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")
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
---
arch/x86/boot/Makefile | 1 +
arch/x86/boot/string.c | 8 --------
2 files changed, 1 insertion(+), 8 deletions(-)
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;
--
2.28.0.297.g1956fa8f8d-goog
