From patchwork Wed Nov 18 22:07:14 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11915971 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=-16.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_ADSP_CUSTOM_MED,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 39CE2C5519F for ; Wed, 18 Nov 2020 22:09:44 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B9FD8246CB for ; Wed, 18 Nov 2020 22:09:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="QsrVrty9"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=google.com header.i=@google.com header.b="FEACl+hP" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B9FD8246CB Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:To:From:Subject:Mime-Version:Message-Id:Date: Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender :Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=1/pASGUF2BWy1YECbhKRdGh3AkRHolMqvjuwbjwxFTo=; b=QsrVrty9xJt8bJV8NEwpUdAeoK 8Jz07DdkIk62L1LdxebZKJ7YdPZUkPB86nWmwSG9FyuniNIPEAtxrTPafC6M+OLKDhdPm/zDJ/A0o j8+WGbv0iTD+HLZrJbscg2mVm6No+cQ1lJZDsogPfVA8Pkl71BycHSMIYKFp52pElygmfyfipDib6 FtWiwlFtfVhpJw2oie7efkqMWDVq8hJYhecY5widl0lVNmAVOVKH2LyPoFJbsQ/AFrB+900tJzWg/ kTFdOwBR8xnAEpt60EsL4kJC1pSt9/M5CfCmlM69U7FckhPyxY1ls1lzeX1rof5r/lpm4875aoJPB YNfWPtkQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kfVc2-0007SR-Tu; Wed, 18 Nov 2020 22:07:38 +0000 Received: from mail-yb1-xb4a.google.com ([2607:f8b0:4864:20::b4a]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kfVc0-0007RU-4M for linux-arm-kernel@lists.infradead.org; Wed, 18 Nov 2020 22:07:37 +0000 Received: by mail-yb1-xb4a.google.com with SMTP id w8so4619461ybq.4 for ; Wed, 18 Nov 2020 14:07:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:message-id:mime-version:subject:from:to:cc; bh=RLGcqGrpsLlRbzosDVd0xMcJRplKck51D58hnCA0m40=; b=FEACl+hPLvLCehd5Y1IKJBTJMbR0QNknmx7JyEdblpLzyJtFGWeraZl9sfry0j3+TK kM1Ew0qwvXu8KiNhkl6/Lts6lfNP0QOtRmYpgESW0VKFUjrDc5GbVOF5mwwP/eHkKFsy FofVx9oGp4zsyD83lrr4uaPQAiM/oxp3HRLr27hBWDGyYPHGds3tdIhKnE0AUSYvkx+1 TwEFXYs+aBQvHKOt2LEYwCaN+5eXT83BFAe3QJVAC6b+iFUY+dDobgfDt2BlWuLx2V4z 3XbU9NTi2LeOeIv8rGJ6XXsrxQN/svzHG1smnTQhehYdm8prrKq5jKeMSosG+9Wvmj5x VHGw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:message-id:mime-version:subject:from :to:cc; bh=RLGcqGrpsLlRbzosDVd0xMcJRplKck51D58hnCA0m40=; b=cVR42WActUY0PIrBR0kim4dn3p/vez9HSIb39UcRsH6DrkgQzGwZdpCFKtZkYdSEa4 RvnUbPOl2aa/HB7usbjv2IePoppr1Onlt7iJAIebh+jwNC0rKic3t/L4t6rbl2+C7KJU 0Ur/30gugaSkWRDEGGonq+rnxUCtZgTdW/yo9Jr8LJWlyHY15+4uZ1Lg1/iJ8meRHupY 9ezgrY//Frgus5o7/YZFn9N5fIZ4EeIIkBcpLnghbZIQcEF+8Pvp3Txx8Q65FccyQXHL jvKhimnZ1LTrPwyKbvpgFxLvw8Yg1CVMk2Or84IwNr4K2DzOvJLC1k53uIgAAp+LJKHp OhBg== X-Gm-Message-State: AOAM531us7G8Z1A4esX37G6ZVWEjf/CiJQiW0mxvY9Y9L3B3Ik7GHTgT UMK2yGA8A1kkPdK8T1KXW6mBYFf31d5QJ2TIkx8= X-Google-Smtp-Source: ABdhPJweJ21RzDAwp/tDBtJMRIUdyZdQmeb2yPsOyAN1xKpWf0eVIsvADvmRn84CHCirimlOu0esu246TN+ciGuGs0Q= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:f693:9fff:fef4:1b6d]) (user=samitolvanen job=sendgmr) by 2002:a25:cb11:: with SMTP id b17mr8848931ybg.236.1605737253032; Wed, 18 Nov 2020 14:07:33 -0800 (PST) Date: Wed, 18 Nov 2020 14:07:14 -0800 Message-Id: <20201118220731.925424-1-samitolvanen@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.29.2.454.gaff20da3a2-goog Subject: [PATCH v7 00/17] Add support for Clang LTO From: Sami Tolvanen To: Masahiro Yamada , Steven Rostedt , Will Deacon X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201118_170736_212269_D4395B2A X-CRM114-Status: GOOD ( 26.99 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Kees Cook , "Paul E. McKenney" , kernel-hardening@lists.openwall.com, Peter Zijlstra , Greg Kroah-Hartman , linux-kbuild@vger.kernel.org, Nick Desaulniers , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, clang-built-linux@googlegroups.com, Sami Tolvanen , Josh Poimboeuf , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This patch series adds support for building the kernel with Clang's Link Time Optimization (LTO). In addition to performance, the primary motivation for LTO is to allow Clang's Control-Flow Integrity (CFI) to be used in the kernel. Google has shipped millions of Pixel devices running three major kernel versions with LTO+CFI since 2018. Most of the patches are build system changes for handling LLVM bitcode, which Clang produces with LTO instead of ELF object files, postponing ELF processing until a later stage, and ensuring initcall ordering. Note that v7 brings back arm64 support as Will has now staged the prerequisite memory ordering patches [1], and drops x86_64 while we work on fixing the remaining objtool warnings [2]. [1] https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/log/?h=for-next/lto [2] https://lore.kernel.org/lkml/20201114004911.aip52eimk6c2uxd4@treble/ You can also pull this series from https://github.com/samitolvanen/linux.git lto-v7 Tested-by: Nick Desaulniers Tested-by: Nathan Chancellor --- Changes in v7: - Rebased to master again. - Added back arm64 patches as the prerequisites are now staged, and dropped x86_64 support until the remaining objtool issues are resolved. - Dropped ifdefs from module.lds.S. Changes in v6: - Added the missing --mcount flag to patch 5. - Dropped the arm64 patches from this series and will repost them later. Changes in v5: - Rebased on top of tip/master. - Changed the command line for objtool to use --vmlinux --duplicate to disable warnings about retpoline thunks and to fix .orc_unwind generation for vmlinux.o. - Added --noinstr flag to objtool, so we can use --vmlinux without also enabling noinstr validation. - Disabled objtool's unreachable instruction warnings with LTO to disable false positives for the int3 padding in vmlinux.o. - Added ANNOTATE_RETPOLINE_SAFE annotations to the indirect jumps in x86 assembly code to fix objtool warnings with retpoline. - Fixed modpost warnings about missing version information with CONFIG_MODVERSIONS. - Included Makefile.lib into Makefile.modpost for ld_flags. Thanks to Sedat for pointing this out. - Updated the help text for ThinLTO to better explain the trade-offs. - Updated commit messages with better explanations. Changes in v4: - Fixed a typo in Makefile.lib to correctly pass --no-fp to objtool. - Moved ftrace configs related to generating __mcount_loc to Kconfig, so they are available also in Makefile.modfinal. - Dropped two prerequisite patches that were merged to Linus' tree. Changes in v3: - Added a separate patch to remove the unused DISABLE_LTO treewide, as filtering out CC_FLAGS_LTO instead is preferred. - Updated the Kconfig help to explain why LTO is behind a choice and disabled by default. - Dropped CC_FLAGS_LTO_CLANG, compiler-specific LTO flags are now appended directly to CC_FLAGS_LTO. - Updated $(AR) flags as KBUILD_ARFLAGS was removed earlier. - Fixed ThinLTO cache handling for external module builds. - Rebased on top of Masahiro's patch for preprocessing modules.lds, and moved the contents of module-lto.lds to modules.lds.S. - Moved objtool_args to Makefile.lib to avoid duplication of the command line parameters in Makefile.modfinal. - Clarified in the commit message for the initcall ordering patch that the initcall order remains the same as without LTO. - Changed link-vmlinux.sh to use jobserver-exec to control the number of jobs started by generate_initcall_ordering.pl. - Dropped the x86/relocs patch to whitelist L4_PAGE_OFFSET as it's no longer needed with ToT kernel. - Disabled LTO for arch/x86/power/cpu.c to work around a Clang bug with stack protector attributes. Changes in v2: - Fixed -Wmissing-prototypes warnings with W=1. - Dropped cc-option from -fsplit-lto-unit and added .thinlto-cache scrubbing to make distclean. - Added a comment about Clang >=11 being required. - Added a patch to disable LTO for the arm64 KVM nVHE code. - Disabled objtool's noinstr validation with LTO unless enabled. - Included Peter's proposed objtool mcount patch in the series and replaced recordmcount with the objtool pass to avoid whitelisting relocations that are not calls. - Updated several commit messages with better explanations. Sami Tolvanen (17): tracing: move function tracer options to Kconfig kbuild: add support for Clang LTO kbuild: lto: fix module versioning kbuild: lto: limit inlining kbuild: lto: merge module sections kbuild: lto: remove duplicate dependencies from .mod files init: lto: ensure initcall ordering init: lto: fix PREL32 relocations PCI: Fix PREL32 relocations for LTO modpost: lto: strip .lto from module names scripts/mod: disable LTO for empty.c efi/libstub: disable LTO drivers/misc/lkdtm: disable LTO for rodata.o arm64: vdso: disable LTO KVM: arm64: disable LTO for the nVHE directory arm64: disable recordmcount with DYNAMIC_FTRACE_WITH_REGS arm64: allow LTO_CLANG and THINLTO to be selected .gitignore | 1 + Makefile | 45 +++-- arch/Kconfig | 74 +++++++ arch/arm64/Kconfig | 4 + arch/arm64/kernel/vdso/Makefile | 3 +- arch/arm64/kvm/hyp/nvhe/Makefile | 4 +- drivers/firmware/efi/libstub/Makefile | 2 + drivers/misc/lkdtm/Makefile | 1 + include/asm-generic/vmlinux.lds.h | 11 +- include/linux/init.h | 79 +++++++- include/linux/pci.h | 19 +- kernel/trace/Kconfig | 16 ++ scripts/Makefile.build | 50 ++++- scripts/Makefile.lib | 6 +- scripts/Makefile.modfinal | 9 +- scripts/Makefile.modpost | 25 ++- scripts/generate_initcall_order.pl | 270 ++++++++++++++++++++++++++ scripts/link-vmlinux.sh | 70 ++++++- scripts/mod/Makefile | 1 + scripts/mod/modpost.c | 16 +- scripts/mod/modpost.h | 9 + scripts/mod/sumversion.c | 6 +- scripts/module.lds.S | 24 +++ 23 files changed, 677 insertions(+), 68 deletions(-) create mode 100755 scripts/generate_initcall_order.pl base-commit: 0fa8ee0d9ab95c9350b8b84574824d9a384a9f7d