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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 42080C352BA for ; Tue, 13 Oct 2020 02:42:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0EE4D221EB for ; Tue, 13 Oct 2020 02:42:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="UojFnS6w" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727695AbgJMAdc (ORCPT ); Mon, 12 Oct 2020 20:33:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47646 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727107AbgJMAcG (ORCPT ); Mon, 12 Oct 2020 20:32:06 -0400 Received: from mail-qv1-xf49.google.com (mail-qv1-xf49.google.com [IPv6:2607:f8b0:4864:20::f49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 299C7C0613D1 for ; Mon, 12 Oct 2020 17:32:06 -0700 (PDT) Received: by mail-qv1-xf49.google.com with SMTP id ec4so11699932qvb.21 for ; Mon, 12 Oct 2020 17:32:06 -0700 (PDT) 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=OJOo2mPtwLVt3Btef9tCd4OBHWCay8DKkoOT1RdZm54=; b=UojFnS6wp9+JkvfRaZdkt/NHiq0Zo5bAk02S+Aq1YdUoQ5nxE3VNdJSkV/kMJ2nw2T 0v1jg0c9rc8Jll2FYmptKRB0cfatcnVKfJDbXsCbITB8hx8EKXIyP9f8QdZXHE80tYoI DUx95eFr58Tlzz6u2QG7P1+GldeGJb5/GaqS8BysO3vyqzJeLHSqFBDPKYO1FIHhaHxb JdxhrPGWineDlAATmjOIdda6W0jJClm7N/Cx516up2FK41rMqqZtXXSkkdoG74dB8ML7 LGMGbxkjwfNozzN1XOkol6/VYuOz3xQRX5iPmzS0Wy9b/Z5N/PVfpYpa1MLWhbgzu4gN Yz1g== 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=OJOo2mPtwLVt3Btef9tCd4OBHWCay8DKkoOT1RdZm54=; b=jA3/YjPAYQBaNeXw60wjtAwQWyNixGvMCC8PjE/+tTLDl0V2WrvJRYEnZinrsR4BLS ZQKBn6HBlPn9anQ8YwwX2AegmUJwmVv0bSsBwkAb2a8i0J33LhDXUsK9Zh9EkdlSDNuT HNCAxbMm6tkx671UL0aa/Im2gmuk/7alBmzkCK2hOwjeosb+FPQe4+IYNtQRN7g7Uz8Z uTgWNd2gwJFuRBVFCG29j4IKF9+SMGpufqM5dMWy0WCR1mjq0oHu8k649ElnmzasMSRJ nAba5Mw+/A+Rr4SFcPxg1M5BcRPdO6QqmTcN1pi7JSryvg1K1wclr7sIailZ4W6bOpg9 gs9Q== X-Gm-Message-State: AOAM531HMawZzYxZKQmQjj/tpUEI2GA6x1kDGhfUpyOEc7GW+H0G8rX7 QSKkhRuGovcJus/g2pdjR/GpmvVjOjh/EYKZEto= X-Google-Smtp-Source: ABdhPJxH4NF2ufwWCu0rT4xNxHqUl6H1eRA5phXQVHXpMwo0zp1WH5b4jhlrx0nHNlt0XKW8iPthPAU05BvJlu74qas= Sender: "samitolvanen via sendgmr" X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:f693:9fff:fef4:1b6d]) (user=samitolvanen job=sendgmr) by 2002:a0c:d848:: with SMTP id i8mr28244513qvj.31.1602549125192; Mon, 12 Oct 2020 17:32:05 -0700 (PDT) Date: Mon, 12 Oct 2020 17:31:38 -0700 Message-Id: <20201013003203.4168817-1-samitolvanen@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.28.0.1011.ga647a8990f-goog Subject: [PATCH v6 00/25] Add support for Clang LTO From: Sami Tolvanen To: Masahiro Yamada , Steven Rostedt Cc: Will Deacon , Peter Zijlstra , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, x86@kernel.org, Sami Tolvanen Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org This patch series adds support for building the x86_64 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 this version is based on tip/master to reduce the number of prerequisite patches, and to make it easier to manage changes to objtool. Patch 1 is from Masahiro's kbuild tree, and while it's not directly related to LTO, it makes the module linker script changes cleaner. Furthermore, patches 2-6 include Peter's patch for generating __mcount_loc with objtool, and build system changes to enable it on x86. With these patches, we no longer need to annotate functions that have non-call references to __fentry__ with LTO, which greatly simplifies supporting dynamic ftrace. You can also pull this series from https://github.com/samitolvanen/linux.git lto-v6 --- 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. Masahiro Yamada (1): kbuild: preprocess module linker script Peter Zijlstra (1): objtool: Add a pass for generating __mcount_loc Sami Tolvanen (23): objtool: Don't autodetect vmlinux.o tracing: move function tracer options to Kconfig tracing: add support for objtool mcount x86, build: use objtool mcount treewide: remove DISABLE_LTO kbuild: add support for Clang LTO kbuild: lto: fix module versioning objtool: Split noinstr validation from --vmlinux kbuild: lto: postpone objtool 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 x86/asm: annotate indirect jumps x86, vdso: disable LTO only for vDSO x86, cpu: disable LTO for cpu.c x86, build: allow LTO_CLANG and THINLTO to be selected .gitignore | 1 + Makefile | 68 +++-- arch/Kconfig | 74 +++++ arch/arm/Makefile | 4 - .../module.lds => include/asm/module.lds.h} | 2 + arch/arm64/Makefile | 4 - .../module.lds => include/asm/module.lds.h} | 2 + arch/arm64/kernel/vdso/Makefile | 1 - arch/ia64/Makefile | 1 - .../{module.lds => include/asm/module.lds.h} | 0 arch/m68k/Makefile | 1 - .../module.lds => include/asm/module.lds.h} | 0 arch/powerpc/Makefile | 1 - .../module.lds => include/asm/module.lds.h} | 0 arch/riscv/Makefile | 3 - .../module.lds => include/asm/module.lds.h} | 3 +- arch/sparc/vdso/Makefile | 2 - arch/um/include/asm/Kbuild | 1 + arch/x86/Kconfig | 3 + arch/x86/Makefile | 5 + arch/x86/entry/vdso/Makefile | 5 +- arch/x86/kernel/acpi/wakeup_64.S | 2 + arch/x86/platform/pvh/head.S | 2 + arch/x86/power/Makefile | 4 + arch/x86/power/hibernate_asm_64.S | 3 + drivers/firmware/efi/libstub/Makefile | 2 + drivers/misc/lkdtm/Makefile | 1 + include/asm-generic/Kbuild | 1 + include/asm-generic/module.lds.h | 10 + include/asm-generic/vmlinux.lds.h | 11 +- include/linux/init.h | 79 ++++- include/linux/pci.h | 19 +- kernel/Makefile | 3 - kernel/trace/Kconfig | 29 ++ scripts/.gitignore | 1 + scripts/Makefile | 3 + scripts/Makefile.build | 69 +++-- scripts/Makefile.lib | 17 +- scripts/Makefile.modfinal | 29 +- scripts/Makefile.modpost | 25 +- scripts/generate_initcall_order.pl | 270 ++++++++++++++++++ scripts/link-vmlinux.sh | 98 ++++++- scripts/mod/Makefile | 1 + scripts/mod/modpost.c | 16 +- scripts/mod/modpost.h | 9 + scripts/mod/sumversion.c | 6 +- scripts/{module-common.lds => module.lds.S} | 31 ++ scripts/package/builddeb | 2 +- tools/objtool/builtin-check.c | 10 +- tools/objtool/builtin.h | 2 +- tools/objtool/check.c | 84 +++++- tools/objtool/check.h | 1 + tools/objtool/objtool.c | 1 + tools/objtool/objtool.h | 1 + 54 files changed, 895 insertions(+), 128 deletions(-) rename arch/arm/{kernel/module.lds => include/asm/module.lds.h} (72%) rename arch/arm64/{kernel/module.lds => include/asm/module.lds.h} (76%) rename arch/ia64/{module.lds => include/asm/module.lds.h} (100%) rename arch/m68k/{kernel/module.lds => include/asm/module.lds.h} (100%) rename arch/powerpc/{kernel/module.lds => include/asm/module.lds.h} (100%) rename arch/riscv/{kernel/module.lds => include/asm/module.lds.h} (84%) create mode 100644 include/asm-generic/module.lds.h create mode 100755 scripts/generate_initcall_order.pl rename scripts/{module-common.lds => module.lds.S} (59%) base-commit: a292570e9f694ed50d3e69afd6d54272fd40deca -- 2.28.0.1011.ga647a8990f-goog