Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754294AbbFPGFj (ORCPT ); Tue, 16 Jun 2015 02:05:39 -0400 Received: from mail9.hitachi.co.jp ([133.145.228.44]:33260 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751346AbbFPGF0 (ORCPT ); Tue, 16 Jun 2015 02:05:26 -0400 Message-ID: <557FBC9D.3070501@hitachi.com> Date: Tue, 16 Jun 2015 15:05:17 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Arnaldo Carvalho de Melo , He Kuang CC: a.p.zijlstra@chello.nl, mingo@redhat.com, namhyung@kernel.org, wangnan0@huawei.com, linux-kernel@vger.kernel.org Subject: Re: Re: [PATCH] perf probe: Fix failure to probe events on arm References: <1434355613-110216-1-git-send-email-hekuang@huawei.com> <20150615144911.GA5845@kernel.org> In-Reply-To: <20150615144911.GA5845@kernel.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3850 Lines: 110 On 2015/06/15 23:49, Arnaldo Carvalho de Melo wrote: > 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? Yeah, it looks good to me, and we finally will replace "_etext" with it :) ---- void map__fixup_end(struct map *map) { struct rb_root *symbols = &map->dso->symbols[map->type]; struct rb_node *nd = rb_last(symbols); if (nd != NULL) { struct symbol *sym = rb_entry(nd, struct symbol, rb_node); map->end = sym->end; } } ---- So, the map->end shows the end address of the symbols. Acked-by: Masami Hiramatsu Thanks! > > - 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 > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- Masami HIRAMATSU Linux Technology Research Center, System Productivity Research Dept. Center for Technology Innovation - Systems Engineering Hitachi, Ltd., Research & Development Group E-mail: masami.hiramatsu.pt@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/