From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751904AbbCFHF7 (ORCPT ); Fri, 6 Mar 2015 02:05:59 -0500 Received: from mail9.hitachi.co.jp ([133.145.228.44]:49071 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750836AbbCFHF4 (ORCPT ); Fri, 6 Mar 2015 02:05:56 -0500 Message-ID: <54F951CD.6060101@hitachi.com> Date: Fri, 06 Mar 2015 16:05:49 +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: Namhyung Kim CC: Arnaldo Carvalho de Melo , Ingo Molnar , Peter Zijlstra , Jiri Olsa , LKML Subject: Re: [RFC/PATCH 2/2] perf probe: Allow weak symbols to be probed References: <1425477143-5310-1-git-send-email-namhyung@kernel.org> <1425477143-5310-2-git-send-email-namhyung@kernel.org> In-Reply-To: <1425477143-5310-2-git-send-email-namhyung@kernel.org> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2015/03/04 22:52), Namhyung Kim wrote: > It currently prevents adding probes in weak symbols. But there're cases > that given name is an only weak symbol so that we cannot add probe. > > $ perf probe -x /usr/lib/libc.so.6 -a calloc > Failed to find symbol calloc in /usr/lib/libc-2.21.so > Error: Failed to add events. > > $ nm /usr/lib/libc.so.6 | grep calloc > 000000000007b1f0 t __calloc > 000000000007b1f0 T __libc_calloc > 000000000007b1f0 W calloc > > This change will result in duplicate probes when strong and weak symbols > co-exist in a binary. But I think it's not a big problem since probes > at the weak symbol will never be hit anyway. > > Cc: Masami Hiramatsu > Signed-off-by: Namhyung Kim > --- > tools/perf/util/probe-event.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c > index 1c570c2fa7cc..12b7d018106e 100644 > --- a/tools/perf/util/probe-event.c > +++ b/tools/perf/util/probe-event.c > @@ -2339,8 +2339,7 @@ static int find_probe_functions(struct map *map, char *name) > struct symbol *sym; > > map__for_each_symbol_by_name(map, name, sym) { > - if (sym->binding == STB_GLOBAL || sym->binding == STB_LOCAL) > - found++; > + found++; > } Ah, I've found this is the magic... Here, we need another fix on my series. diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 22392b06..f9c1e53 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -309,10 +309,8 @@ static int find_alternative_probe_point(struct debuginfo *d /* Find the address of given function */ map__for_each_symbol_by_name(map, pp->function, sym) { - if (sym->binding == STB_GLOBAL || sym->binding == STB_LOCAL) { - address = sym->start; - break; - } + address = sym->start; + break; } if (!address) { ret = -ENOENT; ------- With this fix, I could get variables on waitpid and calloc. ----- # ./perf probe -x /lib64/libc-2.17.so -V waitpid Available variables at waitpid @<__libc_waitpid+0> __pid_t pid int oldtype int options int* stat_loc ----- I'll update and include it my series. Thank you! > > return found; > @@ -2708,8 +2707,7 @@ static struct strfilter *available_func_filter; > static int filter_available_functions(struct map *map __maybe_unused, > struct symbol *sym) > { > - if ((sym->binding == STB_GLOBAL || sym->binding == STB_LOCAL) && > - strfilter__compare(available_func_filter, sym->name)) > + if (strfilter__compare(available_func_filter, sym->name)) > return 0; > return 1; > } > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com