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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 88223C388F3 for ; Tue, 1 Oct 2019 11:12:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 586DB21A4C for ; Tue, 1 Oct 2019 11:12:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569928359; bh=K8AyG+osSytuHwKL2hiV0HvUJXM4yKUd26TB8FEhRMU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=rbH0XRvuPEjWuaqlXNkxVENaY34aJi0sYBM7T4ysC/X3Lkvf65XV9CEjbtSDtgY3d n3IYuY1TzlUrwEr/kWMiawMj6Sbvt/bDxoq/OCQQZGmFmeOVKRCS7LXQXOYVibNzhC bc33seoOZcTZ6ICVyIbkt3xwbOUCPzuzzhZcgwWA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731357AbfJALMi (ORCPT ); Tue, 1 Oct 2019 07:12:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:34504 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730379AbfJALMi (ORCPT ); Tue, 1 Oct 2019 07:12:38 -0400 Received: from quaco.ghostprotocols.net (177.206.223.101.dynamic.adsl.gvt.net.br [177.206.223.101]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D3F2B21924; Tue, 1 Oct 2019 11:12:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569928357; bh=K8AyG+osSytuHwKL2hiV0HvUJXM4yKUd26TB8FEhRMU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=B4Yt3gzwU1CmcnljEmz1WCbdQY31v5gYeN1dCdx+HwaPdb/rE7m1i98rtK6MVc6zg tsZJkEK4hrlZEO2E7co8J9qQnxMN4uncra9pyYNAEmyr/1yR68JyvYlp1Jf+wZEkIm 1q+SBu2COniB4853dx4p638dTvnb9Q0SVTYi2fAQ= From: Arnaldo Carvalho de Melo To: Ingo Molnar , Thomas Gleixner Cc: Jiri Olsa , Namhyung Kim , Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Ian Rogers , Arnaldo Carvalho de Melo , Alexander Shishkin , Andi Kleen , Jiri Olsa , Peter Zijlstra , Stephane Eranian , Wang Nan Subject: [PATCH 02/24] perf tests: Avoid raising SEGV using an obvious NULL dereference Date: Tue, 1 Oct 2019 08:11:54 -0300 Message-Id: <20191001111216.7208-3-acme@kernel.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20191001111216.7208-1-acme@kernel.org> References: <20191001111216.7208-1-acme@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ian Rogers An optimized build such as: make -C tools/perf CLANG=1 CC=clang EXTRA_CFLAGS="-O3 will turn the dereference operation into a ud2 instruction, raising a SIGILL rather than a SIGSEGV. Use raise(..) for correctness and clarity. Similar issues were addressed in Numfor Mbiziwo-Tiapo's patch: https://lkml.org/lkml/2019/7/8/1234 Committer testing: Before: [root@quaco ~]# perf test hooks 55: perf hooks : Ok [root@quaco ~]# perf test -v hooks 55: perf hooks : --- start --- test child forked, pid 17092 SIGSEGV is observed as expected, try to recover. Fatal error (SEGFAULT) in perf hook 'test' test child finished with 0 ---- end ---- perf hooks: Ok [root@quaco ~]# After: [root@quaco ~]# perf test hooks 55: perf hooks : Ok [root@quaco ~]# perf test -v hooks 55: perf hooks : --- start --- test child forked, pid 17909 SIGSEGV is observed as expected, try to recover. Fatal error (SEGFAULT) in perf hook 'test' test child finished with 0 ---- end ---- perf hooks: Ok [root@quaco ~]# Fixes: a074865e60ed ("perf tools: Introduce perf hooks") Signed-off-by: Ian Rogers Tested-by: Arnaldo Carvalho de Melo Cc: Alexander Shishkin Cc: Andi Kleen Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Wang Nan Link: http://lore.kernel.org/lkml/20190925195924.152834-2-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/tests/perf-hooks.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/tools/perf/tests/perf-hooks.c b/tools/perf/tests/perf-hooks.c index dbc27199c65e..dd865e0bea12 100644 --- a/tools/perf/tests/perf-hooks.c +++ b/tools/perf/tests/perf-hooks.c @@ -19,12 +19,11 @@ static void sigsegv_handler(int sig __maybe_unused) static void the_hook(void *_hook_flags) { int *hook_flags = _hook_flags; - int *p = NULL; *hook_flags = 1234; /* Generate a segfault, test perf_hooks__recover */ - *p = 0; + raise(SIGSEGV); } int test__perf_hooks(struct test *test __maybe_unused, int subtest __maybe_unused) -- 2.21.0