Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932181Ab3DWJy5 (ORCPT ); Tue, 23 Apr 2013 05:54:57 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:47231 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755010Ab3DWJy4 (ORCPT ); Tue, 23 Apr 2013 05:54:56 -0400 Date: Tue, 23 Apr 2013 10:54:37 +0100 From: Will Deacon To: Jacob Shin Cc: Ingo Molnar , Oleg Nesterov , Frederic Weisbecker , Peter Zijlstra , Arnaldo Carvalho de Melo , "H. Peter Anvin" , Thomas Gleixner , "x86@kernel.org" , Stephane Eranian , Jiri Olsa , linux-kernel@vger.kernel.org Subject: Re: [PATCH V2 1/4] perf: Add hardware breakpoint address mask Message-ID: <20130423095437.GD17593@mudshark.cambridge.arm.com> References: <1366703825-19373-1-git-send-email-jacob.shin@amd.com> <1366703825-19373-2-git-send-email-jacob.shin@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1366703825-19373-2-git-send-email-jacob.shin@amd.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1067 Lines: 25 Hi Jacob, On Tue, Apr 23, 2013 at 08:57:02AM +0100, Jacob Shin wrote: > Some architectures (for us, AMD Family 16h) allow for "don't care" bit > mask to further qualify a hardware breakpoint address, in order to > trap on range of addresses. Update perf uapi to add bp_addr_mask field. arm and arm64 have a similar feature to this, whereby we currently have to translate the bp_len field into a mask, which is all the hardware understands. Unlike what you describe, our mask indicates the bytes we *are* interested in, but I think we could make use of the same functionality that you're introducing here. There are some funky restrictions on the alignment of the base address, but we can detect those and tell userspace where to go if it tries any funny stuff. Can you see a problem if I simply invert the mask? Will -- 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/