powerpc: use non-set_fs based maccess routines

Provide __get_kernel_nofault and __put_kernel_nofault routines to
implement the maccess routines without messing with set_fs and without
opening up access to user space.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/powerpc/include/asm/uaccess.h

@@ -623,4 +623,20 @@ do {									\
 		__put_user_goto(*(u8*)(_src + _i), (u8 __user *)(_dst + _i), e);\
 } while (0)
 
+#define HAVE_GET_KERNEL_NOFAULT
+
+#define __get_kernel_nofault(dst, src, type, err_label)			\
+do {									\
+	int __kr_err;							\
+									\
+	__get_user_size_allowed(*((type *)(dst)), (__force type __user *)(src),\
+			sizeof(type), __kr_err);			\
+	if (unlikely(__kr_err))						\
+		goto err_label;						\
+} while (0)
+
+#define __put_kernel_nofault(dst, src, type, err_label)			\
+	__put_user_size_goto(*((type *)(src)),				\
+		(__force type __user *)(dst), sizeof(type), err_label)
+
 #endif	/* _ARCH_POWERPC_UACCESS_H */