From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757196AbaIQVZm (ORCPT ); Wed, 17 Sep 2014 17:25:42 -0400 Received: from mail.kernel.org ([198.145.19.201]:58237 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757174AbaIQVZj (ORCPT ); Wed, 17 Sep 2014 17:25:39 -0400 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Anton Blanchard , Ingo Molnar , Paul Mackerras , Peter Zijlstra , Arnaldo Carvalho de Melo Subject: [PATCH 16/20] perf symbols: Ignore stripped vmlinux and fallback to kallsyms Date: Wed, 17 Sep 2014 18:24:19 -0300 Message-Id: <1410989063-14207-17-git-send-email-acme@kernel.org> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1410989063-14207-1-git-send-email-acme@kernel.org> References: <1410989063-14207-1-git-send-email-acme@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Anton Blanchard If a vmlinux is stripped, perf will use it and ignore kallsyms. We end up with useless profiles where everything maps to a few runtime symbols: 63.39% swapper [kernel.kallsyms] [k] hcall_real_table 4.90% beam.smp [kernel.kallsyms] [k] hcall_real_table 4.44% beam.smp [kernel.kallsyms] [k] __sched_text_start 3.72% beam.smp [kernel.kallsyms] [k] __run_at_kexec Detect this case and fallback to using kallsyms. This fixes the issue: 62.81% swapper [kernel.kallsyms] [k] snooze_loop 4.44% beam.smp [kernel.kallsyms] [k] __schedule 0.91% beam.smp [kernel.kallsyms] [k] _switch 0.73% beam.smp [kernel.kallsyms] [k] put_prev_entity Signed-off-by: Anton Blanchard Acked-by: Namhyung Kim Cc: Ingo Molnar Cc: Paul Mackerras Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20140909085929.4a5a81f0@kryten Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/symbol-elf.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index 9c9b27fbc78d..2a92e10317c5 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -717,6 +717,14 @@ int dso__load_sym(struct dso *dso, struct map *map, symbols__delete(&dso->symbols[map->type]); if (!syms_ss->symtab) { + /* + * If the vmlinux is stripped, fail so we will fall back + * to using kallsyms. The vmlinux runtime symbols aren't + * of much use. + */ + if (dso->kernel) + goto out_elf_end; + syms_ss->symtab = syms_ss->dynsym; syms_ss->symshdr = syms_ss->dynshdr; } -- 1.9.3