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=-13.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 2CD85C4338F for ; Mon, 9 Aug 2021 23:04:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1469861004 for ; Mon, 9 Aug 2021 23:04:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236953AbhHIXEs (ORCPT ); Mon, 9 Aug 2021 19:04:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:41140 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236956AbhHIXEo (ORCPT ); Mon, 9 Aug 2021 19:04:44 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D5E0460EE7; Mon, 9 Aug 2021 23:04:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1628550263; bh=OIh9zq+IYhIhIiKupvVvEHfwMY95evZX39qJfIxbmIQ=; h=Subject:To:References:From:Date:In-Reply-To:From; b=X8QGkNyjeiBeJxlag/3SN2Xpw8+OC6Gj+cGkK/KDvR2kMaz8dO92SR2ah14t3AUn7 QEvsvIrJr17Mc59De5xJNqhaOuVxNocXjM3Yo3B2cZMswh85C10nzKhXAXBwA05ja3 8SOA/ErgtlUiuGMylliyQqHxqeeUEjhIRfxEZ3ZMuhVJOtFORoydv5utNDDo6Q23+U afQKwHGApnvhQwEyf/iMawyeTk4ZokAahsi8gDVxwfvP6jYw82QHgZdSyXvabZhqSp 0BqWOwqMQcxjWSmwX1GaHhbeF4UGmmjF9tTGPHkzUsmeik75aOTd8fKRzJlbzOgiag tzAt5zk5K1n8A== Subject: Re: [PATCH v28 04/10] x86/cet/ibt: Disable IBT for ia32 To: Yu-cheng Yu , x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, 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" , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang , Rick P Edgecombe References: <20210722205723.9476-1-yu-cheng.yu@intel.com> <20210722205723.9476-5-yu-cheng.yu@intel.com> From: Andy Lutomirski Message-ID: <3318ca57-7ac3-8296-f9ae-0ae83d5f95dd@kernel.org> Date: Mon, 9 Aug 2021 16:04:18 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210722205723.9476-5-yu-cheng.yu@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On 7/22/21 1:57 PM, Yu-cheng Yu wrote: > In a signal, a task's IBT status needs to be saved to the signal frame, and > later restored in sigreturn. For the purpose, previous versions of the > series add a new struct to the signal frame. However, a new signal frame > format (or re-using a reserved space) introduces complex compatibility > issues. > > In the discussion (see link below), Andy Lutomirski proposed using a > ucontext flag. The approach is clean and eliminates most compatibility > issues. > > However, a legacy IA32 signal frame does not have ucontext and cannot > support a uc flag. Thus, > > - Disable IBT for ia32. > - In ia32 sigreturn, verify ibt is disabled. Acked-by: Andy Lutomirski