1 files changed, 50 insertions, 0 deletions

diff --git a/tools/virtio/linux/uaccess.h b/tools/virtio/linux/uaccess.h
new file mode 100644
index 000000000000..0a578fe18653
--- /dev/null
+++ b/tools/virtio/linux/uaccess.h
@@ -0,0 +1,50 @@
+#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 */