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 B559EC433DF for ; Tue, 25 Aug 2020 18:44:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 716C52071E for ; Tue, 25 Aug 2020 18:44:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 716C52071E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C7D5E6B0026; Tue, 25 Aug 2020 14:44:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C06306B0029; Tue, 25 Aug 2020 14:44:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ACDCA6B002A; Tue, 25 Aug 2020 14:44:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0122.hostedemail.com [216.40.44.122]) by kanga.kvack.org (Postfix) with ESMTP id 92F9C6B0026 for ; Tue, 25 Aug 2020 14:44:16 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 01329180AD838 for ; Tue, 25 Aug 2020 18:44:16 +0000 (UTC) X-FDA: 77189966112.18.slope69_5a049262705e Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin18.hostedemail.com (Postfix) with ESMTP id 6DCE6100EDBF1 for ; Tue, 25 Aug 2020 18:44:08 +0000 (UTC) X-HE-Tag: slope69_5a049262705e X-Filterd-Recvd-Size: 3682 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by imf30.hostedemail.com (Postfix) with ESMTP for ; Tue, 25 Aug 2020 18:43:55 +0000 (UTC) IronPort-SDR: 1S2TAGxViP6ntWnDW2jHLnMxDSQKtEBsf1HCEBGccVABC2R78FI/bm0xu04DPC6JZkqbgptZbe cRLnIkbgVq2Q== X-IronPort-AV: E=McAfee;i="6000,8403,9723"; a="153756985" X-IronPort-AV: E=Sophos;i="5.76,353,1592895600"; d="scan'208";a="153756985" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga102.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 X-Rspamd-Queue-Id: 6DCE6100EDBF1 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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