frv: fix kernel/user segment handling in NOMMU mode

In NOMMU mode, the FRV segment handling is broken because KERNEL_DS ==
USER_DS.  This causes tests of the following sort:

	/* don't pin down non-user-based iovecs */
	if (segment_eq(get_fs(), KERNEL_DS))
		return NULL;

to malfunction.

To fix this, make USER_DS the top of RAM instead of the top of the non-IO
address space, and make KERNEL_DS one more than the top of the non-IO
address space.

Also get rid of FRV's __addr_ok() as nothing uses it.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/frv/include/asm/segment.h

@@ -21,12 +21,12 @@ typedef struct {
 
 #define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
 
-#define KERNEL_DS		MAKE_MM_SEG(0xdfffffffUL)
-
 #ifdef CONFIG_MMU
 #define USER_DS			MAKE_MM_SEG(TASK_SIZE - 1)
+#define KERNEL_DS		MAKE_MM_SEG(0xdfffffffUL)
 #else
-#define USER_DS			KERNEL_DS
+#define USER_DS			MAKE_MM_SEG(memory_end)
+#define KERNEL_DS		MAKE_MM_SEG(0xe0000000UL)
 #endif
 
 #define get_ds()		(KERNEL_DS)

arch/frv/include/asm/uaccess.h

@@ -27,8 +27,6 @@
 #define VERIFY_READ	0
 #define VERIFY_WRITE	1
 
-#define __addr_ok(addr) ((unsigned long)(addr) < get_addr_limit())
-
 /*
  * check that a range of addresses falls within the current address limit
  */