Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757127Ab0BXNmO (ORCPT ); Wed, 24 Feb 2010 08:42:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54263 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756951Ab0BXNmN (ORCPT ); Wed, 24 Feb 2010 08:42:13 -0500 Message-ID: <4B852C79.8000702@redhat.com> Date: Wed, 24 Feb 2010 08:41:13 -0500 From: Masami Hiramatsu User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.7) Gecko/20100120 Fedora/3.0.1-1.fc11 Thunderbird/3.0.1 MIME-Version: 1.0 To: rostedt@goodmis.org CC: Frederic Weisbecker , Ingo Molnar , Ananth N Mavinakayanahalli , lkml , Jim Keniston , Srikar Dronamraju , Christoph Hellwig , "H. Peter Anvin" , Anders Kaseorg , Tim Abbott , Andi Kleen , Jason Baron , Mathieu Desnoyers , systemtap , DLE Subject: Re: [PATCH -tip v10 0/9] kprobes: Kprobes jump optimization support References: <20100218221247.19637.80088.stgit@dhcp-100-2-132.bos.redhat.com> <1266944834.24271.6021.camel@gandalf.stny.rr.com> <4B845668.5090803@redhat.com> In-Reply-To: <4B845668.5090803@redhat.com> X-Enigmail-Version: 1.0.1 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1509 Lines: 43 Masami Hiramatsu wrote: > Steven Rostedt wrote: >> On Thu, 2010-02-18 at 17:12 -0500, Masami Hiramatsu wrote: >> >>> This version of patch series uses text_poke_smp() which >>> update kernel text by stop_machine(). That is 'officially' >>> supported on Intel's processors. text_poke_smp() can't >>> be used for modifying NMI code, >> >> But it can be made to use with NMI code. If you look at what I did to >> allow ftrace to modify NMI code, it may be able to do the same thing. > > Yeah, I know. But basically, kprobes doesn't support probing NMI. > Maybe, it's possibly the next step. :) I mean that it may be overkill for this series, because the kprobes itself doesn't support NMI. So I think it should be done by another series (for simplify patches). BTW, now there are two candidates for NMI supported text_poke() on x86. AFAIK, those have following issues/features. - text_poke_fixup() - Send IPI twice instead of kstop_machine. - Need a detour buffer if replacing code is not a jump. - Unofficial method for x86. - generic ftrace_modify_code - Use kstop_machine and wait an NMI. - Temporarily clear the kernel text read-only flag entirely (can we use text_poke instead?) Thank you, -- Masami Hiramatsu 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/