Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756879AbaFWUJO (ORCPT ); Mon, 23 Jun 2014 16:09:14 -0400 Received: from mga09.intel.com ([134.134.136.24]:61881 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753812AbaFWUJN (ORCPT ); Mon, 23 Jun 2014 16:09:13 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,532,1400050800"; d="scan'208";a="562070122" Message-ID: <53A88966.5080400@intel.com> Date: Mon, 23 Jun 2014 13:09:10 -0700 From: Dave Hansen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Andy Lutomirski , Qiaowei Ren , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar CC: x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 08/10] x86, mpx: add prctl commands PR_MPX_REGISTER, PR_MPX_UNREGISTER References: <1403084656-27284-1-git-send-email-qiaowei.ren@intel.com> <1403084656-27284-9-git-send-email-qiaowei.ren@intel.com> <53A8874A.3050301@mit.edu> In-Reply-To: <53A8874A.3050301@mit.edu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/23/2014 01:00 PM, Andy Lutomirski wrote: > On 06/18/2014 02:44 AM, Qiaowei Ren wrote: >> > This patch adds the PR_MPX_REGISTER and PR_MPX_UNREGISTER prctl() >> > commands. These commands can be used to register and unregister MPX >> > related resource on the x86 platform. >> > >> > The base of the bounds directory is set into mm_struct during >> > PR_MPX_REGISTER command execution. This member can be used to >> > check whether one application is mpx enabled. > The register and unregister operations seem to be almost the same thing. > How about just PR_SYNC_MPX? That wouldn't support a usage model where userspace wanted to keep using MPX, but wanted the kernel to butt out and not try to free unused bounds tables. That's not super-important, but it does lose some level of flexibility. FWIW, I think it would also be handy to support a PR_MPX_DISABLE prctl too. That way, a wrapper program could set a flag that any children could notice if they try a PR_MPX_REGISTER. That way we could software-disable MPX in cases in a process tree where it was not wanted. -- 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/