From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E14F33ABD80; Sat, 26 Sep 2026 12:31:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790425878; cv=none; b=rzLPqspWGJXQMZdEOcNh2JCDBa7KoLI1MqHCP28pL0ukVxgcAfaS459q/M3+d/TaXGH+ck979Hyi1JEl+ACQkY5Nmtq1lTYL2vLUWc9N5EYonlqi/rg7Y5eujvc3mh3CDIXHmGUleQk4fhXMt5TIbhQMOaenZz+3exVHYZOICY4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790425878; c=relaxed/simple; bh=slv2mUguN12KMHBkXDyTurvhj0TSbSsRRo0SbtEdS9E=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=R+wIi8tYAu4fpySj6NtTCepQ8/RpavzLkyo6Tx/jqkcGiWFVeSxI/9Th2RZ5HrFtl0Ef9RuMk3vO5UWNCWQ7BSo3VU35tg1ezCgbQUzSnTju6A90KsY9PCTY3rZF8yt8JUNbJeADhBC4rdxZ/YPNjf4sJYsBwpin0dzyh2XpTA0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SrlTOi2I; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="SrlTOi2I" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CCC041F000FF; Sat, 26 Sep 2026 12:31:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790425876; bh=yyWyRTDztZItehKkx4bjDMd437FH163TOsfRDpL0Umk=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=SrlTOi2IaqpHRA+UgAzI/Wk8QqtrRAHezbJUwO/1sWKhu3VrOAtZCKEWWVq88pj86 bNZ4m+atzTY05GsbLr4Vh4jMt46q+JZJhtyS/g941B0ni6yKD3bugNj//Y6TO0xcYk Wa3bxjInrQ1tGm8ZYYxY0cTOveTzYkFCSEut8f95B3E/oaV/9gSESEnpfkCi0wFxsY TLnUapibFmKSSVZ1MIaM8zGoLd/8FWRiza8g/UCaqHWGApnT1IDZzcVIr/NtiOICre S/8AL8fvzMc61SMaoF3lwv41CpUOMWQEsob7zBMVzYyUPCHpOLB7ThJucZ8mEAyrbM qZxvCQsOxoyhg== Date: Sat, 26 Sep 2026 21:31:12 +0900 From: Masami Hiramatsu (Google) To: Eva Kurchatova Cc: Steven Rostedt , Mathieu Desnoyers , Shuah Khan , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH] selftests/ftrace: skip gcov symbols when picking a function to probe Message-Id: <20260926213112.9f92e7958c2d12c946799a0f@kernel.org> In-Reply-To: <20260925133558.3636030-1-eva.kurchatova@virtuozzo.com> References: <20260925133558.3636030-1-eva.kurchatova@virtuozzo.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 25 Sep 2026 16:35:41 +0300 Eva Kurchatova wrote: > kprobe_eventname.tc takes the last kallsyms entry whose name ends in > vfs_read and puts a probe on it. On a kernel built with > CONFIG_GCOV_PROFILE_ALL=y the counter symbol gcc emits for the function > sorts after it: > > ffffffff819bd1e0 T vfs_read > ffffffff845013e0 t __gcov_.vfs_read > > so the test picks __gcov_.vfs_read, which is not a function entry, and > the write fails: > > kprobe_eventname.tc: line 10: echo: write error: Invalid argument > > Leave those symbols out of the choice. The test then picks vfs_read and > passes; without a coverage build nothing changes, as no such symbol > exists there. > > This is the same class of problem as commit 23a4b108accc > ("tracing/selftests: Fix kprobe event name test for .isra. functions"), > where a compiler-generated symbol was picked instead of a real function. > Oops, good catch! This looks good to me. Acked-by: Masami Hiramatsu (Google) Shuah, can you pick this fix via your selftest tree? I think this is a kind of selftest fix/improvement. Thanks, > Signed-off-by: Eva Kurchatova > --- > .../testing/selftests/ftrace/test.d/kprobe/kprobe_eventname.tc | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_eventname.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_eventname.tc > index ba19b81cef39..0688a5c47d1e 100644 > --- a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_eventname.tc > +++ b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_eventname.tc > @@ -5,7 +5,7 @@ > > :;: "Add an event on function without name" ;: > > -FUNC=`grep " [tT] .*vfs_read$" /proc/kallsyms | tail -n 1 | cut -f 3 -d " "` > +FUNC=`grep " [tT] .*vfs_read$" /proc/kallsyms | grep -v __gcov | tail -n 1 | cut -f 3 -d " "` > [ "x" != "x$FUNC" ] || exit_unresolved > echo "p $FUNC" > kprobe_events > PROBE_NAME=`echo $FUNC | tr ".:" "_"` > -- > 2.55.0 > -- Masami Hiramatsu (Google)