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=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 E42A2C433E2 for ; Fri, 4 Sep 2020 07:54:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A3387206A5 for ; Fri, 4 Sep 2020 07:54:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Nq2T1guw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729784AbgIDHx7 (ORCPT ); Fri, 4 Sep 2020 03:53:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55470 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726415AbgIDHxv (ORCPT ); Fri, 4 Sep 2020 03:53:51 -0400 Received: from mail-ot1-x342.google.com (mail-ot1-x342.google.com [IPv6:2607:f8b0:4864:20::342]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 13F33C061244; Fri, 4 Sep 2020 00:53:50 -0700 (PDT) Received: by mail-ot1-x342.google.com with SMTP id c10so5083189otm.13; Fri, 04 Sep 2020 00:53:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:reply-to:from:date:message-id :subject:to:cc; bh=ocqyzNbaVOZzIdeNzDcK80VX4YtlWAaQQv8brVA+uok=; b=Nq2T1guwkVW6AjrlGB9fPWghdM0XIdzmNU+vWvRDonxY/2F48APQtj4A9ML40oPSWE gNy8jSSGdU/uh49Nuan13e7J01chRakHa4cvFV++kD5GeMvnRK1PDFvkGNc11TFwom7Y X9gk1f6AN8nHnX/8jO+ovjwlYDnt3SAXJthIpS7uYfZmc8twAz/gjOTHw685POv0Jv7t oLDono45aa0F3e/AIav+77dHNgpenH801GxKxi70IabKBrJOGTmp5Z8C8a62JfBwA/NG vIKTVveaTADqVm296iwl2bKAzCQxo7MrtbLxsNRjrVkJS+tWusn1LVp3UFBKfFzXbACg fq5Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:reply-to :from:date:message-id:subject:to:cc; bh=ocqyzNbaVOZzIdeNzDcK80VX4YtlWAaQQv8brVA+uok=; b=G1PcEh8H+WISVvAMdLiHzWhvnSeAGaZlXYMrgwHtgMsqLyIAW+wgkKwRH8yga+CS95 EoaT7jGWW4q1r2aPqHvgCrh6GUCJV1IpZYzAIfE9LRrzgabc2i7cH0h++lZtwq6F+47z WsVF2c/LQVxDsRSGdhwEpnL2oOkGUnjVxdwcJgGuS8x/ozqAKlHEMSnlj+9JUUjIJ8Ka 32ycPtelzTAvwkP6UZOEDQzO+UuxEeZhcYIts5KTtaLy/5oXGSc1vQzYEp+VS+RZfFT7 Lj3DFBVNyKJQ+IbCyPSy+UzH2tmM0WEdC91RmtznkQM4WqY0X/tZdlT5Ek4UBm33IEDG dMpA== X-Gm-Message-State: AOAM533qTAy1WlRxZUmIKqUKJDs/QfDpp9NCc3rSGS1M5rG5iyMyUddn vrBd8MdLut7qm1fr5FtG5JUciVh8UvkKU8e5fnQ= X-Google-Smtp-Source: ABdhPJx8Fu6Q8WDEpmADLpI04M/+EN/6EVFvaEQovvgjSVbHG1rjYRSusAY1dEH9lP0YugsHKl4rs5v2AOHao6YXKcg= X-Received: by 2002:a9d:7656:: with SMTP id o22mr4302332otl.109.1599206029992; Fri, 04 Sep 2020 00:53:49 -0700 (PDT) MIME-Version: 1.0 References: <20200624203200.78870-1-samitolvanen@google.com> <20200903203053.3411268-1-samitolvanen@google.com> In-Reply-To: <20200903203053.3411268-1-samitolvanen@google.com> Reply-To: sedat.dilek@gmail.com From: Sedat Dilek Date: Fri, 4 Sep 2020 09:53:38 +0200 Message-ID: Subject: Re: [PATCH v2 00/28] Add support for Clang LTO To: Sami Tolvanen Cc: Masahiro Yamada , Will Deacon , Peter Zijlstra , Steven Rostedt , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , Nick Desaulniers , Clang-Built-Linux ML , 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 Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 3, 2020 at 10:30 PM 'Sami Tolvanen' via Clang Built Linux wrote: > > 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. > > Note that patches 1-4 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: > > - Patches 1-3 are required for building the kernel with ToT Clang, > and IAS, and patch 4 is needed to build allmodconfig with LTO. > > - Patches 3-4 are already in linux-next, but not yet in 5.9-rc. > I jumped to Sami's clang-cfi Git tree which includes clang-lto v2. My LLVM toolchain is version 11.0.0.0-rc2+ more precisely git 97ac9e82002d6b12831ca2c78f739cca65a4fa05. If this is OK, feel free to add my... Tested-by: Sedat Dilek - Sedat - [1] https://github.com/samitolvanen/linux/commits/clang-cfi > --- > 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 (2): > x86/boot/compressed: Disable relocation relaxation > x86/asm: Replace __force_order with memory clobber > > Luca Stefani (1): > RAS/CEC: Fix cec_init() prototype > > Nick Desaulniers (1): > lib/string.c: implement stpcpy > > Peter Zijlstra (1): > objtool: Add a pass for generating __mcount_loc > > Sami Tolvanen (23): > objtool: Don't autodetect vmlinux.o > kbuild: add support for objtool mcount > x86, build: use objtool mcount > 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: export CC_USING_PATCHABLE_FUNCTION_ENTRY > 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, relocs: Ignore L4_PAGE_OFFSET relocations > x86, build: allow LTO_CLANG and THINLTO to be selected > > .gitignore | 1 + > Makefile | 65 ++++++- > arch/Kconfig | 67 +++++++ > arch/arm64/Kconfig | 2 + > arch/arm64/Makefile | 1 + > arch/arm64/kernel/vdso/Makefile | 4 +- > arch/arm64/kvm/hyp/nvhe/Makefile | 4 +- > arch/x86/Kconfig | 3 + > arch/x86/Makefile | 5 + > arch/x86/boot/compressed/Makefile | 2 + > 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/tools/relocs.c | 1 + > drivers/firmware/efi/libstub/Makefile | 2 + > drivers/misc/lkdtm/Makefile | 1 + > drivers/ras/cec.c | 9 +- > include/asm-generic/vmlinux.lds.h | 11 +- > include/linux/init.h | 79 +++++++- > include/linux/pci.h | 19 +- > kernel/trace/Kconfig | 5 + > lib/string.c | 24 +++ > scripts/Makefile.build | 55 +++++- > scripts/Makefile.lib | 6 +- > scripts/Makefile.modfinal | 31 ++- > scripts/Makefile.modpost | 26 ++- > scripts/generate_initcall_order.pl | 270 ++++++++++++++++++++++++++ > scripts/link-vmlinux.sh | 94 ++++++++- > scripts/mod/Makefile | 1 + > scripts/mod/modpost.c | 16 +- > scripts/mod/modpost.h | 9 + > scripts/mod/sumversion.c | 6 +- > scripts/module-lto.lds | 26 +++ > 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 + > 39 files changed, 883 insertions(+), 108 deletions(-) > create mode 100755 scripts/generate_initcall_order.pl > create mode 100644 scripts/module-lto.lds > > > base-commit: e28f0104343d0c132fa37f479870c9e43355fee4 > -- > 2.28.0.402.g5ffc5be6b7-goog > > -- > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20200903203053.3411268-1-samitolvanen%40google.com.