path: root/sys/uvm/uvm_map.c

/*	$OpenBSD: uvm_map.c,v 1.146 2011/11/08 11:42:43 miod Exp $	*/
/*	$NetBSD: uvm_map.c,v 1.86 2000/11/27 08:40:03 chs Exp $	*/

/* 
 * Copyright (c) 1997 Charles D. Cranor and Washington University.
 * Copyright (c) 1991, 1993, The Regents of the University of California.  
 *
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * The Mach Operating System project at Carnegie-Mellon University.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Charles D. Cranor,
 *      Washington University, the University of California, Berkeley and 
 *      its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)vm_map.c    8.3 (Berkeley) 1/12/94
 * from: Id: uvm_map.c,v 1.1.2.27 1998/02/07 01:16:54 chs Exp
 *
 *
 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
 * All rights reserved.
 * 
 * Permission to use, copy, modify and distribute this software and
 * its documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 
 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */

/*
 * uvm_map.c: uvm map operations
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mman.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/pool.h>
#include <sys/kernel.h>

#include <dev/rndvar.h>

#ifdef SYSVSHM
#include <sys/shm.h>
#endif

#include <uvm/uvm.h>
#undef RB_AUGMENT
#define RB_AUGMENT(x) uvm_rb_augment(x)

#ifdef DDB
#include <uvm/uvm_ddb.h>
#endif

static struct timeval uvm_kmapent_last_warn_time;
static struct timeval uvm_kmapent_warn_rate = { 10, 0 };

const char vmmapbsy[] = "vmmapbsy";

/*
 * pool for vmspace structures.
 */

struct pool uvm_vmspace_pool;

/*
 * pool for dynamically-allocated map entries.
 */

struct pool uvm_map_entry_pool;
struct pool uvm_map_entry_kmem_pool;

#ifdef PMAP_GROWKERNEL
/*
 * This global represents the end of the kernel virtual address
 * space.  If we want to exceed this, we must grow the kernel
 * virtual address space dynamically.
 *
 * Note, this variable is locked by kernel_map's lock.
 */
vaddr_t uvm_maxkaddr;
#endif

/*
 * macros
 */

/*
 * uvm_map_entry_link: insert entry into a map
 *
 * => map must be locked
 */
#define uvm_map_entry_link(map, after_where, entry) do { \
	(map)->nentries++; \
	(entry)->prev = (after_where); \
	(entry)->next = (after_where)->next; \
	(entry)->prev->next = (entry); \
	(entry)->next->prev = (entry); \
	uvm_rb_insert(map, entry); \
} while (0)

/*
 * uvm_map_entry_unlink: remove entry from a map
 *
 * => map must be locked
 */
#define uvm_map_entry_unlink(map, entry) do { \
	(map)->nentries--; \
	(entry)->next->prev = (entry)->prev; \
	(entry)->prev->next = (entry)->next; \
	uvm_rb_remove(map, entry); \
} while (0)

/*
 * SAVE_HINT: saves the specified entry as the hint for future lookups.
 *
 * => map need not be locked (protected by hint_lock).
 */
#define SAVE_HINT(map,check,value) do { \
	simple_lock(&(map)->hint_lock); \
	if ((map)->hint == (check)) \
		(map)->hint = (value); \
	simple_unlock(&(map)->hint_lock); \
} while (0)

/*
 * VM_MAP_RANGE_CHECK: check and correct range
 *
 * => map must at least be read locked
 */

#define VM_MAP_RANGE_CHECK(map, start, end) do { \
	if (start < vm_map_min(map)) 		\
		start = vm_map_min(map);        \
	if (end > vm_map_max(map))              \
		end = vm_map_max(map);          \
	if (start > end)                        \
		start = end;                    \
} while (0)

/*
 * local prototypes
 */

void uvm_mapent_copy(struct vm_map_entry *, struct vm_map_entry *);
void uvm_map_entry_unwire(struct vm_map *, struct vm_map_entry *);
void uvm_map_reference_amap(struct vm_map_entry *, int);
void uvm_map_unreference_amap(struct vm_map_entry *, int);
int uvm_map_spacefits(struct vm_map *, vaddr_t *, vsize_t,
    struct vm_map_entry *, voff_t, vsize_t);

struct vm_map_entry	*uvm_mapent_alloc(struct vm_map *, int);
void			uvm_mapent_free(struct vm_map_entry *);

#ifdef KVA_GUARDPAGES
/*
 * Number of kva guardpages in use.
 */
int kva_guardpages;
#endif


/*
 * Tree manipulation.
 */
void uvm_rb_insert(struct vm_map *, struct vm_map_entry *);
void uvm_rb_remove(struct vm_map *, struct vm_map_entry *);
vsize_t uvm_rb_space(struct vm_map *, struct vm_map_entry *);

#ifdef DEBUG
int _uvm_tree_sanity(struct vm_map *map, const char *name);
#endif
vsize_t uvm_rb_subtree_space(struct vm_map_entry *);
void uvm_rb_fixup(struct vm_map *, struct vm_map_entry *);

static __inline int
uvm_compare(struct vm_map_entry *a, struct vm_map_entry *b)
{
	if (a->start < b->start)
		return (-1);
	else if (a->start > b->start)
		return (1);
	
	return (0);
}


static __inline void
uvm_rb_augment(struct vm_map_entry *entry)
{
	entry->space = uvm_rb_subtree_space(entry);
}

RB_PROTOTYPE(uvm_tree, vm_map_entry, rb_entry, uvm_compare);

RB_GENERATE(uvm_tree, vm_map_entry, rb_entry, uvm_compare);

vsize_t
uvm_rb_space(struct vm_map *map, struct vm_map_entry *entry)
{
	struct vm_map_entry *next;
	vaddr_t space;

	if ((next = entry->next) == &map->header)
		space = map->max_offset - entry->end;
	else {
		KASSERT(next);
		space = next->start - entry->end;
	}
	return (space);
}
		
vsize_t
uvm_rb_subtree_space(struct vm_map_entry *entry)
{
	vaddr_t space, tmp;

	space = entry->ownspace;
	if (RB_LEFT(entry, rb_entry)) {
		tmp = RB_LEFT(entry, rb_entry)->space;
		if (tmp > space)
			space = tmp;
	}

	if (RB_RIGHT(entry, rb_entry)) {
		tmp = RB_RIGHT(entry, rb_entry)->space;
		if (tmp > space)
			space = tmp;
	}

	return (space);
}

void
uvm_rb_fixup(struct vm_map *map, struct vm_map_entry *entry)
{
	/* We need to traverse to the very top */
	do {
		entry->ownspace = uvm_rb_space(map, entry);
		entry->space = uvm_rb_subtree_space(entry);
	} while ((entry = RB_PARENT(entry, rb_entry)) != NULL);
}

void
uvm_rb_insert(struct vm_map *map, struct vm_map_entry *entry)
{
	vaddr_t space = uvm_rb_space(map, entry);
	struct vm_map_entry *tmp;

	entry->ownspace = entry->space = space;
	tmp = RB_INSERT(uvm_tree, &(map)->rbhead, entry);
#ifdef DIAGNOSTIC
	if (tmp != NULL)
		panic("uvm_rb_insert: duplicate entry?");
#endif
	uvm_rb_fixup(map, entry);
	if (entry->prev != &map->header)
		uvm_rb_fixup(map, entry->prev);
}

void
uvm_rb_remove(struct vm_map *map, struct vm_map_entry *entry)
{
	struct vm_map_entry *parent;

	parent = RB_PARENT(entry, rb_entry);
	RB_REMOVE(uvm_tree, &(map)->rbhead, entry);
	if (entry->prev != &map->header)
		uvm_rb_fixup(map, entry->prev);
	if (parent)
		uvm_rb_fixup(map, parent);
}

#ifdef DEBUG
#define uvm_tree_sanity(x,y) _uvm_tree_sanity(x,y)
#else
#define uvm_tree_sanity(x,y)
#endif

#ifdef DEBUG
int
_uvm_tree_sanity(struct vm_map *map, const char *name)
{
	struct vm_map_entry *tmp, *trtmp;
	int n = 0, i = 1;

	RB_FOREACH(tmp, uvm_tree, &map->rbhead) {
		if (tmp->ownspace != uvm_rb_space(map, tmp)) {
			printf("%s: %d/%d ownspace %x != %x %s\n",
			    name, n + 1, map->nentries,
			    tmp->ownspace, uvm_rb_space(map, tmp),
			    tmp->next == &map->header ? "(last)" : "");
			goto error;
		}
	}
	trtmp = NULL;
	RB_FOREACH(tmp, uvm_tree, &map->rbhead) {
		if (tmp->space != uvm_rb_subtree_space(tmp)) {
			printf("%s: space %d != %d\n",
			    name, tmp->space, uvm_rb_subtree_space(tmp));
			goto error;
		}
		if (trtmp != NULL && trtmp->start >= tmp->start) {
			printf("%s: corrupt: 0x%lx >= 0x%lx\n",
			    name, trtmp->start, tmp->start);
			goto error;
		}
		n++;

	    trtmp = tmp;
	}

	if (n != map->nentries) {
		printf("%s: nentries: %d vs %d\n",
		    name, n, map->nentries);
		goto error;
	}

	for (tmp = map->header.next; tmp && tmp != &map->header;
	    tmp = tmp->next, i++) {
		trtmp = RB_FIND(uvm_tree, &map->rbhead, tmp);
		if (trtmp != tmp) {
			printf("%s: lookup: %d: %p - %p: %p\n",
			    name, i, tmp, trtmp,
			    RB_PARENT(tmp, rb_entry));
			goto error;
		}
	}

	return (0);
 error:
#ifdef	DDB
	/* handy breakpoint location for error case */
	__asm(".globl treesanity_label\ntreesanity_label:");
#endif
	return (-1);
}
#endif

/*
 * uvm_mapent_alloc: allocate a map entry
 */

struct vm_map_entry *
uvm_mapent_alloc(struct vm_map *map, int flags)
{
	struct vm_map_entry *me, *ne;
	int s, i;
	int pool_flags;

	pool_flags = PR_WAITOK;
	if (flags & UVM_FLAG_TRYLOCK)
		pool_flags = PR_NOWAIT;

	if (map->flags & VM_MAP_INTRSAFE || cold) {
		s = splvm();
		simple_lock(&uvm.kentry_lock);
		me = uvm.kentry_free;
		if (me == NULL) {
			ne = km_alloc(PAGE_SIZE, &kv_page, &kp_dirty,
			    &kd_nowait);
			if (ne == NULL)
				panic("uvm_mapent_alloc: cannot allocate map "
				    "entry");
			for (i = 0;
			    i < PAGE_SIZE / sizeof(struct vm_map_entry) - 1;
			    i++)
				ne[i].next = &ne[i + 1];
			ne[i].next = NULL;
			me = ne;
			if (ratecheck(&uvm_kmapent_last_warn_time,
			    &uvm_kmapent_warn_rate))
				printf("uvm_mapent_alloc: out of static "
				    "map entries\n");
		}
		uvm.kentry_free = me->next;
		uvmexp.kmapent++;
		simple_unlock(&uvm.kentry_lock);
		splx(s);
		me->flags = UVM_MAP_STATIC;
	} else if (map == kernel_map) {
		splassert(IPL_NONE);
		me = pool_get(&uvm_map_entry_kmem_pool, pool_flags);
		if (me == NULL)
			goto out;
		me->flags = UVM_MAP_KMEM;
	} else {
		splassert(IPL_NONE);
		me = pool_get(&uvm_map_entry_pool, pool_flags);
		if (me == NULL)
			goto out;
		me->flags = 0;
	}

out:
	return(me);
}

/*
 * uvm_mapent_free: free map entry
 *
 * => XXX: static pool for kernel map?
 */

void
uvm_mapent_free(struct vm_map_entry *me)
{
	int s;

	if (me->flags & UVM_MAP_STATIC) {
		s = splvm();
		simple_lock(&uvm.kentry_lock);
		me->next = uvm.kentry_free;
		uvm.kentry_free = me;
		uvmexp.kmapent--;
		simple_unlock(&uvm.kentry_lock);
		splx(s);
	} else if (me->flags & UVM_MAP_KMEM) {
		splassert(IPL_NONE);
		pool_put(&uvm_map_entry_kmem_pool, me);
	} else {
		splassert(IPL_NONE);
		pool_put(&uvm_map_entry_pool, me);
	}
}

/*
 * uvm_mapent_copy: copy a map entry, preserving flags
 */

void
uvm_mapent_copy(struct vm_map_entry *src, struct vm_map_entry *dst)
{
	memcpy(dst, src, ((char *)&src->uvm_map_entry_stop_copy) -
	    ((char *)src));
}

/*
 * uvm_map_entry_unwire: unwire a map entry
 *
 * => map should be locked by caller
 */
void
uvm_map_entry_unwire(struct vm_map *map, struct vm_map_entry *entry)
{

	entry->wired_count = 0;
	uvm_fault_unwire_locked(map, entry->start, entry->end);
}


/*
 * wrapper for calling amap_ref()
 */
void
uvm_map_reference_amap(struct vm_map_entry *entry, int flags)
{
	amap_ref(entry->aref.ar_amap, entry->aref.ar_pageoff,
	    (entry->end - entry->start) >> PAGE_SHIFT, flags);
}


/*
 * wrapper for calling amap_unref() 
 */
void
uvm_map_unreference_amap(struct vm_map_entry *entry, int flags)
{
	amap_unref(entry->aref.ar_amap, entry->aref.ar_pageoff,
	    (entry->end - entry->start) >> PAGE_SHIFT, flags);
}


/*
 * uvm_map_init: init mapping system at boot time.   note that we allocate
 * and init the static pool of structs vm_map_entry for the kernel here.
 */

void
uvm_map_init(void)
{
	static struct vm_map_entry kernel_map_entry[MAX_KMAPENT];
	int lcv;

	/*
	 * set up static pool of kernel map entries ...
	 */

	simple_lock_init(&uvm.kentry_lock);
	uvm.kentry_free = NULL;
	for (lcv = 0 ; lcv < MAX_KMAPENT ; lcv++) {
		kernel_map_entry[lcv].next = uvm.kentry_free;
		uvm.kentry_free = &kernel_map_entry[lcv];
	}

	/*
	 * initialize the map-related pools.
	 */
	pool_init(&uvm_vmspace_pool, sizeof(struct vmspace),
	    0, 0, 0, "vmsppl", &pool_allocator_nointr);
	pool_init(&uvm_map_entry_pool, sizeof(struct vm_map_entry),
	    0, 0, 0, "vmmpepl", &pool_allocator_nointr);
	pool_init(&uvm_map_entry_kmem_pool, sizeof(struct vm_map_entry),
	    0, 0, 0, "vmmpekpl", NULL);
	pool_sethiwat(&uvm_map_entry_pool, 8192);
}

/*
 * clippers
 */

/*
 * uvm_map_clip_start: ensure that the entry begins at or after
 *	the starting address, if it doesn't we split the entry.
 * 
 * => caller should use UVM_MAP_CLIP_START macro rather than calling
 *    this directly
 * => map must be locked by caller
 */

void
uvm_map_clip_start(struct vm_map *map, struct vm_map_entry *entry,
    vaddr_t start)
{
	struct vm_map_entry *new_entry;
	vaddr_t new_adj;

	/* uvm_map_simplify_entry(map, entry); */ /* XXX */

	uvm_tree_sanity(map, "clip_start entry");

	/*
	 * Split off the front portion.  note that we must insert the new
	 * entry BEFORE this one, so that this entry has the specified
	 * starting address.
	 */

	new_entry = uvm_mapent_alloc(map, 0);
	uvm_mapent_copy(entry, new_entry); /* entry -> new_entry */

	new_entry->end = start; 
	new_adj = start - new_entry->start;
	if (entry->object.uvm_obj)
		entry->offset += new_adj;	/* shift start over */

	/* Does not change order for the RB tree */
	entry->start = start;

	if (new_entry->aref.ar_amap) {
		amap_splitref(&new_entry->aref, &entry->aref, new_adj);
	}

	uvm_map_entry_link(map, entry->prev, new_entry);

	if (UVM_ET_ISSUBMAP(entry)) {
		/* ... unlikely to happen, but play it safe */
		 uvm_map_reference(new_entry->object.sub_map);
	} else {
		if (UVM_ET_ISOBJ(entry) && 
		    entry->object.uvm_obj->pgops &&
		    entry->object.uvm_obj->pgops->pgo_reference)
			entry->object.uvm_obj->pgops->pgo_reference(
			    entry->object.uvm_obj);
	}

	uvm_tree_sanity(map, "clip_start leave");
}

/*
 * uvm_map_clip_end: ensure that the entry ends at or before
 *	the ending address, if it doesn't we split the reference
 * 
 * => caller should use UVM_MAP_CLIP_END macro rather than calling
 *    this directly
 * => map must be locked by caller
 */

void
uvm_map_clip_end(struct vm_map *map, struct vm_map_entry *entry, vaddr_t end)
{
	struct vm_map_entry *new_entry;
	vaddr_t new_adj; /* #bytes we move start forward */

	uvm_tree_sanity(map, "clip_end entry");
	/*
	 *	Create a new entry and insert it
	 *	AFTER the specified entry
	 */

	new_entry = uvm_mapent_alloc(map, 0);
	uvm_mapent_copy(entry, new_entry); /* entry -> new_entry */

	new_entry->start = entry->end = end;
	new_adj = end - entry->start;
	if (new_entry->object.uvm_obj)
		new_entry->offset += new_adj;

	if (entry->aref.ar_amap)
		amap_splitref(&entry->aref, &new_entry->aref, new_adj);
	
	uvm_rb_fixup(map, entry);

	uvm_map_entry_link(map, entry, new_entry);

	if (UVM_ET_ISSUBMAP(entry)) {
		/* ... unlikely to happen, but play it safe */
	 	uvm_map_reference(new_entry->object.sub_map);
	} else {
		if (UVM_ET_ISOBJ(entry) &&
		    entry->object.uvm_obj->pgops &&
		    entry->object.uvm_obj->pgops->pgo_reference)
			entry->object.uvm_obj->pgops->pgo_reference(
			    entry->object.uvm_obj);
	}
	uvm_tree_sanity(map, "clip_end leave");
}


/*
 *   M A P   -   m a i n   e n t r y   p o i n t
 */
/*
 * uvm_map: establish a valid mapping in a map
 *
 * => assume startp is page aligned.
 * => assume size is a multiple of PAGE_SIZE.
 * => assume sys_mmap provides enough of a "hint" to have us skip
 *	over text/data/bss area.
 * => map must be unlocked (we will lock it)
 * => <uobj,uoffset> value meanings (4 cases):
 *	 [1] <NULL,uoffset> 		== uoffset is a hint for PMAP_PREFER
 *	 [2] <NULL,UVM_UNKNOWN_OFFSET>	== don't PMAP_PREFER
 *	 [3] <uobj,uoffset>		== normal mapping
 *	 [4] <uobj,UVM_UNKNOWN_OFFSET>	== uvm_map finds offset based on VA
 *	
 *    case [4] is for kernel mappings where we don't know the offset until
 *    we've found a virtual address.   note that kernel object offsets are
 *    always relative to vm_map_min(kernel_map).
 *
 * => if `align' is non-zero, we try to align the virtual address to
 *	the specified alignment.  this is only a hint; if we can't
 *	do it, the address will be unaligned.  this is provided as
 *	a mechanism for large pages.
 *
 * => XXXCDC: need way to map in external amap?
 */

int
uvm_map_p(struct vm_map *map, vaddr_t *startp, vsize_t size,
    struct uvm_object *uobj, voff_t uoffset, vsize_t align, uvm_flag_t flags,
    struct proc *p)
{
	struct vm_map_entry *prev_entry, *new_entry;
#ifdef KVA_GUARDPAGES
	struct vm_map_entry *guard_entry;
#endif
	vm_prot_t prot = UVM_PROTECTION(flags), maxprot =
	    UVM_MAXPROTECTION(flags);
	vm_inherit_t inherit = UVM_INHERIT(flags);
	int advice = UVM_ADVICE(flags);
	int error;

	/*
	 * Holes are incompatible with other types of mappings.
	 */
	if (flags & UVM_FLAG_HOLE) {
		KASSERT(uobj == NULL && (flags & UVM_FLAG_FIXED) != 0 &&
		    (flags & (UVM_FLAG_OVERLAY | UVM_FLAG_COPYONW)) == 0);
	}

#ifdef KVA_GUARDPAGES
	if (map == kernel_map && !(flags & UVM_FLAG_FIXED)) {
		/*
		 * kva_guardstart is initialized to the start of the kernelmap
		 * and cycles through the kva space.
		 * This way we should have a long time between re-use of kva.
		 */
		static vaddr_t kva_guardstart = 0;
		if (kva_guardstart == 0) {
			kva_guardstart = vm_map_min(map);
			printf("uvm_map: kva guard pages enabled: %p\n",
			    kva_guardstart);
		}
		size += PAGE_SIZE;	/* Add guard page at the end. */
		/*
		 * Try to fully exhaust kva prior to wrap-around.
		 * (This may eat your ram!)
		 */
		if (VM_MAX_KERNEL_ADDRESS - kva_guardstart < size) {
			static int wrap_counter = 0;
			printf("uvm_map: kva guard page wrap-around %d\n",
			    ++wrap_counter);
			kva_guardstart = vm_map_min(map);
		}
		*startp = kva_guardstart;
		/*
		 * Prepare for next round.
		 */
		kva_guardstart += size;
	}
#endif

	uvm_tree_sanity(map, "map entry");

	if ((map->flags & VM_MAP_INTRSAFE) == 0)
		splassert(IPL_NONE);
	else
		splassert(IPL_VM);

	/*
	 * step 0: sanity check of protection code
	 */

	if ((prot & maxprot) != prot) {
		return (EACCES);
	}

	/*
	 * step 1: figure out where to put new VM range
	 */

	if (vm_map_lock_try(map) == FALSE) {
		if (flags & UVM_FLAG_TRYLOCK)
			return (EFAULT);
		vm_map_lock(map); /* could sleep here */
	}
	if ((prev_entry = uvm_map_findspace(map, *startp, size, startp, 
	    uobj, uoffset, align, flags)) == NULL) {
		vm_map_unlock(map);
		return (ENOMEM);
	}

#ifdef PMAP_GROWKERNEL
	{
		/*
		 * If the kernel pmap can't map the requested space,
		 * then allocate more resources for it.
		 */
		if (map == kernel_map && !(flags & UVM_FLAG_FIXED) &&
		    uvm_maxkaddr < (*startp + size))
			uvm_maxkaddr = pmap_growkernel(*startp + size);
	}
#endif

	/*
	 * if uobj is null, then uoffset is either a VAC hint for PMAP_PREFER
	 * [typically from uvm_map_reserve] or it is UVM_UNKNOWN_OFFSET.   in 
	 * either case we want to zero it  before storing it in the map entry 
	 * (because it looks strange and confusing when debugging...)
	 * 
	 * if uobj is not null 
	 *   if uoffset is not UVM_UNKNOWN_OFFSET then we have a normal mapping
	 *      and we do not need to change uoffset.
	 *   if uoffset is UVM_UNKNOWN_OFFSET then we need to find the offset
	 *      now (based on the starting address of the map).   this case is
	 *      for kernel object mappings where we don't know the offset until
	 *      the virtual address is found (with uvm_map_findspace).   the
	 *      offset is the distance we are from the start of the map.
	 */

	if (uobj == NULL) {
		uoffset = 0;
	} else {
		if (uoffset == UVM_UNKNOWN_OFFSET) {
			KASSERT(UVM_OBJ_IS_KERN_OBJECT(uobj));
			uoffset = *startp - vm_map_min(kernel_map);
		}
	}

	/*
	 * step 2: try and insert in map by extending previous entry, if
	 * possible
	 * XXX: we don't try and pull back the next entry.   might be useful
	 * for a stack, but we are currently allocating our stack in advance.
	 */

	if ((flags & UVM_FLAG_NOMERGE) == 0 && 
	    prev_entry->end == *startp && prev_entry != &map->header &&
	    prev_entry->object.uvm_obj == uobj) {

		if (uobj && prev_entry->offset +
		    (prev_entry->end - prev_entry->start) != uoffset)
			goto step3;

		if (UVM_ET_ISSUBMAP(prev_entry))
			goto step3;

		if (prev_entry->protection != prot || 
		    prev_entry->max_protection != maxprot)
			goto step3;

		if (prev_entry->inheritance != inherit ||
		    prev_entry->advice != advice)
			goto step3;

		/* wiring status must match (new area is unwired) */
		if (VM_MAPENT_ISWIRED(prev_entry))
			goto step3; 

		/*
		 * can't extend a shared amap.  note: no need to lock amap to 
		 * look at refs since we don't care about its exact value.
		 * if it is one (i.e. we have only reference) it will stay there
		 */

		if (prev_entry->aref.ar_amap &&
		    amap_refs(prev_entry->aref.ar_amap) != 1) {
			goto step3;
		}

		/*
		 * Only merge kernel mappings, but keep track
		 * of how much we skipped.
		 */
		if (map != kernel_map && map != kmem_map) {
			goto step3;
		}

		if (prev_entry->aref.ar_amap) {
			error = amap_extend(prev_entry, size);
			if (error)
				goto step3;
		}

		/*
		 * drop our reference to uobj since we are extending a reference
		 * that we already have (the ref count can not drop to zero).
		 */

		if (uobj && uobj->pgops->pgo_detach)
			uobj->pgops->pgo_detach(uobj);

		prev_entry->end += size;
		uvm_rb_fixup(map, prev_entry);
		map->size += size;
		if (p && uobj == NULL)
			p->p_vmspace->vm_dused += atop(size);

		uvm_tree_sanity(map, "map leave 2");

		vm_map_unlock(map);
		return (0);

	}
step3:

	/*
	 * step 3: allocate new entry and link it in
	 */

#ifdef KVA_GUARDPAGES
	if (map == kernel_map && !(flags & UVM_FLAG_FIXED))
		size -= PAGE_SIZE;
#endif

	new_entry = uvm_mapent_alloc(map, flags);
	if (new_entry == NULL) {
		vm_map_unlock(map);
		return (ENOMEM);
	}
	new_entry->start = *startp;
	new_entry->end = new_entry->start + size;
	new_entry->object.uvm_obj = uobj;
	new_entry->offset = uoffset;

	if (uobj) 
		new_entry->etype = UVM_ET_OBJ;
	else
		new_entry->etype = 0;

	if (flags & UVM_FLAG_COPYONW) {
		new_entry->etype |= UVM_ET_COPYONWRITE;
		if ((flags & UVM_FLAG_OVERLAY) == 0)
			new_entry->etype |= UVM_ET_NEEDSCOPY;
	}
	if (flags & UVM_FLAG_HOLE)
		new_entry->etype |= UVM_ET_HOLE;

	new_entry->protection = prot;
	new_entry->max_protection = maxprot;
	new_entry->inheritance = inherit;
	new_entry->wired_count = 0;
	new_entry->advice = advice;
	if (flags & UVM_FLAG_OVERLAY) {
		/*
		 * to_add: for BSS we overallocate a little since we
		 * are likely to extend
		 */
		vaddr_t to_add = (flags & UVM_FLAG_AMAPPAD) ? 
			UVM_AMAP_CHUNK << PAGE_SHIFT : 0;
		struct vm_amap *amap = amap_alloc(size, to_add, M_WAITOK);
		new_entry->aref.ar_pageoff = 0;
		new_entry->aref.ar_amap = amap;
	} else {
		new_entry->aref.ar_pageoff = 0;
		new_entry->aref.ar_amap = NULL;
	}

	uvm_map_entry_link(map, prev_entry, new_entry);

	map->size += size;
	if (p && uobj == NULL)
		p->p_vmspace->vm_dused += atop(size);


	/*
	 *      Update the free space hint
	 */

	if ((map->first_free == prev_entry) &&
	    (prev_entry->end >= new_entry->start))
		map->first_free = new_entry;

#ifdef KVA_GUARDPAGES
	/*
	 * Create the guard entry.
	 */
	if (map == kernel_map && !(flags & UVM_FLAG_FIXED)) {
		guard_entry = uvm_mapent_alloc(map, flags);
		if (guard_entry != NULL) {
			guard_entry->start = new_entry->end;
			guard_entry->end = guard_entry->start + PAGE_SIZE;
			guard_entry->object.uvm_obj = uobj;
			guard_entry->offset = uoffset;
			guard_entry->etype = MAP_ET_KVAGUARD;
			guard_entry->protection = prot;
			guard_entry->max_protection = maxprot;
			guard_entry->inheritance = inherit;
			guard_entry->wired_count = 0;
			guard_entry->advice = advice;
			guard_entry->aref.ar_pageoff = 0;
			guard_entry->aref.ar_amap = NULL;
			uvm_map_entry_link(map, new_entry, guard_entry);
			map->size += PAGE_SIZE;
			kva_guardpages++;
		}
	}
#endif

	uvm_tree_sanity(map, "map leave");

	vm_map_unlock(map);
	return (0);
}

/*
 * uvm_map_lookup_entry: find map entry at or before an address
 *
 * => map must at least be read-locked by caller
 * => entry is returned in "entry"
 * => return value is true if address is in the returned entry
 */

boolean_t
uvm_map_lookup_entry(struct vm_map *map, vaddr_t address,
    struct vm_map_entry **entry)
{
	struct vm_map_entry *cur;
	struct vm_map_entry *last;
	int			use_tree = 0;

	/*
	 * start looking either from the head of the
	 * list, or from the hint.
	 */

	simple_lock(&map->hint_lock);
	cur = map->hint;
	simple_unlock(&map->hint_lock);

	if (cur == &map->header)
		cur = cur->next;

	if (address >= cur->start) {
	    	/*
		 * go from hint to end of list.
		 *
		 * but first, make a quick check to see if
		 * we are already looking at the entry we
		 * want (which is usually the case).
		 * note also that we don't need to save the hint
		 * here... it is the same hint (unless we are
		 * at the header, in which case the hint didn't
		 * buy us anything anyway).
		 */
		last = &map->header;
		if ((cur != last) && (cur->end > address)) {
			*entry = cur;
			return (TRUE);
		}

		if (map->nentries > 30)
			use_tree = 1;
	} else {
	    	/*
		 * go from start to hint, *inclusively*
		 */
		last = cur->next;
		cur = map->header.next;
		use_tree = 1;
	}

	uvm_tree_sanity(map, __func__);

	if (use_tree) {
		struct vm_map_entry *prev = &map->header;
		cur = RB_ROOT(&map->rbhead);

		/*
		 * Simple lookup in the tree.  Happens when the hint is
		 * invalid, or nentries reach a threshold.
		 */
		while (cur) {
			if (address >= cur->start) {
				if (address < cur->end) {
					*entry = cur;
					SAVE_HINT(map, map->hint, cur);
					return (TRUE);
				}
				prev = cur;
				cur = RB_RIGHT(cur, rb_entry);
			} else
				cur = RB_LEFT(cur, rb_entry);
		}
		*entry = prev;
		return (FALSE);
	}

	/*
	 * search linearly
	 */

	while (cur != last) {
		if (cur->end > address) {
			if (address >= cur->start) {
			    	/*
				 * save this lookup for future
				 * hints, and return
				 */

				*entry = cur;
				SAVE_HINT(map, map->hint, cur);
				return (TRUE);
			}
			break;
		}
		cur = cur->next;
	}

	*entry = cur->prev;
	SAVE_HINT(map, map->hint, *entry);
	return (FALSE);
}

/*
 * Checks if address pointed to by phint fits into the empty
 * space before the vm_map_entry after.  Takes alignment and
 * offset into consideration.
 */

int
uvm_map_spacefits(struct vm_map *map, vaddr_t *phint, vsize_t length,
    struct vm_map_entry *after, voff_t uoffset, vsize_t align)
{
	vaddr_t hint = *phint;
	vaddr_t end;

#ifdef PMAP_PREFER
	/*
	 * push hint forward as needed to avoid VAC alias problems.
	 * we only do this if a valid offset is specified.
	 */
	if (uoffset != UVM_UNKNOWN_OFFSET)
		hint = PMAP_PREFER(uoffset, hint);
#endif
	if (align != 0)
		if ((hint & (align - 1)) != 0)
			hint = roundup(hint, align);
	*phint = hint;

	end = hint + length;
	if (end > map->max_offset || end < hint)
		return (FALSE);
	if (after != NULL && after != &map->header && after->start < end)
		return (FALSE);
	
	return (TRUE);
}

/*
 * uvm_map_pie: return a random load address for a PIE executable
 * properly aligned.
 */

#ifndef VM_PIE_MAX_ADDR
#define VM_PIE_MAX_ADDR (VM_MAXUSER_ADDRESS / 4)
#endif

#ifndef VM_PIE_MIN_ADDR
#define VM_PIE_MIN_ADDR VM_MIN_ADDRESS
#endif

#ifndef VM_PIE_MIN_ALIGN
#define VM_PIE_MIN_ALIGN PAGE_SIZE
#endif

vaddr_t
uvm_map_pie(vaddr_t align)
{
	vaddr_t addr, space, min;

	align = MAX(align, VM_PIE_MIN_ALIGN);

	/* round up to next alignment */
	min = (VM_PIE_MIN_ADDR + align - 1) & ~(align - 1);

	if (align >= VM_PIE_MAX_ADDR || min >= VM_PIE_MAX_ADDR)
		return (align);

	space = (VM_PIE_MAX_ADDR - min) / align;
	space = MIN(space, (u_int32_t)-1);

	addr = (vaddr_t)arc4random_uniform((u_int32_t)space) * align;
	addr += min;

	return (addr);
}

/*
 * uvm_map_hint: return the beginning of the best area suitable for
 * creating a new mapping with "prot" protection.
 */
vaddr_t
uvm_map_hint1(struct proc *p, vm_prot_t prot, int skipheap)
{
	vaddr_t addr;

#ifdef __i386__
	/*
	 * If executable skip first two pages, otherwise start
	 * after data + heap region.
	 */
	if ((prot & VM_PROT_EXECUTE) &&
	    ((vaddr_t)p->p_vmspace->vm_daddr >= I386_MAX_EXE_ADDR)) {
		addr = (PAGE_SIZE*2) +
		    (arc4random() & (I386_MAX_EXE_ADDR / 2 - 1));
		return (round_page(addr));
	}
#endif
	/* start malloc/mmap after the brk */
	addr = (vaddr_t)p->p_vmspace->vm_daddr;
	if (skipheap)
		addr += BRKSIZ;
#if !defined(__vax__)
	addr += arc4random() & (MIN((256 * 1024 * 1024), BRKSIZ) - 1);
#endif
	return (round_page(addr));
}

/*
 * uvm_map_findspace: find "length" sized space in "map".
 *
 * => "hint" is a hint about where we want it, unless FINDSPACE_FIXED is
 *	set (in which case we insist on using "hint").
 * => "result" is VA returned
 * => uobj/uoffset are to be used to handle VAC alignment, if required
 * => if `align' is non-zero, we attempt to align to that value.
 * => caller must at least have read-locked map
 * => returns NULL on failure, or pointer to prev. map entry if success
 * => note this is a cross between the old vm_map_findspace and vm_map_find
 */

struct vm_map_entry *
uvm_map_findspace(struct vm_map *map, vaddr_t hint, vsize_t length,
    vaddr_t *result, struct uvm_object *uobj, voff_t uoffset, vsize_t align,
    int flags)
{
	struct vm_map_entry *entry, *next, *tmp;
	struct vm_map_entry *child, *prev = NULL;
	vaddr_t end, orig_hint;

	KASSERT((align & (align - 1)) == 0);
	KASSERT((flags & UVM_FLAG_FIXED) == 0 || align == 0);

	uvm_tree_sanity(map, "map_findspace entry");

	/*
	 * remember the original hint.  if we are aligning, then we
	 * may have to try again with no alignment constraint if
	 * we fail the first time.
	 */

	orig_hint = hint;
	if (hint < map->min_offset) {	/* check ranges ... */
		if (flags & UVM_FLAG_FIXED) {
			return(NULL);
		}
		hint = map->min_offset;
	}
	if (hint > map->max_offset) {
		return(NULL);
	}

	/*
	 * Look for the first possible address; if there's already
	 * something at this address, we have to start after it.
	 */

	if ((flags & UVM_FLAG_FIXED) == 0 && hint == map->min_offset) {
		if ((entry = map->first_free) != &map->header) 
			hint = entry->end;
	} else {
		if (uvm_map_lookup_entry(map, hint, &tmp)) {
			/* "hint" address already in use ... */
			if (flags & UVM_FLAG_FIXED) {
				return(NULL);
			}
			hint = tmp->end;
		}
		entry = tmp;
	}

	if (flags & UVM_FLAG_FIXED) {
		end = hint + length;
		if (end > map->max_offset || end < hint) {
			goto error;
		}
		next = entry->next;
		if (next == &map->header || next->start >= end)
			goto found;
		return(NULL); /* only one shot at it ... */
	}

	/* Try to find the space in the red-black tree */

	/* Check slot before any entry */
	if (uvm_map_spacefits(map, &hint, length, entry->next, uoffset, align))
		goto found;
	
	/* If there is not enough space in the whole tree, we fail */
	tmp = RB_ROOT(&map->rbhead);
	if (tmp == NULL || tmp->space < length)
		goto error;

	/* Find an entry close to hint that has enough space */
	for (; tmp;) {
		if (tmp->end >= hint &&
		    (prev == NULL || tmp->end < prev->end)) {
			if (tmp->ownspace >= length)
				prev = tmp;
			else if ((child = RB_RIGHT(tmp, rb_entry)) != NULL &&
			    child->space >= length)
				prev = tmp;
		}
		if (tmp->end < hint)
			child = RB_RIGHT(tmp, rb_entry);
		else if (tmp->end > hint)
			child = RB_LEFT(tmp, rb_entry);
		else {
			if (tmp->ownspace >= length)
				break;
			child = RB_RIGHT(tmp, rb_entry);
		}
		if (child == NULL || child->space < length)
			break;
		tmp = child;
	}
	
	if (tmp != NULL && hint < tmp->end + tmp->ownspace) {
		/* 
		 * Check if the entry that we found satifies the
		 * space requirement
		 */
		if (hint < tmp->end)
			hint = tmp->end;
		if (uvm_map_spacefits(map, &hint, length, tmp->next, uoffset,
			align)) {
			entry = tmp;
			goto found;
		} else if (tmp->ownspace >= length)
			goto listsearch;
	}
	if (prev == NULL)
		goto error;
	
	hint = prev->end;
	if (uvm_map_spacefits(map, &hint, length, prev->next, uoffset,
		align)) {
		entry = prev;
		goto found;
	} else if (prev->ownspace >= length)
		goto listsearch;
	
	tmp = RB_RIGHT(prev, rb_entry);
	for (;;) {
		KASSERT(tmp && tmp->space >= length);
		child = RB_LEFT(tmp, rb_entry);
		if (child && child->space >= length) {
			tmp = child;
			continue;
		}
		if (tmp->ownspace >= length)
			break;
		tmp = RB_RIGHT(tmp, rb_entry);
	}
	
	hint = tmp->end;
	if (uvm_map_spacefits(map, &hint, length, tmp->next, uoffset, align)) {
		entry = tmp;
		goto found;
	}

	/* 
	 * The tree fails to find an entry because of offset or alignment
	 * restrictions.  Search the list instead.
	 */
 listsearch:
	/*
	 * Look through the rest of the map, trying to fit a new region in
	 * the gap between existing regions, or after the very last region.
	 * note: entry->end   = base VA of current gap,
	 *	 next->start  = VA of end of current gap
	 */
	for (;; hint = (entry = next)->end) {
		/*
		 * Find the end of the proposed new region.  Be sure we didn't
		 * go beyond the end of the map, or wrap around the address;
		 * if so, we lose.  Otherwise, if this is the last entry, or
		 * if the proposed new region fits before the next entry, we
		 * win.
		 */

#ifdef PMAP_PREFER
		/*
		 * push hint forward as needed to avoid VAC alias problems.
		 * we only do this if a valid offset is specified.
		 */
		if (uoffset != UVM_UNKNOWN_OFFSET)
			hint = PMAP_PREFER(uoffset, hint);
#endif
		if (align != 0) {
			if ((hint & (align - 1)) != 0)
				hint = roundup(hint, align);
			/*
			 * XXX Should we PMAP_PREFER() here again?
			 */
		}
		end = hint + length;
		if (end > map->max_offset || end < hint) {
			goto error;
		}
		next = entry->next;
		if (next == &map->header || next->start >= end)
			break;
	}
 found:
	SAVE_HINT(map, map->hint, entry);
	*result = hint;
	return (entry);

 error:
	if (align != 0) {
		return (uvm_map_findspace(map, orig_hint,
			    length, result, uobj, uoffset, 0, flags));
	}
	return (NULL);
}

/*
 *   U N M A P   -   m a i n   e n t r y   p o i n t
 */

/*
 * uvm_unmap: remove mappings from a vm_map (from "start" up to "stop")
 *
 * => caller must check alignment and size 
 * => map must be unlocked (we will lock it)
 */
void
uvm_unmap_p(vm_map_t map, vaddr_t start, vaddr_t end, struct proc *p)
{
	vm_map_entry_t dead_entries;

	/*
	 * work now done by helper functions.   wipe the pmap's and then
	 * detach from the dead entries...
	 */
	vm_map_lock(map);
	uvm_unmap_remove(map, start, end, &dead_entries, p, FALSE);
	vm_map_unlock(map);

	if (dead_entries != NULL)
		uvm_unmap_detach(dead_entries, 0);

}


/*
 *   U N M A P   -   m a i n   h e l p e r   f u n c t i o n s
 */

/*
 * uvm_unmap_remove: remove mappings from a vm_map (from "start" up to "stop")
 *
 * => caller must check alignment and size 
 * => map must be locked by caller
 * => we return a list of map entries that we've remove from the map
 *    in "entry_list"
 */

void
uvm_unmap_remove(struct vm_map *map, vaddr_t start, vaddr_t end,
    struct vm_map_entry **entry_list, struct proc *p, boolean_t remove_holes)
{
	struct vm_map_entry *entry, *first_entry, *next;
	vaddr_t len;

	VM_MAP_RANGE_CHECK(map, start, end);

	uvm_tree_sanity(map, "unmap_remove entry");

	if ((map->flags & VM_MAP_INTRSAFE) == 0)
		splassert(IPL_NONE);
	else
		splassert(IPL_VM);

	/*
	 * find first entry
	 */
	if (uvm_map_lookup_entry(map, start, &first_entry) == TRUE) {
		/* clip and go... */
		entry = first_entry;
		UVM_MAP_CLIP_START(map, entry, start);
		/* critical!  prevents stale hint */
		SAVE_HINT(map, entry, entry->prev);

	} else {
		entry = first_entry->next;
	}

	/*
	 * Save the free space hint
	 */

	if (map->first_free->start >= start)
		map->first_free = entry->prev;

	/*
	 * note: we now re-use first_entry for a different task.  we remove
	 * a number of map entries from the map and save them in a linked
	 * list headed by "first_entry".  once we remove them from the map
	 * the caller should unlock the map and drop the references to the
	 * backing objects [c.f. uvm_unmap_detach].  the object is to
	 * separate unmapping from reference dropping.  why?
	 *   [1] the map has to be locked for unmapping
	 *   [2] the map need not be locked for reference dropping
	 *   [3] dropping references may trigger pager I/O, and if we hit
	 *       a pager that does synchronous I/O we may have to wait for it.
	 *   [4] we would like all waiting for I/O to occur with maps unlocked
	 *       so that we don't block other threads.  
	 */
	first_entry = NULL;
	*entry_list = NULL;		/* to be safe */

	/*
	 * break up the area into map entry sized regions and unmap.  note 
	 * that all mappings have to be removed before we can even consider
	 * dropping references to amaps or VM objects (otherwise we could end
	 * up with a mapping to a page on the free list which would be very bad)
	 */

	while ((entry != &map->header) && (entry->start < end)) {

		UVM_MAP_CLIP_END(map, entry, end); 
		next = entry->next;
		len = entry->end - entry->start;
		if (p && entry->object.uvm_obj == NULL)
			p->p_vmspace->vm_dused -= atop(len);

		/*
		 * unwire before removing addresses from the pmap; otherwise
		 * unwiring will put the entries back into the pmap (XXX).
		 */

		if (VM_MAPENT_ISWIRED(entry))
			uvm_map_entry_unwire(map, entry);

		/*
		 * special case: handle mappings to anonymous kernel objects.
		 * we want to free these pages right away...
		 */
#ifdef KVA_GUARDPAGES
		if (map == kernel_map && entry->etype & MAP_ET_KVAGUARD) {
			entry->etype &= ~MAP_ET_KVAGUARD;
			kva_guardpages--;
		} else		/* (code continues across line-break) */
#endif
		if (UVM_ET_ISHOLE(entry)) {
			if (!remove_holes) {
				entry = next;
				continue;
			}
		} else if (map->flags & VM_MAP_INTRSAFE) {
			uvm_km_pgremove_intrsafe(entry->start, entry->end);
			pmap_kremove(entry->start, len);
		} else if (UVM_ET_ISOBJ(entry) &&
		    UVM_OBJ_IS_KERN_OBJECT(entry->object.uvm_obj)) {
			KASSERT(vm_map_pmap(map) == pmap_kernel());

			/*
			 * note: kernel object mappings are currently used in
			 * two ways:
			 *  [1] "normal" mappings of pages in the kernel object
			 *  [2] uvm_km_valloc'd allocations in which we
			 *      pmap_enter in some non-kernel-object page
			 *      (e.g. vmapbuf).
			 *
			 * for case [1], we need to remove the mapping from
			 * the pmap and then remove the page from the kernel
			 * object (because, once pages in a kernel object are
			 * unmapped they are no longer needed, unlike, say,
			 * a vnode where you might want the data to persist
			 * until flushed out of a queue).
			 *
			 * for case [2], we need to remove the mapping from
			 * the pmap.  there shouldn't be any pages at the
			 * specified offset in the kernel object [but it
			 * doesn't hurt to call uvm_km_pgremove just to be
			 * safe?]
			 *
			 * uvm_km_pgremove currently does the following: 
			 *   for pages in the kernel object in range: 
			 *     - drops the swap slot
			 *     - uvm_pagefree the page
			 *
			 * note there is version of uvm_km_pgremove() that
			 * is used for "intrsafe" objects.
			 */

			/*
			 * remove mappings from pmap and drop the pages
			 * from the object.  offsets are always relative
			 * to vm_map_min(kernel_map).
			 */
			pmap_remove(pmap_kernel(), entry->start, entry->end);
			uvm_km_pgremove(entry->object.uvm_obj,
			    entry->start - vm_map_min(kernel_map),
			    entry->end - vm_map_min(kernel_map));

			/*
			 * null out kernel_object reference, we've just
			 * dropped it
			 */
			entry->etype &= ~UVM_ET_OBJ;
			entry->object.uvm_obj = NULL;	/* to be safe */

		} else {
			/*
		 	 * remove mappings the standard way.
		 	 */
			pmap_remove(map->pmap, entry->start, entry->end);
		}

		/*
		 * remove entry from map and put it on our list of entries 
		 * that we've nuked.  then go do next entry.
		 */
		/* critical! prevents stale hint */
		SAVE_HINT(map, entry, entry->prev);

		uvm_map_entry_unlink(map, entry);
		map->size -= len;
		entry->next = first_entry;
		first_entry = entry;
		entry = next;		/* next entry, please */
	}
#ifdef KVA_GUARDPAGES
	/*
	 * entry points at the map-entry after the last-removed map-entry.
	 */
	if (map == kernel_map && entry != &map->header &&
	    entry->etype & MAP_ET_KVAGUARD && entry->start == end) {
		/*
		 * Removed range is followed by guard page;
		 * remove that guard page now (or it will stay forever).
		 */
		entry->etype &= ~MAP_ET_KVAGUARD;
		kva_guardpages--;

		uvm_map_entry_unlink(map, entry);
		map->size -= len;
		entry->next = first_entry;
		first_entry = entry;
		entry = next;		/* next entry, please */
	}
#endif
	/* if ((map->flags & VM_MAP_DYING) == 0) { */
		pmap_update(vm_map_pmap(map));
	/* } */


	uvm_tree_sanity(map, "unmap_remove leave");

	/*
	 * now we've cleaned up the map and are ready for the caller to drop
	 * references to the mapped objects.  
	 */

	*entry_list = first_entry;
}

/*
 * uvm_unmap_detach: drop references in a chain of map entries
 *
 * => we will free the map entries as we traverse the list.
 */

void
uvm_unmap_detach(struct vm_map_entry *first_entry, int flags)
{
	struct vm_map_entry *next_entry;

	while (first_entry) {
		KASSERT(!VM_MAPENT_ISWIRED(first_entry));

		/*
		 * drop reference to amap, if we've got one
		 */

		if (first_entry->aref.ar_amap)
			uvm_map_unreference_amap(first_entry, flags);

		/*
		 * drop reference to our backing object, if we've got one
		 */

		if (UVM_ET_ISSUBMAP(first_entry)) {
			/* ... unlikely to happen, but play it safe */
			uvm_map_deallocate(first_entry->object.sub_map);
		} else {
			if (UVM_ET_ISOBJ(first_entry) &&
			    first_entry->object.uvm_obj->pgops->pgo_detach)
				first_entry->object.uvm_obj->pgops->
				    pgo_detach(first_entry->object.uvm_obj);
		}

		next_entry = first_entry->next;
		uvm_mapent_free(first_entry);
		first_entry = next_entry;
	}
}

/*
 *   E X T R A C T I O N   F U N C T I O N S
 */

/* 
 * uvm_map_reserve: reserve space in a vm_map for future use.
 *
 * => we reserve space in a map by putting a dummy map entry in the 
 *    map (dummy means obj=NULL, amap=NULL, prot=VM_PROT_NONE)
 * => map should be unlocked (we will write lock it)
 * => we return true if we were able to reserve space
 * => XXXCDC: should be inline?
 */

int
uvm_map_reserve(struct vm_map *map, vsize_t size, vaddr_t offset,
    vsize_t align, vaddr_t *raddr)
{

	size = round_page(size);
	if (*raddr < vm_map_min(map))
		*raddr = vm_map_min(map);                /* hint */

	/*
	 * reserve some virtual space.
	 */

	if (uvm_map(map, raddr, size, NULL, offset, 0,
	    UVM_MAPFLAG(UVM_PROT_NONE, UVM_PROT_NONE, UVM_INH_NONE,
	    UVM_ADV_RANDOM, UVM_FLAG_NOMERGE)) != 0) {
		return (FALSE);
	}     

	return (TRUE);
}

/*
 * uvm_map_replace: replace a reserved (blank) area of memory with 
 * real mappings.
 *
 * => caller must WRITE-LOCK the map 
 * => we return TRUE if replacement was a success
 * => we expect the newents chain to have nnewents entries on it and
 *    we expect newents->prev to point to the last entry on the list
 * => note newents is allowed to be NULL
 */

int
uvm_map_replace(struct vm_map *map, vaddr_t start, vaddr_t end,
    struct vm_map_entry *newents, int nnewents)
{
	struct vm_map_entry *oldent, *last;

	uvm_tree_sanity(map, "map_replace entry");

	/*
	 * first find the blank map entry at the specified address
	 */

	if (!uvm_map_lookup_entry(map, start, &oldent)) {
		return(FALSE);
	}

	/*
	 * check to make sure we have a proper blank entry
	 */

	if (oldent->start != start || oldent->end != end || 
	    oldent->object.uvm_obj != NULL || oldent->aref.ar_amap != NULL) {
		return (FALSE);
	}

#ifdef DIAGNOSTIC
	/*
	 * sanity check the newents chain
	 */
	{
		struct vm_map_entry *tmpent = newents;
		int nent = 0;
		vaddr_t cur = start;

		while (tmpent) {
			nent++;
			if (tmpent->start < cur)
				panic("uvm_map_replace1");
			if (tmpent->start > tmpent->end || tmpent->end > end) {
		printf("tmpent->start=0x%lx, tmpent->end=0x%lx, end=0x%lx\n",
			    tmpent->start, tmpent->end, end);
				panic("uvm_map_replace2");
			}
			cur = tmpent->end;
			if (tmpent->next) {
				if (tmpent->next->prev != tmpent)
					panic("uvm_map_replace3");
			} else {
				if (newents->prev != tmpent)
					panic("uvm_map_replace4");
			}
			tmpent = tmpent->next;
		}
		if (nent != nnewents)
			panic("uvm_map_replace5");
	}
#endif

	/*
	 * map entry is a valid blank!   replace it.   (this does all the
	 * work of map entry link/unlink...).
	 */

	if (newents) {
		last = newents->prev;		/* we expect this */

		/* critical: flush stale hints out of map */
		SAVE_HINT(map, map->hint, newents);
		if (map->first_free == oldent)
			map->first_free = last;

		last->next = oldent->next;
		last->next->prev = last;

		/* Fix RB tree */
		uvm_rb_remove(map, oldent);

		newents->prev = oldent->prev;
		newents->prev->next = newents;
		map->nentries = map->nentries + (nnewents - 1);

		/* Fixup the RB tree */
		{
			int i;
			struct vm_map_entry *tmp;

			tmp = newents;
			for (i = 0; i < nnewents && tmp; i++) {
				uvm_rb_insert(map, tmp);
				tmp = tmp->next;
			}
		}
	} else {

		/* critical: flush stale hints out of map */
		SAVE_HINT(map, map->hint, oldent->prev);
		if (map->first_free == oldent)
			map->first_free = oldent->prev;

		/* NULL list of new entries: just remove the old one */
		uvm_map_entry_unlink(map, oldent);
	}


	uvm_tree_sanity(map, "map_replace leave");

	/*
	 * now we can free the old blank entry, unlock the map and return.
	 */

	uvm_mapent_free(oldent);
	return(TRUE);
}

/*
 * uvm_map_extract: extract a mapping from a map and put it somewhere
 *	(maybe removing the old mapping)
 *
 * => maps should be unlocked (we will write lock them)
 * => returns 0 on success, error code otherwise
 * => start must be page aligned
 * => len must be page sized
 * => flags:
 *      UVM_EXTRACT_REMOVE: remove mappings from srcmap
 *      UVM_EXTRACT_CONTIG: abort if unmapped area (advisory only)
 *      UVM_EXTRACT_QREF: for a temporary extraction do quick obj refs
 *      UVM_EXTRACT_FIXPROT: set prot to maxprot as we go
 *    >>>NOTE: if you set REMOVE, you are not allowed to use CONTIG or QREF!<<<
 *    >>>NOTE: QREF's must be unmapped via the QREF path, thus should only
 *             be used from within the kernel in a kernel level map <<<
 */

int
uvm_map_extract(struct vm_map *srcmap, vaddr_t start, vsize_t len,
    struct vm_map *dstmap, vaddr_t *dstaddrp, int flags)
{
	vaddr_t dstaddr, end, newend, oldoffset, fudge, orig_fudge,
	    oldstart;
	struct vm_map_entry *chain, *endchain, *entry, *orig_entry, *newentry;
	struct vm_map_entry *deadentry, *oldentry;
	vsize_t elen;
	int nchain, error, copy_ok;

	uvm_tree_sanity(srcmap, "map_extract src enter");
	uvm_tree_sanity(dstmap, "map_extract dst enter");

	/*
	 * step 0: sanity check: start must be on a page boundary, length
	 * must be page sized.  can't ask for CONTIG/QREF if you asked for
	 * REMOVE.
	 */

	KASSERT((start & PAGE_MASK) == 0 && (len & PAGE_MASK) == 0);
	KASSERT((flags & UVM_EXTRACT_REMOVE) == 0 ||
		(flags & (UVM_EXTRACT_CONTIG|UVM_EXTRACT_QREF)) == 0);

	/*
	 * step 1: reserve space in the target map for the extracted area
	 */

	dstaddr = vm_map_min(dstmap);
	if (uvm_map_reserve(dstmap, len, start, 0, &dstaddr) == FALSE)
		return(ENOMEM);
	*dstaddrp = dstaddr;	/* pass address back to caller */

	/*
	 * step 2: setup for the extraction process loop by init'ing the 
	 * map entry chain, locking src map, and looking up the first useful
	 * entry in the map.
	 */

	end = start + len;
	newend = dstaddr + len;
	chain = endchain = NULL;
	nchain = 0;
	vm_map_lock(srcmap);

	if (uvm_map_lookup_entry(srcmap, start, &entry)) {

		/* "start" is within an entry */
		if (flags & UVM_EXTRACT_QREF) {

			/*
			 * for quick references we don't clip the entry, so
			 * the entry may map space "before" the starting
			 * virtual address... this is the "fudge" factor
			 * (which can be non-zero only the first time
			 * through the "while" loop in step 3).
			 */

			fudge = start - entry->start;
		} else {

			/*
			 * normal reference: we clip the map to fit (thus
			 * fudge is zero)
			 */

			UVM_MAP_CLIP_START(srcmap, entry, start);
			SAVE_HINT(srcmap, srcmap->hint, entry->prev);
			fudge = 0;
		}
	} else {

		/* "start" is not within an entry ... skip to next entry */
		if (flags & UVM_EXTRACT_CONTIG) {
			error = EINVAL;
			goto bad;    /* definite hole here ... */
		}

		entry = entry->next;
		fudge = 0;
	}

	/* save values from srcmap for step 6 */
	orig_entry = entry;
	orig_fudge = fudge;

	/*
	 * step 3: now start looping through the map entries, extracting
	 * as we go.
	 */

	while (entry->start < end && entry != &srcmap->header) {

		/* if we are not doing a quick reference, clip it */
		if ((flags & UVM_EXTRACT_QREF) == 0)
			UVM_MAP_CLIP_END(srcmap, entry, end);

		/* clear needs_copy (allow chunking) */
		if (UVM_ET_ISNEEDSCOPY(entry)) {
			if (fudge)
				oldstart = entry->start;
			else
				oldstart = 0;	/* XXX: gcc */
			amap_copy(srcmap, entry, M_NOWAIT, TRUE, start, end);
			if (UVM_ET_ISNEEDSCOPY(entry)) {  /* failed? */
				error = ENOMEM;
				goto bad;
			}

			/* amap_copy could clip (during chunk)!  update fudge */
			if (fudge) {
				fudge = fudge - (entry->start - oldstart);
				orig_fudge = fudge;
			}
		}

		/* calculate the offset of this from "start" */
		oldoffset = (entry->start + fudge) - start;

		/* allocate a new map entry */
		newentry = uvm_mapent_alloc(dstmap, flags);
		if (newentry == NULL) {
			error = ENOMEM;
			goto bad;
		}

		/* set up new map entry */
		newentry->next = NULL;
		newentry->prev = endchain;
		newentry->start = dstaddr + oldoffset;
		newentry->end =
		    newentry->start + (entry->end - (entry->start + fudge));
		if (newentry->end > newend || newentry->end < newentry->start)
			newentry->end = newend;
		newentry->object.uvm_obj = entry->object.uvm_obj;
		if (newentry->object.uvm_obj) {
			if (newentry->object.uvm_obj->pgops->pgo_reference)
				newentry->object.uvm_obj->pgops->
				    pgo_reference(newentry->object.uvm_obj);
			newentry->offset = entry->offset + fudge;
		} else {
			newentry->offset = 0;
		}
		newentry->etype = entry->etype;
		newentry->protection = (flags & UVM_EXTRACT_FIXPROT) ? 
			entry->max_protection : entry->protection; 
		newentry->max_protection = entry->max_protection;
		newentry->inheritance = entry->inheritance;
		newentry->wired_count = 0;
		newentry->aref.ar_amap = entry->aref.ar_amap;
		if (newentry->aref.ar_amap) {
			newentry->aref.ar_pageoff =
			    entry->aref.ar_pageoff + (fudge >> PAGE_SHIFT);
			uvm_map_reference_amap(newentry, AMAP_SHARED |
			    ((flags & UVM_EXTRACT_QREF) ? AMAP_REFALL : 0));
		} else {
			newentry->aref.ar_pageoff = 0;
		}
		newentry->advice = entry->advice;

		/* now link it on the chain */
		nchain++;
		if (endchain == NULL) {
			chain = endchain = newentry;
		} else {
			endchain->next = newentry;
			endchain = newentry;
		}

		/* end of 'while' loop! */
		if ((flags & UVM_EXTRACT_CONTIG) && entry->end < end && 
		    (entry->next == &srcmap->header ||
		    entry->next->start != entry->end)) {
			error = EINVAL;
			goto bad;
		}
		entry = entry->next;
		fudge = 0;
	}

	/*
	 * step 4: close off chain (in format expected by uvm_map_replace)
	 */

	if (chain)
		chain->prev = endchain;

	/*
	 * step 5: attempt to lock the dest map so we can pmap_copy.
	 * note usage of copy_ok: 
	 *   1 => dstmap locked, pmap_copy ok, and we "replace" here (step 5)
	 *   0 => dstmap unlocked, NO pmap_copy, and we will "replace" in step 7
	 */

	if (srcmap == dstmap || vm_map_lock_try(dstmap) == TRUE) {
		copy_ok = 1;
		if (!uvm_map_replace(dstmap, dstaddr, dstaddr+len, chain,
		    nchain)) {
			if (srcmap != dstmap)
				vm_map_unlock(dstmap);
			error = EIO;
			goto bad;
		}
	} else {
		copy_ok = 0;
		/* replace defered until step 7 */
	}

	/*
	 * step 6: traverse the srcmap a second time to do the following:
	 *  - if we got a lock on the dstmap do pmap_copy
	 *  - if UVM_EXTRACT_REMOVE remove the entries
	 * we make use of orig_entry and orig_fudge (saved in step 2)
	 */

	if (copy_ok || (flags & UVM_EXTRACT_REMOVE)) {

		/* purge possible stale hints from srcmap */
		if (flags & UVM_EXTRACT_REMOVE) {
			SAVE_HINT(srcmap, srcmap->hint, orig_entry->prev);
			if (srcmap->first_free->start >= start)
				srcmap->first_free = orig_entry->prev;
		}

		entry = orig_entry;
		fudge = orig_fudge;
		deadentry = NULL;	/* for UVM_EXTRACT_REMOVE */

		while (entry->start < end && entry != &srcmap->header) {
			if (copy_ok) {
				oldoffset = (entry->start + fudge) - start;
				elen = MIN(end, entry->end) -
				    (entry->start + fudge);
				pmap_copy(dstmap->pmap, srcmap->pmap,
				    dstaddr + oldoffset, elen,
				    entry->start + fudge);
			}

			/* we advance "entry" in the following if statement */
			if (flags & UVM_EXTRACT_REMOVE) {
				pmap_remove(srcmap->pmap, entry->start, 
						entry->end);
        			oldentry = entry;	/* save entry */
        			entry = entry->next;	/* advance */
				uvm_map_entry_unlink(srcmap, oldentry);
							/* add to dead list */
				oldentry->next = deadentry;
				deadentry = oldentry;
      			} else {
        			entry = entry->next;		/* advance */
			}

			/* end of 'while' loop */
			fudge = 0;
		}
		pmap_update(srcmap->pmap);

		/*
		 * unlock dstmap.  we will dispose of deadentry in
		 * step 7 if needed
		 */

		if (copy_ok && srcmap != dstmap)
			vm_map_unlock(dstmap);

	}
	else
		deadentry = NULL; /* XXX: gcc */

	/*
	 * step 7: we are done with the source map, unlock.   if copy_ok
	 * is 0 then we have not replaced the dummy mapping in dstmap yet
	 * and we need to do so now.
	 */

	vm_map_unlock(srcmap);
	if ((flags & UVM_EXTRACT_REMOVE) && deadentry)
		uvm_unmap_detach(deadentry, 0);   /* dispose of old entries */

	/* now do the replacement if we didn't do it in step 5 */
	if (copy_ok == 0) {
		vm_map_lock(dstmap);
		error = uvm_map_replace(dstmap, dstaddr, dstaddr+len, chain,
		    nchain);
		vm_map_unlock(dstmap);

		if (error == FALSE) {
			error = EIO;
			goto bad2;
		}
	}

	uvm_tree_sanity(srcmap, "map_extract src leave");
	uvm_tree_sanity(dstmap, "map_extract dst leave");

	return(0);

	/*
	 * bad: failure recovery
	 */
bad:
	vm_map_unlock(srcmap);
bad2:			/* src already unlocked */
	if (chain)
		uvm_unmap_detach(chain,
		    (flags & UVM_EXTRACT_QREF) ? AMAP_REFALL : 0);

	uvm_tree_sanity(srcmap, "map_extract src err leave");
	uvm_tree_sanity(dstmap, "map_extract dst err leave");

	uvm_unmap(dstmap, dstaddr, dstaddr+len);   /* ??? */
	return(error);
}

/* end of extraction functions */

/*
 * uvm_map_submap: punch down part of a map into a submap
 *
 * => only the kernel_map is allowed to be submapped
 * => the purpose of submapping is to break up the locking granularity
 *	of a larger map
 * => the range specified must have been mapped previously with a uvm_map()
 *	call [with uobj==NULL] to create a blank map entry in the main map.
 *	[And it had better still be blank!]
 * => maps which contain submaps should never be copied or forked.
 * => to remove a submap, use uvm_unmap() on the main map 
 *	and then uvm_map_deallocate() the submap.
 * => main map must be unlocked.
 * => submap must have been init'd and have a zero reference count.
 *	[need not be locked as we don't actually reference it]
 */

int
uvm_map_submap(struct vm_map *map, vaddr_t start, vaddr_t end,
    struct vm_map *submap)
{
	struct vm_map_entry *entry;
	int result;

	vm_map_lock(map);

	VM_MAP_RANGE_CHECK(map, start, end);

	if (uvm_map_lookup_entry(map, start, &entry)) {
		UVM_MAP_CLIP_START(map, entry, start);
		UVM_MAP_CLIP_END(map, entry, end);		/* to be safe */
	} else {
		entry = NULL;
	}

	if (entry != NULL && 
	    entry->start == start && entry->end == end &&
	    entry->object.uvm_obj == NULL && entry->aref.ar_amap == NULL &&
	    !UVM_ET_ISCOPYONWRITE(entry) && !UVM_ET_ISNEEDSCOPY(entry)) {
		entry->etype |= UVM_ET_SUBMAP;
		entry->object.sub_map = submap;
		entry->offset = 0;
		uvm_map_reference(submap);
		result = 0;
	} else {
		result = EINVAL;
	}
	vm_map_unlock(map);
	return(result);
}


/*
 * uvm_map_protect: change map protection
 *
 * => set_max means set max_protection.
 * => map must be unlocked.
 */

#define MASK(entry)     (UVM_ET_ISCOPYONWRITE(entry) ? \
			 ~VM_PROT_WRITE : VM_PROT_ALL)
#define max(a,b)        ((a) > (b) ? (a) : (b))

int
uvm_map_protect(struct vm_map *map, vaddr_t start, vaddr_t end,
    vm_prot_t new_prot, boolean_t set_max)
{
	struct vm_map_entry *current, *entry;
	int error = 0;

	vm_map_lock(map);

	VM_MAP_RANGE_CHECK(map, start, end);

	if (uvm_map_lookup_entry(map, start, &entry)) {
		UVM_MAP_CLIP_START(map, entry, start);
	} else {
		entry = entry->next;
	}

	/*
	 * make a first pass to check for protection violations.
	 */

	current = entry;
	while ((current != &map->header) && (current->start < end)) {
		if (UVM_ET_ISSUBMAP(current)) {
			error = EINVAL;
			goto out;
		}
		if ((new_prot & current->max_protection) != new_prot) {
			error = EACCES;
			goto out;
		}
		current = current->next;
	}

	/* go back and fix up protections (no need to clip this time). */

	current = entry;

	while ((current != &map->header) && (current->start < end)) {
		vm_prot_t old_prot;

		UVM_MAP_CLIP_END(map, current, end);

		old_prot = current->protection;
		if (set_max)
			current->protection =
			    (current->max_protection = new_prot) & old_prot;
		else
			current->protection = new_prot;

		/*
		 * update physical map if necessary.  worry about copy-on-write 
		 * here -- CHECK THIS XXX
		 */

		if (current->protection != old_prot) {
			/* update pmap! */
			if ((current->protection & MASK(entry)) == PROT_NONE &&
			    VM_MAPENT_ISWIRED(entry))
				current->wired_count--;
			pmap_protect(map->pmap, current->start, current->end,
			    current->protection & MASK(entry));
		}

		/*
		 * If the map is configured to lock any future mappings,
		 * wire this entry now if the old protection was VM_PROT_NONE
		 * and the new protection is not VM_PROT_NONE.
		 */

		if ((map->flags & VM_MAP_WIREFUTURE) != 0 &&
		    VM_MAPENT_ISWIRED(entry) == 0 &&
		    old_prot == VM_PROT_NONE &&
		    new_prot != VM_PROT_NONE) {
			if (uvm_map_pageable(map, entry->start, entry->end,
			    FALSE, UVM_LK_ENTER|UVM_LK_EXIT) != 0) {
				/*
				 * If locking the entry fails, remember the
				 * error if it's the first one.  Note we
				 * still continue setting the protection in
				 * the map, but will return the resource
				 * shortage condition regardless.
				 *
				 * XXX Ignore what the actual error is,
				 * XXX just call it a resource shortage
				 * XXX so that it doesn't get confused
				 * XXX what uvm_map_protect() itself would
				 * XXX normally return.
				 */
				error = ENOMEM;
			}
		}

		current = current->next;
	}
	pmap_update(map->pmap);

 out:
	vm_map_unlock(map);
	return (error);
}

#undef  max
#undef  MASK

/* 
 * uvm_map_inherit: set inheritance code for range of addrs in map.
 *
 * => map must be unlocked
 * => note that the inherit code is used during a "fork".  see fork
 *	code for details.
 */

int
uvm_map_inherit(struct vm_map *map, vaddr_t start, vaddr_t end,
    vm_inherit_t new_inheritance)
{
	struct vm_map_entry *entry;

	switch (new_inheritance) {
	case MAP_INHERIT_NONE:
	case MAP_INHERIT_COPY:
	case MAP_INHERIT_SHARE:
		break;
	default:
		return (EINVAL);
	}

	vm_map_lock(map);
	
	VM_MAP_RANGE_CHECK(map, start, end);
	
	if (uvm_map_lookup_entry(map, start, &entry)) {
		UVM_MAP_CLIP_START(map, entry, start);
	} else {
		entry = entry->next;
	}

	while ((entry != &map->header) && (entry->start < end)) {
		UVM_MAP_CLIP_END(map, entry, end);
		entry->inheritance = new_inheritance;
		entry = entry->next;
	}

	vm_map_unlock(map);
	return (0);
}

/* 
 * uvm_map_advice: set advice code for range of addrs in map.
 *
 * => map must be unlocked
 */

int
uvm_map_advice(struct vm_map *map, vaddr_t start, vaddr_t end, int new_advice)
{
	struct vm_map_entry *entry;

	switch (new_advice) {
	case MADV_NORMAL:
	case MADV_RANDOM:
	case MADV_SEQUENTIAL:
		/* nothing special here */
		break;

	default:
		return (EINVAL);
	}
	vm_map_lock(map);
	VM_MAP_RANGE_CHECK(map, start, end);
	if (uvm_map_lookup_entry(map, start, &entry)) {
		UVM_MAP_CLIP_START(map, entry, start);
	} else {
		entry = entry->next;
	}

	/*
	 * XXXJRT: disallow holes?
	 */

	while ((entry != &map->header) && (entry->start < end)) {
		UVM_MAP_CLIP_END(map, entry, end);

		entry->advice = new_advice;
		entry = entry->next;
	}

	vm_map_unlock(map);
	return (0);
}

/*
 * uvm_map_pageable: sets the pageability of a range in a map.
 *
 * => wires map entries.  should not be used for transient page locking.
 *	for that, use uvm_fault_wire()/uvm_fault_unwire() (see uvm_vslock()).
 * => regions sepcified as not pageable require lock-down (wired) memory
 *	and page tables.
 * => map must never be read-locked
 * => if islocked is TRUE, map is already write-locked
 * => we always unlock the map, since we must downgrade to a read-lock
 *	to call uvm_fault_wire()
 * => XXXCDC: check this and try and clean it up.
 */

int
uvm_map_pageable(struct vm_map *map, vaddr_t start, vaddr_t end,
    boolean_t new_pageable, int lockflags)
{
	struct vm_map_entry *entry, *start_entry, *failed_entry;
	int rv;
#ifdef DIAGNOSTIC
	u_int timestamp_save;
#endif
	KASSERT(map->flags & VM_MAP_PAGEABLE);

	if ((lockflags & UVM_LK_ENTER) == 0)
		vm_map_lock(map);

	VM_MAP_RANGE_CHECK(map, start, end);

	/* 
	 * only one pageability change may take place at one time, since
	 * uvm_fault_wire assumes it will be called only once for each
	 * wiring/unwiring.  therefore, we have to make sure we're actually
	 * changing the pageability for the entire region.  we do so before
	 * making any changes.  
	 */

	if (uvm_map_lookup_entry(map, start, &start_entry) == FALSE) {
		if ((lockflags & UVM_LK_EXIT) == 0)
			vm_map_unlock(map);

		return (EFAULT);
	}
	entry = start_entry;

	/* 
	 * handle wiring and unwiring separately.
	 */

	if (new_pageable) {		/* unwire */
		UVM_MAP_CLIP_START(map, entry, start);

		/*
		 * unwiring.  first ensure that the range to be unwired is
		 * really wired down and that there are no holes.  
		 */

		while ((entry != &map->header) && (entry->start < end)) {
			if (entry->wired_count == 0 ||
			    (entry->end < end &&
			     (entry->next == &map->header ||
			      entry->next->start > entry->end))) {
				if ((lockflags & UVM_LK_EXIT) == 0)
					vm_map_unlock(map);
				return (EINVAL);
			}
			entry = entry->next;
		}

		/* 
		 * POSIX 1003.1b - a single munlock call unlocks a region,
		 * regardless of the number of mlock calls made on that
		 * region.
		 */

		entry = start_entry;
		while ((entry != &map->header) && (entry->start < end)) {
			UVM_MAP_CLIP_END(map, entry, end);
			if (VM_MAPENT_ISWIRED(entry))
				uvm_map_entry_unwire(map, entry);
			entry = entry->next;
		}
		if ((lockflags & UVM_LK_EXIT) == 0)
			vm_map_unlock(map);
		return (0);
	}

	/*
	 * wire case: in two passes [XXXCDC: ugly block of code here]
	 *
	 * 1: holding the write lock, we create any anonymous maps that need
	 *    to be created.  then we clip each map entry to the region to
	 *    be wired and increment its wiring count.  
	 *
	 * 2: we downgrade to a read lock, and call uvm_fault_wire to fault
	 *    in the pages for any newly wired area (wired_count == 1).
	 *
	 *    downgrading to a read lock for uvm_fault_wire avoids a possible
	 *    deadlock with another thread that may have faulted on one of
	 *    the pages to be wired (it would mark the page busy, blocking
	 *    us, then in turn block on the map lock that we hold).  because
	 *    of problems in the recursive lock package, we cannot upgrade
	 *    to a write lock in vm_map_lookup.  thus, any actions that
	 *    require the write lock must be done beforehand.  because we
	 *    keep the read lock on the map, the copy-on-write status of the
	 *    entries we modify here cannot change.
	 */

	while ((entry != &map->header) && (entry->start < end)) {
		if (VM_MAPENT_ISWIRED(entry) == 0) { /* not already wired? */

			/*
			 * perform actions of vm_map_lookup that need the
			 * write lock on the map: create an anonymous map
			 * for a copy-on-write region, or an anonymous map
			 * for a zero-fill region.  (XXXCDC: submap case
			 * ok?)
			 */

			if (!UVM_ET_ISSUBMAP(entry)) {  /* not submap */
				if (UVM_ET_ISNEEDSCOPY(entry) && 
				    ((entry->protection & VM_PROT_WRITE) ||
				     (entry->object.uvm_obj == NULL))) {
					amap_copy(map, entry, M_WAITOK, TRUE,
					    start, end); 
					/* XXXCDC: wait OK? */
				}
			}
		}
		UVM_MAP_CLIP_START(map, entry, start);
		UVM_MAP_CLIP_END(map, entry, end);
		entry->wired_count++;

		/*
		 * Check for holes 
		 */

		if (entry->protection == VM_PROT_NONE ||
		    (entry->end < end &&
		     (entry->next == &map->header ||
		      entry->next->start > entry->end))) {

			/*
			 * found one.  amap creation actions do not need to
			 * be undone, but the wired counts need to be restored. 
			 */

			while (entry != &map->header && entry->end > start) {
				entry->wired_count--;
				entry = entry->prev;
			}
			if ((lockflags & UVM_LK_EXIT) == 0)
				vm_map_unlock(map);
			return (EINVAL);
		}
		entry = entry->next;
	}

	/*
	 * Pass 2.
	 */

#ifdef DIAGNOSTIC
	timestamp_save = map->timestamp;
#endif
	vm_map_busy(map);
	vm_map_downgrade(map);

	rv = 0;
	entry = start_entry;
	while (entry != &map->header && entry->start < end) {
		if (entry->wired_count == 1) {
			rv = uvm_fault_wire(map, entry->start, entry->end,
			    entry->protection);
			if (rv) {
				/*
				 * wiring failed.  break out of the loop.
				 * we'll clean up the map below, once we
				 * have a write lock again.
				 */
				break;
			}
		}
		entry = entry->next;
	}

	if (rv) {        /* failed? */

		/*
		 * Get back to an exclusive (write) lock.
		 */

		vm_map_upgrade(map);
		vm_map_unbusy(map);

#ifdef DIAGNOSTIC
		if (timestamp_save != map->timestamp)
			panic("uvm_map_pageable: stale map");
#endif

		/*
		 * first drop the wiring count on all the entries
		 * which haven't actually been wired yet.
		 */

		failed_entry = entry;
		while (entry != &map->header && entry->start < end) {
			entry->wired_count--;
			entry = entry->next;
		}

		/*
		 * now, unwire all the entries that were successfully
		 * wired above.
		 */

		entry = start_entry;
		while (entry != failed_entry) {
			entry->wired_count--;
			if (VM_MAPENT_ISWIRED(entry) == 0)
				uvm_map_entry_unwire(map, entry);
			entry = entry->next;
		}
		if ((lockflags & UVM_LK_EXIT) == 0)
			vm_map_unlock(map);
		return(rv);
	}

	/* We are holding a read lock here. */
	if ((lockflags & UVM_LK_EXIT) == 0) {
		vm_map_unbusy(map);
		vm_map_unlock_read(map);
	} else {

		/*
		 * Get back to an exclusive (write) lock.
		 */

		vm_map_upgrade(map);
		vm_map_unbusy(map);
	}

	return (0);
}

/*
 * uvm_map_pageable_all: special case of uvm_map_pageable - affects
 * all mapped regions.
 *
 * => map must not be locked.
 * => if no flags are specified, all regions are unwired.
 * => XXXJRT: has some of the same problems as uvm_map_pageable() above.
 */

int
uvm_map_pageable_all(struct vm_map *map, int flags, vsize_t limit)
{
	struct vm_map_entry *entry, *failed_entry;
	vsize_t size;
	int error;
#ifdef DIAGNOSTIC
	u_int timestamp_save;
#endif

	KASSERT(map->flags & VM_MAP_PAGEABLE);

	vm_map_lock(map);

	/*
	 * handle wiring and unwiring separately.
	 */

	if (flags == 0) {			/* unwire */
		/*
		 * POSIX 1003.1b -- munlockall unlocks all regions,
		 * regardless of how many times mlockall has been called.
		 */
		for (entry = map->header.next; entry != &map->header;
		     entry = entry->next) {
			if (VM_MAPENT_ISWIRED(entry))
				uvm_map_entry_unwire(map, entry);
		}
		vm_map_modflags(map, 0, VM_MAP_WIREFUTURE);
		vm_map_unlock(map);
		return (0);

		/*
		 * end of unwire case!
		 */
	}

	if (flags & MCL_FUTURE) {
		/*
		 * must wire all future mappings; remember this.
		 */
		vm_map_modflags(map, VM_MAP_WIREFUTURE, 0);
	}

	if ((flags & MCL_CURRENT) == 0) {
		/*
		 * no more work to do!
		 */
		vm_map_unlock(map);
		return (0);
	}

	/*
	 * wire case: in three passes [XXXCDC: ugly block of code here]
	 *
	 * 1: holding the write lock, count all pages mapped by non-wired
	 *    entries.  if this would cause us to go over our limit, we fail.
	 *
	 * 2: still holding the write lock, we create any anonymous maps that
	 *    need to be created.  then we increment its wiring count.
	 *
	 * 3: we downgrade to a read lock, and call uvm_fault_wire to fault
	 *    in the pages for any newly wired area (wired_count == 1).
	 *
	 *    downgrading to a read lock for uvm_fault_wire avoids a possible
	 *    deadlock with another thread that may have faulted on one of
	 *    the pages to be wired (it would mark the page busy, blocking
	 *    us, then in turn block on the map lock that we hold).  because
	 *    of problems in the recursive lock package, we cannot upgrade
	 *    to a write lock in vm_map_lookup.  thus, any actions that
	 *    require the write lock must be done beforehand.  because we
	 *    keep the read lock on the map, the copy-on-write status of the
	 *    entries we modify here cannot change.
	 */

	for (size = 0, entry = map->header.next; entry != &map->header;
	     entry = entry->next) {
		if (entry->protection != VM_PROT_NONE &&
		    VM_MAPENT_ISWIRED(entry) == 0) { /* not already wired? */
			size += entry->end - entry->start;
		}
	}

	if (atop(size) + uvmexp.wired > uvmexp.wiredmax) {
		vm_map_unlock(map);
		return (ENOMEM);		/* XXX overloaded */
	}

	/* XXX non-pmap_wired_count case must be handled by caller */
#ifdef pmap_wired_count
	if (limit != 0 &&
	    (size + ptoa(pmap_wired_count(vm_map_pmap(map))) > limit)) {
		vm_map_unlock(map);
		return (ENOMEM);		/* XXX overloaded */
	}
#endif

	/*
	 * Pass 2.
	 */

	for (entry = map->header.next; entry != &map->header;
	     entry = entry->next) {
		if (entry->protection == VM_PROT_NONE)
			continue;
		if (VM_MAPENT_ISWIRED(entry) == 0) { /* not already wired? */
			/*
			 * perform actions of vm_map_lookup that need the
			 * write lock on the map: create an anonymous map
			 * for a copy-on-write region, or an anonymous map
			 * for a zero-fill region.  (XXXCDC: submap case
			 * ok?)
			 */
			if (!UVM_ET_ISSUBMAP(entry)) {	/* not submap */
				if (UVM_ET_ISNEEDSCOPY(entry) && 
				    ((entry->protection & VM_PROT_WRITE) ||
				     (entry->object.uvm_obj == NULL))) {
					amap_copy(map, entry, M_WAITOK, TRUE,
					    entry->start, entry->end);
					/* XXXCDC: wait OK? */
				}
			}
		}
		entry->wired_count++;
	}

	/*
	 * Pass 3.
	 */

#ifdef DIAGNOSTIC
	timestamp_save = map->timestamp;
#endif
	vm_map_busy(map);
	vm_map_downgrade(map);

	for (error = 0, entry = map->header.next;
	    entry != &map->header && error == 0;
	    entry = entry->next) {
		if (entry->wired_count == 1) {
			error = uvm_fault_wire(map, entry->start, entry->end,
			     entry->protection);
		}
	}

	if (error) {	/* failed? */
		/*
		 * Get back an exclusive (write) lock.
		 */
		vm_map_upgrade(map);
		vm_map_unbusy(map);

#ifdef DIAGNOSTIC
		if (timestamp_save != map->timestamp)
			panic("uvm_map_pageable_all: stale map");
#endif

		/*
		 * first drop the wiring count on all the entries
		 * which haven't actually been wired yet.
		 *
		 * Skip VM_PROT_NONE entries like we did above.
		 */
		failed_entry = entry;
		for (/* nothing */; entry != &map->header;
		     entry = entry->next) {
			if (entry->protection == VM_PROT_NONE)
				continue;
			entry->wired_count--;
		}

		/*
		 * now, unwire all the entries that were successfully
		 * wired above.
		 *
		 * Skip VM_PROT_NONE entries like we did above.
		 */
		for (entry = map->header.next; entry != failed_entry;
		     entry = entry->next) {
			if (entry->protection == VM_PROT_NONE)
				continue;
			entry->wired_count--;
			if (VM_MAPENT_ISWIRED(entry))
				uvm_map_entry_unwire(map, entry);
		}
		vm_map_unlock(map);
		return (error);
	}

	/* We are holding a read lock here. */
	vm_map_unbusy(map);
	vm_map_unlock_read(map);

	return (0);
}

/*
 * uvm_map_clean: clean out a map range
 *
 * => valid flags:
 *   if (flags & PGO_CLEANIT): dirty pages are cleaned first
 *   if (flags & PGO_SYNCIO): dirty pages are written synchronously
 *   if (flags & PGO_DEACTIVATE): any cached pages are deactivated after clean
 *   if (flags & PGO_FREE): any cached pages are freed after clean
 * => returns an error if any part of the specified range isn't mapped
 * => never a need to flush amap layer since the anonymous memory has 
 *	no permanent home, but may deactivate pages there
 * => called from sys_msync() and sys_madvise()
 * => caller must not write-lock map (read OK).
 * => we may sleep while cleaning if SYNCIO [with map read-locked]
 */

int	amap_clean_works = 1;	/* XXX for now, just in case... */

int
uvm_map_clean(struct vm_map *map, vaddr_t start, vaddr_t end, int flags)
{
	struct vm_map_entry *current, *entry;
	struct uvm_object *uobj;
	struct vm_amap *amap;
	struct vm_anon *anon;
	struct vm_page *pg;
	vaddr_t offset;
	vsize_t size;
	int rv, error, refs;

	KASSERT((flags & (PGO_FREE|PGO_DEACTIVATE)) !=
		(PGO_FREE|PGO_DEACTIVATE));

	vm_map_lock_read(map);
	VM_MAP_RANGE_CHECK(map, start, end);
	if (uvm_map_lookup_entry(map, start, &entry) == FALSE) {
		vm_map_unlock_read(map);
		return (EFAULT);
	}

	/*
	 * Make a first pass to check for holes.
	 */

	for (current = entry; current->start < end; current = current->next) {
		if (UVM_ET_ISSUBMAP(current)) {
			vm_map_unlock_read(map);
			return (EINVAL);
		}
		if (end > current->end && (current->next == &map->header ||
		    current->end != current->next->start)) {
			vm_map_unlock_read(map);
			return (EFAULT);
		}
	}

	error = 0;

	for (current = entry; current->start < end; current = current->next) {
		amap = current->aref.ar_amap;	/* top layer */
		uobj = current->object.uvm_obj;	/* bottom layer */
		KASSERT(start >= current->start);

		/*
		 * No amap cleaning necessary if:
		 *
		 *	(1) There's no amap.
		 *
		 *	(2) We're not deactivating or freeing pages.
		 */

		if (amap == NULL || (flags & (PGO_DEACTIVATE|PGO_FREE)) == 0)
			goto flush_object;

		/* XXX for now, just in case... */
		if (amap_clean_works == 0)
			goto flush_object;

		offset = start - current->start;
		size = MIN(end, current->end) - start;
		for ( ; size != 0; size -= PAGE_SIZE, offset += PAGE_SIZE) {
			anon = amap_lookup(&current->aref, offset);
			if (anon == NULL)
				continue;

			simple_lock(&anon->an_lock);

			pg = anon->an_page;
			if (pg == NULL) {
				simple_unlock(&anon->an_lock);
				continue;
			}

			switch (flags & (PGO_CLEANIT|PGO_FREE|PGO_DEACTIVATE)) {

			/*
			 * XXX In these first 3 cases, we always just
			 * XXX deactivate the page.  We may want to
			 * XXX handle the different cases more
			 * XXX specifically, in the future.
			 */

			case PGO_CLEANIT|PGO_FREE:
			case PGO_CLEANIT|PGO_DEACTIVATE:
			case PGO_DEACTIVATE:
 deactivate_it:
				/* skip the page if it's loaned or wired */
				if (pg->loan_count != 0 ||
				    pg->wire_count != 0) {
					simple_unlock(&anon->an_lock);
					continue;
				}

				uvm_lock_pageq();

				/*
				 * skip the page if it's not actually owned
				 * by the anon (may simply be loaned to the
				 * anon).
				 */

				if ((pg->pg_flags & PQ_ANON) == 0) {
					KASSERT(pg->uobject == NULL);
					uvm_unlock_pageq();
					simple_unlock(&anon->an_lock);
					continue;
				}
				KASSERT(pg->uanon == anon);

#ifdef UBC
				/* ...and deactivate the page. */
				pmap_clear_reference(pg);
#else
				/* zap all mappings for the page. */
				pmap_page_protect(pg, VM_PROT_NONE);

				/* ...and deactivate the page. */
#endif
				uvm_pagedeactivate(pg);

				uvm_unlock_pageq();
				simple_unlock(&anon->an_lock);
				continue;

			case PGO_FREE:

				/*
				 * If there are multiple references to
				 * the amap, just deactivate the page.
				 */

				if (amap_refs(amap) > 1)
					goto deactivate_it;

				/* XXX skip the page if it's wired */
				if (pg->wire_count != 0) {
					simple_unlock(&anon->an_lock);
					continue;
				}
				amap_unadd(&current->aref, offset);
				refs = --anon->an_ref;
				simple_unlock(&anon->an_lock);
				if (refs == 0)
					uvm_anfree(anon);
				continue;

			default:
				panic("uvm_map_clean: weird flags");
			}
		}

flush_object:
		/*
		 * flush pages if we've got a valid backing object.
		 *
		 * Don't PGO_FREE if we don't have write permission
	 	 * and don't flush if this is a copy-on-write object
		 * since we can't know our permissions on it.
		 */

		offset = current->offset + (start - current->start);
		size = MIN(end, current->end) - start;
		if (uobj != NULL &&
		    ((flags & PGO_FREE) == 0 ||
		     ((entry->max_protection & VM_PROT_WRITE) != 0 &&
		      (entry->etype & UVM_ET_COPYONWRITE) == 0))) {
			simple_lock(&uobj->vmobjlock);
			rv = uobj->pgops->pgo_flush(uobj, offset,
			    offset + size, flags);
			simple_unlock(&uobj->vmobjlock);

			if (rv == FALSE)
				error = EFAULT;
		}
		start += size;
	}
	vm_map_unlock_read(map);
	return (error); 
}


/*
 * uvm_map_checkprot: check protection in map
 *
 * => must allow specified protection in a fully allocated region.
 * => map must be read or write locked by caller.
 */

boolean_t
uvm_map_checkprot(struct vm_map *map, vaddr_t start, vaddr_t end,
    vm_prot_t protection)
{
	struct vm_map_entry *entry;
	struct vm_map_entry *tmp_entry;

	if (!uvm_map_lookup_entry(map, start, &tmp_entry)) {
		return(FALSE);
	}
	entry = tmp_entry;
	while (start < end) {
		if (entry == &map->header) {
			return(FALSE);
		}

		/*
		 * no holes allowed
		 */

		if (start < entry->start) {
			return(FALSE);
		}

		/*
		 * check protection associated with entry
		 */

		if ((entry->protection & protection) != protection) {
			return(FALSE);
		}

		/* go to next entry */

		start = entry->end;
		entry = entry->next;
	}
	return(TRUE);
}

/*
 * uvmspace_alloc: allocate a vmspace structure.
 *
 * - structure includes vm_map and pmap
 * - XXX: no locking on this structure
 * - refcnt set to 1, rest must be init'd by caller
 */
struct vmspace *
uvmspace_alloc(vaddr_t min, vaddr_t max, boolean_t pageable,
    boolean_t remove_holes)
{
	struct vmspace *vm;

	vm = pool_get(&uvm_vmspace_pool, PR_WAITOK | PR_ZERO);
	uvmspace_init(vm, NULL, min, max, pageable, remove_holes);
	return (vm);
}

/*
 * uvmspace_init: initialize a vmspace structure.
 *
 * - XXX: no locking on this structure
 * - refcnt set to 1, rest must be init'd by caller
 */
void
uvmspace_init(struct vmspace *vm, struct pmap *pmap, vaddr_t min, vaddr_t max,
    boolean_t pageable, boolean_t remove_holes)
{

	uvm_map_setup(&vm->vm_map, min, max, pageable ? VM_MAP_PAGEABLE : 0);

	if (pmap)
		pmap_reference(pmap);
	else
		pmap = pmap_create();
	vm->vm_map.pmap = pmap;

	vm->vm_refcnt = 1;

	if (remove_holes)
		pmap_remove_holes(&vm->vm_map);
}

/*
 * uvmspace_share: share a vmspace between two proceses
 *
 * - XXX: no locking on vmspace
 * - used for vfork, threads(?)
 */

void
uvmspace_share(struct proc *p1, struct proc *p2)
{
	p2->p_vmspace = p1->p_vmspace;
	p1->p_vmspace->vm_refcnt++;
}

/*
 * uvmspace_exec: the process wants to exec a new program
 *
 * - XXX: no locking on vmspace
 */

void
uvmspace_exec(struct proc *p, vaddr_t start, vaddr_t end)
{
	struct vmspace *nvm, *ovm = p->p_vmspace;
	struct vm_map *map = &ovm->vm_map;

	pmap_unuse_final(p);   /* before stack addresses go away */

	/*
	 * see if more than one process is using this vmspace...
	 */

	if (ovm->vm_refcnt == 1) {

		/*
		 * if p is the only process using its vmspace then we can safely
		 * recycle that vmspace for the program that is being exec'd.
		 */

#ifdef SYSVSHM
		/*
		 * SYSV SHM semantics require us to kill all segments on an exec
		 */
		if (ovm->vm_shm)
			shmexit(ovm);
#endif

		/*
		 * POSIX 1003.1b -- "lock future mappings" is revoked
		 * when a process execs another program image.
		 */
		vm_map_lock(map);
		vm_map_modflags(map, 0, VM_MAP_WIREFUTURE);
		vm_map_unlock(map);

		/*
		 * now unmap the old program
		 */
		uvm_unmap(map, map->min_offset, map->max_offset);

		/*
		 * but keep MMU holes unavailable
		 */
		pmap_remove_holes(map);

		/*
		 * resize the map
		 */
		vm_map_lock(map);
		map->min_offset = start;
		uvm_tree_sanity(map, "resize enter");
		map->max_offset = end;
		if (map->header.prev != &map->header)
			uvm_rb_fixup(map, map->header.prev);
		uvm_tree_sanity(map, "resize leave");
		vm_map_unlock(map);
	

	} else {

		/*
		 * p's vmspace is being shared, so we can't reuse it for p since
		 * it is still being used for others.   allocate a new vmspace
		 * for p
		 */
		nvm = uvmspace_alloc(start, end,
			 (map->flags & VM_MAP_PAGEABLE) ? TRUE : FALSE, TRUE);

		/*
		 * install new vmspace and drop our ref to the old one.
		 */

		pmap_deactivate(p);
		p->p_vmspace = nvm;
		pmap_activate(p);

		uvmspace_free(ovm);
	}
}

/*
 * uvmspace_free: free a vmspace data structure
 *
 * - XXX: no locking on vmspace
 */

void
uvmspace_free(struct vmspace *vm)
{
	struct vm_map_entry *dead_entries;

	if (--vm->vm_refcnt == 0) {
		/*
		 * lock the map, to wait out all other references to it.  delete
		 * all of the mappings and pages they hold, then call the pmap
		 * module to reclaim anything left.
		 */
#ifdef SYSVSHM
		/* Get rid of any SYSV shared memory segments. */
		if (vm->vm_shm != NULL)
			shmexit(vm);
#endif
		vm_map_lock(&vm->vm_map);
		if (vm->vm_map.nentries) {
			uvm_unmap_remove(&vm->vm_map,
			    vm->vm_map.min_offset, vm->vm_map.max_offset,
			    &dead_entries, NULL, TRUE);
			if (dead_entries != NULL)
				uvm_unmap_detach(dead_entries, 0);
		}
		pmap_destroy(vm->vm_map.pmap);
		vm->vm_map.pmap = NULL;
		pool_put(&uvm_vmspace_pool, vm);
	}
}

/*
 * uvm_map_create: create map
 */
vm_map_t
uvm_map_create(pmap_t pmap, vaddr_t min, vaddr_t max, int flags)
{
	vm_map_t result;

	result = malloc(sizeof(struct vm_map), M_VMMAP, M_WAITOK);
	uvm_map_setup(result, min, max, flags);
	result->pmap = pmap;
	return(result);
}

/*
 * uvm_map_setup: init map
 *
 * => map must not be in service yet.
 */
void
uvm_map_setup(vm_map_t map, vaddr_t min, vaddr_t max, int flags)
{

	RB_INIT(&map->rbhead);
	map->header.next = map->header.prev = &map->header;
	map->nentries = 0;
	map->size = 0;
	map->ref_count = 1;
	map->min_offset = min;
	map->max_offset = max;
	map->flags = flags;
	map->first_free = &map->header;
	map->hint = &map->header;
	map->timestamp = 0;
	rw_init(&map->lock, "vmmaplk");
	simple_lock_init(&map->ref_lock);
	simple_lock_init(&map->hint_lock);
}



/*
 * uvm_map_reference: add reference to a map
 *
 * => map need not be locked (we use ref_lock).
 */
void
uvm_map_reference(vm_map_t map)
{
	simple_lock(&map->ref_lock);
	map->ref_count++; 
	simple_unlock(&map->ref_lock);
}

/*
 * uvm_map_deallocate: drop reference to a map
 *
 * => caller must not lock map
 * => we will zap map if ref count goes to zero
 */
void
uvm_map_deallocate(vm_map_t map)
{
	int c;

	simple_lock(&map->ref_lock);
	c = --map->ref_count;
	simple_unlock(&map->ref_lock);
	if (c > 0) {
		return;
	}

	/*
	 * all references gone.   unmap and free.
	 */

	uvm_unmap(map, map->min_offset, map->max_offset);
	pmap_destroy(map->pmap);
	free(map, M_VMMAP);
}

/*
 *   F O R K   -   m a i n   e n t r y   p o i n t
 */
/*
 * uvmspace_fork: fork a process' main map
 *
 * => create a new vmspace for child process from parent.
 * => parent's map must not be locked.
 */

struct vmspace *
uvmspace_fork(struct vmspace *vm1)
{
	struct vmspace *vm2;
	struct vm_map *old_map = &vm1->vm_map;
	struct vm_map *new_map;
	struct vm_map_entry *old_entry;
	struct vm_map_entry *new_entry;
	pmap_t          new_pmap;
	boolean_t	protect_child;

	vm_map_lock(old_map);

	vm2 = uvmspace_alloc(old_map->min_offset, old_map->max_offset,
	    (old_map->flags & VM_MAP_PAGEABLE) ? TRUE : FALSE, FALSE);
	memcpy(&vm2->vm_startcopy, &vm1->vm_startcopy,
	(caddr_t) (vm1 + 1) - (caddr_t) &vm1->vm_startcopy);
	new_map = &vm2->vm_map;		  /* XXX */
	new_pmap = new_map->pmap;

	old_entry = old_map->header.next;

	/*
	 * go entry-by-entry
	 */

	while (old_entry != &old_map->header) {

		/*
		 * first, some sanity checks on the old entry
		 */
		if (UVM_ET_ISSUBMAP(old_entry))
		    panic("fork: encountered a submap during fork (illegal)");

		if (!UVM_ET_ISCOPYONWRITE(old_entry) &&
			    UVM_ET_ISNEEDSCOPY(old_entry))
	panic("fork: non-copy_on_write map entry marked needs_copy (illegal)");


		switch (old_entry->inheritance) {
		case MAP_INHERIT_NONE:
			/*
			 * drop the mapping
			 */
			break;

		case MAP_INHERIT_SHARE:
			/*
			 * share the mapping: this means we want the old and
			 * new entries to share amaps and backing objects.
			 */

			/*
			 * if the old_entry needs a new amap (due to prev fork)
			 * then we need to allocate it now so that we have
			 * something we own to share with the new_entry.   [in
			 * other words, we need to clear needs_copy]
			 */

			if (UVM_ET_ISNEEDSCOPY(old_entry)) {
				/* get our own amap, clears needs_copy */
				amap_copy(old_map, old_entry, M_WAITOK, FALSE,
				    0, 0); 
				/* XXXCDC: WAITOK??? */
			}

			new_entry = uvm_mapent_alloc(new_map, 0);
			/* old_entry -> new_entry */
			uvm_mapent_copy(old_entry, new_entry);

			/* new pmap has nothing wired in it */
			new_entry->wired_count = 0;

			/*
			 * gain reference to object backing the map (can't
			 * be a submap, already checked this case).
			 */
			if (new_entry->aref.ar_amap)
				/* share reference */
				uvm_map_reference_amap(new_entry, AMAP_SHARED);

			if (new_entry->object.uvm_obj &&
			    new_entry->object.uvm_obj->pgops->pgo_reference)
				new_entry->object.uvm_obj->
				    pgops->pgo_reference(
				        new_entry->object.uvm_obj);

			/* insert entry at end of new_map's entry list */
			uvm_map_entry_link(new_map, new_map->header.prev,
			    new_entry);

			/* 
			 * pmap_copy the mappings: this routine is optional
			 * but if it is there it will reduce the number of
			 * page faults in the new proc.
			 */

			pmap_copy(new_pmap, old_map->pmap, new_entry->start,
			    (old_entry->end - old_entry->start),
			    old_entry->start);

			break;

		case MAP_INHERIT_COPY:

			/*
			 * copy-on-write the mapping (using mmap's
			 * MAP_PRIVATE semantics)
			 *
			 * allocate new_entry, adjust reference counts.  
			 * (note that new references are read-only).
			 */

			new_entry = uvm_mapent_alloc(new_map, 0);
			/* old_entry -> new_entry */
			uvm_mapent_copy(old_entry, new_entry);

			if (new_entry->aref.ar_amap)
				uvm_map_reference_amap(new_entry, 0);

			if (new_entry->object.uvm_obj &&
			    new_entry->object.uvm_obj->pgops->pgo_reference)
				new_entry->object.uvm_obj->pgops->pgo_reference
				    (new_entry->object.uvm_obj);

			/* new pmap has nothing wired in it */
			new_entry->wired_count = 0;

			new_entry->etype |=
			    (UVM_ET_COPYONWRITE|UVM_ET_NEEDSCOPY);
			uvm_map_entry_link(new_map, new_map->header.prev,
			    new_entry);

			/*
			 * the new entry will need an amap.  it will either
			 * need to be copied from the old entry or created
			 * from scratch (if the old entry does not have an
			 * amap).  can we defer this process until later
			 * (by setting "needs_copy") or do we need to copy
			 * the amap now?
			 *
			 * we must copy the amap now if any of the following
			 * conditions hold:
			 * 1. the old entry has an amap and that amap is
			 *    being shared.  this means that the old (parent)
			 *    process is sharing the amap with another 
			 *    process.  if we do not clear needs_copy here
			 *    we will end up in a situation where both the
			 *    parent and child process are referring to the
			 *    same amap with "needs_copy" set.  if the 
			 *    parent write-faults, the fault routine will
			 *    clear "needs_copy" in the parent by allocating
			 *    a new amap.   this is wrong because the 
			 *    parent is supposed to be sharing the old amap
			 *    and the new amap will break that.
			 *
			 * 2. if the old entry has an amap and a non-zero
			 *    wire count then we are going to have to call
			 *    amap_cow_now to avoid page faults in the 
			 *    parent process.   since amap_cow_now requires
			 *    "needs_copy" to be clear we might as well
			 *    clear it here as well.
			 *
			 */

			if (old_entry->aref.ar_amap != NULL) {

			  if ((amap_flags(old_entry->aref.ar_amap) & 
			       AMAP_SHARED) != 0 ||
			      VM_MAPENT_ISWIRED(old_entry)) {

			    amap_copy(new_map, new_entry, M_WAITOK, FALSE,
				      0, 0);
			    /* XXXCDC: M_WAITOK ... ok? */
			  }
			}

			/*
			 * if the parent's entry is wired down, then the
			 * parent process does not want page faults on
			 * access to that memory.  this means that we
			 * cannot do copy-on-write because we can't write
			 * protect the old entry.   in this case we
			 * resolve all copy-on-write faults now, using
			 * amap_cow_now.   note that we have already
			 * allocated any needed amap (above).
			 */

			if (VM_MAPENT_ISWIRED(old_entry)) {

			  /* 
			   * resolve all copy-on-write faults now
			   * (note that there is nothing to do if 
			   * the old mapping does not have an amap).
			   * XXX: is it worthwhile to bother with pmap_copy
			   * in this case?
			   */
			  if (old_entry->aref.ar_amap)
			    amap_cow_now(new_map, new_entry);

			} else { 

			  /*
			   * setup mappings to trigger copy-on-write faults
			   * we must write-protect the parent if it has
			   * an amap and it is not already "needs_copy"...
			   * if it is already "needs_copy" then the parent
			   * has already been write-protected by a previous
			   * fork operation.
			   *
			   * if we do not write-protect the parent, then
			   * we must be sure to write-protect the child
			   * after the pmap_copy() operation.
			   *
			   * XXX: pmap_copy should have some way of telling
			   * us that it didn't do anything so we can avoid
			   * calling pmap_protect needlessly.
			   */

			  if (old_entry->aref.ar_amap) {

			    if (!UVM_ET_ISNEEDSCOPY(old_entry)) {
			      if (old_entry->max_protection & VM_PROT_WRITE) {
				pmap_protect(old_map->pmap,
					     old_entry->start,
					     old_entry->end,
					     old_entry->protection &
					     ~VM_PROT_WRITE);
			        pmap_update(old_map->pmap);

			      }
			      old_entry->etype |= UVM_ET_NEEDSCOPY;
			    }

			    /*
			     * parent must now be write-protected
			     */
			    protect_child = FALSE;
			  } else {

			    /*
			     * we only need to protect the child if the 
			     * parent has write access.
			     */
			    if (old_entry->max_protection & VM_PROT_WRITE)
			      protect_child = TRUE;
			    else
			      protect_child = FALSE;

			  }

			  /*
			   * copy the mappings
			   * XXX: need a way to tell if this does anything
			   */

			  pmap_copy(new_pmap, old_map->pmap,
				    new_entry->start,
				    (old_entry->end - old_entry->start),
				    old_entry->start);

			  /*
			   * protect the child's mappings if necessary
			   */
			  if (protect_child) {
			    pmap_protect(new_pmap, new_entry->start,
					 new_entry->end, 
					 new_entry->protection & 
					          ~VM_PROT_WRITE);
			  }

			}
			break;
		}  /* end of switch statement */
		old_entry = old_entry->next;
	}

	new_map->size = old_map->size;
	vm_map_unlock(old_map); 

#ifdef SYSVSHM
	if (vm1->vm_shm)
		shmfork(vm1, vm2);
#endif

#ifdef PMAP_FORK
	pmap_fork(vm1->vm_map.pmap, vm2->vm_map.pmap);
#endif

	return(vm2);    
}

#if defined(DDB)

/*
 * DDB hooks
 */

/*
 * uvm_map_printit: actually prints the map
 */

void
uvm_map_printit(struct vm_map *map, boolean_t full,
    int (*pr)(const char *, ...))
{
	struct vm_map_entry *entry;

	(*pr)("MAP %p: [0x%lx->0x%lx]\n", map, map->min_offset,map->max_offset);
	(*pr)("\t#ent=%d, sz=%u, ref=%d, version=%u, flags=0x%x\n",
	    map->nentries, map->size, map->ref_count, map->timestamp,
	    map->flags);
#ifdef pmap_resident_count
	(*pr)("\tpmap=%p(resident=%d)\n", map->pmap, 
	    pmap_resident_count(map->pmap));
#else
	/* XXXCDC: this should be required ... */
	(*pr)("\tpmap=%p(resident=<<NOT SUPPORTED!!!>>)\n", map->pmap);
#endif
	if (!full)
		return;
	for (entry = map->header.next; entry != &map->header;
	    entry = entry->next) {
		(*pr)(" - %p: 0x%lx->0x%lx: obj=%p/0x%llx, amap=%p/%d\n",
		    entry, entry->start, entry->end, entry->object.uvm_obj,
		    (long long)entry->offset, entry->aref.ar_amap,
		    entry->aref.ar_pageoff);
		(*pr)(
		    "\tsubmap=%c, cow=%c, nc=%c, prot(max)=%d/%d, inh=%d, "
		    "wc=%d, adv=%d\n",
		    (entry->etype & UVM_ET_SUBMAP) ? 'T' : 'F',
		    (entry->etype & UVM_ET_COPYONWRITE) ? 'T' : 'F', 
		    (entry->etype & UVM_ET_NEEDSCOPY) ? 'T' : 'F',
		    entry->protection, entry->max_protection,
		    entry->inheritance, entry->wired_count, entry->advice);
	}
} 

/*
 * uvm_object_printit: actually prints the object
 */

void
uvm_object_printit(struct uvm_object *uobj, boolean_t full,
    int (*pr)(const char *, ...))
{
	struct vm_page *pg;
	int cnt = 0;

	(*pr)("OBJECT %p: pgops=%p, npages=%d, ",
	    uobj, uobj->pgops, uobj->uo_npages);
	if (UVM_OBJ_IS_KERN_OBJECT(uobj))
		(*pr)("refs=<SYSTEM>\n");
	else
		(*pr)("refs=%d\n", uobj->uo_refs);

	if (!full) {
		return;
	}
	(*pr)("  PAGES <pg,offset>:\n  ");
	RB_FOREACH(pg, uvm_objtree, &uobj->memt) {
		(*pr)("<%p,0x%llx> ", pg, (long long)pg->offset);
		if ((cnt % 3) == 2) {
			(*pr)("\n  ");
		}
		cnt++;
	}
	if ((cnt % 3) != 2) {
		(*pr)("\n");
	}
} 

/*
 * uvm_page_printit: actually print the page
 */

static const char page_flagbits[] =
	"\20\1BUSY\2WANTED\3TABLED\4CLEAN\5CLEANCHK\6RELEASED\7FAKE\10RDONLY"
	"\11ZERO\15PAGER1\20FREE\21INACTIVE\22ACTIVE\24ENCRYPT\30PMAP0"
	"\31PMAP1\32PMAP2\33PMAP3";

void
uvm_page_printit(struct vm_page *pg, boolean_t full,
    int (*pr)(const char *, ...))
{
	struct vm_page *tpg;
	struct uvm_object *uobj;
	struct pglist *pgl;

	(*pr)("PAGE %p:\n", pg);
	(*pr)("  flags=%b, vers=%d, wire_count=%d, pa=0x%llx\n",
	    pg->pg_flags, page_flagbits, pg->pg_version, pg->wire_count,
	    (long long)pg->phys_addr);
	(*pr)("  uobject=%p, uanon=%p, offset=0x%llx loan_count=%d\n",
	    pg->uobject, pg->uanon, (long long)pg->offset, pg->loan_count);
#if defined(UVM_PAGE_TRKOWN)
	if (pg->pg_flags & PG_BUSY)
		(*pr)("  owning process = %d, tag=%s",
		    pg->owner, pg->owner_tag);
	else
		(*pr)("  page not busy, no owner");
#else
	(*pr)("  [page ownership tracking disabled]");
#endif
#ifdef __HAVE_VM_PAGE_MD
	(*pr)("\tvm_page_md %p\n", &pg->mdpage);
#else
	(*pr)("\n");
#endif

	if (!full)
		return;

	/* cross-verify object/anon */
	if ((pg->pg_flags & PQ_FREE) == 0) {
		if (pg->pg_flags & PQ_ANON) {
			if (pg->uanon == NULL || pg->uanon->an_page != pg)
			    (*pr)("  >>> ANON DOES NOT POINT HERE <<< (%p)\n",
				(pg->uanon) ? pg->uanon->an_page : NULL);
			else
				(*pr)("  anon backpointer is OK\n");
		} else {
			uobj = pg->uobject;
			if (uobj) {
				(*pr)("  checking object list\n");
				RB_FOREACH(tpg, uvm_objtree, &uobj->memt) {
					if (tpg == pg) {
						break;
					}
				}
				if (tpg)
					(*pr)("  page found on object list\n");
				else
			(*pr)("  >>> PAGE NOT FOUND ON OBJECT LIST! <<<\n");
			}
		}
	}

	/* cross-verify page queue */
	if (pg->pg_flags & PQ_FREE) {
		if (uvm_pmr_isfree(pg))
			printf("  page found in uvm_pmemrange\n");
		else
			printf("  >>> page not found in uvm_pmemrange <<<\n");
		pgl = NULL;
	} else if (pg->pg_flags & PQ_INACTIVE) {
		pgl = (pg->pg_flags & PQ_SWAPBACKED) ?
		    &uvm.page_inactive_swp : &uvm.page_inactive_obj;
	} else if (pg->pg_flags & PQ_ACTIVE) {
		pgl = &uvm.page_active;
 	} else {
		pgl = NULL;
	}

	if (pgl) {
		(*pr)("  checking pageq list\n");
		TAILQ_FOREACH(tpg, pgl, pageq) {
			if (tpg == pg) {
				break;
			}
		}
		if (tpg)
			(*pr)("  page found on pageq list\n");
		else
			(*pr)("  >>> PAGE NOT FOUND ON PAGEQ LIST! <<<\n");
	}
}
#endif