Change the vm_ooffset_t type to unsigned.

The type represents byte offset in the vm_object_t data space, which
does not span negative offsets in FreeBSD VM.  The change matches byte
offset signess with the unsignedness of the vm_pindex_t which
represents the type of the page indexes in the objects.

This allows to remove the UOFF_TO_IDX() macro which was used when we
have to forcibly interpret the type as unsigned anyway.  Also it fixes
a lot of implicit bugs in the device drivers d_mmap methods.

Reviewed by:	alc, markj (previous version)
Tested by:	pho
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation

sys/dev/xen/gntdev/gntdev.c

@@ -814,8 +814,8 @@ gntdev_gmap_pg_fault(vm_object_t object, vm_ooffset_t offset, int prot,
 
 	relative_offset = offset - gmap->file_index;
 
-	pidx = UOFF_TO_IDX(offset);
+	pidx = OFF_TO_IDX(offset);
-	ridx = UOFF_TO_IDX(relative_offset);
+	ridx = OFF_TO_IDX(relative_offset);
 	if (ridx >= gmap->count ||
 	    gmap->grant_map_ops[ridx].status != GNTST_okay)
 		return (VM_PAGER_FAIL);
@@ -1085,7 +1085,7 @@ mmap_gref(struct per_user_data *priv_user, struct gntdev_gref *gref_start,
 			break;
 
 		vm_page_insert(gref->page, mem_obj,
-		    UOFF_TO_IDX(gref->file_index));
+		    OFF_TO_IDX(gref->file_index));
 
 		count--;
 	}
@@ -1225,7 +1225,7 @@ gntdev_mmap_single(struct cdev *cdev, vm_ooffset_t *offset, vm_size_t size,
 	if (error != 0)
 		return (EINVAL);
 
-	count = UOFF_TO_IDX(size);
+	count = OFF_TO_IDX(size);
 
 	gref_start = gntdev_find_grefs(priv_user, *offset, count);
 	if (gref_start) {

sys/sys/types.h

@@ -261,7 +261,7 @@ typedef	__uint64_t	kvaddr_t;
 typedef	__uint64_t	ksize_t;
 
 typedef	__vm_offset_t	vm_offset_t;
-typedef	__int64_t	vm_ooffset_t;
+typedef	__uint64_t	vm_ooffset_t;
 typedef	__vm_paddr_t	vm_paddr_t;
 typedef	__uint64_t	vm_pindex_t;
 typedef	__vm_size_t	vm_size_t;

sys/vm/device_pager.c

@@ -150,9 +150,9 @@ cdev_pager_allocate(void *handle, enum obj_type tp, struct cdev_pager_ops *ops,
 	 * of the page size.  Do a check to avoid wrap.
 	 */
 	size = round_page(size);
-	pindex = UOFF_TO_IDX(foff) + UOFF_TO_IDX(size);
+	pindex = OFF_TO_IDX(foff) + OFF_TO_IDX(size);
-	if (pindex > OBJ_MAX_SIZE || pindex < UOFF_TO_IDX(foff) ||
+	if (pindex > OBJ_MAX_SIZE || pindex < OFF_TO_IDX(foff) ||
-	    pindex < UOFF_TO_IDX(size))
+	    pindex < OFF_TO_IDX(size))
 		return (NULL);
 
 	if (ops->cdev_pg_ctor(handle, size, prot, foff, cred, &color) != 0)

sys/vm/sg_pager.c

@@ -100,9 +100,9 @@ sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
 	 * to map beyond that.
 	 */
 	size = round_page(size);
-	pindex = UOFF_TO_IDX(foff) + UOFF_TO_IDX(size);
+	pindex = OFF_TO_IDX(foff) + OFF_TO_IDX(size);
-	if (pindex > npages || pindex < UOFF_TO_IDX(foff) ||
+	if (pindex > npages || pindex < OFF_TO_IDX(foff) ||
-	    pindex < UOFF_TO_IDX(size))
+	    pindex < OFF_TO_IDX(size))
 		return (NULL);
 
 	/*

sys/vm/vm_map.c

@@ -4213,7 +4213,7 @@ vm_map_lookup(vm_map_t *var_map,		/* IN/OUT */
 	 * Return the object/offset from this entry.  If the entry was
 	 * copy-on-write or empty, it has been fixed up.
 	 */
-	*pindex = UOFF_TO_IDX((vaddr - entry->start) + entry->offset);
+	*pindex = OFF_TO_IDX((vaddr - entry->start) + entry->offset);
 	*object = entry->object.vm_object;
 
 	*out_prot = prot;
@@ -4294,7 +4294,7 @@ vm_map_lookup_locked(vm_map_t *var_map,		/* IN/OUT */
 	 * Return the object/offset from this entry.  If the entry was
 	 * copy-on-write or empty, it has been fixed up.
 	 */
-	*pindex = UOFF_TO_IDX((vaddr - entry->start) + entry->offset);
+	*pindex = OFF_TO_IDX((vaddr - entry->start) + entry->offset);
 	*object = entry->object.vm_object;
 
 	*out_prot = prot;

sys/vm/vm_object.h

@@ -196,20 +196,13 @@ struct vm_object {
 /*
  * Helpers to perform conversion between vm_object page indexes and offsets.
  * IDX_TO_OFF() converts an index into an offset.
- * OFF_TO_IDX() converts an offset into an index.  Since offsets are signed
+ * OFF_TO_IDX() converts an offset into an index.
- *   by default, the sign propagation in OFF_TO_IDX(), when applied to
- *   negative offsets, is intentional and returns a vm_object page index
- *   that cannot be created by a userspace mapping.
- * UOFF_TO_IDX() treats the offset as an unsigned value and converts it
- *   into an index accordingly.  Use it only when the full range of offset
- *   values are allowed.  Currently, this only applies to device mappings.
  * OBJ_MAX_SIZE specifies the maximum page index corresponding to the
  *   maximum unsigned offset.
  */
 #define	IDX_TO_OFF(idx) (((vm_ooffset_t)(idx)) << PAGE_SHIFT)
 #define	OFF_TO_IDX(off) ((vm_pindex_t)(((vm_ooffset_t)(off)) >> PAGE_SHIFT))
-#define	UOFF_TO_IDX(off) (((vm_pindex_t)(off)) >> PAGE_SHIFT)
+#define	OBJ_MAX_SIZE	(OFF_TO_IDX(UINT64_MAX) + 1)
-#define	OBJ_MAX_SIZE	(UOFF_TO_IDX(UINT64_MAX) + 1)
 
 #ifdef	_KERNEL