From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754119AbbFOIHe (ORCPT ); Mon, 15 Jun 2015 04:07:34 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:30921 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753243AbbFOIHY (ORCPT ); Mon, 15 Jun 2015 04:07:24 -0400 From: He Kuang To: , , , , CC: , Subject: [PATCH] perf probe: Fix failure to probe events on arm Date: Mon, 15 Jun 2015 08:06:53 +0000 Message-ID: <1434355613-110216-1-git-send-email-hekuang@huawei.com> X-Mailer: git-send-email 1.8.3.4 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.197.210] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 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