; Fixes: 3087c61ed2c4 ("tools/testing/selftests/bpf: replace open-coded 16 with TASK_COMM_LEN") Reported-by: John Stultz Debugged-by: Mathieu Desnoyers Suggested-by: Mathieu Desnoyers Signed-off-by: Yafang Shao Cc: Mathieu Desnoyers Cc: Alexei Starovoitov Cc: Kajetan Puchalski Cc: Steven Rostedt Cc: John Stultz Cc: stable@vger.kernel.org # v5.17+ --- include/linux/trace_events.h | 1 + include/trace/stages/stage4_event_fields.h | 3 ++- kernel/trace/trace.h | 1 + kernel/trace/trace_events.c | 24 ++++++++++++++++-------- 4 files changed, 20 insertions(+), 9 deletions(-) diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 4342e99..0e37322 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -270,6 +270,7 @@ struct trace_event_fields { const int align; const int is_signed; const int filter_type; + const int len; }; int (*define_fields)(struct trace_event_call *); }; diff --git a/include/trace/stages/stage4_event_fields.h b/include/trace/stages/stage4_event_fields.h index affd541..306f39a 100644 --- a/include/trace/stages/stage4_event_fields.h +++ b/include/trace/stages/stage4_event_fields.h @@ -26,7 +26,8 @@ #define __array(_type, _item, _len) { \ .type = #_type"["__stringify(_len)"]", .name = #_item, \ .size = sizeof(_type[_len]), .align = ALIGN_STRUCTFIELD(_type), \ - .is_signed = is_signed_type(_type), .filter_type = FILTER_OTHER }, + .is_signed = is_signed_type(_type), .filter_type = FILTER_OTHER, \ + .len = _len}, #undef __dynamic_array #define __dynamic_array(_type, _item, _len) { \ diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index e46a492..19caf15 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1282,6 +1282,7 @@ struct ftrace_event_field { int offset; int size; int is_signed; + int len; }; struct prog_entry; diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 33e0b4f..70f6725 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -114,7 +114,7 @@ struct ftrace_event_field * static int __trace_define_field(struct list_head *head, const char *type, const char *name, int offset, int size, - int is_signed, int filter_type) + int is_signed, int filter_type, int len) { struct ftrace_event_field *field; @@ -133,6 +133,7 @@ static int __trace_define_field(struct list_head *head, const char *type, field->offset = offset; field->size = size; field->is_signed = is_signed; + field->len = len; list_add(&field->link, head); @@ -150,14 +151,14 @@ int trace_define_field(struct trace_event_call *call, const char *type, head = trace_get_fields(call); return __trace_define_field(head, type, name, offset, size, - is_signed, filter_type); + is_signed, filter_type, 0); } EXPORT_SYMBOL_GPL(trace_define_field); #define __generic_field(type, item, filter_type) \ ret = __trace_define_field(&ftrace_generic_fields, #type, \ #item, 0, 0, is_signed_type(type), \ - filter_type); \ + filter_type, 0); \ if (ret) \ return ret; @@ -166,7 +167,7 @@ int trace_define_field(struct trace_event_call *call, const char *type, "common_" #item, \ offsetof(typeof(ent), item), \ sizeof(ent.item), \ - is_signed_type(type), FILTER_OTHER); \ + is_signed_type(type), FILTER_OTHER, 0); \ if (ret) \ return ret; @@ -1589,10 +1590,10 @@ static int f_show(struct seq_file *m, void *v) field->type, field->name, field->offset, field->size, !!field->is_signed); else - seq_printf(m, "\tfield:%.*s %s%s;\toffset:%u;\tsize:%u;\tsigned:%d;\n", + seq_printf(m, "\tfield:%.*s %s[%d];\toffset:%u;\tsize:%u;\tsigned:%d;\n", (int)(array_descriptor - field->type), field->type, field->name, - array_descriptor, field->offset, + field->len, field->offset, field->size, !!field->is_signed); return 0; @@ -2371,6 +2372,7 @@ static int ftrace_event_release(struct inode *inode, struct file *file) if (list_empty(head)) { struct trace_event_fields *field = call->class->fields_array; unsigned int offset = sizeof(struct trace_entry); + struct list_head *head; for (; field->type; field++) { if (field->type == TRACE_FUNCTION_TYPE) { @@ -2379,9 +2381,15 @@ static int ftrace_event_release(struct inode *inode, struct file *file) } offset = ALIGN(offset, field->align); - ret = trace_define_field(call, field->type, field->name, + if (WARN_ON(!call->class)) { + offset += field->size; + continue; + } + head = trace_get_fields(call); + ret = __trace_define_field(head, field->type, field->name, offset, field->size, - field->is_signed, field->filter_type); + field->is_signed, field->filter_type, + field->len); if (WARN_ON_ONCE(ret)) { pr_err("error code is %d\n", ret); break;