[PATCH] s390: const pointer uaccess

Using __typeof__(*ptr) on a pointer to const makes the __x variable in
__get_user const as well.  The latest gcc will refuse to write to it.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

include/asm-s390/uaccess.h

@@ -200,21 +200,37 @@ extern int __put_user_bad(void) __attribute__((noreturn));
 
 #define __get_user(x, ptr)					\
 ({								\
-	__typeof__(*(ptr)) __x;					\
 	int __gu_err;						\
         __chk_user_ptr(ptr);                                    \
 	switch (sizeof(*(ptr))) {				\
-	case 1:							\
-	case 2:							\
-	case 4:							\
-	case 8:							\
+	case 1: {						\
+		unsigned char __x;				\
+		__get_user_asm(__x, ptr, __gu_err);		\
+		(x) = (__typeof__(*(ptr))) __x;			\
+		break;						\
+	};							\
+	case 2: {						\
+		unsigned short __x;				\
+		__get_user_asm(__x, ptr, __gu_err);		\
+		(x) = (__typeof__(*(ptr))) __x;			\
+		break;						\
+	};							\
+	case 4: {						\
+		unsigned int __x;				\
+		__get_user_asm(__x, ptr, __gu_err);		\
+		(x) = (__typeof__(*(ptr))) __x;			\
+		break;						\
+	};							\
+	case 8: {						\
+		unsigned long long __x;				\
 		__get_user_asm(__x, ptr, __gu_err);		\
+		(x) = (__typeof__(*(ptr))) __x;			\
 		break;						\
+	};							\
 	default:						\
 		__get_user_bad();				\
 		break;						\
 	}							\
-	(x) = __x;						\
 	__gu_err;						\
 })