Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751319AbZIXV6O (ORCPT ); Thu, 24 Sep 2009 17:58:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751125AbZIXV6N (ORCPT ); Thu, 24 Sep 2009 17:58:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58015 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751105AbZIXV6M (ORCPT ); Thu, 24 Sep 2009 17:58:12 -0400 Message-ID: <4ABBEBBF.9080400@redhat.com> Date: Thu, 24 Sep 2009 14:59:27 -0700 From: Masami Hiramatsu User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.1) Gecko/20090814 Fedora/3.0-2.6.b3.fc11 Thunderbird/3.0b3 MIME-Version: 1.0 To: Mathieu Desnoyers CC: Peter Zijlstra , anil.s.keshavamurthy@intel.com, Jason Yeh , Robert Richter , Andi Kleen , "H. Peter Anvin" , Chuck Ebbert , Christoph Hellwig , Jeremy Fitzhardinge , Thomas Gleixner , Ingo Molnar , Ingo Molnar , linux-kernel@vger.kernel.org, "Frank Ch. Eigler" , Hideo AOKI , Takashi Nishiie , Steven Rostedt , Ananth N Mavinakayanahalli Subject: Re: [RFC patch] Immediate Values - x86 Optimization NMI and MCE support References: <20090924132626.485545323@polymtl.ca> <20090924133400.830759403@polymtl.ca> <1253803872.18939.28.camel@laptop> <20090924150333.GA26389@Krystal> <1253804779.18939.38.camel@laptop> <20090924160118.GA28846@Krystal> In-Reply-To: <20090924160118.GA28846@Krystal> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2480 Lines: 71 Mathieu Desnoyers wrote: > [Ingo: this patch is for RFC only. Do not merge.] > > * Peter Zijlstra (peterz@infradead.org) wrote: >> On Thu, 2009-09-24 at 11:03 -0400, Mathieu Desnoyers wrote: >>> * Peter Zijlstra (peterz@infradead.org) wrote: >>>> On Thu, 2009-09-24 at 09:26 -0400, Mathieu Desnoyers wrote: >>>>> plain text document attachment (tracepoints-immediate-values.patch) >>>>> Use immediate values in tracepoints. >>>> >>>> I might have missed it, but did both the Intel and AMD cpu folks clear >>>> the SMP code rewrite bits? >>>> >>> >>> SMP handling is performed with stop_machine() in this patchset. Nothing >>> fancy here. >>> >>> I've got other patches, not included in this patchset, which implements >>> nmi-safe code modification, based on a scheme using breakpoints and >>> IPIs, inspired from djprobes. That one might be worth clearing with >>> intel/amd devs before merging. >>> >>> However, doing code patching within stop_machine() is pretty safe, given >>> all other CPUs are busy-looping with interrupts off while this happens. >>> Ftrace already does this. >> >> Agreed, I missed this relied on stopmachine. No problem then. >> >> It would be good to reduce reliance on stopmachine, so it would be good >> to get some CPU folks looking at your alternative implementation. >> >> Thanks! >> > > Sure, here is the patch applying on top of the immediate values > patchset. It implements the breakpoint-based instruction patching > scheme. I just provide this one for review. There is a following patch > which makes the immediate values infrastructure use this arch-specific > file, which I'll leave out for now. Mathieu, could you check my previous patch? http://lkml.org/lkml/2009/9/14/551 I think we can share some code and ideas about generic XMC:-). But since it seems that the imv requires a dedicated method, I don't think we can share the code entirely. :-) > +#include > + > +#define BREAKPOINT_INSTRUCTION 0xcc > +#define BREAKPOINT_INS_LEN 1 > +#define NR_NOPS 10 Why don't you reuse macros in asm/include/kprobes.h? :) Thank you, -- Masami Hiramatsu Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division e-mail: mhiramat@redhat.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/