Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754719AbZFGQ1L (ORCPT ); Sun, 7 Jun 2009 12:27:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752873AbZFGQ06 (ORCPT ); Sun, 7 Jun 2009 12:26:58 -0400 Received: from mail-ew0-f210.google.com ([209.85.219.210]:64372 "EHLO mail-ew0-f210.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752695AbZFGQ05 (ORCPT ); Sun, 7 Jun 2009 12:26:57 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer; b=dGM8eZCJhYombX1rfAwQEU2dxBU9CZPJj/fHF9sURkfhBXkgbILIBMcJLhtsmdqxgt 6ALDTlPA2iuKqTddWkN1foG8VNh2M2PkMCDbPrOMJx5AHU1/bpq+KTSAv6ld7X3mrrzu +0/slqwFT9zyPVK6QSrn6weqmFnE3U/PmEIiI= From: Vegard Nossum Cc: linux-kernel@vger.kernel.org, Vegard Nossum , Alexander van Heukelum , "K.Prasad" , Alan Stern , Frederic Weisbecker , Pekka Enberg Subject: [PATCH] kmemcheck: move hook before preempt_conditional_sti() Date: Sun, 7 Jun 2009 18:26:52 +0200 Message-Id: <1244392012-638-1-git-send-email-vegard.nossum@gmail.com> X-Mailer: git-send-email 1.6.2.rc0.61.g5cd12 To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2565 Lines: 77 There are actually two problems here: 1. We absolutely cannot enable IRQs in case the fault was caused by kmemcheck. 2. We cannot enable preemption and then return from the debug handler without disabling preemption afterwards. The problem seems to be a merge fallout between three commits: commit 3d2a71a596bd9c761c8487a2178e95f8a61da083 Author: Alexander van Heukelum Date: Tue Sep 30 18:41:37 2008 +0200 x86, traps: converge do_debug handlers commit 08d68323d1f0c34452e614263b212ca556dae47f Author: K.Prasad Date: Mon Jun 1 23:44:08 2009 +0530 hw-breakpoints: modifying generic debug exception to use thread-specific deb commit 787ecfaa503dc63ff1831ddc74b15dad49bace1d Author: Vegard Nossum Date: Fri Apr 4 00:53:23 2008 +0200 x86: add hooks for kmemcheck I encourage the kprobe developers to check whether their code is correct as it stands in current tip/master. Also, comments on this particular change is welcome. Reported-by: Ingo Molnar Cc: Alexander van Heukelum Cc: K.Prasad Cc: Alan Stern Cc: Frederic Weisbecker Cc: Pekka Enberg Signed-off-by: Vegard Nossum --- arch/x86/kernel/traps.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index c8a7f87..a898c6b 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -550,6 +550,10 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) SIGTRAP) == NOTIFY_STOP) return; + /* Catch kmemcheck conditions first of all! */ + if ((dr6 & DR_STEP) && kmemcheck_trap(regs)) + return; + /* It's safe to allow irq's after DR6 has been saved */ preempt_conditional_sti(regs); @@ -559,10 +563,6 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) return; } - /* Catch kmemcheck conditions first of all! */ - if ((dr6 & DR_STEP) && kmemcheck_trap(regs)) - return; - /* * Single-stepping through system calls: ignore any exceptions in * kernel space, but re-enable TF when returning to user mode. -- 1.6.0.6 -- 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/