| Message ID | 20200819191654.1130563-3-ndesaulniers@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | -ffreestanding/-fno-builtin-* patches | expand |
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@chromium.org> > Suggested-by: Nathan Chancellor <natechancellor@gmail.com> > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> > --- > 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 >
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
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@chromium.org> Suggested-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> --- Makefile | 1 + 1 file changed, 1 insertion(+)