Allow non-privileged tasks to wire 64KiB task memory

* doc/mach.texi (vm_wire): Document that the host port does not have to be
privileged.
* include/mach/mach_hosts.defs (vm_wire): Use mach_port_t instead of
host_priv_t.
* vm/vm_map.h (vm_map): Add user_wired field.
* vm/vm_map.c (vm_map_setup): Initialize user_wired field to 0.
(vm_map_pageable_common, vm_map_entry_delete, vm_map_copy_overwrite,
vm_map_copyout_page_list, vm_map_copyin_page_list): When switching
user_wired_count field of entry between 0 and non-0, accumulate the
corresponding size into the user_wired field of map.
* vm/vm_user.c (vm_wire): Turn host parameter into port parameter, and
inline a version of convert_port_to_host_priv which records whether the host
port is privileged or not.  When it is not privileged, check whether
the additional amount to user_wired will overcome 64KiB.

1 files changed, 24 insertions, 3 deletions

diff --git a/vm/vm_user.c b/vm/vm_user.c
index f7c87cc..8c7a5d8 100644
--- a/vm/vm_user.c
+++ b/vm/vm_user.c
@@ -405,15 +405,32 @@ kern_return_t vm_map(
  *
  *	[ To unwire the pages, specify VM_PROT_NONE. ]
  */
-kern_return_t vm_wire(host, map, start, size, access)
-	const host_t		host;
+kern_return_t vm_wire(port, map, start, size, access)
+	const ipc_port_t	port;
 	vm_map_t		map;
 	vm_offset_t		start;
 	vm_size_t		size;
 	vm_prot_t		access;
 {
-	if (host == HOST_NULL)
+	host_t host;
+	boolean_t priv;
+
+	if (!IP_VALID(port))
+		return KERN_INVALID_HOST;
+
+	ip_lock(port);
+	if (!ip_active(port) ||
+		  (ip_kotype(port) != IKOT_HOST_PRIV
+		&& ip_kotype(port) != IKOT_HOST))
+	{
+		ip_unlock(port);
 		return KERN_INVALID_HOST;
+	}
+
+	priv = ip_kotype(port) == IKOT_HOST_PRIV;
+	ip_unlock(port);
+
+	host = (host_t) port->ip_kobject;
 
 	if (map == VM_MAP_NULL)
 		return KERN_INVALID_TASK;
@@ -426,6 +443,10 @@ kern_return_t vm_wire(host, map, start, size, access)
 	if (projected_buffer_in_range(map, start, start+size))
 		return(KERN_INVALID_ARGUMENT);
 
+	/* TODO: make it tunable */
+	if (!priv && access != VM_PROT_NONE && map->user_wired + size > 65536)
+		return KERN_NO_ACCESS;
+
 	return vm_map_pageable_user(map,
 				    trunc_page(start),
 				    round_page(start+size),