On Wed, Dec 2, 2020 at 2:31 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. What I dislike about this implementation is it cannot drop any unreachable function/data. (and it is completely different from GCC LTO) This is not real LTO. > -- > Kees Cook > > -- > 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@xxxxxxxxxxxxxxxx. > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/202012010929.3788AF5%40keescook. -- Best Regards Masahiro Yamada
