nios2: drop access_ok() check from __put_user()

Unlike other architectures, the nios2 version of __put_user() has an
extra check for access_ok(), preventing it from being used to implement
__put_kernel_nofault().

Split up put_user() along the same lines as __get_user()/get_user()
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/nios2/include/asm/uaccess.h

@@ -167,12 +167,9 @@ do {									\
 	: "r" (val), "r" (ptr), "i" (-EFAULT));				\
 }
 
-#define put_user(x, ptr)						\
+#define __put_user_common(__pu_val, __pu_ptr)				\
 ({									\
 	long __pu_err = -EFAULT;					\
-	__typeof__(*(ptr)) __user *__pu_ptr = (ptr);			\
-	__typeof__(*(ptr)) __pu_val = (__typeof(*ptr))(x);		\
-	if (access_ok(__pu_ptr, sizeof(*__pu_ptr))) {	\
 	switch (sizeof(*__pu_ptr)) {					\
 	case 1:								\
 		__put_user_asm(__pu_val, "stb", __pu_ptr, __pu_err);	\
@@ -186,15 +183,28 @@ do {									\
 	default:							\
 		/* XXX: This looks wrong... */				\
 		__pu_err = 0;						\
-			if (copy_to_user(__pu_ptr, &(__pu_val),		\
+		if (__copy_to_user(__pu_ptr, &(__pu_val),		\
 			sizeof(*__pu_ptr)))				\
 			__pu_err = -EFAULT;				\
 		break;							\
 	}								\
-	}								\
 	__pu_err;							\
 })
 
-#define __put_user(x, ptr) put_user(x, ptr)
+#define __put_user(x, ptr)						\
+({									\
+	__auto_type __pu_ptr = (ptr);					\
+	typeof(*__pu_ptr) __pu_val = (typeof(*__pu_ptr))(x);		\
+	__put_user_common(__pu_val, __pu_ptr);				\
+})
+
+#define put_user(x, ptr)						\
+({									\
+	__auto_type __pu_ptr = (ptr);					\
+	typeof(*__pu_ptr) __pu_val = (typeof(*__pu_ptr))(x);		\
+	access_ok(__pu_ptr, sizeof(*__pu_ptr)) ?			\
+		__put_user_common(__pu_val, __pu_ptr) :			\
+		-EFAULT;						\
+})
 
 #endif /* _ASM_NIOS2_UACCESS_H */