From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1CCDC433DF for ; Tue, 25 Aug 2020 18:43:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DE5A82071E for ; Tue, 25 Aug 2020 18:43:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726119AbgHYSny (ORCPT ); Tue, 25 Aug 2020 14:43:54 -0400 Received: from mga14.intel.com ([192.55.52.115]:12410 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726090AbgHYSnx (ORCPT ); Tue, 25 Aug 2020 14:43:53 -0400 IronPort-SDR: m4yz0HROXZ6HZHWPpqSWLqH4xlzxUW5911DRcp6s3J96xOmtJXoOKIw3etxahgiQvP3qMf/sTu 3Db6of0SNJig== X-IronPort-AV: E=McAfee;i="6000,8403,9723"; a="155439471" X-IronPort-AV: E=Sophos;i="5.76,353,1592895600"; d="scan'208";a="155439471" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Aug 2020 11:43:53 -0700 IronPort-SDR: qetOCdbrXhUWR50LkuRroCI0FBVBMcDQk5TuarjRNg+/M+0SIrJkeab98uN4ag6jhMxZrjXlKR d/7/Qx64Pq9g== X-IronPort-AV: E=Sophos;i="5.76,353,1592895600"; d="scan'208";a="322866093" Received: from yyu32-mobl1.amr.corp.intel.com (HELO [10.213.162.112]) ([10.213.162.112]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Aug 2020 11:43:52 -0700 Subject: Re: [PATCH v11 25/25] x86/cet/shstk: Add arch_prctl functions for shadow stack To: Andy Lutomirski Cc: X86 ML , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , LKML , "open list:DOCUMENTATION" , Linux-MM , linux-arch , Linux API , Arnd Bergmann , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang References: <20200825002540.3351-1-yu-cheng.yu@intel.com> <20200825002540.3351-26-yu-cheng.yu@intel.com> From: "Yu, Yu-cheng" Message-ID: <2d253891-9393-44d0-35e0-4b9a2da23cec@intel.com> Date: Tue, 25 Aug 2020 11:43:51 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-api-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On 8/24/2020 5:36 PM, Andy Lutomirski wrote: > On Mon, Aug 24, 2020 at 5:30 PM Yu-cheng Yu wrote: > >> arch_prctl(ARCH_X86_CET_MMAP_SHSTK, u64 *args) >> Allocate a new shadow stack. >> >> The parameter 'args' is a pointer to a user buffer. >> >> *args = desired size >> *(args + 1) = MAP_32BIT or MAP_POPULATE >> >> On returning, *args is the allocated shadow stack address. > > This is hideous. Would this be better as a new syscall? Could you point out why this is hideous, so that I can modify the arch_prctl? I think this is more arch-specific. Even if it becomes a new syscall, we still need to pass the same parameters. Yu-cheng