From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755782AbbFOOtb (ORCPT ); Mon, 15 Jun 2015 10:49:31 -0400 Received: from mail.kernel.org ([198.145.29.136]:34441 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754139AbbFOOtW (ORCPT ); Mon, 15 Jun 2015 10:49:22 -0400 Date: Mon, 15 Jun 2015 11:49:11 -0300 From: Arnaldo Carvalho de Melo To: He Kuang , Masami Hiramatsu Cc: a.p.zijlstra@chello.nl, mingo@redhat.com, namhyung@kernel.org, wangnan0@huawei.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] perf probe: Fix failure to probe events on arm Message-ID: <20150615144911.GA5845@kernel.org> References: <1434355613-110216-1-git-send-email-hekuang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1434355613-110216-1-git-send-email-hekuang@huawei.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Mon, Jun 15, 2015 at 08:06:53AM +0000, He Kuang escreveu: > Fix failure to probe events on arm, problem is introduced by commit > 5a51fcd1f30c ("perf probe: Skip kernel symbols which is out of > .text"). For some architectures, label '_etext' is not in the .text > section(in .notes section for arm/arm64). Label out of .text section is > not loaded as symbols and we got a zero value when look up its address, > which causes all events be wrongly skiped. > > This patch uses kernel map->end when failed to get the address of > '_etext' and fixes the problem. Masami, can't we always use map->end then? Can you please take a look at this patch and ack/nack it? - Arnaldo > Problem can be reproduced on arm as following: > > # perf probe --add='generic_perform_write' > generic_perform_write+0 is out of .text, skip it. > Probe point 'generic_perform_write' not found. > Error: Failed to add events. Reason: No such file or directory (Code: -2) > > After this patch: > > # perf probe --add='generic_perform_write' > Added new event: > probe:generic_perform_write (on generic_perform_write) > > You can now use it in all perf tools, such as: > > perf record -e probe:generic_perform_write -aR sleep 1 > > Signed-off-by: He Kuang > --- > tools/perf/util/probe-event.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c > index daa24a2..ee26961 100644 > --- a/tools/perf/util/probe-event.c > +++ b/tools/perf/util/probe-event.c > @@ -575,8 +575,22 @@ static int post_process_probe_trace_events(struct probe_trace_event *tevs, > pr_warning("Relocated base symbol is not found!\n"); > return -EINVAL; > } > - /* Get the address of _etext for checking non-probable text symbol */ > + /* Get the address of _etext for checking non-probable text symbol, > + for some architectures (e.g. arm, arm64), _etext is out of .text > + section and not loaded as symbols, use kernel map->end instead. > + */ > etext_addr = kernel_get_symbol_address_by_name("_etext", false); > + if (etext_addr == 0) { > + struct map *map; > + > + map = kernel_get_module_map(NULL); > + if (!map) { > + pr_err("Failed to get a map for kernel\n"); > + return -EINVAL; > + } > + > + etext_addr = map->end; > + } > > for (i = 0; i < ntevs; i++) { > if (tevs[i].point.address && !tevs[i].point.retprobe) { > -- > 1.8.5.2