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=ham 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 106ABC4338F for ; Mon, 9 Aug 2021 23:04:26 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8D36660F35 for ; Mon, 9 Aug 2021 23:04:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 8D36660F35 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id EB68D8D0001; Mon, 9 Aug 2021 19:04:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E66D66B0072; Mon, 9 Aug 2021 19:04:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D7C948D0001; Mon, 9 Aug 2021 19:04:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0077.hostedemail.com [216.40.44.77]) by kanga.kvack.org (Postfix) with ESMTP id BB4FF6B0071 for ; Mon, 9 Aug 2021 19:04:24 -0400 (EDT) Received: from smtpin40.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 655871802186D for ; Mon, 9 Aug 2021 23:04:24 +0000 (UTC) X-FDA: 78457072848.40.DEB405F Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf20.hostedemail.com (Postfix) with ESMTP id 0D9AAD00064F for ; Mon, 9 Aug 2021 23:04:23 +0000 (UTC) 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 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 0D9AAD00064F Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=X8QGkNyj; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf20.hostedemail.com: domain of luto@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=luto@kernel.org X-Stat-Signature: 6wf97ew1wrjyt6x7punfwxjruxeh8ykk X-HE-Tag: 1628550263-985591 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 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