Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756482Ab3DPN2m (ORCPT ); Tue, 16 Apr 2013 09:28:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51973 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755221Ab3DPN2k (ORCPT ); Tue, 16 Apr 2013 09:28:40 -0400 Date: Tue, 16 Apr 2013 15:25:45 +0200 From: Oleg Nesterov To: Frederic Weisbecker Cc: Andrew Morton , Alan Stern , Ingo Molnar , Jan Kratochvil , Maneesh Soni , Prasad , linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/2] ptrace/x86: simplify ptrace_write_dr7() Message-ID: <20130416132545.GA9189@redhat.com> References: <20130414191205.GA28791@redhat.com> <20130415233652.GE17561@somewhere.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130415233652.GE17561@somewhere.redhat.com> 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: 1233 Lines: 38 On 04/16, Frederic Weisbecker wrote: > > On Sun, Apr 14, 2013 at 09:12:05PM +0200, Oleg Nesterov wrote: > > Looking at the bug report, it seems they only reproduced with a homemade > test. No real app has reported that issue? iirc (Jan can correct me) gdb hit this problem, but it was already changed to change DR0 first. > > Jan, Frederic, et all. What do you think we should do? > > > > 1. Change ptrace_write_dr7() to do register_user_hw_breakpoint() > > if necessary. > > > > This is what I was going to do, but I am no longer sure > > we want this. For what? Unlikely it is very useful to use > > the "default" addr == 0 for debugging. > > So you mean assume that the addr is 0 in dr[0-3] if we write dr7 before writing > the addr register? Yes, > Yes, I'm convinced that's the right direction! OK. Thanks Jan and Frederic. I'll send v2 tomorrow with the 3rd patch which adds _register into write_dr7. Plus another minor/offtopic fix I forgot to send. Oleg. -- 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/