From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753747AbaIKWS2 (ORCPT ); Thu, 11 Sep 2014 18:18:28 -0400 Received: from www.linutronix.de ([62.245.132.108]:43915 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751282AbaIKWSZ (ORCPT ); Thu, 11 Sep 2014 18:18:25 -0400 Date: Fri, 12 Sep 2014 00:18:15 +0200 (CEST) From: Thomas Gleixner To: Qiaowei Ren cc: "H. Peter Anvin" , Ingo Molnar , Dave Hansen , x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v8 07/10] x86, mpx: decode MPX instruction to get bound violation information In-Reply-To: <1410425210-24789-8-git-send-email-qiaowei.ren@intel.com> Message-ID: References: <1410425210-24789-1-git-send-email-qiaowei.ren@intel.com> <1410425210-24789-8-git-send-email-qiaowei.ren@intel.com> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 11 Sep 2014, Qiaowei Ren wrote: > This patch sets bound violation fields of siginfo struct in #BR > exception handler by decoding the user instruction and constructing > the faulting pointer. > > This patch does't use the generic decoder, and implements a limited > special-purpose decoder to decode MPX instructions, simply because the > generic decoder is very heavyweight not just in terms of performance > but in terms of interface -- because it has to. And why is that an argument to add another special purpose decoder? If a bound violation happens it is completely irrelevant whether the decoder is heavyweight or not. So unless you come up with a convincing argument why the generic decoder is the wrong place, this won't happen. Thanks, tglx