xref: /src/sys/uvm/uvm_map.c

/*	$NetBSD: uvm_map.c,v 1.7 1998/02/18 14:50:32 drochner Exp $	*/

/*
 * XXXCDC: "ROUGH DRAFT" QUALITY UVM PRE-RELEASE FILE!
 *         >>>USE AT YOUR OWN RISK, WORK IS NOT FINISHED<<<
 */
/*
 * 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 (at) 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.
 */

#include "opt_uvmhist.h"
#include "opt_pmap_new.h"

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

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

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

#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_kern.h>

#include <sys/syscallargs.h>

#define UVM_MAP
#include <uvm/uvm.h>

struct uvm_cnt uvm_map_call, map_backmerge, map_forwmerge;
struct uvm_cnt uvm_mlk_call, uvm_mlk_hint;

/*
 * macros
 */

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

/*
 * 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,value) \
                simple_lock(&(map)->hint_lock); \
                (map)->hint = (value); \
                simple_unlock(&(map)->hint_lock);

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

#define VM_MAP_RANGE_CHECK(map, start, end)             \
                {                                       \
                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;                    \
                }

/*
 * local prototypes
 */

static vm_map_entry_t	uvm_mapent_alloc __P((vm_map_t));
static void		uvm_mapent_copy __P((vm_map_entry_t,vm_map_entry_t));
static void		uvm_mapent_free __P((vm_map_entry_t));
static void		uvm_map_entry_unwire __P((vm_map_t, vm_map_entry_t));

/*
 * local inlines
 */

/*
 * uvm_mapent_alloc: allocate a map entry
 *
 * => XXX: static pool for kernel map?
 */

static __inline vm_map_entry_t uvm_mapent_alloc(map)

vm_map_t map;

{
  vm_map_entry_t me;
  int s;
  UVMHIST_FUNC("uvm_mapent_alloc");
  UVMHIST_CALLED(maphist);

  if (map->entries_pageable) {
    MALLOC(me, vm_map_entry_t, sizeof(struct vm_map_entry),
						M_VMMAPENT, M_WAITOK);
    me->flags = 0;
    /* me can't be null, wait ok */

  } else {
    s = splimp();		/* protect kentry_free list with splimp */
    simple_lock(&uvm.kentry_lock);
    me = uvm.kentry_free;
    if (me) uvm.kentry_free = me->next;
    simple_unlock(&uvm.kentry_lock);
    splx(s);
    if (!me)
      panic("mapent_alloc: out of kernel map entries, check MAX_KMAPENT");
    me->flags = UVM_MAP_STATIC;
  }

  UVMHIST_LOG(maphist, "<- new entry=0x%x [pageable=%d]",
		me, map->entries_pageable, 0, 0);
  return(me);

}

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

static __inline void uvm_mapent_free(me)

vm_map_entry_t me;

{
  int s;
  UVMHIST_FUNC("uvm_mapent_free");
  UVMHIST_CALLED(maphist);
  UVMHIST_LOG(maphist,"<- freeing map entry=0x%x [flags=%d]",
		me, me->flags, 0, 0);
  if ((me->flags & UVM_MAP_STATIC) == 0) {
    FREE(me, M_VMMAPENT);
  } else {
    s = splimp();		/* protect kentry_free list with splimp */
    simple_lock(&uvm.kentry_lock);
    me->next = uvm.kentry_free;
    uvm.kentry_free = me;
    simple_unlock(&uvm.kentry_lock);
    splx(s);
  }
}

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

static __inline void uvm_mapent_copy(src, dst)

vm_map_entry_t src;
vm_map_entry_t dst;

{
  bcopy(src, dst, ((char *)&src->uvm_map_entry_stop_copy) - ((char *)src));
}

/*
 * uvm_map_entry_unwire: unwire a map entry
 *
 * => map should be locked by caller
 */

static __inline void uvm_map_entry_unwire(map, entry)

vm_map_t map;
vm_map_entry_t entry;

{
  uvm_fault_unwire(map->pmap, entry->start, entry->end);
  entry->wired_count = 0;
}

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

void uvm_map_init()

{
  static struct vm_map_entry kernel_map_entry[MAX_KMAPENT];
#if defined(UVMHIST)
  static struct uvm_history_ent maphistbuf[100];
  static struct uvm_history_ent pdhistbuf[100];
#endif
  int lcv;

  /*
   * first, init logging system.
   */

  UVMHIST_FUNC("uvm_map_init");
  UVMHIST_INIT_STATIC(maphist, maphistbuf);
  UVMHIST_INIT_STATIC(pdhist, pdhistbuf);
  UVMHIST_CALLED(maphist);
  UVMHIST_LOG(maphist,"<starting uvm map system>", 0, 0, 0, 0);
  UVMCNT_INIT(uvm_map_call,  UVMCNT_CNT, 0, "# uvm_map() successful calls", 0);
  UVMCNT_INIT(map_backmerge, UVMCNT_CNT, 0, "# uvm_map() back merges", 0);
  UVMCNT_INIT(map_forwmerge, UVMCNT_CNT, 0, "# uvm_map() missed forward", 0);
  UVMCNT_INIT(uvm_mlk_call,  UVMCNT_CNT, 0, "# map lookup calls", 0);
  UVMCNT_INIT(uvm_mlk_hint,  UVMCNT_CNT, 0, "# map lookup hint hits", 0);

  /*
   * now set up static pool of kernel map entrys ...
   */

  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];
  }

}

/*
 * 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(map, entry, start)

register vm_map_t       map;
register vm_map_entry_t entry;
register vm_offset_t    start;

{
        register vm_map_entry_t new_entry;
	vm_offset_t new_adj;

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

        /*
         * 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);
	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 */
        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_ISMAP(entry)) {
               uvm_map_reference(new_entry->object.share_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_map_clip_end: ensure that the entry ends at or before
 *	the ending address, if it does'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(map, entry, end)

register vm_map_t	map;
register vm_map_entry_t	entry;
register vm_offset_t	end;

{
	register vm_map_entry_t	new_entry;
	vm_offset_t new_adj; /* #bytes we move start forward */

	/*
	 *	Create a new entry and insert it
	 *	AFTER the specified entry
	 */

	new_entry = uvm_mapent_alloc(map);
	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_map_entry_link(map, entry, new_entry);

	if (UVM_ET_ISMAP(entry)) {
	 	uvm_map_reference(new_entry->object.share_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);
	}
}


/*
 *   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.
 * => XXXCDC: need way to map in external amap?
 */

int uvm_map(map, startp, size, uobj, uoffset, flags)

vm_map_t map;
vm_offset_t *startp;	/* IN/OUT */
vm_size_t size;
struct uvm_object *uobj;
vm_offset_t uoffset;
uvm_flag_t flags;

{

  vm_map_entry_t prev_entry, new_entry;
  vm_prot_t prot = UVM_PROTECTION(flags), maxprot = UVM_MAXPROTECTION(flags);
  vm_inherit_t inherit = UVM_INHERIT(flags);
  int advice = UVM_ADVICE(flags);
  UVMHIST_FUNC("uvm_map");
  UVMHIST_CALLED(maphist);

  UVMHIST_LOG(maphist, "(map=0x%x, *startp=0x%x, size=%d, flags=0x%x)",
	map, *startp, size, flags);
  UVMHIST_LOG(maphist, "  uobj/offset 0x%x/%d", uobj, uoffset,0,0);

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

  if ((prot & maxprot) != prot) {
    UVMHIST_LOG(maphist, "<- prot. failure:  prot=0x%x, max=0x%x",
		prot, maxprot,0,0);
    return(KERN_PROTECTION_FAILURE);
  }

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

  if (vm_map_lock_try(map) == FALSE) {
    if (flags & UVM_FLAG_TRYLOCK)
      return(KERN_FAILURE);
    vm_map_lock(map); /* could sleep here */
  }
  if ((prev_entry = uvm_map_findspace(map, *startp, size, startp,
		uobj, uoffset, flags & UVM_FLAG_FIXED)) == NULL) {
	UVMHIST_LOG(maphist,"<- uvm_map_findspace failed!",0,0,0,0);
	vm_map_unlock(map);
	return(KERN_NO_SPACE);
  }

#if defined(PMAP_GROWKERNEL)	/* hack */
  {
    static vm_offset_t maxkaddr = 0;	/* locked by kernel_map lock */

    /*
     * hack: grow kernel PTPs in advance.
     */
    if (map == kernel_map && maxkaddr < (*startp + size)) {
      pmap_growkernel(*startp + size);
      maxkaddr = *startp + size;
    }
  }
#endif

  UVMCNT_INCR(uvm_map_call);

  /*
   * 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)
      uoffset = *startp - vm_map_min(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_ISMAP(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;

	/* wired_count's must match (new area is unwired) */
	if (prev_entry->wired_count)
		goto step3;

	/*
	 * can't extend a shared amap.  note: no need to lock amap to
	 * look at am_ref 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 && prev_entry->aref.ar_amap->am_ref != 1) {
	  goto step3;
	}

	/* got it! */

  	UVMCNT_INCR(map_backmerge);
	UVMHIST_LOG(maphist,"  starting back merge", 0, 0, 0, 0);

	/*
	 * 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);

	if (prev_entry->aref.ar_amap) {
	  amap_extend(prev_entry, size);
	}

	prev_entry->end += size;
	map->size += size;

	UVMHIST_LOG(maphist,"<- done (via backmerge)!", 0, 0, 0, 0);
	vm_map_unlock(map);
	return(KERN_SUCCESS);

  }

step3:
  UVMHIST_LOG(maphist,"  allocating new map entry", 0, 0, 0, 0);

  /* check for possible forward merge (which we don't do) and count
   * the number of times we missed a *possible* chance to merge more
   */

  if ((flags & UVM_FLAG_NOMERGE) == 0 && prev_entry->next != &map->header &&
	prev_entry->next->start == (*startp + size))
  	UVMCNT_INCR(map_forwmerge);

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

  new_entry = uvm_mapent_alloc(map);
  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;
  }

  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 */
    vm_offset_t to_add = (flags & UVM_FLAG_AMAPPAD) ?
      UVM_AMAP_CHUNK * PAGE_SIZE : 0;
    struct vm_amap *amap = amap_alloc(size, to_add, M_WAITOK);
    new_entry->aref.ar_slotoff = 0;
    new_entry->aref.ar_amap = amap;
  } else {
    new_entry->aref.ar_amap = NULL;
  }

  uvm_map_entry_link(map, prev_entry, new_entry);

  map->size += size;

  /*
   *      Update the free space hint
   */

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

  UVMHIST_LOG(maphist,"<- done!", 0, 0, 0, 0);
  vm_map_unlock(map);
  return(KERN_SUCCESS);
}

/*
 * 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(map, address, entry)

register vm_map_t	map;
register vm_offset_t	address;
vm_map_entry_t		*entry;		/* OUT */

{
	register vm_map_entry_t		cur;
	register vm_map_entry_t		last;
	UVMHIST_FUNC("uvm_map_lookup_entry");
	UVMHIST_CALLED(maphist);

	UVMHIST_LOG(maphist,"(map=0x%x,addr=0x%x,ent=0x%x)",
		map, address, entry, 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;

	UVMCNT_INCR(uvm_mlk_call);
	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)) {
			UVMCNT_INCR(uvm_mlk_hint);
			*entry = cur;
			UVMHIST_LOG(maphist,"<- got it via hint (0x%x)",
					cur,0,0,0);
			return(TRUE);
		}
	}
	else {
	    	/*
		 *	Go from start to hint, *inclusively*
		 */
		last = cur->next;
		cur = map->header.next;
	}

	/*
	 *	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, cur);
				UVMHIST_LOG(maphist,"<- search got it (0x%x)",
					cur, 0,0,0);
				return(TRUE);
			}
			break;
		}
		cur = cur->next;
	}
	*entry = cur->prev;
	SAVE_HINT(map, *entry);
	UVMHIST_LOG(maphist,"<- failed!",0,0,0,0);
	return(FALSE);
}


/*
 * uvm_map_findspace: find "length" sized space in "map".
 *
 * => "hint" is a hint about where we want it, unless fixed is true
 *	(in which case we insist on using "hint").
 * => "result" is VA returned
 * => uobj/uoffset are to be used to handle VAC alignment, if required
 * => 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
 */


vm_map_entry_t uvm_map_findspace(map, hint, length, result,
				 uobj, uoffset, fixed)

vm_map_t map;
vm_offset_t hint;
vm_size_t length;
vm_offset_t *result; /* OUT */
struct uvm_object *uobj;
vm_offset_t uoffset;
boolean_t fixed;

{
	vm_map_entry_t entry, next, tmp;
	vm_offset_t end;
	UVMHIST_FUNC("uvm_map_findspace");
	UVMHIST_CALLED(maphist);

	UVMHIST_LOG(maphist, "(map=0x%x, hint=0x%x, len=%d, fixed=%d)",
		map, hint, length, fixed);

	if (hint < map->min_offset) {	/* check ranges ... */
		if (fixed) {
			UVMHIST_LOG(maphist,"<- VA below map range",0,0,0,0);
			return(NULL);
		}
		hint = map->min_offset;
	}
	if (hint > map->max_offset) {
		UVMHIST_LOG(maphist,"<- VA 0x%x > range [0x%x->0x%x]",
				hint, map->min_offset, map->max_offset, 0);
		return(NULL);
	}

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

	if (!fixed && 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 (fixed) {
				UVMHIST_LOG(maphist,"<- fixed & VA in use",
						0,0,0,0);
				return(NULL);
			}
			hint = tmp->end;
		}
		entry = tmp;
	}

	/*
	 * 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 (!fixed && uoffset != UVM_UNKNOWN_OFFSET)
		  PMAP_PREFER(uoffset, &hint);
#endif
		end = hint + length;
		if (end > map->max_offset || end < hint) {
			UVMHIST_LOG(maphist,"<- failed (off end)", 0,0,0,0);
			return (NULL);
		}
		next = entry->next;
		if (next == &map->header || next->start >= end)
			break;
		if (fixed) {
			UVMHIST_LOG(maphist,"<- fixed mapping failed", 0,0,0,0);
			return(NULL); /* only one shot at it ... */
		}
	}
	SAVE_HINT(map, entry);
	*result = hint;
	UVMHIST_LOG(maphist,"<- got it!  (result=0x%x)", hint, 0,0,0);
	return (entry);
}

/*
 *   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
 * => if the "start"/"stop" range lie within a mapping of a share map,
 *    then the unmap takes place within the context of that share map
 *    rather than in the main map, unless the "mainonly" flag is set.
 *    (e.g. the "exit" system call would want to set "mainonly").
 * => we return a list of map entries that we've remove from the map
 *    in "entry_list"
 */

int uvm_unmap_remove(map, start, end, mainonly, entry_list)

vm_map_t map;
vm_offset_t start,end;
boolean_t mainonly;
vm_map_entry_t *entry_list;	/* OUT */

{
  int result, refs;
  vm_map_entry_t entry, first_entry, next;
  vm_offset_t len;
  boolean_t already_removed;
  struct uvm_object *uobj;
  UVMHIST_FUNC("uvm_unmap_remove");
  UVMHIST_CALLED(maphist);

  UVMHIST_LOG(maphist,"(map=0x%x, start=0x%x, end=0x%x)", map,start,end,0);

  VM_MAP_RANGE_CHECK(map, start, end);

  /*
   * find first entry
   */
  if (uvm_map_lookup_entry(map, start, &first_entry) == TRUE) {

    /*
     * start lies within a mapped region.   first check to see if
     * it is within a sharemap (in which case we recurse and unmap
     * within the context of the share map).
     */
    if (UVM_ET_ISMAP(first_entry) && !UVM_ET_ISSUBMAP(first_entry) &&
	mainonly == 0 && end <= first_entry->end) {
      /* is a share map and in range ... */
      /* XXX: do address transforms if share VA's != main VA's */
      /* note: main map kept locked during share map unlock */
      result = uvm_unmap(first_entry->object.share_map, start, end, 0);
      *entry_list = NULL;
      return(result);
    }
    /* non-share map: clip and go... */
    entry = first_entry;
    UVM_MAP_CLIP_START(map, entry, start);
    SAVE_HINT(map, entry->prev);	/* critical!  prevents stale hint */

  } 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
   * seperate 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;

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

    if (entry->wired_count)
      uvm_map_entry_unwire(map, entry);

    /*
     * special case: handle mappings to anonymous kernel objects.
     * we want to free these pages right away...
     */
    if (UVM_ET_ISOBJ(entry) && entry->object.uvm_obj->uo_refs == UVM_OBJ_KERN) {

#ifdef DIAGNOSTIC
      if (vm_map_pmap(map) != pmap_kernel())
	panic("uvm_unmap_remove: kernel object mapped by non-kernel map");
#endif

      /*
       * 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:
       *     - pmap_page_protect them out of all pmaps
       *     - uvm_pagefree the page
       *
       * note that in case [1] the pmap_page_protect call in uvm_km_pgremove
       * may very well be redundant because we have already removed the
       * mappings beforehand with pmap_remove (or pmap_kremove).
       * in the PMAP_NEW case, the pmap_page_protect call may not do
       * anything, since PMAP_NEW allows the kernel to enter/remove
       * kernel mappings without bothing to keep track of the mappings
       * (e.g. via pv_entry lists).    XXX: because of this, in the
       * future we should consider removing the pmap_page_protect from
       * uvm_km_pgremove some time in the future.
       */

      /*
       * remove mappings from pmap
       */
#if defined(PMAP_NEW)
      pmap_kremove(entry->start, len);
#else
      pmap_remove(pmap_kernel(), entry->start, entry->start+len);
#endif

      /*
       * remove pages from kernel object
       */
      uvm_km_pgremove(entry->object.uvm_obj, entry->start - vm_map_min(map),
		      entry->end - vm_map_min(map));

      already_removed = TRUE;

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

    } else {

      already_removed = FALSE;

    }

    /*
     * remove mappings now.   for sharemaps, check to see if the reference
     * count is one (i.e. not being shared right now).   if so, use the
     * cheaper pmap_remove() rather than the more expensive share_protect
     * functions.
     */

    if (!map->is_main_map) {
      simple_lock(&map->ref_lock);
      refs = map->ref_count;
      simple_unlock(&map->ref_lock);
    }
#if defined(sparc)
    else { refs = 0; } /* XXX: shutup unused var gcc warning */
#endif

    if (map->is_main_map || (!map->is_main_map && refs == 1)) {
      if (!already_removed)
	pmap_remove(map->pmap, entry->start, entry->end);
    } else {
      /* share map... must remove all mappings */
      if (entry->aref.ar_amap) {
	simple_lock(&entry->aref.ar_amap->am_l);
	amap_share_protect(entry, VM_PROT_NONE);
	simple_unlock(&entry->aref.ar_amap->am_l);
      }
      if (UVM_ET_ISOBJ(entry)) {
	uobj = entry->object.uvm_obj;
	simple_lock(&uobj->vmobjlock);
	uobj->pgops->pgo_shareprot(entry, VM_PROT_NONE);
	simple_unlock(&uobj->vmobjlock);
      }
    }

    /*
     * remove from map and put it on our list of entries that we've nuked.
     * then go do next entry.
     */
    UVMHIST_LOG(maphist, "  removed map entry 0x%x", entry, 0, 0, 0);
    uvm_map_entry_unlink(map, entry);
    map->size -= len;
    entry->next = first_entry;
    first_entry = entry;
    entry = next;		/* next entry, please */
  }

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

  *entry_list = first_entry;
  UVMHIST_LOG(maphist,"<- done!", 0, 0, 0, 0);
  return(KERN_SUCCESS);
}

/*
 * 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(first_entry, amap_unref_flags)

vm_map_entry_t first_entry;
int amap_unref_flags;

{
  vm_map_entry_t next_entry;
  UVMHIST_FUNC("uvm_unmap_detach"); UVMHIST_CALLED(maphist);

  while (first_entry) {

#ifdef DIAGNOSTIC
    /*
     * sanity check
     */
    if (first_entry->wired_count)   /* was part of vm_map_entry_delete() */
      panic("unmap: still wired!");
#endif

    UVMHIST_LOG(maphist, "  detach 0x%x: amap=0x%x, obj=0x%x, map?=%d",
	first_entry, first_entry->aref.ar_amap, first_entry->object.uvm_obj,
		UVM_ET_ISMAP(first_entry));

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

    if (first_entry->aref.ar_amap)
      amap_unref(first_entry, amap_unref_flags);

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

    if (UVM_ET_ISMAP(first_entry)) {
      uvm_map_deallocate(first_entry->object.share_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
     */
    next_entry = first_entry->next;
    uvm_mapent_free(first_entry);
    first_entry = next_entry;
  }

  /*
   * done!
   */
  UVMHIST_LOG(maphist, "<- done", 0,0,0,0);
  return;
}

/*
 *   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(map, size, offset, raddr)

vm_map_t map;
vm_size_t size;
vm_offset_t offset;    /* hint for pmap_prefer */
vm_offset_t *raddr;	/* OUT: reserved VA */

{
  UVMHIST_FUNC("uvm_map_reserve"); UVMHIST_CALLED(maphist);

  UVMHIST_LOG(maphist, "(map=0x%x, size=0x%x, offset=0x%x,addr=0x%x)",
	      map,size,offset,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,
              UVM_MAPFLAG(UVM_PROT_NONE, UVM_PROT_NONE, UVM_INH_NONE,
                          UVM_ADV_RANDOM, UVM_FLAG_NOMERGE)) != KERN_SUCCESS) {
    UVMHIST_LOG(maphist, "<- done (no VM)", 0,0,0,0);
    return(FALSE);
  }

  UVMHIST_LOG(maphist, "<- done (*raddr=0x%x)", *raddr,0,0,0);
  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 entrys 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(map, start, end, newents, nnewents)

struct vm_map *map;
vm_offset_t start, end;
vm_map_entry_t newents;
int nnewents;

{
  vm_map_entry_t oldent, last;
  UVMHIST_FUNC("uvm_map_replace");
  UVMHIST_CALLED(maphist);

  /*
   * 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
   */
  {
    vm_map_entry_t tmpent = newents;
    int nent = 0;
    vm_offset_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, newents);
    if (map->first_free == oldent)
      map->first_free = last;

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

  } else {

    /* critical: flush stale hints out of map */
    SAVE_HINT(map, 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);
  }


  /*
   * 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(srcmap, start, len, dstmap, dstaddrp, flags)

vm_map_t srcmap, dstmap;
vm_offset_t start, *dstaddrp;
vm_size_t len;
int flags;

{
  vm_offset_t dstaddr, end, newend, oldoffset, fudge, orig_fudge, oldstart;
  vm_map_entry_t chain, endchain, entry, orig_entry, newentry, deadentry;
  vm_size_t elen;
  int nchain, error, copy_ok;
  UVMHIST_FUNC("uvm_map_extract"); UVMHIST_CALLED(maphist);
  UVMHIST_LOG(maphist,"(srcmap=0x%x,start=0x%x, len=0x%x", srcmap,start,len,0);
  UVMHIST_LOG(maphist," ...,dstmap=0x%x, flags=0x%x)", dstmap,flags,0,0);

#ifdef DIAGNOSTIC
  /*
   * 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.
   */
  if ((start & PAGE_MASK) || (len & PAGE_MASK))
    panic("uvm_map_extract1");
  if (flags & UVM_EXTRACT_REMOVE)
    if (flags & (UVM_EXTRACT_CONTIG|UVM_EXTRACT_QREF))
      panic("uvm_map_extract2");
#endif


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

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


  /*
   * 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, 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: unecessary, to avert gcc warning */
      amap_copy(srcmap, entry, M_NOWAIT, TRUE, start, end);
      if (UVM_ET_ISNEEDSCOPY(entry)) {  /* failed? */
	error = ENOMEM;
	goto bad;
      }
      if (fudge) {    /* amap_copy could clip (during chunk)!  update 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);
    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 = 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_slotoff = entry->aref.ar_slotoff + (fudge / PAGE_SIZE);
      amap_ref(newentry,
	       AMAP_SHARED | ((flags & UVM_EXTRACT_QREF) ? AMAP_REFALL : 0));
    } else {
      newentry->aref.ar_slotoff = 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, 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);
      }

      if (flags & UVM_EXTRACT_REMOVE) {
	pmap_remove(srcmap->pmap, entry->start, entry->end);
	uvm_map_entry_unlink(srcmap, entry);
	entry->next = deadentry;
	deadentry = entry;
      }

      /* end of 'while' loop */
      entry = entry->next;
      fudge = 0;
    }

    /* 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: shut up gcc warning */

  /*
   * 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;
    }
  }

  /*
   * done!
   */
  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_unmap(dstmap, dstaddr, dstaddr+len, 1);   /* ??? */
  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(map, start, end, submap)

vm_map_t map, submap;
vm_offset_t start, end;

{
  vm_map_entry_t entry;
  int result;
  UVMHIST_FUNC("uvm_map_submap"); UVMHIST_CALLED(maphist);

  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)) {

    /*
     * doit!
     */
    entry->etype |= (UVM_ET_MAP|UVM_ET_SUBMAP);
    entry->object.sub_map = submap;
    entry->offset = 0;
    uvm_map_reference(submap);
    result = KERN_SUCCESS;
  } else {
    result = KERN_INVALID_ARGUMENT;
  }
  vm_map_unlock(map);

  return(result);
}


/*
 * uvm_map_protect: change map protection
 *
 * => set_max means set max_protection.
 * => map must be unlocked.
 * => XXXCDC: does not work properly with share maps.  rethink.
 */

#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(map, start, end, new_prot, set_max)

vm_map_t map;
vm_offset_t start, end;
vm_prot_t new_prot;
boolean_t set_max;

{
  vm_map_entry_t current, entry;
  UVMHIST_FUNC("uvm_map_protect"); UVMHIST_CALLED(maphist);
  UVMHIST_LOG(maphist,"(map=0x%x,start=0x%x,end=0x%x,new_prot=0x%x)",
	map, start, end, new_prot);

  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))
      return(KERN_INVALID_ARGUMENT);
    if ((new_prot & current->max_protection) != new_prot) {
      vm_map_unlock(map);
      return(KERN_PROTECTION_FAILURE);
    }
      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) {

      if (UVM_ET_ISMAP(current) && !UVM_ET_ISSUBMAP(current)) {
	/* share map?   gotta go down a level */
	vm_map_entry_t  share_entry;
	vm_offset_t     share_end;

	/*
	 * note: a share map has its own address space (starting at zero).
	 * current->offset is the offset into the share map our mapping
	 * starts.    the length of our mapping is (current->end -
	 * current->start).    thus, our mapping goes from current->offset
	 * to share_end (which is: current->offset + length) in the share
	 * map's address space.
	 *
	 * thus for any share_entry we need to make sure that the addresses
	 * we've got fall in the range we want.   we use:
	 *   max(any share_entry->start, current->offset)
	 *   min(any share_entry->end, share_end)
	 *
	 * of course to change our pmap we've got to convert the share
	 * map address back to our map's virtual address space using:
	 *   our_va = share_va - current->offset + current->start
	 *
	 * XXXCDC: protection change in sharemap may require use
	 * of pmap_page_protect.   needs a rethink.
	 */

	vm_map_lock(current->object.share_map);
	/* note: current->offset is offset into share map */
	(void) uvm_map_lookup_entry(current->object.share_map,
				    current->offset, &share_entry);
	share_end = current->offset + (current->end - current->start);
	while ((share_entry != &current->object.share_map->header) &&
	       (share_entry->start < share_end)) {

	  pmap_protect(map->pmap, (max(share_entry->start,  current->offset)
	  - current->offset + current->start),
		       min(share_entry->end, share_end)
		       - current->offset + current->start,
		       current->protection & MASK(share_entry));

	  share_entry = share_entry->next;
	}
	vm_map_unlock(current->object.share_map);

      } else {             /* not share map! */

	pmap_protect(map->pmap, current->start, current->end,
		     current->protection & MASK(entry));

      }
    }
    current = current->next;
  }

  vm_map_unlock(map);
  UVMHIST_LOG(maphist, "<- done",0,0,0,0);
  return(KERN_SUCCESS);
}

#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.
 * => XXXCDC: currently only works in main map.  what about share map?
 */

int uvm_map_inherit(map, start, end, new_inheritance)

vm_map_t map;
vm_offset_t start;
vm_offset_t end;
vm_inherit_t new_inheritance;

{
  vm_map_entry_t entry, temp_entry;
  UVMHIST_FUNC("uvm_map_inherit"); UVMHIST_CALLED(maphist);
  UVMHIST_LOG(maphist,"(map=0x%x,start=0x%x,end=0x%x,new_inh=0x%x)",
	map, start, end, new_inheritance);

  switch (new_inheritance) {
  case VM_INHERIT_NONE:
  case VM_INHERIT_COPY:
  case VM_INHERIT_SHARE:
    break;
  default:
    UVMHIST_LOG(maphist,"<- done (INVALID ARG)",0,0,0,0);
    return(KERN_INVALID_ARGUMENT);
  }

  vm_map_lock(map);

  VM_MAP_RANGE_CHECK(map, start, end);

  if (uvm_map_lookup_entry(map, start, &temp_entry)) {
    entry = temp_entry;
    UVM_MAP_CLIP_START(map, entry, start);
  }  else {
    entry = temp_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);
  UVMHIST_LOG(maphist,"<- done (OK)",0,0,0,0);
  return(KERN_SUCCESS);
}

/*
 * uvm_map_pageable: sets the pageability of a range in a map.
 *
 * => regions sepcified as not pageable require lock-down (wired) memory
 *	and page tables.
 * => map must not be locked.
 * => XXXCDC: check this and try and clean it up.
 */

int uvm_map_pageable(map, start, end, new_pageable)

vm_map_t map;
vm_offset_t start, end;
boolean_t new_pageable;

{
  vm_map_entry_t entry, start_entry;
  vm_offset_t failed = 0;
  int rv;
  UVMHIST_FUNC("uvm_map_pageable"); UVMHIST_CALLED(maphist);
  UVMHIST_LOG(maphist,"(map=0x%x,start=0x%x,end=0x%x,new_pageable=0x%x)",
	map, start, end, new_pageable);

  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) {
    vm_map_unlock(map);

    UVMHIST_LOG(maphist,"<- done (INVALID ARG)",0,0,0,0);
    return(KERN_INVALID_ADDRESS);
  }
  entry = start_entry;

  /*
   * handle wiring and unwiring seperately.
   */

  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))) {
	vm_map_unlock(map);
        UVMHIST_LOG(maphist,"<- done (INVALID UNWIRE ARG)",0,0,0,0);
	return(KERN_INVALID_ARGUMENT);
      }
      entry = entry->next;
    }

    /*
     * now decrement the wiring count for each region.  if a region
     * becomes completely unwired, unwire its physical pages and mappings.
     */
#if 0		/* not necessary: uvm_fault_unwire does not lock */
    lock_set_recursive(&map->lock);
#endif  /* XXXCDC */

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

      entry->wired_count--;
      if (entry->wired_count == 0)
	uvm_map_entry_unwire(map, entry);

      entry = entry->next;
    }
#if 0 /* XXXCDC: not necessary, see above */
    lock_clear_recursive(&map->lock);
#endif
    vm_map_unlock(map);
    UVMHIST_LOG(maphist,"<- done (OK UNWIRE)",0,0,0,0);
    return(KERN_SUCCESS);

    /*
     * end of unwire case!
     */
  }

  /*
   * 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 is 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 (entry->wired_count == 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.
       *
       * we don't have to do this for entries that point to sharing
       * maps, because we won't hold the lock on the sharing map.
       */

      if (!UVM_ET_ISMAP(entry)) {      /* not sharing map */
	/*
	 * XXXCDC: protection vs. max_protection??  (wirefault uses max?)
	 * XXXCDC: used to do it always if uvm_obj == NULL (wrong?)
	 */
	if ( UVM_ET_ISNEEDSCOPY(entry) &&
	     (entry->protection & VM_PROT_WRITE) != 0) {

	  amap_copy(map, entry, M_WAITOK, TRUE, start, end);
	  /* XXXCDC: wait OK? */

        }
      }
    }     /* wired_count == 0 */
    UVM_MAP_CLIP_START(map, entry, start);
    UVM_MAP_CLIP_END(map, entry, end);
    entry->wired_count++;

    /*
     * Check for holes
     */
    if (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;
      }
      vm_map_unlock(map);
      UVMHIST_LOG(maphist,"<- done (INVALID WIRE)",0,0,0,0);
      return(KERN_INVALID_ARGUMENT);
    }
    entry = entry->next;
  }

  /*
   * Pass 2.
   */
  /*
   * HACK HACK HACK HACK
   *
   * if we are wiring in the kernel map or a submap of it, unlock the
   * map to avoid deadlocks.  we trust that the kernel threads are
   * well-behaved, and therefore will not do anything destructive to
   * this region of the map while we have it unlocked.  we cannot
   * trust user threads to do the same.
   *
   * HACK HACK HACK HACK
   */
  if (vm_map_pmap(map) == pmap_kernel()) {
    vm_map_unlock(map);         /* trust me ... */
  } else {
    vm_map_set_recursive(&map->lock);
    lockmgr(&map->lock, LK_DOWNGRADE, (void *)0, curproc);
  }

  rv = 0;
  entry = start_entry;
  while (entry != &map->header && entry->start < end) {
    /*
     * if uvm_fault_wire fails for any page we need to undo what has
     * been done.  we decrement the wiring count for those pages which
     * have not yet been wired (now) and unwire those that have
     * (later).
     *
     * XXX this violates the locking protocol on the map,
     * needs to be fixed.  [because we only have a read lock on map we
     * shouldn't be changing wired_count?]
     */
    if (rv) {
      entry->wired_count--;
    } else if (entry->wired_count == 1) {
      rv = uvm_fault_wire(map, entry->start, entry->end);
      if (rv) {
	failed = entry->start;
	entry->wired_count--;
      }
    }
    entry = entry->next;
  }

  if (vm_map_pmap(map) == pmap_kernel()) {
    vm_map_lock(map);     /* relock */
  }
  else {
    vm_map_clear_recursive(&map->lock);
  }

  if (rv) {        /* failed? */
    vm_map_unlock(map);
    (void) uvm_map_pageable(map, start, failed, TRUE);
    UVMHIST_LOG(maphist, "<- done (RV=%d)", rv,0,0,0);
    return(rv);
  }
  vm_map_unlock(map);

  UVMHIST_LOG(maphist,"<- done (OK WIRE)",0,0,0,0);
  return(KERN_SUCCESS);
}

/*
 * uvm_map_clean: push dirty pages off to backing store.
 *
 * => valid flags:
 *   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...
 * => called from sys_msync()
 * => caller must not write-lock map (read OK).
 * => we may sleep while cleaning if SYNCIO [with map read-locked]
 * => XXX: does this handle share maps properly?
 */

int uvm_map_clean(map, start, end, flags)

vm_map_t map;
vm_offset_t start, end;
int flags;

{
  vm_map_entry_t current;
  vm_map_entry_t entry;
  vm_size_t size;
  struct uvm_object *object;
  vm_offset_t offset;
  UVMHIST_FUNC("uvm_map_clean"); UVMHIST_CALLED(maphist);
  UVMHIST_LOG(maphist,"(map=0x%x,start=0x%x,end=0x%x,flags=0x%x)",
	map, start, end, flags);

  vm_map_lock_read(map);
  VM_MAP_RANGE_CHECK(map, start, end);
  if (!uvm_map_lookup_entry(map, start, &entry)) {
    vm_map_unlock_read(map);
    return(KERN_INVALID_ADDRESS);
  }

  /*
   * 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(KERN_INVALID_ARGUMENT);
    }
    if (end > current->end &&
	(current->next == &map->header ||
	 current->end != current->next->start)) {
      vm_map_unlock_read(map);
      return(KERN_INVALID_ADDRESS);
    }
  }

  /*
   * add "cleanit" flag to flags (for generic flush routine).
   * then make a second pass, cleaning/uncaching pages from
   * the indicated objects as we go.
   */
  flags = flags | PGO_CLEANIT;
  for (current = entry; current->start < end; current = current->next) {
    offset = current->offset + (start - current->start);
    size = (end <= current->end ? end : current->end) - start;

    /*
     * get object/offset.   special case to handle share maps.
     */
    if (UVM_ET_ISMAP(current)) {   /* share map? */
      register vm_map_t smap;
      vm_map_entry_t tentry;
      vm_size_t tsize;

      smap = current->object.share_map;
      vm_map_lock_read(smap);
      (void) uvm_map_lookup_entry(smap, offset, &tentry);
      tsize = tentry->end - offset;
      if (tsize < size)
	size = tsize;
      object = tentry->object.uvm_obj;
      offset = tentry->offset + (offset - tentry->start);
      simple_lock(&object->vmobjlock);
      vm_map_unlock_read(smap);
    } else {
      object = current->object.uvm_obj;
      simple_lock(&object->vmobjlock);
    }

    /*
     * flush pages if writing is allowed.   note that object is locked.
     * XXX should we continue on an error?
     */

    if (object && object->pgops &&
	(current->protection & VM_PROT_WRITE) != 0) {
      if (!object->pgops->pgo_flush(object, offset, offset+size, flags)) {
	simple_unlock(&object->vmobjlock);
	vm_map_unlock_read(map);
	return(KERN_FAILURE);
      }
    }
    simple_unlock(&object->vmobjlock);
    start += size;
  }
  vm_map_unlock_read(map);
  return(KERN_SUCCESS);
}


/*
 * 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(map, start, end, protection)

vm_map_t       map;
vm_offset_t    start, end;
vm_prot_t      protection;

{
   vm_map_entry_t entry;
   vm_map_entry_t 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(min, max, pageable)

vm_offset_t min, max;
int pageable;

{
  struct vmspace *vm;
  UVMHIST_FUNC("uvmspace_alloc"); UVMHIST_CALLED(maphist);

  MALLOC(vm, struct vmspace *, sizeof(struct vmspace), M_VMMAP, M_WAITOK);
  bzero(vm, sizeof(*vm));
  uvm_map_setup(&vm->vm_map, min, max, pageable);
#if defined(PMAP_NEW)
  vm->vm_map.pmap = pmap_create();
#else
  vm->vm_map.pmap = pmap_create(0);
#endif
  vm->vm_refcnt = 1;
  UVMHIST_LOG(maphist,"<- done (vm=0x%x)", vm,0,0,0);
  return (vm);
}

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

void uvmspace_share(p1, p2)

struct proc *p1, *p2;

{
  p2->p_vmspace = p1->p_vmspace;
  p1->p_vmspace->vm_refcnt++;
}

/*
 * uvmspace_unshare: ensure that process "p" has its own, unshared, vmspace
 *
 * - XXX: no locking on vmspace
 */

void uvmspace_unshare(p)

struct proc *p;

{
  struct vmspace *nvm, *ovm = p->p_vmspace;

  if (ovm->vm_refcnt == 1)
    return;	/* nothing to do: vmspace isn't shared in the first place */

  nvm = uvmspace_fork(ovm);	/* make a new vmspace, still holding old one */
  p->p_vmspace = nvm;
  pmap_activate(p);		/* switch to new vmspace */
  uvmspace_free(ovm);		/* drop reference to old vmspace */
}

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

void uvmspace_exec(p)

struct proc *p;

{
  struct vmspace *nvm, *ovm = p->p_vmspace;
  vm_map_t map = &ovm->vm_map;

#ifdef sparc
  /* XXX cgd 960926: the sparc #ifdef should be a MD hook */
  kill_user_windows(p);   /* before stack addresses go away */
#endif

  /*
   * 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

    /*
     * now unmap the old program
     */
    uvm_unmap(map, VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS, 0);

  } 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(map->min_offset, map->max_offset,
			 map->entries_pageable);

#if (defined(i386) && !defined(PMAP_NEW)) || defined(pc532)
    /*
     * allocate zero fill area in the new vmspace's map for user page
     * tables for ports that have old style pmaps that keep user page
     * tables in the top part of the process' address space.
     *
     * XXXCDC: this should go away once all pmaps are fixed
     */
    {
      vm_offset_t addr = VM_MAXUSER_ADDRESS;
      if (uvm_map(&nvm->vm_map, &addr, VM_MAX_ADDRESS - addr,
		  NULL, UVM_UNKNOWN_OFFSET,
		  UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
			      UVM_ADV_NORMAL, UVM_FLAG_FIXED|UVM_FLAG_COPYONW))
	  != KERN_SUCCESS)
	panic("vm_allocate of PT page area failed");
    }
#endif

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

    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(vm)

struct vmspace *vm;

{
  vm_map_entry_t dead_entries;
  UVMHIST_FUNC("uvmspace_free"); UVMHIST_CALLED(maphist);

  UVMHIST_LOG(maphist,"(vm=0x%x) ref=%d", vm, vm->vm_refcnt,0,0);
  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.
     */
    vm_map_lock(&vm->vm_map);
    if (vm->vm_map.nentries) {
      (void) uvm_unmap_remove(&vm->vm_map, vm->vm_map.min_offset,
			      vm->vm_map.max_offset, TRUE, &dead_entries);
      if (dead_entries != NULL)
        uvm_unmap_detach(dead_entries, 0);
    }
    pmap_destroy(vm->vm_map.pmap);
    vm->vm_map.pmap = NULL;
    FREE(vm, M_VMMAP);
  }
  UVMHIST_LOG(maphist,"<- done", 0,0,0,0);
}

/*
 *   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(vm1)

struct vmspace *vm1;

{
  struct vmspace *vm2;
  vm_map_t        old_map = &vm1->vm_map;
  vm_map_t        new_map;
  vm_map_entry_t  old_entry;
  vm_map_entry_t  new_entry;
  pmap_t          new_pmap;
  UVMHIST_FUNC("uvmspace_fork"); UVMHIST_CALLED(maphist);

#if (defined(i386) && !defined(PMAP_NEW)) || defined(pc532)
  /*
   * avoid copying any of the parent's pagetables or other per-process
   * objects that reside in the map by marking all of them non-inheritable
   * XXXCDC: should go away
   */
  (void) uvm_map_inherit(old_map, VM_MAXUSER_ADDRESS, VM_MAX_ADDRESS,
			 VM_INHERIT_NONE);
#endif

  vm_map_lock(old_map);

  vm2 = uvmspace_alloc(old_map->min_offset, old_map->max_offset,
		      old_map->entries_pageable);
  bcopy(&vm1->vm_startcopy, &vm2->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)");
    else if (UVM_ET_ISMAP(old_entry)) {
      if (UVM_ET_ISNEEDSCOPY(old_entry))
	panic("fork: encountered a share map entry that needs_copy (illegal)");
      if (UVM_ET_ISCOPYONWRITE(old_entry))
	panic("fork: encountered a copy_on_write share map entry (illegal)");
      if (old_entry->aref.ar_amap)
	panic("fork: detected share map entry that has an amap (illegal)");
    } else {
      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 VM_INHERIT_NONE:

      /*
       * drop the mapping
       */

      break;

    case VM_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);
      uvm_mapent_copy(old_entry, new_entry); /* old_entry -> new_entry */
      new_entry->wired_count = 0;  /* new pmap has nothing wired in it */

      /*
       * gain reference to objects backing the map
       */
      if (UVM_ET_ISMAP(new_entry)) {   /* share map? */
	uvm_map_reference(old_entry->object.share_map);
      } else {
	if (new_entry->aref.ar_amap)
	  amap_ref(new_entry, AMAP_SHARED); /* share reference */
	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 VM_INHERIT_COPY:

      /*
       * copy-on-write the mapping (using mmap's MAP_PRIVATE semantics)
       */

      /*
       * share maps: we special case it (handled by uvm_map_sharemapcopy)
       */

      if (UVM_ET_ISMAP(old_entry)) {   /* share map? */
	uvm_map_sharemapcopy(old_map, old_entry, new_map);
	break;
      }

      /*
       * not a share map.   allocate new_entry, adjust reference counts.
       * (note that new references are read-only).
       */

      new_entry = uvm_mapent_alloc(new_map);
      uvm_mapent_copy(old_entry, new_entry); /* old_entry -> new_entry */
      if (new_entry->aref.ar_amap) {
	amap_ref(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_entry->wired_count = 0;  /* new pmap has nothing wired in it */
      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 scrach (if the old
       * does not have an amap).  can we defer this process until
       * later (by setting needs_copy) or do we need to do it now?
       *
       * we must do it now if any of the following conditions hold:
       *
       * 1. the old entry has an amap and it is not copy_on_write [i.e.
       *    shared].
       *    why: we would have to write-protect the old mapping in the
       *    parent's pmap [thus needlessly changing the protection of a
       *    shared mapping, something we don't want to do]
       *    note: a non-copy-on-write old entry will not have an
       *    amap unless we've used non-standard features of this VM system.
       *    [also, see semantic note below...]
       *
       * 2. the old entry has an amap and that amap is being shared.
       *    why: if the amap is being shared between 2 or more processes
       *    they need to continue sharing the amap.   if we try and defer
       *    the copy there is no easy to determine which process needs to
       *    break off their references to the amap and which ones are supposed
       *    to keep it at fault time.
       *
       * 3. if the old entry was copy_on_write and wired then we
       *    are going to have to call fault_copy_entry now (see below).
       *    that needs to have the amap copied also, so we do it here
       *    too.
       *
       * semantic note: if the old entry was shared and had an amap
       * then the child gets a snapshot copy of the pages in the amap
       * now, but the child does not want to see any new pages added
       * to the amap by the parent after the fork.  the child will see
       * changes made by the parent to any amap pages it inherits
       * until it writes them itself.  to get these semantics we need
       * to copy the amap now (as per [1] above).
       */

      if ((old_entry->aref.ar_amap &&
	   (UVM_ET_ISCOPYONWRITE(old_entry) == FALSE ||
	    (old_entry->aref.ar_amap->am_flags & AMAP_SHARED) != 0)) ||
	  (old_entry->wired_count != 0 && UVM_ET_ISCOPYONWRITE(old_entry)) ) {
	amap_copy(new_map, new_entry, M_WAITOK, FALSE, 0, 0);
		/* XXXCDC: M_WAITOK? */
      }

      /*
       * if an entry is wired down, then we can not get faults on access.
       * this means that we can't do COW because we can't write protect
       * the old entry (otherwise we could get a protection fault on wired
       * memory).   if that is the case we must copy things now.   note
       * that we've already allocated the new amap (above).
       */

      if (old_entry->wired_count != 0 && UVM_ET_ISCOPYONWRITE(old_entry)) {

	/*
	 * copy it now
	 */

	amap_cow_now(new_map, new_entry); /* was fault_copy_entry */

      } else {

	/*
	 * do a copy-on-write.   two cases to consider:
	 * 1. old_entry is MAP_SHARE (old_entry->copy_on_write == FALSE)
	 *    => no need to protect old mappings
	 * 2. old_entry is MAP_PRIVATE (old_entry->copy_on_write == TRUE)
	 *    => must protect both old and new mappings
	 */

	if (UVM_ET_ISCOPYONWRITE(old_entry)) { /* private mapping? */

	  /*
	   * protect old mappings.   note that if needs_copy is true then
	   * the mappings have already been protected elsewhere and there
	   * is no need to do it again.   also note that pmap_copy will
	   * copy the protected mappings to the child.
	   */

	  if (!UVM_ET_ISNEEDSCOPY(old_entry)) {
	    /* write protect pages */
	    pmap_protect(old_map->pmap, old_entry->start, old_entry->end,
			 old_entry->protection & ~VM_PROT_WRITE);
	    old_entry->etype |= UVM_ET_NEEDSCOPY;
	  }
	}

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

	/*
	 * protect new mappings.   already taken care of for private
	 * mappings by the call to pmap_protect above.
	 */

	if (!UVM_ET_ISCOPYONWRITE(old_entry)) {
	  pmap_protect(new_pmap, new_entry->start, new_entry->end,
		       new_entry->protection & ~VM_PROT_WRITE);
	}
      }

      break;
    }
    old_entry = old_entry->next;
  }

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

#if (defined(i386) && !defined(PMAP_NEW)) || defined(pc532)
    /*
     * allocate zero fill area in the new vmspace's map for user page
     * tables for ports that have old style pmaps that keep user page
     * tables in the top part of the process' address space.
     *
     * XXXCDC: this should go away once all pmaps are fixed
     */
    {
      vm_offset_t addr = VM_MAXUSER_ADDRESS;
      if (uvm_map(new_map, &addr, VM_MAX_ADDRESS - addr,
		  NULL, UVM_UNKNOWN_OFFSET,
		  UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
			      UVM_ADV_NORMAL, UVM_FLAG_FIXED|UVM_FLAG_COPYONW))
	  != KERN_SUCCESS)
	panic("vm_allocate of PT page area failed");
    }
#endif

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

  UVMHIST_LOG(maphist,"<- done",0,0,0,0);
  return(vm2);
}


/*
 * uvm_map_sharemapcopy: handle the copying of a share map during a
 * fork.  this is a helper function for uvmspace_fork.  it is called
 * when we are doing a fork and we have encountered a map entry which
 * has two attributes: [1] its inherit code is VM_INHERIT_COPY, and
 * [2] it points to a share map (i.e. is_a_map is true).  in this case
 * we must traverse the area of the share map pointed to by the
 * old_entry and make private copies of the map entries in the share
 * map.  this is somewhat similar to what happens in the non-share map
 * case in fork, but it has to handle multiple map entries which may
 * not be the proper size.  it was seperated out into its own function
 * in order to make the main body of the fork code easier to read and
 * understand!
 *
 * main_entry->offset = starting VA in share map for our mapping
 *
 * => main map is locked by caller.
 * => we lock share map.
 * => new map isn't in use yet (still being set up for the first time).
 */

void uvm_map_sharemapcopy(main_map, main_entry, new_map)

vm_map_t main_map, new_map;
vm_map_entry_t main_entry;

{
  vm_map_t share_map = main_entry->object.share_map;
  vm_map_entry_t share_entry, new_entry;
  vm_offset_t shend = main_entry->offset +
    (main_entry->end - main_entry->start);
  int refs;

  /*
   * lock share map.  find first map entry of interest.   clip if needed.
   */

  vm_map_lock(share_map);
  if (uvm_map_lookup_entry(share_map, main_entry->offset, &share_entry))
    UVM_MAP_CLIP_START(share_map, share_entry, main_entry->offset);

  while (share_entry != &share_map->header && share_entry->start < shend) {

    /*
     * at this point we have a map entry that we need to make a copy of.
     */

    UVM_MAP_CLIP_END(share_map, share_entry, shend); /* may need to clip? */

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

    /* convert share map addresses back to main map addresses */
    new_entry->start = main_entry->start +
      (new_entry->start - main_entry->offset);
    new_entry->end = main_entry->start + (new_entry->end - main_entry->offset);

    /* gain references */
    if (new_entry->aref.ar_amap) {
      amap_ref(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);

    /* init rest of new entry and insert at end of new map */
    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);

    /* don't bother trying to defer the copy in the share map case */
    amap_copy(new_map, new_entry, M_WAITOK, FALSE, 0, 0);  /* XXXCDC: WAITOK? */

    /* just like non-share case: can't COW wired memory */
    if (share_entry->wired_count != 0 && UVM_ET_ISCOPYONWRITE(share_entry)) {


      amap_cow_now(new_map, new_entry); /* was fault copy entry */

    } else {

      /* just like non-share case */
      if (UVM_ET_ISCOPYONWRITE(share_entry)) {

	if (!UVM_ET_ISNEEDSCOPY(share_entry)) {

	  /*
	   * must write protect pages.   if we have the sole reference
	   * to the share map we can use good old pmap_protect.   if we
	   * don't, then we have to use pmap_page_protect.
	   *
	   * note that the VA new_entry->start (starting entry of this
	   * segment of the share map in child process) is the same
	   * virtual address it is mapped in in the parent (thus we
	   * can mix main_map and new_entry in the pmap_protect call below).
	   */

	  simple_lock(&share_map->ref_lock);
	  refs = share_map->ref_count;
	  simple_unlock(&share_map->ref_lock);
	  if (refs == 1) {
	    pmap_protect(main_map->pmap, new_entry->start, new_entry->end,
			 share_entry->protection & ~VM_PROT_WRITE);
	  } else {
	    if (share_entry->aref.ar_amap) {
	      simple_lock(&share_entry->aref.ar_amap->am_l);
	      amap_share_protect(share_entry,
				 share_entry->protection & ~VM_PROT_WRITE);
	      simple_unlock(&share_entry->aref.ar_amap->am_l);
	    }
	    if (share_entry->object.uvm_obj) {
#ifdef DIAGNOSTIC
	      if (!share_entry->object.uvm_obj->pgops->pgo_shareprot)
		panic("fork: share_entry with no prot function");
#endif
	      simple_lock(&share_entry->object.uvm_obj->vmobjlock);
	      share_entry->object.uvm_obj->pgops->
		pgo_shareprot(share_entry,
			      share_entry->protection & ~VM_PROT_WRITE);
	      simple_unlock(&share_entry->object.uvm_obj->vmobjlock);
	    }
	  }

	  share_entry->etype |= UVM_ET_NEEDSCOPY;
	}
      }

      /*
       * now copy the mappings: note address are the same in both
       * main_map and new_map
       */
      pmap_copy(new_map->pmap, main_map->pmap, new_entry->start,
		(new_entry->end - new_entry->start), new_entry->start);

      /* just like non-share case */
      if (!UVM_ET_ISCOPYONWRITE(share_entry)) {
	pmap_protect(new_map->pmap, new_entry->start, new_entry->end,
		     new_entry->protection & ~VM_PROT_WRITE);
      }
    }

    /* next entry in share map, please */
    share_entry = share_entry->next;

  }
  /* done! */
}

#if defined(DDB)

/*
 * DDB hooks
 */

/*
 * uvm_map_print: print out a map
 */

void uvm_map_print(map, full)

vm_map_t map;
boolean_t full;

{
  uvm_map_printit(map, full, printf);
}

/*
 * uvm_map_printit: actually prints the map
 */

void uvm_map_printit(map, full, pr)

vm_map_t map;
boolean_t full;
void (*pr) __P((const char *, ...));

{
  vm_map_entry_t entry;
  (*pr)("MAP %p: [0x%lx->0x%lx]\n", map, map->min_offset, map->max_offset);
  (*pr)("\tpmap=%p, #ent=%d, sz=%d, ref=%d, main=%c, version=%d\n",
        map->pmap, map->nentries, map->size, map->ref_count,
        (map->is_main_map) ? 'T' : 'F', map->timestamp);
  if (!full) return;
  for (entry = map->header.next; entry != &map->header; entry = entry->next) {
    (*pr)(" - %p: 0x%lx->0x%lx: obj=%p/0x%x, amap=%p/%d\n",
	entry, entry->start, entry->end, entry->object.uvm_obj, entry->offset,
	entry->aref.ar_amap, entry->aref.ar_slotoff);
    (*pr)(
"\tmap=%c, submap=%c, cow=%c, nc=%c, prot(max)=%d/%d, inh=%d, wc=%d, adv=%d\n",
	(entry->etype & UVM_ET_MAP) ? 'T' : 'F',
	(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_print: print out an object
 */

void uvm_object_print(uobj, full)

struct uvm_object *uobj;
boolean_t full;

{
  uvm_object_printit(uobj, full, printf);
}

/*
 * uvm_object_printit: actually prints the object
 */

void uvm_object_printit(uobj, full, pr)

struct uvm_object *uobj;
boolean_t full;
void (*pr) __P((const char *, ...));

{
  struct vm_page *pg;
  int cnt = 0;

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

  if (!full) return;
  (*pr)("  PAGES <pg,offset>:\n  ");
  for (pg = uobj->memq.tqh_first ; pg ; pg = pg->listq.tqe_next, cnt++) {
    (*pr)("<%p,0x%lx> ", pg, pg->offset);
    if ((cnt % 3) == 2) (*pr)("\n  ");
  }
  if ((cnt % 3) != 2) (*pr)("\n");
}

/*
 * uvm_page_print: print out a page
 */

void uvm_page_print(pg, full)

struct vm_page *pg;
boolean_t full;

{
  uvm_page_printit(pg, full, printf);
}

/*
 * uvm_page_printit: actually print the page
 */

void uvm_page_printit(pg, full, pr)

struct vm_page *pg;
boolean_t full;
void (*pr) __P((const char *, ...));

{
  struct vm_page *lcv;
  struct uvm_object *uobj;
  struct pglist *pgl;

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

  if (!full) return;

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

  /* cross-verify page queue */
  if (pg->pqflags & PQ_FREE)
    pgl = &uvm.page_free;
  else if (pg->pqflags & PQ_INACTIVE)
    pgl = (pg->pqflags & PQ_SWAPBACKED) ?
           &uvm.page_inactive_swp : &uvm.page_inactive_obj;
  else if (pg->pqflags & PQ_ACTIVE)
    pgl = &uvm.page_active;
  else
    pgl = NULL;

  if (pgl) {
    (*pr)("  checking pageq list\n");
    for (lcv = pgl->tqh_first ; lcv ; lcv = lcv->pageq.tqe_next) {
      if (lcv == pg) break;
    }
    if (lcv)
      (*pr)("  page found on pageq list\n");
    else
      (*pr)("  >>> PAGE NOT FOUND ON PAGEQ LIST! <<<\n");
  }
}
#endif