Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755217AbZCFPgc (ORCPT ); Fri, 6 Mar 2009 10:36:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754833AbZCFPgT (ORCPT ); Fri, 6 Mar 2009 10:36:19 -0500 Received: from mx2.redhat.com ([66.187.237.31]:60590 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754514AbZCFPgS (ORCPT ); Fri, 6 Mar 2009 10:36:18 -0500 Message-ID: <49B142D8.7020601@redhat.com> Date: Fri, 06 Mar 2009 10:35:52 -0500 From: Masami Hiramatsu User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: Mathieu Desnoyers , Ingo Molnar CC: Andrew Morton , Nick Piggin , Steven Rostedt , Andi Kleen , Linux Kernel Mailing List , Thomas Gleixner , Peter Zijlstra , Frederic Weisbecker , Linus Torvalds , Arjan van de Ven , Rusty Russell , "H. Peter Anvin" Subject: [PATCH -tip 1/4] Text Edit Lock - Architecture Independent Code (v2) References: <49B1428A.9050500@redhat.com> In-Reply-To: <49B1428A.9050500@redhat.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2453 Lines: 81 From: Mathieu Desnoyers 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: 2.6.29-rc7/include/linux/memory.h =================================================================== --- 2.6.29-rc7.orig/include/linux/memory.h +++ 2.6.29-rc7/include/linux/memory.h @@ -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: 2.6.29-rc7/mm/memory.c =================================================================== --- 2.6.29-rc7.orig/mm/memory.c +++ 2.6.29-rc7/mm/memory.c @@ -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; -- 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/