Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752730AbaAZEpd (ORCPT ); Sat, 25 Jan 2014 23:45:33 -0500 Received: from mga09.intel.com ([134.134.136.24]:36480 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752425AbaAZEpc (ORCPT ); Sat, 25 Jan 2014 23:45:32 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.95,721,1384329600"; d="scan'208";a="444669336" Message-ID: <52E4919B.8050408@intel.com> Date: Sun, 26 Jan 2014 12:39:55 +0800 From: Ren Qiaowei User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.1 MIME-Version: 1.0 To: David Rientjes CC: "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 4/4] x86, mpx: extend siginfo structure to include bound violation information References: <1390727338-20487-1-git-send-email-qiaowei.ren@intel.com> <1390727338-20487-5-git-send-email-qiaowei.ren@intel.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/26/2014 12:22 PM, David Rientjes wrote: > On Sun, 26 Jan 2014, Qiaowei Ren wrote: > >> This patch adds new fields about bound violation into siginfo >> structure. si_lower and si_upper are respectively lower bound >> and upper bound when bound violation is caused. >> >> These fields will be set in #BR exception handler by decoding >> the user instruction and constructing the faulting pointer. >> A userspace application can get violation address, lower bound >> and upper bound for bound violation from this new siginfo structure. >> >> Signed-off-by: Qiaowei Ren > > Same 32-bit warnings I reported for v2: > > arch/x86/kernel/mpx.c: In function ‘do_mpx_bounds’: > arch/x86/kernel/mpx.c:407:3: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] > arch/x86/kernel/mpx.c:409:3: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] > > and the documentation says you explicitly want to support this config. > > These types of warnings are usually indicative of real problems when > you're storing upper and lower bits in 32-bit fields after casting them > from 64-bit values. > > I'm also not sure if the added fields to the generic struct siginfo can be > justified for this. > According to MPX spec, for 32-bit case, the upper 32-bits of 64-bits bound register are ignored, and so casting to pointer from 64-bit values should be not produce any problems. Thanks, Qiaowei -- 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/