[PATCH 2/4] Revert "lib/string.c: implement a basic bcmp"
From: Nick Desaulniers <hidden>
Date: 2020-08-17 22:02:40
Also in:
lkml
Subsystem:
generic string library, kernel build + files below scripts/ (unless maintained elsewhere), library code, the rest · Maintainers:
Kees Cook, Nathan Chancellor, Nicolas Schier, Andrew Morton, Linus Torvalds
This reverts commit 5f074f3e192f10c9fade898b9b3b8812e3d83342. Use `-fno-builtin-bcmp` instead. 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. Signed-off-by: Nick Desaulniers <redacted> --- Makefile | 1 + include/linux/string.h | 3 --- lib/string.c | 20 -------------------- 3 files changed, 1 insertion(+), 23 deletions(-)
diff --git a/Makefile b/Makefile
index 211a1b6f6478..722ff5864275 100644
--- a/Makefile
+++ b/Makefile@@ -964,6 +964,7 @@ endif # to provide implementations of these routines, then prevent the compiler from # emitting calls to what will be undefined symbols. KBUILD_CFLAGS += -fno-builtin-stpcpy +KBUILD_CFLAGS += -fno-builtin-bcmp # include additional Makefiles when needed include-y := scripts/Makefile.extrawarn
diff --git a/include/linux/string.h b/include/linux/string.h
index b1f3894a0a3e..f3bdb74bc230 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h@@ -155,9 +155,6 @@ extern void * memscan(void *,int,__kernel_size_t); #ifndef __HAVE_ARCH_MEMCMP extern int memcmp(const void *,const void *,__kernel_size_t); #endif -#ifndef __HAVE_ARCH_BCMP -extern int bcmp(const void *,const void *,__kernel_size_t); -#endif #ifndef __HAVE_ARCH_MEMCHR extern void * memchr(const void *,int,__kernel_size_t); #endif
diff --git a/lib/string.c b/lib/string.c
index 6012c385fb31..69328b8353e1 100644
--- a/lib/string.c
+++ b/lib/string.c@@ -922,26 +922,6 @@ __visible int memcmp(const void *cs, const void *ct, size_t count) EXPORT_SYMBOL(memcmp); #endif -#ifndef __HAVE_ARCH_BCMP -/** - * bcmp - returns 0 if and only if the buffers have identical contents. - * @a: pointer to first buffer. - * @b: pointer to second buffer. - * @len: size of buffers. - * - * The sign or magnitude of a non-zero return value has no particular - * meaning, and architectures may implement their own more efficient bcmp(). So - * while this particular implementation is a simple (tail) call to memcmp, do - * not rely on anything but whether the return value is zero or non-zero. - */ -#undef bcmp -int bcmp(const void *a, const void *b, size_t len) -{ - return memcmp(a, b, len); -} -EXPORT_SYMBOL(bcmp); -#endif - #ifndef __HAVE_ARCH_MEMSCAN /** * memscan - Find a character in an area of memory.
--
2.28.0.220.ged08abb693-goog