From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753035AbZLZS1f (ORCPT ); Sat, 26 Dec 2009 13:27:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752707AbZLZS1f (ORCPT ); Sat, 26 Dec 2009 13:27:35 -0500 Received: from e23smtp06.au.ibm.com ([202.81.31.148]:45197 "EHLO e23smtp06.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752576AbZLZS1e (ORCPT ); Sat, 26 Dec 2009 13:27:34 -0500 Date: Sat, 26 Dec 2009 23:57:25 +0530 From: "K.Prasad" To: LKML Cc: Ingo Molnar , Frederic Weisbecker , Roland McGrath , Alan Stern , Ananth N Mavinakayanahalli , Pekka Enberg , Vegard Nossum , Oleg Nesterov Subject: [RFC Patch 1/2][Bugfix][x86][hw-breakpoint] Clear reserved bits of DR6 in do_debug() Message-ID: <20091226182725.GB9494@in.ibm.com> References: <20091226175533.149765731@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename=fix_dr6_reserved_01 User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Clear the reserved bits from the stored copy of debug status register (DR6). This will help easy bitwise operations. Signed-off-by: K.Prasad --- arch/x86/include/asm/debugreg.h | 3 +++ arch/x86/kernel/traps.c | 3 +++ 2 files changed, 6 insertions(+) Index: linux-2.6-tip/arch/x86/include/asm/debugreg.h =================================================================== --- linux-2.6-tip.orig/arch/x86/include/asm/debugreg.h +++ linux-2.6-tip/arch/x86/include/asm/debugreg.h @@ -14,6 +14,9 @@ which debugging register was responsible for the trap. The other bits are either reserved or not of interest to us. */ +/* Define reserved bits in DR6 which are always set to 1 */ +#define DR6_RESERVED (0xFFFF0FF0) + #define DR_TRAP0 (0x1) /* db0 */ #define DR_TRAP1 (0x2) /* db1 */ #define DR_TRAP2 (0x4) /* db2 */ Index: linux-2.6-tip/arch/x86/kernel/traps.c =================================================================== --- linux-2.6-tip.orig/arch/x86/kernel/traps.c +++ linux-2.6-tip/arch/x86/kernel/traps.c @@ -534,6 +534,9 @@ dotraplinkage void __kprobes do_debug(st get_debugreg(dr6, 6); + /* Filter out all the reserved bits which are preset to 1 */ + dr6 &= ~DR6_RESERVED; + /* Catch kmemcheck conditions first of all! */ if ((dr6 & DR_STEP) && kmemcheck_trap(regs)) return;