From patchwork Mon Feb 27 13:18:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Petr Pavlu X-Patchwork-Id: 61946 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:5915:0:0:0:0:0 with SMTP id v21csp2411478wrd; Mon, 27 Feb 2023 05:19:53 -0800 (PST) X-Google-Smtp-Source: AK7set92KTDEJ4D31xc8XfgmB+LsliseCKoMjrJOVQRwmnnf/FtdtXPPsATKTLvVXTqNf7Cp8Trt X-Received: by 2002:aa7:d64d:0:b0:4af:7390:b488 with SMTP id v13-20020aa7d64d000000b004af7390b488mr11994051edr.40.1677503992990; Mon, 27 Feb 2023 05:19:52 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1677503992; cv=none; d=google.com; s=arc-20160816; b=HrhTsem/WhQJ2lRVtcFaN6Gocx9e1JCxOij9O0z6qcs5aApiL1Do4vRoe1tBqUn7dw nm0bnpNhWRNDEVdfd1jOylLDS2d7Q8lxD9qTJe0ypfbND1K7WkXPlwBOBkt8IUK9U0VX D8ct6oB5G4tKjDA1Jw3s2nzph/q9nBMG5i/XijiHvhD6Cuil/GRDMlWDgDkw8Nbd6HV4 VaW5Iqr5a6Xlnh8Nm93wF2WE5IpUhFJusLtuMGDX7BYWUE65A+WhY0dYyuyy1rYcXvUb A5OWk9A+o6HHcqWcni17wKbYXGGSTkDI16ltYU+khRmm75Ad/kL/QyCUQZ8aRd3OFxUT 6Bmg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :message-id:date:subject:cc:to:from:dkim-signature; bh=9ECJneu3XfYwEqhsgqHRN+XdG1YJYS7sQp3PmHlNv5c=; b=A3mBYzMfGD/bbrjbf0qW1L7qBmHewMxiSaXbqEh48yrJ08F3vuPiK4SxuF9LnTZNrP DZkHNKTxyaNg2Ca2oukDusVSydHfI9ScXM92r4+FKGp/yWJLPI25vk7lqZ1SniON/f+x Yrq1bfZCBbhh/FNVUmvzmSvXtWAbL+gy97EsYudk2EGWtCwlpwB6BZpltrCg45sv+E5L lQm5kayTMMV9oxzjimpSDKs/juI02NzgskpG86nKiZALqEGn1Jxi/4EbA9w9ID9CLxXB ye74YC3yrUXezaKvYGB2SPJV5zop+Y5l7gOarawQzGi02HOPJKuBfFUZ3A820aPz4R8X LjIg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@suse.com header.s=susede1 header.b=VkXaQglE; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=suse.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id r5-20020a056402034500b004ad035e01fdsi8964116edw.418.2023.02.27.05.19.30; Mon, 27 Feb 2023 05:19:52 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@suse.com header.s=susede1 header.b=VkXaQglE; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=suse.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229980AbjB0NS4 (ORCPT + 99 others); Mon, 27 Feb 2023 08:18:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229994AbjB0NSy (ORCPT ); Mon, 27 Feb 2023 08:18:54 -0500 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 361BE15CA7 for ; Mon, 27 Feb 2023 05:18:52 -0800 (PST) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id C26B0219AB; Mon, 27 Feb 2023 13:18:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1677503930; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=9ECJneu3XfYwEqhsgqHRN+XdG1YJYS7sQp3PmHlNv5c=; b=VkXaQglEEVpbFP8gGcH4XeF/nQWn/yOTsjM9qEdDKW86eHlkdzznZHJq0DWXIJo/gafPDG DREWI7EaPmro5ahK9CVCPNMtxmAlPQtUkK0He2R8vIb6VygwIUb39CbWtUp6wtXZeFOe8M jLHSw5g2gzWVgOGIl5K+h5wV/u8xFpk= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 8202C13A43; Mon, 27 Feb 2023 13:18:50 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 2bavHrqt/GM8YAAAMHmgww (envelope-from ); Mon, 27 Feb 2023 13:18:50 +0000 From: Petr Pavlu To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com Cc: nathan@kernel.org, ndesaulniers@google.com, trix@redhat.com, corbet@lwn.net, linux-kernel@vger.kernel.org, Petr Pavlu Subject: [PATCH v4] x86: Avoid relocation information in final vmlinux Date: Mon, 27 Feb 2023 14:18:29 +0100 Message-Id: <20230227131829.26824-1-petr.pavlu@suse.com> X-Mailer: git-send-email 2.35.3 MIME-Version: 1.0 X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1758990427138509158?= X-GMAIL-MSGID: =?utf-8?q?1758990427138509158?= The Linux build process on x86 roughly consists of compiling all input files, statically linking them into a vmlinux ELF file, and then taking and turning this file into an actual bzImage bootable file. vmlinux has in this process two main purposes: 1) It is an intermediate build target on the way to produce the final bootable image. 2) It is a file that is expected to be used by debuggers and standard ELF tooling to work with the built kernel. For the second purpose, a vmlinux file is typically collected by various package build recipes, such as distribution spec files, including the kernel's own binrpm-pkg target. When building a kernel supporting KASLR with CONFIG_X86_NEED_RELOCS, vmlinux contains also relocation information produced by using the --emit-relocs linker option. This is utilized by subsequent build steps to create vmlinux.relocs and produce a relocatable image. However, the information is not needed by debuggers and other standard ELF tooling. The issue is then that the collected vmlinux file and hence distribution packages end up unnecessarily large because of this extra data. The following is a size comparison of vmlinux v6.0 with and without the relocation information: | Configuration | With relocs | Stripped relocs | | x86_64_defconfig | 70 MB | 43 MB | | +CONFIG_DEBUG_INFO | 818 MB | 367 MB | Optimize a resulting vmlinux by adding a postlink step that splits the relocation information into vmlinux.relocs and then strips it from the vmlinux binary. Signed-off-by: Petr Pavlu --- Changes since v3 [1]: - Update the Kbuild.include path in arch/x86/Makefile.postlink to work after 67d7c3023a67 ("kbuild: remove --include-dir MAKEFLAG from top Makefile"). Changes since v2 [2]: - Ignore only the moved vmlinux.relocs, add it to .gitignore and Documentation/dontdiff. - Clean up the patch description. Changes since v1 [3]: - Fix the command to remove relocations to work with llvm-objcopy too. [1] https://lore.kernel.org/lkml/20221211141227.7622-1-petr.pavlu@suse.com/ [2] https://lore.kernel.org/lkml/20220927084632.14531-1-petr.pavlu@suse.com/ [3] https://lore.kernel.org/lkml/20220913132911.6850-1-petr.pavlu@suse.com/ .gitignore | 1 + Documentation/dontdiff | 1 + arch/x86/Makefile.postlink | 41 +++++++++++++++++++++++++++++ arch/x86/boot/compressed/.gitignore | 1 - arch/x86/boot/compressed/Makefile | 10 +++---- 5 files changed, 47 insertions(+), 7 deletions(-) create mode 100644 arch/x86/Makefile.postlink diff --git a/.gitignore b/.gitignore index 8fe465f251c0..ab47fd6a04ef 100644 --- a/.gitignore +++ b/.gitignore @@ -65,6 +65,7 @@ modules.order /vmlinux /vmlinux.32 /vmlinux.map +/vmlinux.relocs /vmlinux.symvers /vmlinux-gdb.py /vmlinuz diff --git a/Documentation/dontdiff b/Documentation/dontdiff index 3c399f132e2d..a62ad01e6d11 100644 --- a/Documentation/dontdiff +++ b/Documentation/dontdiff @@ -254,6 +254,7 @@ vmlinux.aout vmlinux.bin.all vmlinux.lds vmlinux.map +vmlinux.relocs vmlinux.symvers vmlinuz voffset.h diff --git a/arch/x86/Makefile.postlink b/arch/x86/Makefile.postlink new file mode 100644 index 000000000000..195af937aa4d --- /dev/null +++ b/arch/x86/Makefile.postlink @@ -0,0 +1,41 @@ +# SPDX-License-Identifier: GPL-2.0 +# =========================================================================== +# Post-link x86 pass +# =========================================================================== +# +# 1. Separate relocations from vmlinux into vmlinux.relocs. +# 2. Strip relocations from vmlinux. + +PHONY := __archpost +__archpost: + +-include include/config/auto.conf +include $(srctree)/scripts/Kbuild.include + +CMD_RELOCS = arch/x86/tools/relocs +quiet_cmd_relocs = RELOCS $@.relocs + cmd_relocs = $(CMD_RELOCS) $@ > $@.relocs;$(CMD_RELOCS) --abs-relocs $@ + +quiet_cmd_strip_relocs = RSTRIP $@ + cmd_strip_relocs = $(OBJCOPY) --remove-section='.rel.*' --remove-section='.rel__*' --remove-section='.rela.*' --remove-section='.rela__*' $@ + +# `@true` prevents complaint when there is nothing to be done + +vmlinux: FORCE + @true +ifeq ($(CONFIG_X86_NEED_RELOCS),y) + $(call cmd,relocs) + $(call cmd,strip_relocs) +endif + +%.ko: FORCE + @true + +clean: + @rm -f vmlinux.relocs + +PHONY += FORCE clean + +FORCE: + +.PHONY: $(PHONY) diff --git a/arch/x86/boot/compressed/.gitignore b/arch/x86/boot/compressed/.gitignore index 25805199a506..b2968175fc27 100644 --- a/arch/x86/boot/compressed/.gitignore +++ b/arch/x86/boot/compressed/.gitignore @@ -1,7 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only relocs vmlinux.bin.all -vmlinux.relocs vmlinux.lds mkpiggy piggy.S diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 6b6cfe607bdb..19d1fb601796 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -121,14 +121,12 @@ $(obj)/vmlinux.bin: vmlinux FORCE targets += $(patsubst $(obj)/%,%,$(vmlinux-objs-y)) vmlinux.bin.all vmlinux.relocs -CMD_RELOCS = arch/x86/tools/relocs -quiet_cmd_relocs = RELOCS $@ - cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $< -$(obj)/vmlinux.relocs: vmlinux FORCE - $(call if_changed,relocs) +# vmlinux.relocs is created by the vmlinux postlink step. +vmlinux.relocs: vmlinux + @true vmlinux.bin.all-y := $(obj)/vmlinux.bin -vmlinux.bin.all-$(CONFIG_X86_NEED_RELOCS) += $(obj)/vmlinux.relocs +vmlinux.bin.all-$(CONFIG_X86_NEED_RELOCS) += vmlinux.relocs $(obj)/vmlinux.bin.gz: $(vmlinux.bin.all-y) FORCE $(call if_changed,gzip)