Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752689AbZC1IrT (ORCPT ); Sat, 28 Mar 2009 04:47:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751102AbZC1IrG (ORCPT ); Sat, 28 Mar 2009 04:47:06 -0400 Received: from e23smtp06.au.ibm.com ([202.81.31.148]:34744 "EHLO e23smtp06.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751092AbZC1IrD (ORCPT ); Sat, 28 Mar 2009 04:47:03 -0400 Date: Sat, 28 Mar 2009 14:16:48 +0530 From: "K.Prasad" To: Alan Stern Cc: Ingo Molnar , Linux Kernel Mailing List , Andrew Morton , Benjamin Herrenschmidt , Frederic Weisbecker , maneesh@linux.vnet.ibm.com, Roland McGrath , Steven Rostedt Subject: Re: [Patch 00/11] Hardware Breakpoint interfaces Message-ID: <20090328084647.GB5297@in.ibm.com> Reply-To: prasad@linux.vnet.ibm.com References: <20090324152435.GA17918@in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1520 Lines: 40 On Wed, Mar 25, 2009 at 03:48:31PM -0400, Alan Stern wrote: > > + > > +/* > > + * Handle debug exception notifications. > > + */ > > +int __kprobes hw_breakpoint_handler(struct die_args *args) > > +{ > > + int i, rc = NOTIFY_DONE; > > + struct hw_breakpoint *bp; > > + /* The DR6 value is stored in args->err */ > > + unsigned long dr7, dr6 = args->err; > > Please change this. (I should have changed it long ago, but I never > got around to it.) Instead of passing the DR6 value in args->err, > pass a pointer to the dr6 variable in do_debug(). That way the > handler routines can turn off bits in that variable and do_debug() can > see which bits remain set at the end. > > Of course, this will require a corresponding change to the > post_kprobe_handler() routine. > As I looked at the code with an intention of changing it, I don't find a place - in hw_breakpoint_handler() and in functions called by kprobe_exceptions_notify() where bits in dr6 are written into. The thread-specific thread->debugreg6 is updated with causative bits in ptrace_triggered() to help send signals to the user-space. I don't see a user for the change you propose. I should send out the revised patchset sometime tomorrow. Kindly let me know your comments about them. Thanks, K.Prasad -- 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/