Re: [PATCH v7 00/17] Add support for Clang LTO

On Tue, Dec 1, 2020 at 9:31 AM Kees Cook [off-list ref] wrote:

On Mon, Nov 30, 2020 at 12:01:31PM +0000, Will Deacon wrote:

quoted

Hi Sami,

On Wed, Nov 18, 2020 at 02:07:14PM -0800, Sami Tolvanen wrote:

quoted

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].

Sounds like you're going to post a v8, but that's the plan for merging
that? The arm64 parts look pretty good to me now.

I haven't seen Masahiro comment on this in a while, so given the review
history and its use (for years now) in Android, I will carry v8 (assuming
all is fine with it) it in -next unless there are objections.

I had some minor stylistic feedback on the Kconfig changes; I'm happy
for you to land the bulk of the changes and then I follow up with
patches to the Kconfig after.
-- 
Thanks,
~Nick Desaulniers

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel