Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754677Ab0A1LOY (ORCPT ); Thu, 28 Jan 2010 06:14:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754543Ab0A1LOW (ORCPT ); Thu, 28 Jan 2010 06:14:22 -0500 Received: from e28smtp05.in.ibm.com ([122.248.162.5]:34536 "EHLO e28smtp05.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754469Ab0A1LOT (ORCPT ); Thu, 28 Jan 2010 06:14:19 -0500 Date: Thu, 28 Jan 2010 16:44:15 +0530 From: "K.Prasad" To: LKML Cc: Ingo Molnar , Frederic Weisbecker , Roland McGrath , Alan Stern , Jan Kiszka , "K.Prasad" Subject: [Patch 2/2 v2] Return proper code to notifier chain in hw_breakpoint_handler Message-ID: <20100128111415.GC13935@in.ibm.com> References: <20100128110936.399448739@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename=fix_notify_code_02 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 Content-Length: 1764 Lines: 46 Processing of debug exceptions (in do_debug()) can stop if it originated from a hw-breakpoint exception (return NOTIFY_STOP). For certain cases such as a) user-space breakpoints with pending SIGTRAP signal delivery (as in the case of ptrace induced breakpoints) and b) exceptions due to multiple causes (other than breakpoints) we will continue to process the exception (by returning NOTIFY_DONE). Signed-off-by: K.Prasad --- arch/x86/kernel/hw_breakpoint.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) Index: linux-2.6-tip.bugfix_perf_hbkpt/arch/x86/kernel/hw_breakpoint.c =================================================================== --- linux-2.6-tip.bugfix_perf_hbkpt.orig/arch/x86/kernel/hw_breakpoint.c +++ linux-2.6-tip.bugfix_perf_hbkpt/arch/x86/kernel/hw_breakpoint.c @@ -502,8 +502,6 @@ static int __kprobes hw_breakpoint_handl rcu_read_lock(); bp = per_cpu(bp_per_reg[i], cpu); - if (bp) - rc = NOTIFY_DONE; /* * Reset the 'i'th TRAP bit in dr6 to denote completion of * exception handling @@ -522,7 +520,13 @@ static int __kprobes hw_breakpoint_handl rcu_read_unlock(); } - if (dr6 & (~DR_TRAP_BITS)) + /* + * Further processing in do_debug() is needed for a) user-space + * breakpoints (to generate signals) and b) when the system has + * taken exception due to multiple causes + */ + if ((current->thread.debugreg6 & DR_TRAP_BITS) || + (dr6 & (~DR_TRAP_BITS))) rc = NOTIFY_DONE; set_debugreg(dr7, 7); -- 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/