Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757936AbZGCMp7 (ORCPT ); Fri, 3 Jul 2009 08:45:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757741AbZGCMpW (ORCPT ); Fri, 3 Jul 2009 08:45:22 -0400 Received: from hera.kernel.org ([140.211.167.34]:59928 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757557AbZGCMpS (ORCPT ); Fri, 3 Jul 2009 08:45:18 -0400 Date: Fri, 3 Jul 2009 12:44:43 GMT From: tip-bot for 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, stable@kernel.org, tglx@linutronix.de, mhiramat@redhat.com, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, mathieu.desnoyers@polymtl.ca, linux-kernel@vger.kernel.org, stable@kernel.org, tglx@linutronix.de, mhiramat@redhat.com, mingo@elte.hu In-Reply-To: <20090701213722.GH19926@Krystal> References: <20090701213722.GH19926@Krystal> Subject: [tip:x86/urgent] x86: Fix fixmap page order for FIX_TEXT_POKE0,1 Message-ID: Git-Commit-ID: 12b9d7ccb841805e347fec8f733f368f43ddba40 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]); Fri, 03 Jul 2009 12:44:43 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2293 Lines: 61 Commit-ID: 12b9d7ccb841805e347fec8f733f368f43ddba40 Gitweb: http://git.kernel.org/tip/12b9d7ccb841805e347fec8f733f368f43ddba40 Author: Mathieu Desnoyers AuthorDate: Wed, 1 Jul 2009 17:37:22 -0400 Committer: Ingo Molnar CommitDate: Fri, 3 Jul 2009 14:34:09 +0200 x86: Fix fixmap page order for FIX_TEXT_POKE0,1 Masami reported: > Since the fixmap pages are assigned higher address to lower, > text_poke() has to use it with inverted order (FIX_TEXT_POKE1 > to FIX_TEXT_POKE0). I prefer to just invert the order of the fixmap declaration. It's simpler and more straightforward. Backward fixmaps seems to be used by both x86 32 and 64. It's really rare but a nasty bug, because it only hurts when instructions to patch are crossing a page boundary. If this happens, the fixmap write accesses will spill on the following fixmap, which may very well crash the system. And this does not crash the system, it could leave illegal instructions in place. Thanks Masami for finding this. It seems to have crept into the 2.6.30-rc series, so this calls for a -stable inclusion. Signed-off-by: Mathieu Desnoyers Acked-by: Masami Hiramatsu Cc: LKML-Reference: <20090701213722.GH19926@Krystal> Signed-off-by: Ingo Molnar --- arch/x86/include/asm/fixmap.h | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h index 3eb0f79..7b2d71d 100644 --- a/arch/x86/include/asm/fixmap.h +++ b/arch/x86/include/asm/fixmap.h @@ -111,8 +111,8 @@ enum fixed_addresses { #ifdef CONFIG_PARAVIRT FIX_PARAVIRT_BOOTMAP, #endif - FIX_TEXT_POKE0, /* reserve 2 pages for text_poke() */ - FIX_TEXT_POKE1, + FIX_TEXT_POKE1, /* reserve 2 pages for text_poke() */ + FIX_TEXT_POKE0, /* first page is last, because allocation is backward */ __end_of_permanent_fixed_addresses, /* * 256 temporary boot-time mappings, used by early_ioremap(), -- 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/