ipv6: 64bit version of ipv6_addr_loopback().

index ace1113..c5049b0 100644
@@ -475,8 +475,14 @@ static inline u32 ipv6_addr_hash(const struct in6_addr *a)
 
 static inline bool ipv6_addr_loopback(const struct in6_addr *a)
 {
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
+	const unsigned long *ul = (const unsigned long *)a;
+
+	return (ul[0] | (ul[1] ^ cpu_to_be64(1))) == 0UL;
+#else
 	return (a->s6_addr32[0] | a->s6_addr32[1] |
 		a->s6_addr32[2] | (a->s6_addr32[3] ^ htonl(1))) == 0;
+#endif
 }
 
 static inline bool ipv6_addr_v4mapped(const struct in6_addr *a)