On Tue, Dec 1, 2020 at 11:51 AM 'Nick Desaulniers' via Clang Built Linux <clang-built-linux@xxxxxxxxxxxxxxxx> wrote: > > On Tue, Dec 1, 2020 at 9:31 AM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > > > On Mon, Nov 30, 2020 at 12:01:31PM +0000, Will Deacon wrote: > > > Hi Sami, > > > > > > On Wed, Nov 18, 2020 at 02:07:14PM -0800, Sami Tolvanen wrote: > > > > 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. These are included in v8, which I just sent out. Sami
