diff --git a/xen/crypto/vmac.c b/xen/crypto/vmac.c
index 294dd16a52..acb4e015f5 100644
--- a/xen/crypto/vmac.c
+++ b/xen/crypto/vmac.c
@@ -8,6 +8,7 @@
 
 /* start for Xen */
 #include <xen/init.h>
+#include <xen/byteswap.h>
 #include <xen/types.h>
 #include <xen/lib.h>
 #include <crypto/vmac.h>
@@ -50,7 +51,6 @@ const uint64_t mpoly = UINT64_C(0x1fffffff1fffffff);  /* Poly key mask     */
  * MUL64: 64x64->128-bit multiplication
  * PMUL64: assumes top bits cleared on inputs
  * ADD128: 128x128->128-bit addition
- * GET_REVERSED_64: load and byte-reverse 64-bit word  
  * ----------------------------------------------------------------------- */
 
 /* ----------------------------------------------------------------------- */
@@ -68,22 +68,6 @@ const uint64_t mpoly = UINT64_C(0x1fffffff1fffffff);  /* Poly key mask     */
 
 #define PMUL64 MUL64
 
-#define GET_REVERSED_64(p)                                                \
-    ({uint64_t x;                                                         \
-     asm ("bswapq %0" : "=r" (x) : "0"(*(uint64_t *)(p))); x;})
-
-/* ----------------------------------------------------------------------- */
-#elif (__GNUC__ && __i386__)
-/* ----------------------------------------------------------------------- */
-
-#define GET_REVERSED_64(p)                                                \
-    ({ uint64_t x;                                                        \
-    uint32_t *tp = (uint32_t *)(p);                                       \
-    asm  ("bswap %%edx\n\t"                                               \
-          "bswap %%eax"                                                   \
-    : "=A"(x)                                                             \
-    : "a"(tp[1]), "d"(tp[0]));                                            \
-    x; })
 
 /* ----------------------------------------------------------------------- */
 #elif (__GNUC__ && __ppc64__)
@@ -103,37 +87,6 @@ const uint64_t mpoly = UINT64_C(0x1fffffff1fffffff);  /* Poly key mask     */
 
 #define PMUL64 MUL64
 
-#define GET_REVERSED_64(p)                                                \
-    ({ uint32_t hi, lo, *_p = (uint32_t *)(p);                            \
-       asm volatile ("lwbrx %0, %1, %2" : "=r"(lo) : "b%"(0), "r"(_p) );  \
-       asm volatile ("lwbrx %0, %1, %2" : "=r"(hi) : "b%"(4), "r"(_p) );  \
-       ((uint64_t)hi << 32) | (uint64_t)lo; } )
-
-/* ----------------------------------------------------------------------- */
-#elif (__GNUC__ && (__ppc__ || __PPC__))
-/* ----------------------------------------------------------------------- */
-
-#define GET_REVERSED_64(p)                                                \
-    ({ uint32_t hi, lo, *_p = (uint32_t *)(p);                            \
-       asm volatile ("lwbrx %0, %1, %2" : "=r"(lo) : "b%"(0), "r"(_p) );  \
-       asm volatile ("lwbrx %0, %1, %2" : "=r"(hi) : "b%"(4), "r"(_p) );  \
-       ((uint64_t)hi << 32) | (uint64_t)lo; } )
-
-/* ----------------------------------------------------------------------- */
-#elif (__GNUC__ && (__ARMEL__ || __ARM__))
-/* ----------------------------------------------------------------------- */
-
-#define bswap32(v)                                                        \
-({ uint32_t tmp,out;                                                      \
-    asm volatile(                                                         \
-        "eor    %1, %2, %2, ror #16\n"                                    \
-        "bic    %1, %1, #0x00ff0000\n"                                    \
-        "mov    %0, %2, ror #8\n"                                         \
-        "eor    %0, %0, %1, lsr #8"                                       \
-    : "=r" (out), "=&r" (tmp)                                             \
-    : "r" (v));                                                           \
-    out;})
-
 /* ----------------------------------------------------------------------- */
 #elif _MSC_VER
 /* ----------------------------------------------------------------------- */
@@ -154,11 +107,6 @@ const uint64_t mpoly = UINT64_C(0x1fffffff1fffffff);  /* Poly key mask     */
         (rh) += (ih) + ((rl) < (_il));                               \
     }
 
-#if _MSC_VER >= 1300
-#define GET_REVERSED_64(p) _byteswap_uint64(*(uint64_t *)(p))
-#pragma intrinsic(_byteswap_uint64)
-#endif
-
 #if _MSC_VER >= 1400 && \
     (!defined(__INTEL_COMPILER) || __INTEL_COMPILER >= 1000)
 #define MUL32(i1,i2)    (__emulu((uint32_t)(i1),(uint32_t)(i2)))
@@ -219,24 +167,6 @@ const uint64_t mpoly = UINT64_C(0x1fffffff1fffffff);  /* Poly key mask     */
     }
 #endif
 
-#ifndef GET_REVERSED_64
-#ifndef bswap64
-#ifndef bswap32
-#define bswap32(x)                                                        \
-  ({ uint32_t bsx = (x);                                                  \
-      ((((bsx) & 0xff000000u) >> 24) | (((bsx) & 0x00ff0000u) >>  8) |    \
-       (((bsx) & 0x0000ff00u) <<  8) | (((bsx) & 0x000000ffu) << 24)); })
-#endif
-#define bswap64(x)                                                        \
-     ({ union { uint64_t ll; uint32_t l[2]; } w, r;                       \
-         w.ll = (x);                                                      \
-         r.l[0] = bswap32 (w.l[1]);                                       \
-         r.l[1] = bswap32 (w.l[0]);                                       \
-         r.ll; })
-#endif
-#define GET_REVERSED_64(p) bswap64(*(uint64_t *)(p)) 
-#endif
-
 /* ----------------------------------------------------------------------- */
 
 #if (VMAC_PREFER_BIG_ENDIAN)
@@ -247,9 +177,9 @@ const uint64_t mpoly = UINT64_C(0x1fffffff1fffffff);  /* Poly key mask     */
 
 #if (VMAC_ARCH_BIG_ENDIAN)
 #  define get64BE(ptr) (*(uint64_t *)(ptr))
-#  define get64LE(ptr) GET_REVERSED_64(ptr)
+#  define get64LE(ptr) bswap64(*(uint64_t *)(ptr))
 #else /* assume little-endian */
-#  define get64BE(ptr) GET_REVERSED_64(ptr)
+#  define get64BE(ptr) bswap64(*(uint64_t *)(ptr))
 #  define get64LE(ptr) (*(uint64_t *)(ptr))
 #endif
 
