Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759999AbZDWTmT (ORCPT ); Thu, 23 Apr 2009 15:42:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753358AbZDWTmD (ORCPT ); Thu, 23 Apr 2009 15:42:03 -0400 Received: from BISCAYNE-ONE-STATION.MIT.EDU ([18.7.7.80]:46193 "EHLO biscayne-one-station.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751445AbZDWTmB convert rfc822-to-8bit (ORCPT ); Thu, 23 Apr 2009 15:42:01 -0400 Date: Thu, 23 Apr 2009 15:40:42 -0400 (EDT) From: Anders Kaseorg To: Masami Hiramatsu cc: Tim Abbott , Ingo Molnar , Rusty Russell , Steven Rostedt , linux-kernel@vger.kernel.org, Andrew Morton , Thomas Gleixner , Peter Zijlstra , Frederic Weisbecker , Jeffrey B Arnold , Mathieu Desnoyers , Ananth N Mavinakayanahalli Subject: Re: [PATCH 1/5] ftrace: use module notifier for function tracer In-Reply-To: <49EFA0DE.9070407@redhat.com> Message-ID: References: <20090416021830.556671772@goodmis.org> <20090416021928.040177084@goodmis.org> <200904192055.04213.rusty@rustcorp.com.au> <20090422091645.GB18226@elte.hu> <49EFA0DE.9070407@redhat.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=UTF-8 Content-Transfer-Encoding: 8BIT X-Spam-Flag: NO X-Spam-Score: 0.00 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1227 Lines: 26 On Wed, 22 Apr 2009, Masami Hiramatsu wrote: > Could you also add "use text_poke() on x86" to your plan? :-) That should be possible now that it is usable inside stop_machine(). It would be nicer to have an API that isn’t x86-specific, though. Another issue is that Ksplice supports patching rodata as well as text, and text_poke() does not support changes bigger than PAGE_SIZE. Though perhaps text_poke() is not the right function for rodata patches anyway. > Hmm, I can't agree that we allow module to modify kernel text... > Is that possible to separate kernel-text swapping routine from Ksplice > module? In that case, we don't need to export text_mutex. No, it’s not enough for Ksplice to lock the kernel text only while actively swapping it. We also need to prevent changes to the kernel text while Ksplice is doing run-pre matching to ensure safety. This means that Ksplice wants to hold text_mutex for essentially the entire time it’s running. Anders -- 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/