From patchwork Tue Sep 29 21:46:02 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11807013 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 42BF9139F for ; Tue, 29 Sep 2020 21:46:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1537F207F7 for ; Tue, 29 Sep 2020 21:46:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="pxKmqbIy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728228AbgI2Vqe (ORCPT ); Tue, 29 Sep 2020 17:46:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48156 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727922AbgI2Vqe (ORCPT ); Tue, 29 Sep 2020 17:46:34 -0400 Received: from mail-qv1-xf4a.google.com (mail-qv1-xf4a.google.com [IPv6:2607:f8b0:4864:20::f4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3FFB4C0613D0 for ; Tue, 29 Sep 2020 14:46:34 -0700 (PDT) Received: by mail-qv1-xf4a.google.com with SMTP id de12so3336186qvb.12 for ; Tue, 29 Sep 2020 14:46:34 -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=Ap+f/PgcipKb6Xwr77y488UFXUT7vfttNzHvf2XvHy4=; b=pxKmqbIyigake3W0fjk0CRWa/igqGxUHw3qFQELTPLC8nWdshs6mmWUCsQ6mIdj9mG uR5ZhLNSIBFiqGVc359gKgBsTxJNJ8p21PXv3uvfxnXCxmkNLh5wwhzGsP0HgoPqWeAO VjS8ZUqRHIykm1dP4nBu0NuaOvVgSyeBdxKSa0NKmaABqVUoEwbij5ohsdr/EJXpG30x orV+/IJfgecdn4qvWQ4NZpRQ3MXZCbtccw1nAVaWSBwDCbW3uVrbh0YwHbOTc6+nUKSI RwLmbxOmZQOdsU3BP0kHwmms5vuVFkSvwH1o+lLIJ+TNqdvCZDhucmsmE/67Tu8vBWfm jbTA== 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=Ap+f/PgcipKb6Xwr77y488UFXUT7vfttNzHvf2XvHy4=; b=ORFRP7lZi0Yo5GmtJ/suZi8KqrXp8Ey5ZYrV1HNSc1FgdwbM9a4xebgPnOhype6r3v JdLQFKXzSXpQM30yY6YrPRw7psJjhGaqpQsMmoJzZc//h2b4EOzsFBECZXQyiB8SDYyo AhGFFamAVLWpc4ak3ldmjnECXC1LMm3pFBzL8+gtZIc7YfI//+CIfvE8DhN1QjyBTxTK 9QMtePsXsI4gJWxTiG2RTK/+x6LlPp2GUhJ0IK1SaiiqYZvGT49AuAU7uXGuWz60mum4 xTQTe3xwyfx/qGxcgH/wcqEX7fcfuspuQqoTO0QicaychXxVnbZs6vx3GiVhi8OddFZT eXkA== X-Gm-Message-State: AOAM530ARo7xwmUW4cS0wrPRf2r6tXMeoS03j64Gre/7JeS7EddbvXNW X+wEfcIO8LU7VIgDJz0lPvuokNrAr8D6B8cse4I= X-Google-Smtp-Source: ABdhPJz55DdleGieWMtR/fQtUn1HHck6f+hJzMa/0ZjSBmixhPTxqRcXtmlftsciZe+KGj3y0OcPa3T2LEQ42XxFFxA= 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:b409:: with SMTP id u9mr6416334qve.9.1601415993082; Tue, 29 Sep 2020 14:46:33 -0700 (PDT) Date: Tue, 29 Sep 2020 14:46:02 -0700 Message-Id: <20200929214631.3516445-1-samitolvanen@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.28.0.709.gb0816b6eb0-goog Subject: [PATCH v4 00/29] Add support for Clang LTO From: Sami Tolvanen To: Masahiro Yamada , Will Deacon , Steven Rostedt Cc: 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 Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org This patch series adds support for building x86_64 and arm64 kernels 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. Again, patches 1-3 are not directly related to LTO, but are needed to compile LTO kernels with ToT Clang, so I'm including them in the series for your convenience: - Patch 1 ("RAS/CEC: Fix cec_init() prototype") fixes an initcall type mismatch which breaks allmodconfig with LTO. This patch is in linux-next. - Patch 2 ("x86/asm: Replace __force_order with memory clobber") fixes x86 builds with LLVM's integrated assembler, which we use with LTO for inline assembly. This patch hasn't been picked up by maintainers yet. - Patch 3 ("kbuild: preprocess module linker script") is from Masahiro's kbuild tree and makes the LTO linker script changes much cleaner. Furthermore, patches 4-8 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 makes supporting dynamic ftrace much simpler. Patch 9 disables recordmcount for arm64 when patchable function entry is used (enabled by default if the compiler supports the feature), which removes thousands of unnecessary recordmcount invocations from a defconfig build. Note that you can also pull this series from https://github.com/samitolvanen/linux.git lto-v4 --- 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. Arvind Sankar (1): x86/asm: Replace __force_order with memory clobber Luca Stefani (1): RAS/CEC: Fix cec_init() prototype Masahiro Yamada (1): kbuild: preprocess module linker script Peter Zijlstra (1): objtool: Add a pass for generating __mcount_loc Sami Tolvanen (25): objtool: Don't autodetect vmlinux.o tracing: move function tracer options to Kconfig tracing: add support for objtool mcount x86, build: use objtool mcount arm64: disable recordmcount with DYNAMIC_FTRACE_WITH_REGS treewide: remove DISABLE_LTO kbuild: add support for Clang LTO kbuild: lto: fix module versioning 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 arm64: vdso: disable LTO KVM: arm64: disable LTO for the nVHE directory arm64: allow LTO_CLANG and THINLTO to be selected 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 | 68 +++++ arch/arm/Makefile | 4 - .../module.lds => include/asm/module.lds.h} | 2 + arch/arm64/Kconfig | 4 + arch/arm64/Makefile | 4 - .../module.lds => include/asm/module.lds.h} | 2 + arch/arm64/kernel/vdso/Makefile | 4 +- arch/arm64/kvm/hyp/nvhe/Makefile | 4 +- 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/boot/compressed/pgtable_64.c | 9 - arch/x86/entry/vdso/Makefile | 5 +- arch/x86/include/asm/special_insns.h | 28 +- arch/x86/kernel/cpu/common.c | 4 +- arch/x86/power/Makefile | 4 + drivers/firmware/efi/libstub/Makefile | 2 + drivers/misc/lkdtm/Makefile | 1 + drivers/ras/cec.c | 9 +- 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 | 22 +- scripts/generate_initcall_order.pl | 270 ++++++++++++++++++ scripts/link-vmlinux.sh | 95 +++++- 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 | 13 +- tools/objtool/builtin.h | 2 +- tools/objtool/check.c | 83 ++++++ tools/objtool/check.h | 1 + tools/objtool/objtool.h | 1 + 56 files changed, 906 insertions(+), 160 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: ccc1d052eff9f3cfe59d201263903fe1d46c79a5