From: Vasily Gorbik <gor@linux.ibm.com>
Date: Mon, 12 Aug 2019 15:52:07 +0200
Subject: s390/kasan: provide uninstrumented __strlen
Git-commit: f45f7b5bdaa4828ce871cf03f7c01599a0de57a5
Patch-mainline: 5.4-rc1
References: bnc#1151927 5.3.4

s390 kasan code uses sclp_early_printk to report initialization
failures. The code doing that should not be instrumented, because kasan
shadow memory has not been set up yet. Even though sclp_early_core.c is
compiled with instrumentation disabled it uses strlen function, which
is instrumented and would produce shadow memory access if used. To
avoid that, introduce uninstrumented __strlen function to be used
instead.

Before commit 7e0d92f00246 ("s390/kasan: improve string/memory functions
checks") few string functions (including strlen) were escaping kasan
instrumentation due to usage of platform specific versions which are
implemented in inline assembly.

Fixes: 7e0d92f00246 ("s390/kasan: improve string/memory functions checks")
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 arch/s390/include/asm/string.h |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/arch/s390/include/asm/string.h
+++ b/arch/s390/include/asm/string.h
@@ -71,11 +71,16 @@ extern void *__memmove(void *dest, const
 #define memcpy(dst, src, len) __memcpy(dst, src, len)
 #define memmove(dst, src, len) __memmove(dst, src, len)
 #define memset(s, c, n) __memset(s, c, n)
+#define strlen(s) __strlen(s)
+
+#define __no_sanitize_prefix_strfunc(x) __##x
 
 #ifndef __NO_FORTIFY
 #define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
 #endif
 
+#else
+#define __no_sanitize_prefix_strfunc(x) x
 #endif /* defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__) */
 
 void *__memset16(uint16_t *s, uint16_t v, size_t count);
@@ -163,8 +168,8 @@ static inline char *strcpy(char *dst, co
 }
 #endif
 
-#ifdef __HAVE_ARCH_STRLEN
-static inline size_t strlen(const char *s)
+#if defined(__HAVE_ARCH_STRLEN) || (defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__))
+static inline size_t __no_sanitize_prefix_strfunc(strlen)(const char *s)
 {
 	register unsigned long r0 asm("0") = 0;
 	const char *tmp = s;