From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752842AbcFNRFO (ORCPT ); Tue, 14 Jun 2016 13:05:14 -0400 Received: from mail.kernel.org ([198.145.29.136]:33308 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751153AbcFNRFK (ORCPT ); Tue, 14 Jun 2016 13:05:10 -0400 Date: Tue, 14 Jun 2016 14:05:04 -0300 From: Arnaldo Carvalho de Melo To: Masami Hiramatsu Cc: Linux Kernel Mailing List Subject: perf probe issues Message-ID: <20160614170504.GD3978@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.6.1 (2016-04-27) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Masami, While investigating a problem in the annotation code reported by Linus, with "kaslr" on the kernel command line and this in .config: [root@jouet ~]# egrep 'CONFIG_(RANDOMIZE_BASE|DEBUG_INFO)' ~acme/git/build/v4.7.0-rc3/.config CONFIG_RANDOMIZE_BASE=y # CONFIG_DEBUG_INFO is not set [root@jouet ~]# [root@jouet ~]# grep -w vfs_write /proc/kallsyms ffffffffac2404c0 T vfs_write [root@jouet ~]# perf probe vfs_write vfs_write is out of .text, skip it. Error: Failed to add events. [root@jouet ~]# perf probe -v vfs_write probe-definition(0): vfs_write symbol:vfs_write file:(null) line:0 offset:0 return:0 lazy:(null) 0 arguments Looking at the vmlinux_path (8 entries long) Using /lib/modules/4.7.0-rc3/build/vmlinux for symbols Could not open debuginfo. Try to use symbols. vfs_write is out of .text, skip it. Error: Failed to add events. Reason: No such file or directory (Code: -2) [root@jouet ~]# Can you try to test with this config to investigate this problem? We need to improve the error messages, for instance: "Could not open debuginfo. Try to use symbols." I think should be rewritten as: "Trying to use kallsyms", no? I.e. if it doesn't manage to find a vmlinux file, it will try to use kallsyms as a fallback, is that what is happening here? - Arnaldo