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=-7.6 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 15CBCC433E6 for ; Tue, 1 Sep 2020 17:58:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EE0592071B for ; Tue, 1 Sep 2020 17:58:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728074AbgIAR6a (ORCPT ); Tue, 1 Sep 2020 13:58:30 -0400 Received: from mga18.intel.com ([134.134.136.126]:21068 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726140AbgIAR63 (ORCPT ); Tue, 1 Sep 2020 13:58:29 -0400 IronPort-SDR: tsaXhVb5DH2Pqio5lfj0Dj4oJhOMtQMkHO/iirC3pO/QCkzQ1DxXAJobuqs34X4DY9dRa1Mcc8 IukZZxe/vxKw== X-IronPort-AV: E=McAfee;i="6000,8403,9731"; a="144922321" X-IronPort-AV: E=Sophos;i="5.76,379,1592895600"; d="scan'208";a="144922321" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Sep 2020 10:58:27 -0700 IronPort-SDR: XwMESqPFxr04kLMfyQaui9VPnLF/D1itQuPP2/9KGJduUhBwiqOg07SfbLgLhc4VMmOKQNhS4d WGuXhXSy4f2Q== X-IronPort-AV: E=Sophos;i="5.76,379,1592895600"; d="scan'208";a="477293602" Received: from yyu32-mobl1.amr.corp.intel.com (HELO [10.212.241.30]) ([10.212.241.30]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Sep 2020 10:58:25 -0700 Subject: Re: [PATCH v11 25/25] x86/cet/shstk: Add arch_prctl functions for shadow stack To: Florian Weimer Cc: "H.J. Lu" , Dave Martin , Dave Hansen , Andy Lutomirski , 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 , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Weijiang Yang References: <20200825002540.3351-1-yu-cheng.yu@intel.com> <20200825002540.3351-26-yu-cheng.yu@intel.com> <2d253891-9393-44d0-35e0-4b9a2da23cec@intel.com> <086c73d8-9b06-f074-e315-9964eb666db9@intel.com> <73c2211f-8811-2d9f-1930-1c5035e6129c@intel.com> <20200826164604.GW6642@arm.com> <87ft892vvf.fsf@oldenburg2.str.redhat.com> <20200826170841.GX6642@arm.com> <87tuwow7kg.fsf@oldenburg2.str.redhat.com> <873648w6qr.fsf@oldenburg2.str.redhat.com> <3c12b6ee-7c93-dcf4-fbf7-2698003386dd@intel.com> <87o8mpqtcn.fsf@oldenburg2.str.redhat.com> From: "Yu, Yu-cheng" Message-ID: Date: Tue, 1 Sep 2020 10:58:25 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <87o8mpqtcn.fsf@oldenburg2.str.redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On 9/1/2020 10:50 AM, Florian Weimer wrote: > * Yu-cheng Yu: > >> Like other arch_prctl()'s, this parameter was 'unsigned long' >> earlier. The idea was, since this arch_prctl is only implemented for >> the 64-bit kernel, we wanted it to look as 64-bit only. I will change >> it back to 'unsigned long'. > > What about x32? In general, long is rather problematic for x32. The problem is the size of 'long', right? Because this parameter is passed in a register, and only the lower bits are used, x32 works as well.