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=-8.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 4647EC4360C for ; Thu, 26 Sep 2019 15:24:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 13081222C6 for ; Thu, 26 Sep 2019 15:24:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="L6jds7wj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727322AbfIZPYZ (ORCPT ); Thu, 26 Sep 2019 11:24:25 -0400 Received: from mail-qt1-f194.google.com ([209.85.160.194]:45966 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726845AbfIZPYY (ORCPT ); Thu, 26 Sep 2019 11:24:24 -0400 Received: by mail-qt1-f194.google.com with SMTP id c21so3286268qtj.12 for ; Thu, 26 Sep 2019 08:24:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=uRMtahzZaS317ydZu6zP9hU9Uft5Q7Gg/uXverRsTDI=; b=L6jds7wjJ6rGQVFP/NMPnfMT6Qx8UympuyaEL0on40XNkxBuQZdycNp/n6yAZFqGbb Fdx95IQ5Gd/xNnut4GryuuX16Sc46t46Ccdzz3Kf6I1hdJsgJvSsQ9FgnKJ731uc4P8p 0SidU4qVada1RM/mdwIVbMzdRhpLB2ZByTscHaPlasqtDwyXgXxTj8U/Oy/McRkANPyB sneS3MPRRLzSTsfHQJAehmjNNTLYJIi/bzrZWm8yPYcC1TE/o8v4QCOYpsUmE5nBQs00 8KxW1dOTMTXSCio9/uSOosLewn5y/rBExrsSlYYHEM6igvFalpcsdUJi8LmaFQJDRigt g9hg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=uRMtahzZaS317ydZu6zP9hU9Uft5Q7Gg/uXverRsTDI=; b=gjnp/mSA4bhUbS7bOJD5ds2sxEi4WI8JjZeKPAywnFbWCBpdXfoKnlLQ4mKcoNL3bh ChvMtnBmpKKgFrK8I62LagNHMbqL/S6i83o1kBJkvggpr0sXI1HMGAxJLb3LzJW8URN5 FtLr+yigiMmzTmWFihCPwElMZhx/r1mse+TWdeaRmP04IhoI+HQ9XMCpd1JeK7d0xXJV KAmrpZUGVxzy2r6eVJ+5sr/MpoqdQ5H0K4kqxHXs0c0FSjRS3bd1b+SII5fn884Dpy0P Cca6DBbGtumZxdsfb3ngBGTODugA75dh4UPWq16xui/cd//tuMrm9GCgcRJS7Tj9iAly pFkw== X-Gm-Message-State: APjAAAXl2SWrHd5oA+q5HABeCEpKcz+2Om8UUCXZ+fl/eJYReJU+Ly1p oHtxQpBQYJki6t8rw8SagLk= X-Google-Smtp-Source: APXvYqx7RyptnqymzB0HhHx3k0IoSqRWOdLV4TYDxrMHlQjw+ncN46PfKKuOhdCyKMXK38DL5V8gJg== X-Received: by 2002:a0c:9638:: with SMTP id 53mr3202541qvx.13.1569511463902; Thu, 26 Sep 2019 08:24:23 -0700 (PDT) Received: from quaco.ghostprotocols.net ([179.97.35.50]) by smtp.gmail.com with ESMTPSA id i25sm1081901qkk.30.2019.09.26.08.24.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Sep 2019 08:24:22 -0700 (PDT) From: Arnaldo Carvalho de Melo X-Google-Original-From: Arnaldo Carvalho de Melo Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id DE60240396; Thu, 26 Sep 2019 12:24:19 -0300 (-03) Date: Thu, 26 Sep 2019 12:24:19 -0300 To: Ian Rogers Cc: Peter Zijlstra , Ingo Molnar , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Andi Kleen , linux-kernel@vger.kernel.org, Stephane Eranian Subject: Re: [PATCH 2/2] Avoid raising segv using an obvious null dereference Message-ID: <20190926152419.GD10129@kernel.org> References: <20190925195924.152834-1-irogers@google.com> <20190925195924.152834-2-irogers@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190925195924.152834-2-irogers@google.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Wed, Sep 25, 2019 at 12:59:24PM -0700, Ian Rogers escreveu: > 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 Added: Cc: Numfor Mbiziwo-Tiapo And: Cc: Wang Nan Fixes: a074865e60ed ("perf tools: Introduce perf hooks") And: 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 ~]# ---------------------------------------------------------------------------- Thanks, applied. - Arnaldo > Signed-off-by: Ian Rogers > --- > 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) > -- > 2.23.0.351.gc4317032e6-goog -- - Arnaldo