From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Martin Subject: Re: [PATCH v8 22/27] binfmt_elf: Extract .note.gnu.property from an ELF file Date: Tue, 20 Aug 2019 11:02:10 +0100 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 Return-path: Content-Disposition: inline In-Reply-To: <20190813205225.12032-23-yu-cheng.yu@intel.com> Sender: linux-kernel-owner@vger.kernel.org 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 List-Id: linux-arch.vger.kernel.org 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/ From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.110.172]:37940 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729452AbfHTKCQ (ORCPT ); Tue, 20 Aug 2019 06:02:16 -0400 Date: Tue, 20 Aug 2019 11:02:10 +0100 From: Dave Martin 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> Sender: linux-arch-owner@vger.kernel.org List-ID: 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 Message-ID: <20190820100210.Ptjwx9fkCTRaSg_AIEy1JqNRO2AOxQquJgs8t-lE_CU@z> 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/