xtensa: switch to providing csum_and_copy_from_user()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/xtensa/include/asm/checksum.h

@@ -44,8 +44,6 @@ asmlinkage __wsum csum_partial_copy_generic(const void *src, void *dst,
 /*
  *	Note: when you get a NULL pointer exception here this means someone
  *	passed in an incorrect kernel address to one of these functions.
- *
- *	If you use these functions directly please don't forget the access_ok().
  */
 static inline
 __wsum csum_partial_copy_nocheck(const void *src, void *dst,
@@ -54,12 +52,17 @@ __wsum csum_partial_copy_nocheck(const void *src, void *dst,
 	return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
 }
 
+#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
 static inline
-__wsum csum_partial_copy_from_user(const void __user *src, void *dst,
+__wsum csum_and_copy_from_user(const void __user *src, void *dst,
 				   int len, __wsum sum, int *err_ptr)
 {
+	if (access_ok(dst, len))
 		return csum_partial_copy_generic((__force const void *)src, dst,
 					len, sum, err_ptr, NULL);
+	if (len)
+		*err_ptr = -EFAULT;
+	return sum;
 }
 
 /*