From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752538AbZH0PZo (ORCPT ); Thu, 27 Aug 2009 11:25:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752292AbZH0PZn (ORCPT ); Thu, 27 Aug 2009 11:25:43 -0400 Received: from mail-ew0-f206.google.com ([209.85.219.206]:59503 "EHLO mail-ew0-f206.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752304AbZH0PZm (ORCPT ); Thu, 27 Aug 2009 11:25:42 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=QaeUzxaCPJBwBhVsJgeubMAjRhJ1uoCV+Fx7pjF0vJAKddRFEtSZJZSo6Pyo5Wewqb tblE5VcAEEXH9FiG5H/qO+tJ0HQ8Nz1ElVA18nxW0qF24AdvnvYMX4KK6vBH0PTu7FTS cKO9Q9dj+fSTkNsRKkHAzcfu103wL/K1wfrlA= Date: Thu, 27 Aug 2009 17:25:41 +0200 From: Frederic Weisbecker To: Masami Hiramatsu Cc: Ingo Molnar , LKML , Steven Rostedt Subject: Re: [GIT PULL] tracing/kprobes: Add dynamic tracepoints + instruction decoder Message-ID: <20090827152539.GE6058@nowhere> References: <1251340337-5640-1-git-send-email-fweisbec@gmail.com> <4A969F96.2020107@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A969F96.2020107@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 27, 2009 at 11:00:38AM -0400, Masami Hiramatsu wrote: > Frederic Weisbecker wrote: > > Ingo, > > > > This is the kprobes tracing pile of patches. I've tested it > > successfully by setting some kprobes through debugfs by hand. > > > > It brings no known regressions. > > > > However, the stress test provided by Masami have revealed some > > unstable points. Some symbols are unsafe to probe and raise > > probing recursion. > > > > I've added a tiny patch in the series that helps identifying the > > kprobe that has raised such situation. > > For example it has learned me today that it's unsafe to trace > > ret_from_exception() (obviously: it's on the int 3 handler path). > > Thank you, Frederic. > > I'm currently fixing those problems on x86-64 (on kvm). > I'll also check it on x86-32, and fix it. > > Thanks Cool. Don't hesitate to interate through small patches that fix these sites. So that I can continue to test it over time and report you what I find, may be I can try to fix some of them too. I haven't fixed ret_from_exception because I wasn't sure about the right thing to do: putting it in the kprobes section or blacklist its name. It's a bit more delicate to put assembly code into sections so... :)