diff --git a/arch/um/include/um_uaccess.h b/arch/um/include/um_uaccess.h
index 84c0868cd561..f8760a3f43b0 100644
--- a/arch/um/include/um_uaccess.h
+++ b/arch/um/include/um_uaccess.h
@@ -17,8 +17,25 @@
 #include "uaccess-skas.h"
 #endif
 
+#define __under_task_size(addr, size) \
+	(((unsigned long) (addr) < TASK_SIZE) && \
+         (((unsigned long) (addr) + (size)) < TASK_SIZE))
+
+#define __access_ok_vsyscall(type, addr, size) \
+	 ((type == VERIFY_READ) && \
+	  ((unsigned long) (addr) >= FIXADDR_USER_START) && \
+	  ((unsigned long) (addr) + (size) <= FIXADDR_USER_END) && \
+	  ((unsigned long) (addr) + (size) >= (unsigned long)(addr)))
+
+#define __addr_range_nowrap(addr, size) \
+	((unsigned long) (addr) <= ((unsigned long) (addr) + (size)))
+
 #define access_ok(type, addr, size) \
-	CHOOSE_MODE_PROC(access_ok_tt, access_ok_skas, type, addr, size)
+	(__addr_range_nowrap(addr, size) && \
+	 (__under_task_size(addr, size) || \
+	  __access_ok_vsyscall(type, addr, size) || \
+	  segment_eq(get_fs(), KERNEL_DS) || \
+	  CHOOSE_MODE_PROC(access_ok_tt, access_ok_skas, type, addr, size)))
 
 static inline int copy_from_user(void *to, const void __user *from, int n)
 {
diff --git a/arch/um/kernel/skas/include/uaccess-skas.h b/arch/um/kernel/skas/include/uaccess-skas.h
index 7da0c2def0ef..f611f83ad4ff 100644
--- a/arch/um/kernel/skas/include/uaccess-skas.h
+++ b/arch/um/kernel/skas/include/uaccess-skas.h
@@ -9,14 +9,8 @@
 #include "asm/errno.h"
 #include "asm/fixmap.h"
 
-#define access_ok_skas(type, addr, size) \
-	((segment_eq(get_fs(), KERNEL_DS)) || \
-	 (((unsigned long) (addr) < TASK_SIZE) && \
-	  ((unsigned long) (addr) + (size) <= TASK_SIZE)) || \
-	 ((type == VERIFY_READ ) && \
-	  ((unsigned long) (addr) >= FIXADDR_USER_START) && \
-	  ((unsigned long) (addr) + (size) <= FIXADDR_USER_END) && \
-	  ((unsigned long) (addr) + (size) >= (unsigned long)(addr))))
+/* No SKAS-specific checking. */
+#define access_ok_skas(type, addr, size) 0
 
 extern int copy_from_user_skas(void *to, const void __user *from, int n);
 extern int copy_to_user_skas(void __user *to, const void *from, int n);
diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c
index 75195281081e..a5a47528dec7 100644
--- a/arch/um/kernel/skas/uaccess.c
+++ b/arch/um/kernel/skas/uaccess.c
@@ -143,7 +143,7 @@ int copy_from_user_skas(void *to, const void __user *from, int n)
 		return(0);
 	}
 
-	return(access_ok_skas(VERIFY_READ, from, n) ?
+	return(access_ok(VERIFY_READ, from, n) ?
 	       buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to):
 	       n);
 }
@@ -164,7 +164,7 @@ int copy_to_user_skas(void __user *to, const void *from, int n)
 		return(0);
 	}
 
-	return(access_ok_skas(VERIFY_WRITE, to, n) ?
+	return(access_ok(VERIFY_WRITE, to, n) ?
 	       buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from) :
 	       n);
 }
@@ -193,7 +193,7 @@ int strncpy_from_user_skas(char *dst, const char __user *src, int count)
 		return(strnlen(dst, count));
 	}
 
-	if(!access_ok_skas(VERIFY_READ, src, 1))
+	if(!access_ok(VERIFY_READ, src, 1))
 		return(-EFAULT);
 
 	n = buffer_op((unsigned long) src, count, 0, strncpy_chunk_from_user,
@@ -221,7 +221,7 @@ int clear_user_skas(void __user *mem, int len)
 		return(0);
 	}
 
-	return(access_ok_skas(VERIFY_WRITE, mem, len) ?
+	return(access_ok(VERIFY_WRITE, mem, len) ?
 	       buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL) : len);
 }
 
diff --git a/arch/um/kernel/tt/include/uaccess-tt.h b/arch/um/kernel/tt/include/uaccess-tt.h
index dc2ebfa8c54f..b9bfe9c481c4 100644
--- a/arch/um/kernel/tt/include/uaccess-tt.h
+++ b/arch/um/kernel/tt/include/uaccess-tt.h
@@ -19,19 +19,13 @@
 extern unsigned long end_vm;
 extern unsigned long uml_physmem;
 
-#define under_task_size(addr, size) \
-	(((unsigned long) (addr) < TASK_SIZE) && \
-         (((unsigned long) (addr) + (size)) < TASK_SIZE))
-
 #define is_stack(addr, size) \
 	(((unsigned long) (addr) < STACK_TOP) && \
 	 ((unsigned long) (addr) >= STACK_TOP - ABOVE_KMEM) && \
 	 (((unsigned long) (addr) + (size)) <= STACK_TOP))
 
 #define access_ok_tt(type, addr, size) \
-	((type == VERIFY_READ) || (segment_eq(get_fs(), KERNEL_DS)) || \
-         (((unsigned long) (addr) <= ((unsigned long) (addr) + (size))) && \
-          (under_task_size(addr, size) || is_stack(addr, size))))
+	(is_stack(addr, size))
 
 extern unsigned long get_fault_addr(void);
 
diff --git a/arch/um/kernel/tt/uaccess.c b/arch/um/kernel/tt/uaccess.c
index a72aa632972f..1cb60726567e 100644
--- a/arch/um/kernel/tt/uaccess.c
+++ b/arch/um/kernel/tt/uaccess.c
@@ -8,7 +8,7 @@
 
 int copy_from_user_tt(void *to, const void __user *from, int n)
 {
-	if(!access_ok_tt(VERIFY_READ, from, n))
+	if(!access_ok(VERIFY_READ, from, n))
 		return(n);
 
 	return(__do_copy_from_user(to, from, n, &current->thread.fault_addr,
@@ -17,7 +17,7 @@ int copy_from_user_tt(void *to, const void __user *from, int n)
 
 int copy_to_user_tt(void __user *to, const void *from, int n)
 {
-	if(!access_ok_tt(VERIFY_WRITE, to, n))
+	if(!access_ok(VERIFY_WRITE, to, n))
 		return(n);
 
 	return(__do_copy_to_user(to, from, n, &current->thread.fault_addr,
@@ -28,7 +28,7 @@ int strncpy_from_user_tt(char *dst, const char __user *src, int count)
 {
 	int n;
 
-	if(!access_ok_tt(VERIFY_READ, src, 1))
+	if(!access_ok(VERIFY_READ, src, 1))
 		return(-EFAULT);
 
 	n = __do_strncpy_from_user(dst, src, count,
@@ -47,7 +47,7 @@ int __clear_user_tt(void __user *mem, int len)
 
 int clear_user_tt(void __user *mem, int len)
 {
-	if(!access_ok_tt(VERIFY_WRITE, mem, len))
+	if(!access_ok(VERIFY_WRITE, mem, len))
 		return(len);
 
 	return(__do_clear_user(mem, len, &current->thread.fault_addr,