--- util.h 2010-12-07 22:41:57.156243001 -0600
+++ util.h 2010-12-07 22:43:47.616243002 -0600
@@ -37,4 +37,13 @@
 #define cpu_relax()     asm volatile("" ::: "memory");
 #endif
 
+#ifdef __arm__
+/*
+ * Use the __kuser_memory_barrier helper in the CPU helper page. See
+ * arch/arm/kernel/entry-armv.S in the kernel source for details.
+ */
+#define rmb()           ((void(*)(void))0xffff0fa0)()
+#define cpu_relax()     asm volatile("":::"memory")
+#endif
+
 #endif
