[PATCH RFC v2 21/25] kmsan: use __msan_memcpy() where possible.

[glider@google.com]

Unless stated otherwise (by explicitly calling __memcpy()) we want all
memcpy() calls to call __msan_memcpy() so that shadow and origin values
are updated accordingly.

Signed-off-by: Alexander Potapenko <glider@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: linux-mm@kvack.org
---

Change-Id: Ib2512ce5aa8d457453dd38caa12f58f002166813
---
 arch/x86/include/asm/string_64.h | 9 ++++++++-
 include/linux/compiler.h         | 9 ++++++++-
 include/linux/string.h           | 2 ++
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
index 75314c3dbe47..d3c76d910c23 100644
--- a/arch/x86/include/asm/string_64.h
+++ b/arch/x86/include/asm/string_64.h
@@ -11,7 +11,13 @@
    function. */
 
 #define __HAVE_ARCH_MEMCPY 1
+#if defined(CONFIG_KMSAN)
+#undef memcpy
+/* __msan_memcpy() is defined in compiler.h */
+#define memcpy(dst, src, len) __msan_memcpy(dst, src, len)
+#else
 extern void *memcpy(void *to, const void *from, size_t len);
+#endif
 extern void *__memcpy(void *to, const void *from, size_t len);
 
 #define __HAVE_ARCH_MEMSET
@@ -64,7 +70,8 @@ char *strcpy(char *dest, const char *src);
 char *strcat(char *dest, const char *src);
 int strcmp(const char *cs, const char *ct);
 
-#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
+#if (defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)) || \
+	(defined(CONFIG_KMSAN) && !defined(__SANITIZE_MEMORY__))
 
 /*
  * For files that not instrumented (e.g. mm/slub.c) we
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index e8c86debdb2b..d0bc367e9164 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -179,6 +179,13 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 
 #include <uapi/linux/types.h>
 
+#ifdef CONFIG_KMSAN
+void *__msan_memcpy(void *dst, const void *src, u64 size);
+#define __DO_MEMCPY(res, p, size) __msan_memcpy(res, p, size)
+#else
+#define __DO_MEMCPY(res, p, size) __builtin_memcpy(res, p, size)
+#endif
+
 #define __READ_ONCE_SIZE						\
 ({									\
 	switch (size) {							\
@@ -188,7 +195,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 	case 8: *(__u64 *)res = *(volatile __u64 *)p; break;		\
 	default:							\
 		barrier();						\
-		__builtin_memcpy((void *)res, (const void *)p, size);	\
+		__DO_MEMCPY((void *)res, (const void *)p, size);	\
 		barrier();						\
 	}								\
 })
diff --git a/include/linux/string.h b/include/linux/string.h
index b6ccdc2c7f02..5d8ce09cba2e 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -363,6 +363,7 @@ __FORTIFY_INLINE void *memset(void *p, int c, __kernel_size_t size)
 	return __builtin_memset(p, c, size);
 }
 
+#ifndef CONFIG_KMSAN
 __FORTIFY_INLINE void *memcpy(void *p, const void *q, __kernel_size_t size)
 {
 	size_t p_size = __builtin_object_size(p, 0);
@@ -377,6 +378,7 @@ __FORTIFY_INLINE void *memcpy(void *p, const void *q, __kernel_size_t size)
 		fortify_panic(__func__);
 	return __builtin_memcpy(p, q, size);
 }
+#endif
 
 __FORTIFY_INLINE void *memmove(void *p, const void *q, __kernel_size_t size)
 {
-- 
2.24.0.rc0.303.g954a862665-goog