Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757136AbZCCBar (ORCPT ); Mon, 2 Mar 2009 20:30:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752731AbZCCBaj (ORCPT ); Mon, 2 Mar 2009 20:30:39 -0500 Received: from tomts5-srv.bellnexxia.net ([209.226.175.25]:49937 "EHLO tomts5-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751948AbZCCBai (ORCPT ); Mon, 2 Mar 2009 20:30:38 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AhwFACMXrElMQW1W/2dsb2JhbACBWdMlhAYG Date: Mon, 2 Mar 2009 20:30:29 -0500 From: Mathieu Desnoyers To: Ingo Molnar Cc: Peter Zijlstra , Masami Hiramatsu , Andrew Morton , Nick Piggin , Steven Rostedt , Andi Kleen , linux-kernel@vger.kernel.org, Thomas Gleixner , Peter Zijlstra , Frederic Weisbecker , Linus Torvalds , Arjan van de Ven , Rusty Russell , "H. Peter Anvin" , Steven Rostedt Subject: [PATCH] Text Edit Lock - Architecture Independent Code (v2) Message-ID: <20090303013029.GA7783@Krystal> References: <49AC10E9.1090102@redhat.com> <20090302171914.GB21735@Krystal> <49AC5A87.7000604@redhat.com> <20090302222254.GA31962@elte.hu> <49AC63FA.70801@redhat.com> <20090302230915.GA11626@elte.hu> <49AC6DEA.2050304@redhat.com> <20090302234910.GA17956@elte.hu> <20090303000054.GC3906@Krystal> <20090303003237.GA30221@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <20090303003237.GA30221@elte.hu> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 20:29:56 up 2 days, 21:56, 4 users, load average: 0.28, 0.39, 0.56 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 Content-Length: 2532 Lines: 73 This is an architecture independant synchronization around kernel text modifications through use of a global mutex. A mutex has been chosen so that kprobes, the main user of this, can sleep during memory allocation between the memory read of the instructions it must replace and the memory write of the breakpoint. Other user of this interface: immediate values. Paravirt and alternatives are always done when SMP is inactive, so there is no need to use locks. Changelog : Export text_mutex directly. Signed-off-by: Mathieu Desnoyers CC: Andi Kleen CC: Ingo Molnar --- include/linux/memory.h | 6 ++++++ mm/memory.c | 9 +++++++++ 2 files changed, 15 insertions(+) Index: linux-2.6-lttng/include/linux/memory.h =================================================================== --- linux-2.6-lttng.orig/include/linux/memory.h 2009-03-02 13:13:35.000000000 -0500 +++ linux-2.6-lttng/include/linux/memory.h 2009-03-02 19:23:52.000000000 -0500 @@ -99,4 +99,10 @@ enum mem_add_context { BOOT, HOTPLUG }; #define hotplug_memory_notifier(fn, pri) do { } while (0) #endif +/* + * Kernel text modification mutex, used for code patching. Users of this lock + * can sleep. + */ +extern struct mutex text_mutex; + #endif /* _LINUX_MEMORY_H_ */ Index: linux-2.6-lttng/mm/memory.c =================================================================== --- linux-2.6-lttng.orig/mm/memory.c 2009-03-02 13:13:35.000000000 -0500 +++ linux-2.6-lttng/mm/memory.c 2009-03-02 19:24:33.000000000 -0500 @@ -48,6 +48,8 @@ #include #include #include +#include +#include #include #include #include @@ -99,6 +101,13 @@ int randomize_va_space __read_mostly = 2; #endif +/* + * mutex protecting text section modification (dynamic code patching). + * some users need to sleep (allocating memory...) while they hold this lock. + */ +DEFINE_MUTEX(text_mutex); +EXPORT_SYMBOL_GPL(text_mutex); + static int __init disable_randmaps(char *s) { randomize_va_space = 0; -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 -- 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/