From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757202AbaE2LDW (ORCPT ); Thu, 29 May 2014 07:03:22 -0400 Received: from mail9.hitachi.co.jp ([133.145.228.44]:41295 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751217AbaE2LDV (ORCPT ); Thu, 29 May 2014 07:03:21 -0400 Message-ID: <538713F1.6000801@hitachi.com> Date: Thu, 29 May 2014 20:03:13 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: linux-kernel@vger.kernel.org, Arnaldo Carvalho de Melo Cc: Namhyung Kim , Jiri Olsa , Ingo Molnar , Paul Mackerras , Peter Zijlstra Subject: Re: [PATCH -tip/urgent ] [BUGFIX] perf/probe: Fix a segfault if asked for variable it doesn't find References: <20140528214406.GE2764@kernel.org> <20140529105232.28251.30447.stgit@ltc230.yrl.intra.hitachi.co.jp> In-Reply-To: <20140529105232.28251.30447.stgit@ltc230.yrl.intra.hitachi.co.jp> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Arnaldo, this fixes the SEGV bug which you reported. But I've found that perf probe sometimes loses the location of variables with recent DWARF implementation. I need to check and fix that too. Anyway, this patch should be applied for fixing critical bug. Thank you, (2014/05/29 19:52), Masami Hiramatsu wrote: > Fix a segfault bug by asking for variable it doesn't find. > Since the convert_variable() didn't handle error code returned > from convert_variable_location(), it just passed an incomplete > variable field and then a segfault was occured when formatting > the field. > > This fixes that bug by handling success code correctly in > convert_variable(). Other callers of convert_variable_location() > are correctly checking the return code. > > This bug was introduced by following commit. But another hidden > erroneous error handling has been there previuosly (-ENOMEM case). > > commit 3d918a12a1b3088ac16ff37fa52760639d6e2403 > > Signed-off-by: Masami Hiramatsu > Reported-by: Arnaldo Carvalho de Melo > Cc: Peter Zijlstra > Cc: Paul Mackerras > Cc: Ingo Molnar > Cc: Namhyung Kim > Cc: Jiri Olsa > --- > tools/perf/util/probe-finder.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c > index 5627621..9d8eb26 100644 > --- a/tools/perf/util/probe-finder.c > +++ b/tools/perf/util/probe-finder.c > @@ -511,12 +511,12 @@ static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf) > > ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops, > &pf->sp_die, pf->tvar); > - if (ret == -ENOENT) > + if (ret == -ENOENT || ret == -EINVAL) > pr_err("Failed to find the location of %s at this address.\n" > " Perhaps, it has been optimized out.\n", pf->pvar->var); > else if (ret == -ENOTSUP) > pr_err("Sorry, we don't support this variable location yet.\n"); > - else if (pf->pvar->field) { > + else if (ret == 0 && pf->pvar->field) { > ret = convert_variable_fields(vr_die, pf->pvar->var, > pf->pvar->field, &pf->tvar->ref, > &die_mem); > > > > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com