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 705D8C433F5 for ; Fri, 29 Apr 2022 00:32:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351511AbiD2AfP (ORCPT ); Thu, 28 Apr 2022 20:35:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234331AbiD2AfO (ORCPT ); Thu, 28 Apr 2022 20:35:14 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 288A6B9F02; Thu, 28 Apr 2022 17:31:57 -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 ams.source.kernel.org (Postfix) with ESMTPS id AD912B83260; Fri, 29 Apr 2022 00:31:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D298DC385A9; Fri, 29 Apr 2022 00:31:53 +0000 (UTC) Date: Thu, 28 Apr 2022 20:31:52 -0400 From: Steven Rostedt To: Andrii Nakryiko Cc: Alexei Starovoitov , Masami Hiramatsu , Jiri Olsa , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Networking , bpf , lkml , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh Subject: Re: [RFC bpf-next 4/4] selftests/bpf: Add attach bench test Message-ID: <20220428203152.41693bbe@gandalf.local.home> In-Reply-To: <20220428200945.5f6a5ba2@gandalf.local.home> References: <20220407125224.310255-1-jolsa@kernel.org> <20220407125224.310255-5-jolsa@kernel.org> <20220412094923.0abe90955e5db486b7bca279@kernel.org> <20220416232103.c0b241c2ec7f2b3b985a2f99@kernel.org> <20220428095803.66c17c32@gandalf.local.home> <20220428160519.04cc40c0@gandalf.local.home> <20220428195303.6295e90b@gandalf.local.home> <20220428200945.5f6a5ba2@gandalf.local.home> X-Mailer: Claws Mail 3.17.8 (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: netdev@vger.kernel.org On Thu, 28 Apr 2022 20:09:45 -0400 Steven Rostedt wrote: > OK, I think I see the issue you have. Because the functions shown in > available_filter_functions which uses the simple "%ps" to show the function > name: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/trace/ftrace.c#n3692 > > And the code that does the actual matching uses kallsyms_lookup() > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/trace/ftrace.c#n4017 > > Which appears not to match the function for the address, you can't pass in > __bpf_tramp_exit because it wont match the symbol returned by > kallsyms_lookup. Never mind, in testing this I had marked the weak function as notrace, which was the reason I couldn't add it to the set_ftrace_notrace. After removing the notrace, kallsyms_lookup() doesn't make a difference. It appears that kallsyms will include overridden weak functions into the size of the function before it. I tried: ret = kallsyms_lookup(rec->ip, &size, &offset, &modname, str); if (!ret || offset > size) { seq_printf(m, "no function at %lx", rec->ip); } else { seq_printf(m, "%s", str); if (modname) seq_printf(m, " [%s]", modname); } And it made no difference. > > This does indeed look like a bug in %ps. > Yes, this does appear to be a issue with kallsyms in general. -- Steve