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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 78A5FC35242 for ; Sat, 8 Feb 2020 18:35:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5E485217BA for ; Sat, 8 Feb 2020 18:35:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727599AbgBHSfI (ORCPT ); Sat, 8 Feb 2020 13:35:08 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:34206 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727883AbgBHS3o (ORCPT ); Sat, 8 Feb 2020 13:29:44 -0500 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1j0UrJ-0003fe-ID; Sat, 08 Feb 2020 18:29:37 +0000 Received: from ben by deadeye with local (Exim 4.93) (envelope-from ) id 1j0UrI-000CPJ-5p; Sat, 08 Feb 2020 18:29:36 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Namhyung Kim" , "Arnaldo Carvalho de Melo" , "Masami Hiramatsu" , "Jiri Olsa" Date: Sat, 08 Feb 2020 18:20:12 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 073/148] perf probe: Skip end-of-sequence and non statement lines In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.82-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Masami Hiramatsu commit f4d99bdfd124823a81878b44b5e8750b97f73902 upstream. Skip end-of-sequence and non-statement lines while walking through lines list. The "end-of-sequence" line information means: "the current address is that of the first byte after the end of a sequence of target machine instructions." (DWARF version 4 spec 6.2.2) This actually means out of scope and we can not probe on it. On the other hand, the statement lines (is_stmt) means: "the current instruction is a recommended breakpoint location. A recommended breakpoint location is intended to “represent” a line, a statement and/or a semantically distinct subpart of a statement." (DWARF version 4 spec 6.2.2) So, non-statement line info also should be skipped. These can reduce unneeded probe points and also avoid an error. E.g. without this patch: # perf probe -a "clear_tasks_mm_cpumask:1" Added new events: probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask:1) probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask:1) probe:clear_tasks_mm_cpumask_2 (on clear_tasks_mm_cpumask:1) probe:clear_tasks_mm_cpumask_3 (on clear_tasks_mm_cpumask:1) probe:clear_tasks_mm_cpumask_4 (on clear_tasks_mm_cpumask:1) You can now use it in all perf tools, such as: perf record -e probe:clear_tasks_mm_cpumask_4 -aR sleep 1 # This puts 5 probes on one line, but acutally it's not inlined function. This is because there are many non statement instructions at the function prologue. With this patch: # perf probe -a "clear_tasks_mm_cpumask:1" Added new event: probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask:1) You can now use it in all perf tools, such as: perf record -e probe:clear_tasks_mm_cpumask -aR sleep 1 # Now perf-probe skips unneeded addresses. Committer testing: Slightly different results, but similar: Before: # uname -a Linux quaco 5.3.8-200.fc30.x86_64 #1 SMP Tue Oct 29 14:46:22 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux # # perf probe -a "clear_tasks_mm_cpumask:1" Added new events: probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask:1) probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask:1) probe:clear_tasks_mm_cpumask_2 (on clear_tasks_mm_cpumask:1) You can now use it in all perf tools, such as: perf record -e probe:clear_tasks_mm_cpumask_2 -aR sleep 1 # After: # perf probe -a "clear_tasks_mm_cpumask:1" Added new event: probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask:1) You can now use it in all perf tools, such as: perf record -e probe:clear_tasks_mm_cpumask -aR sleep 1 # perf probe -l probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask@kernel/cpu.c) # Fixes: 4cc9cec636e7 ("perf probe: Introduce lines walker interface") Signed-off-by: Masami Hiramatsu Tested-by: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Namhyung Kim Link: http://lore.kernel.org/lkml/157241936090.32002.12156347518596111660.stgit@devnote2 Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Ben Hutchings --- tools/perf/util/dwarf-aux.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/tools/perf/util/dwarf-aux.c +++ b/tools/perf/util/dwarf-aux.c @@ -712,6 +712,7 @@ int die_walk_lines(Dwarf_Die *rt_die, li int decl = 0, inl; Dwarf_Die die_mem, *cu_die; size_t nlines, i; + bool flag; /* Get the CU die */ if (dwarf_tag(rt_die) != DW_TAG_compile_unit) { @@ -742,6 +743,12 @@ int die_walk_lines(Dwarf_Die *rt_die, li "Possible error in debuginfo.\n"); continue; } + /* Skip end-of-sequence */ + if (dwarf_lineendsequence(line, &flag) != 0 || flag) + continue; + /* Skip Non statement line-info */ + if (dwarf_linebeginstatement(line, &flag) != 0 || !flag) + continue; /* Filter lines based on address */ if (rt_die != cu_die) { /*