Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753369AbcJMKWg (ORCPT ); Thu, 13 Oct 2016 06:22:36 -0400 Received: from mail-qk0-f174.google.com ([209.85.220.174]:34500 "EHLO mail-qk0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754013AbcJMKWZ (ORCPT ); Thu, 13 Oct 2016 06:22:25 -0400 Subject: Re: [PATCH 3/4] arm64: Allow hw watchpoint of length 3,5,6 and 7 To: Yao Qi , onestero@redhat.com References: Cc: will.deacon@arm.com, Mark Rutland , labath@google.com, linux-kernel@vger.kernel.org, Jan Kratochvil , linux-arm-kernel@lists.infradead.org From: Pratyush Anand Message-ID: <1bc0dce6-eb26-dbf5-dd0c-d36055f5f1fe@redhat.com> Date: Thu, 13 Oct 2016 15:52:17 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 950 Lines: 28 On Wednesday 12 October 2016 04:46 PM, Yao Qi wrote: > On Wed, Oct 12, 2016 at 6:58 AM, Pratyush Anand wrote: >> Since, arm64 can support all offset within a double word limit. Therefore, >> now support other lengths within that range as well. > > How does ptracer (like GDB) detect kernel has already supported all byte > address select values? I suppose ptrace(NT_ARM_HW_WATCH, ) with > len is 3 or 5 fail on current kernel but is of success after your patches > applied. > Thanks for testing these patches. I do not know if we can know that other than the failure of ptrace(PTRACE_SETREGSET, .., NT_ARM_HW_WATCH, ..). I do not see any such option in `man ptrace`. > GDB is aware of the byte address select limitation in kernel, so it always > sets 1,2,4,8 in len in ctrl. GDB needs to know whether the limitation is still > there or not. > Not sure if other than "kernel version" anything will help here. ~Pratyush