Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753136AbZCHPwR (ORCPT ); Sun, 8 Mar 2009 11:52:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752579AbZCHPv7 (ORCPT ); Sun, 8 Mar 2009 11:51:59 -0400 Received: from hera.kernel.org ([140.211.167.34]:34089 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752479AbZCHPv6 (ORCPT ); Sun, 8 Mar 2009 11:51:58 -0400 Date: Sun, 8 Mar 2009 15:51:24 GMT From: Mathieu Desnoyers To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, mathieu.desnoyers@polymtl.ca, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, mathieu.desnoyers@polymtl.ca, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <49B142D8.7020601@redhat.com> References: <49B142D8.7020601@redhat.com> Subject: [tip:tracing/core] tracing, Text Edit Lock - Architecture Independent Code Message-ID: Git-Commit-ID: 0e39ac444636ff5be39b26f1cb56d79594654dda X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Sun, 08 Mar 2009 15:51:27 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2596 Lines: 79 Commit-ID: 0e39ac444636ff5be39b26f1cb56d79594654dda Gitweb: http://git.kernel.org/tip/0e39ac444636ff5be39b26f1cb56d79594654dda Author: "Mathieu Desnoyers" AuthorDate: Fri, 6 Mar 2009 10:35:52 -0500 Commit: Ingo Molnar CommitDate: Fri, 6 Mar 2009 16:48:59 +0100 tracing, Text Edit Lock - Architecture Independent Code 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. Signed-off-by: Mathieu Desnoyers LKML-Reference: <49B142D8.7020601@redhat.com> Signed-off-by: Ingo Molnar --- include/linux/memory.h | 6 ++++++ mm/memory.c | 10 ++++++++++ 2 files changed, 16 insertions(+), 0 deletions(-) diff --git a/include/linux/memory.h b/include/linux/memory.h index 3fdc108..86a6c0f 100644 --- a/include/linux/memory.h +++ b/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_ */ diff --git a/mm/memory.c b/mm/memory.c index baa999e..05fab3b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -48,6 +48,8 @@ #include #include #include +#include +#include #include #include #include @@ -99,6 +101,14 @@ 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. + * + * NOT exported to modules - patching kernel text is a really delicate matter. + */ +DEFINE_MUTEX(text_mutex); + static int __init disable_randmaps(char *s) { randomize_va_space = 0; -- 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/