--- /dev/null
+#ifndef UACCESS_H
+#define UACCESS_H
+extern void *__user_addr_min, *__user_addr_max;
+
+#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
+
+static inline void __chk_user_ptr(const volatile void *p, size_t size)
+{
+ assert(p >= __user_addr_min && p + size <= __user_addr_max);
+}
+
+#define put_user(x, ptr) \
+({ \
+ typeof(ptr) __pu_ptr = (ptr); \
+ __chk_user_ptr(__pu_ptr, sizeof(*__pu_ptr)); \
+ ACCESS_ONCE(*(__pu_ptr)) = x; \
+ 0; \
+})
+
+#define get_user(x, ptr) \
+({ \
+ typeof(ptr) __pu_ptr = (ptr); \
+ __chk_user_ptr(__pu_ptr, sizeof(*__pu_ptr)); \
+ x = ACCESS_ONCE(*(__pu_ptr)); \
+ 0; \
+})
+
+static void volatile_memcpy(volatile char *to, const volatile char *from,
+ unsigned long n)
+{
+ while (n--)
+ *(to++) = *(from++);
+}
+
+static inline int copy_from_user(void *to, const void __user volatile *from,
+ unsigned long n)
+{
+ __chk_user_ptr(from, n);
+ volatile_memcpy(to, from, n);
+ return 0;
+}
+
+static inline int copy_to_user(void __user volatile *to, const void *from,
+ unsigned long n)
+{
+ __chk_user_ptr(to, n);
+ volatile_memcpy(to, from, n);
+ return 0;
+}
+#endif /* UACCESS_H */