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 E1D32C54EBC for ; Thu, 12 Jan 2023 16:00:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231879AbjALQAQ (ORCPT ); Thu, 12 Jan 2023 11:00:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42144 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236370AbjALP7n (ORCPT ); Thu, 12 Jan 2023 10:59:43 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 981384FCED; Thu, 12 Jan 2023 07:51:59 -0800 (PST) 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 ams.source.kernel.org (Postfix) with ESMTPS id 564FAB81EBD; Thu, 12 Jan 2023 15:51:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7FAECC433EF; Thu, 12 Jan 2023 15:51:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1673538717; bh=yTTb2Tm+5+3xMGeFN/U2gUsQGw74zuDp1qN2tQFtvZo=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Q9RZ/4cZNvwQ/2InsNasQMBAY2PsqCImDaXEPkTDxFENN1J/trHfYW+X+aRu2OIF3 PcITO8JK3/iQgHnKdTxl2eKkPL5NsAKN7XKbaCugZx7dGXHWb2PyoAJ+6xomgHethw rNj0gBpCPRqi4bcnDlEZhJ7ncdWM7h99PWNgBbjZmdId2NqEjHa8TKrh21ddCSBMgv CnW1RL5kRgwo9LB9CO0HTp50JPF4udILV53qGcFZGPlx27SlojaJNC8HpS/clhVzl1 3DT8ln1dPZ5YPUk1eMiA2LYkIW0G3BFy+MeOPWmAwLRURULD0by7JXn9dyOSw40tJM Ky88arOiAPu/w== Date: Fri, 13 Jan 2023 00:51:53 +0900 From: Masami Hiramatsu (Google) To: "Naveen N. Rao" Cc: Akanksha J N , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-trace-kernel@vger.kernel.org, mhiramat@kernel.org, rostedt@goodmis.org, shuah@kernel.org Subject: Re: [PATCH] selftests/ftrace: Extend multiple_kprobes.tc to add multiple consecutive probes in a function Message-Id: <20230113005153.c6ca2f75b9d12627eb63308a@kernel.org> In-Reply-To: <1673529279.3c5f8oes3z.naveen@linux.ibm.com> References: <20230112095600.37665-1-akanksha@linux.ibm.com> <1673529279.3c5f8oes3z.naveen@linux.ibm.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; 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-trace-kernel@vger.kernel.org On Thu, 12 Jan 2023 18:51:14 +0530 "Naveen N. Rao" wrote: > Akanksha J N wrote: > > Commit 97f88a3d723162 ("powerpc/kprobes: Fix null pointer reference in > > arch_prepare_kprobe()") fixed a recent kernel oops that was caused as > > ftrace-based kprobe does not generate kprobe::ainsn::insn and it gets > > set to NULL. > > Extend multiple kprobes test to add kprobes on first 256 bytes within a > > function, to be able to test potential issues with kprobes on > > successive instructions. What is the purpose of that test? If you intended to add a kprobe events with some offset so that it becomes ftrace-based kprobe, it should be a different test case, because - This is a test case for checking multiple (at least 256) kprobe events can be defined and enabled. - If you want to check the ftrace-based kprobe, it should be near the function entry, maybe within 16 bytes or so. - Also, you don't need to enable it at once (and should not for this case). > > The '|| true' is added with the echo statement to ignore errors that are > > caused by trying to add kprobes to non probeable lines and continue with > > the test. Can you add another test case for that? (and send it to the MLs which Cc'd to this mail) e.g. for i in `seq 0 16`; do echo p:testprobe $FUNCTION_FORK+${i} >> kprobe_events || continue echo 1 > events/kprobes/testprobe/enable ( echo "forked" ) echo 0 > events/kprobes/testprobe/enable echo > kprobe_events done BTW, after we introduce the fprobe event (https://lore.kernel.org/linux-trace-kernel/166792255429.919356.14116090269057513181.stgit@devnote3/) that test case may be update to check fprobe events. Thank you, > > > > Signed-off-by: Akanksha J N > > --- > > .../selftests/ftrace/test.d/kprobe/multiple_kprobes.tc | 4 ++++ > > 1 file changed, 4 insertions(+) > > Thanks for adding this test! > > > > > diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc b/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc > > index be754f5bcf79..f005c2542baa 100644 > > --- a/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc > > +++ b/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc > > @@ -25,6 +25,10 @@ if [ $L -ne 256 ]; then > > exit_fail > > fi > > > > +for i in `seq 0 255`; do > > + echo p $FUNCTION_FORK+${i} >> kprobe_events || true > > +done > > + > > cat kprobe_events >> $testlog > > > > echo 1 > events/kprobes/enable > > Thinking about this more, I wonder if we should add an explicit fork > after enabling the events, similar to kprobe_args.tc: > ( echo "forked" ) > > That will ensure we hit all the probes we added. With that change: > Acked-by: Naveen N. Rao > > > - Naveen -- Masami Hiramatsu (Google)