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 X-Spam-Level: X-Spam-Status: No, score=-16.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BA5CC433E0 for ; Wed, 20 Jan 2021 04:20:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D955723131 for ; Wed, 20 Jan 2021 04:20:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729162AbhATEUC (ORCPT ); Tue, 19 Jan 2021 23:20:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:47994 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730784AbhATEOv (ORCPT ); Tue, 19 Jan 2021 23:14:51 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9C4532312D; Wed, 20 Jan 2021 04:14:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1611116050; bh=3ePYciKZe3v9kuW41JjidNDqr1nlrNykqTEuwNB1IL0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=DwjLbCBOdNNktFj/uoJZxURFfmA5Mh7PI0PiR/Vy510SSVEf1N9yw6zimSXnxYCao Ajf6/4Wbg2QdRnJAmNZ8tontWlp7tRIov7ciR+3EnXJmQOo3NEGgwkk8WhCMyUUENT w4Adg2la3cDBWmomcgtn3kg0CRNSjuMrRph9f+vqbZUyZkDtJ570JqBXbVkHW5YnbX xWcfrDlpTjdelxdggw0u/AqZTbSXbcX0DZG81K02ycr0dLZ6ypMWgfBxFSgh8v4Aen uItMqPdOGdvMKmFnTmZxNQHYSry4LbopZ3DdSSuM94cLqW+98BXWeR/IUUlOOJu8sC fprguD7kNllfQ== Date: Wed, 20 Jan 2021 13:14:06 +0900 From: Masami Hiramatsu To: Masami Hiramatsu Cc: Steven Rostedt , Jianlin Lv , mingo@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] tracing: precise log info for kretprobe addr err Message-Id: <20210120131406.5a992c1e434681750a0cd5d4@kernel.org> In-Reply-To: <20210120122415.76fa3539ce031bfb90e1c862@kernel.org> References: <20210119151014.3822465-1-Jianlin.Lv@arm.com> <20210119104106.2213a49c@gandalf.local.home> <20210120122415.76fa3539ce031bfb90e1c862@kernel.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 20 Jan 2021 12:24:15 +0900 Masami Hiramatsu wrote: > Hi, > > On Tue, 19 Jan 2021 10:41:06 -0500 > Steven Rostedt wrote: > > > Masami, > > > > Looks fine to me. What do you think? > > Agreed. Since register_kretprobe() checks the address by kprobe_on_func_entry(), > if it is not passed, it should always fail to register at last. > > Acked-by: Masami Hiramatsu Oops, sorry I missed one case. Since kprobe_events can accept a symbol with module name (MOD:symbol) If the given symbol is on a module which is not loaded, kprobe_on_func_entry(NULL, symbol, offset) may return false too. (But that kretprobe must be enabled after the target module is loaded) To confirm it correctly, add !strchr(symbol, ':') there to check it is really bad symbol or not. diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 5fff39541b8a..0170f8e6430b 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -830,7 +830,7 @@ static int trace_kprobe_create(int argc, const char *argv[]) flags |= TPARG_FL_RETURN; if (kprobe_on_func_entry(NULL, symbol, offset)) flags |= TPARG_FL_FENTRY; - if (offset && is_return && !(flags & TPARG_FL_FENTRY)) { + if (!strchr(symbol, ':') && is_return && !(flags & TPARG_FL_FENTRY)) { trace_probe_log_err(0, BAD_RETPROBE); goto parse_error; } Thank you, > > Thank you! > > > > > -- Steve > > > > > > On Tue, 19 Jan 2021 23:10:14 +0800 > > Jianlin Lv wrote: > > > > > When trying to create kretprobe with the wrong function symbol in tracefs; > > > The error is triggered in the register_trace_kprobe() and recorded as > > > FAIL_REG_PROBE issue, > > > > > > Example: > > > $ cd /sys/kernel/debug/tracing > > > $ echo 'r:myprobe ERROR_SYMBOL_XXX ret=%x0' >> kprobe_events > > > bash: echo: write error: Invalid argument > > > $ cat error_log > > > [142797.347877] trace_kprobe: error: Failed to register probe event > > > Command: r:myprobe ERROR_SYMBOL_XXX ret=%x0 > > > ^ > > > > > > This error can be detected in the parameter parsing stage, the effect of > > > applying this patch is as follows: > > > > > > $ echo 'r:myprobe ERROR_SYMBOL_XXX ret=%x0' >> kprobe_events > > > bash: echo: write error: Invalid argument > > > $ cat error_log > > > [415.89]trace_kprobe: error: Retprobe address must be an function entry > > > Command: r:myprobe ERROR_SYMBOL_XXX ret=%x0 > > > ^ > > > > > > Signed-off-by: Jianlin Lv > > > --- > > > kernel/trace/trace_kprobe.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > > > index e6fba1798771..3dfd1b6711a3 100644 > > > --- a/kernel/trace/trace_kprobe.c > > > +++ b/kernel/trace/trace_kprobe.c > > > @@ -830,7 +830,7 @@ static int trace_kprobe_create(int argc, const char *argv[]) > > > flags |= TPARG_FL_RETURN; > > > if (kprobe_on_func_entry(NULL, symbol, offset)) > > > flags |= TPARG_FL_FENTRY; > > > - if (offset && is_return && !(flags & TPARG_FL_FENTRY)) { > > > + if (is_return && !(flags & TPARG_FL_FENTRY)) { > > > trace_probe_log_err(0, BAD_RETPROBE); > > > goto parse_error; > > > } > > > > > -- > Masami Hiramatsu -- Masami Hiramatsu