From: Kees Cook <keesc...@chromium.org>
Date: Tue, 16 Feb 2021 12:34:37 -0800
> Hi Linus,
>
> Please pull this Clang Link Time Optimization series for v5.12-rc1. This
> has been in linux-next for the entire last development cycle, and is
> built on the work done preparing[0] for LTO by arm64 folks, tracing folks,
> etc. This series includes the core changes as well as the remaining pieces
> for arm64 (LTO has been the default build method on Android for about
> 3 years now, as it is the prerequisite for the Control Flow Integrity
> protections). While x86 LTO support is done[1], there is still some
> on-going clean-up work happening for objtool[2] that should hopefully
> land by the v5.13 merge window.
>
> For merge log posterity, and as detailed in commit dc5723b02e52 ("kbuild:
> add support for Clang LTO"), here is the lt;dr to do an LTO build:
>
> make LLVM=1 LLVM_IAS=1 defconfig
> scripts/config -e LTO_CLANG_THIN
> make LLVM=1 LLVM_IAS=1
>
> (To do a cross-compile of arm64, add "CROSS_COMPILE=aarch64-linux-gnu-"
> and "ARCH=arm64" to the "make" command lines.)
>
> Thanks!
>
> -Kees
>
> [0] https://git.kernel.org/linus/3c09ec59cdea5b132212d97154d625fd34e436dd
> [1] https://github.com/samitolvanen/linux/commits/clang-lto
> [2] https://lore.kernel.org/lkml/cover.1611263461.git.jpoim...@redhat.com/
>
> The following changes since commit e71ba9452f0b5b2e8dc8aa5445198cd9214a6a62:
>
> Linux 5.11-rc2 (2021-01-03 15:55:30 -0800)
>
> are available in the Git repository at:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git
> tags/clang-lto-v5.12-rc1
>
> for you to fetch changes up to 112b6a8e038d793d016e330f53acb9383ac504b3:
>
> arm64: allow LTO to be selected (2021-01-14 08:21:10 -0800)
>
> ----------------------------------------------------------------
> clang-lto for v5.12-rc1
>
> Provide build infrastructure for arm64 Clang LTO.
>
> ----------------------------------------------------------------
> Sami Tolvanen (16):
> 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: add a default list of used symbols
> 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
> arm64: disable recordmcount with DYNAMIC_FTRACE_WITH_REGS
> arm64: allow LTO to be selected
Seems like you forgot the fix from [0], didn't you?
> .gitignore | 1 +
> Makefile | 45 ++++--
> arch/Kconfig | 90 ++++++++++++
> arch/arm64/Kconfig | 4 +
> arch/arm64/kernel/vdso/Makefile | 3 +-
> 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 | 27 +++-
> init/Kconfig | 1 +
> kernel/trace/Kconfig | 16 ++
> scripts/Makefile.build | 48 +++++-
> scripts/Makefile.lib | 6 +-
> scripts/Makefile.modfinal | 9 +-
> scripts/Makefile.modpost | 25 +++-
> scripts/generate_initcall_order.pl | 270
> ++++++++++++++++++++++++++++++++++
> scripts/link-vmlinux.sh | 70 +++++++--
> scripts/lto-used-symbollist.txt | 5 +
> scripts/mod/Makefile | 1 +
> scripts/mod/modpost.c | 16 +-
> scripts/mod/modpost.h | 9 ++
> scripts/mod/sumversion.c | 6 +-
> scripts/module.lds.S | 24 +++
> 24 files changed, 707 insertions(+), 62 deletions(-)
> create mode 100755 scripts/generate_initcall_order.pl
> create mode 100644 scripts/lto-used-symbollist.txt
>
> --
> Kees Cook
>
[0] https://lore.kernel.org/lkml/20210121184544.659998-1-aloba...@pm.me
Al
