| Message ID | 20200817220212.338670-4-ndesaulniers@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | -ffreestanding/-fno-builtin-* patches | expand |
On Mon, Aug 17, 2020 at 03:02:11PM -0700, Nick Desaulniers wrote: > We're reverting > commit 5f074f3e192f ("lib/string.c: implement a basic bcmp") > in favor of -fno-builtin-bcmp. Remove the additional definition here, > too. > > arch/x86/purgatory/Makefile uses -ffreestanding, so there's no risk of > this libcall optimization occurring for arch/x86/boot/purgatory.ro. > > arch/x86/boot/Makefile resets KBUILD_CFLAGS, so make sure to reset this > flag that was set for the top level Makefile. > > Fixes: 4ce97317f41d ("x86/purgatory: Do not use __builtin_memcpy and __builtin_memset") > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Kees Cook <keescook@chromium.org>
diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile index fe605205b4ce..ef7f15bfceab 100644 --- a/arch/x86/boot/Makefile +++ b/arch/x86/boot/Makefile @@ -70,6 +70,7 @@ KBUILD_CFLAGS := $(REALMODE_CFLAGS) -D_SETUP KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__ KBUILD_CFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=) KBUILD_CFLAGS += -fno-asynchronous-unwind-tables +KBUILD_CFLAGS += -fno-builtin-bcmp GCOV_PROFILE := n UBSAN_SANITIZE := n diff --git a/arch/x86/boot/string.c b/arch/x86/boot/string.c index 8a3fff9128bb..23d91aa7691e 100644 --- a/arch/x86/boot/string.c +++ b/arch/x86/boot/string.c @@ -37,14 +37,6 @@ int memcmp(const void *s1, const void *s2, size_t len) return diff; } -/* - * Clang may lower `memcmp == 0` to `bcmp == 0`. - */ -int bcmp(const void *s1, const void *s2, size_t len) -{ - return memcmp(s1, s2, len); -} - int strcmp(const char *str1, const char *str2) { const unsigned char *s1 = (const unsigned char *)str1;
We're reverting commit 5f074f3e192f ("lib/string.c: implement a basic bcmp") in favor of -fno-builtin-bcmp. Remove the additional definition here, too. arch/x86/purgatory/Makefile uses -ffreestanding, so there's no risk of this libcall optimization occurring for arch/x86/boot/purgatory.ro. arch/x86/boot/Makefile resets KBUILD_CFLAGS, so make sure to reset this flag that was set for the top level Makefile. Fixes: 4ce97317f41d ("x86/purgatory: Do not use __builtin_memcpy and __builtin_memset") Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> --- arch/x86/boot/Makefile | 1 + arch/x86/boot/string.c | 8 -------- 2 files changed, 1 insertion(+), 8 deletions(-)