On Wed, Aug 19, 2020 at 12:16:51PM -0700, Nick Desaulniers wrote: > The issue with using `-fno-builtin-*` flags was that they were not > retained during an LTO link with LLVM. This was fixed in clang-11 by > https://reviews.llvm.org/D71193 > (0508c994f0b14144041f2cfd3ba9f9a80f03de08), which is also the minimum > supported version of clang for LTO. Use `-fno-builtin-bcmp` instead. > > With this applid, we can cleanly revert > commit 5f074f3e192f ("lib/string.c: implement a basic bcmp") > > Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> > Suggested-by: Nathan Chancellor <natechancellor@xxxxxxxxx> > Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx> > --- > Makefile | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/Makefile b/Makefile > index e523dc8d30e0..def590b743a9 100644 > --- a/Makefile > +++ b/Makefile > @@ -579,6 +579,7 @@ CLANG_FLAGS += -no-integrated-as > endif > CLANG_FLAGS += -Werror=unknown-warning-option > CLANG_FLAGS += -fno-builtin-stpcpy > +CLANG_FLAGS += -fno-builtin-bcmp > KBUILD_CFLAGS += $(CLANG_FLAGS) > KBUILD_AFLAGS += $(CLANG_FLAGS) > export CLANG_FLAGS > -- > 2.28.0.297.g1956fa8f8d-goog >
