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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 97DCDC3A59E for ; Tue, 20 Aug 2019 10:02:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 67427206BB for ; Tue, 20 Aug 2019 10:02:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 67427206BB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EE0216B0010; Tue, 20 Aug 2019 06:02:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E90F26B0269; Tue, 20 Aug 2019 06:02:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DA7A76B026A; Tue, 20 Aug 2019 06:02:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0180.hostedemail.com [216.40.44.180]) by kanga.kvack.org (Postfix) with ESMTP id B9C766B0010 for ; Tue, 20 Aug 2019 06:02:18 -0400 (EDT) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 545841CBE for ; Tue, 20 Aug 2019 10:02:18 +0000 (UTC) X-FDA: 75842365956.07.arm58_3119ad640cd32 X-HE-Tag: arm58_3119ad640cd32 X-Filterd-Recvd-Size: 3515 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf36.hostedemail.com (Postfix) with ESMTP for ; Tue, 20 Aug 2019 10:02:17 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E6723344; Tue, 20 Aug 2019 03:02:15 -0700 (PDT) Received: from arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5C5113F706; Tue, 20 Aug 2019 03:02:12 -0700 (PDT) Date: Tue, 20 Aug 2019 11:02:10 +0100 From: Dave Martin To: Yu-cheng Yu Cc: 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 , Andy Lutomirski , 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 Subject: Re: [PATCH v8 22/27] binfmt_elf: Extract .note.gnu.property from an ELF file Message-ID: <20190820100208.GO10425@arm.com> References: <20190813205225.12032-1-yu-cheng.yu@intel.com> <20190813205225.12032-23-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190813205225.12032-23-yu-cheng.yu@intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) 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 Tue, Aug 13, 2019 at 01:52:20PM -0700, Yu-cheng Yu wrote: > An ELF file's .note.gnu.property indicates features the executable file > can support. For example, the property GNU_PROPERTY_X86_FEATURE_1_AND > indicates the file supports GNU_PROPERTY_X86_FEATURE_1_IBT and/or > GNU_PROPERTY_X86_FEATURE_1_SHSTK. > > With this patch, if an arch needs to setup features from ELF properties, > it needs CONFIG_ARCH_USE_GNU_PROPERTY to be set, and specific > arch_parse_property() and arch_setup_property(). > > For example, for X86_64: > > int arch_setup_property(void *ehdr, void *phdr, struct file *f, bool inter) > { > int r; > uint32_t property; > > r = get_gnu_property(ehdr, phdr, f, GNU_PROPERTY_X86_FEATURE_1_AND, > &property); > ... > } > > This patch is derived from code provided by H.J. Lu . > > Signed-off-by: Yu-cheng Yu [...] For the hell of it, I tried implementing an alternate version [1] that tries to integrate into the existing ELF loader more directly. This may or may not be a better approach, but tries to solve some issues such as not repeatedly reading and parsing the properties. Cheers ---Dave [1] [RFC PATCH 0/2] ELF: Alternate program property parser https://lore.kernel.org/lkml/1566295063-7387-1-git-send-email-Dave.Martin@arm.com/