NetBSD/sys/uvm/uvm_km.c

/*	$NetBSD: uvm_km.c,v 1.3 1998/02/07 02:29:21 chs 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_kern.c   8.3 (Berkeley) 1/12/94
 *
 *
 * 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_km.c: handle kernel memory allocation and management
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>

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

#include <uvm/uvm.h>

/*
 * global data structures
 */

vm_map_t kernel_map = NULL;

/*
 * local functions
 */

static int uvm_km_get __P((struct uvm_object *, vm_offset_t, 
                           vm_page_t *, int *, int, vm_prot_t, int, int));
/*
 * local data structues
 */

static struct vm_map		kernel_map_store;
static struct uvm_object	kmem_object_store;
static struct uvm_object	mb_object_store;

static struct uvm_pagerops km_pager = {
  NULL,	/* init */
  NULL, /* attach */
  NULL, /* reference */
  NULL, /* detach */
  NULL, /* fault */
  NULL, /* flush */
  uvm_km_get, /* get */
  /* ... rest are NULL */
};

/*
 * uvm_km_get: pager get function for kernel objects
 *
 * => currently we do not support pageout to the swap area, so this
 *    pager is very simple.    eventually we may want an anonymous 
 *    object pager which will do paging.
 */


static int uvm_km_get(uobj, offset, pps, npagesp, centeridx, access_type,
        	      advice, flags)

struct uvm_object *uobj;
vm_offset_t offset;
struct vm_page **pps;
int *npagesp;
int centeridx, advice, flags;
vm_prot_t access_type;

{
  vm_offset_t current_offset;
  vm_page_t ptmp;
  int lcv, gotpages, maxpages;
  boolean_t done;
  UVMHIST_FUNC("uvm_km_get"); UVMHIST_CALLED(maphist);

  UVMHIST_LOG(maphist, "flags=%d", flags,0,0,0);
  
  /*
   * get number of pages
   */

  maxpages = *npagesp;

  /*
   * step 1: handled the case where fault data structures are locked.
   */

  if (flags & PGO_LOCKED) {

    /*
     * step 1a: get pages that are already resident.   only do this
     * if the data structures are locked (i.e. the first time through).
     */

    done = TRUE;	/* be optimistic */
    gotpages = 0;	/* # of pages we got so far */

    for (lcv = 0, current_offset = offset ; 
	 lcv < maxpages ; lcv++, current_offset += PAGE_SIZE) {

      /* do we care about this page?  if not, skip it */
      if (pps[lcv] == PGO_DONTCARE)
	continue;

      /* lookup page */
      ptmp = uvm_pagelookup(uobj, current_offset);
      
      /* null?  attempt to allocate the page */
      if (ptmp == NULL) {
	ptmp = uvm_pagealloc(uobj, current_offset, NULL);
	if (ptmp) {
	  ptmp->flags &= ~(PG_BUSY|PG_FAKE);	/* new page */
          UVM_PAGE_OWN(ptmp, NULL);
	  ptmp->wire_count = 1;		/* XXX: prevents pageout attempts */
	  uvm_pagezero(ptmp);
	}
      }

      /* to be useful must get a non-busy, non-released page */
      if (ptmp == NULL || (ptmp->flags & (PG_BUSY|PG_RELEASED)) != 0) {
	if (lcv == centeridx || (flags & PGO_ALLPAGES) != 0)
	  done = FALSE;		/* need to do a wait or I/O! */
	continue;
      }

      /* useful page: busy/lock it and plug it in our result array */
      ptmp->flags |= PG_BUSY;		/* caller must un-busy this page */
      UVM_PAGE_OWN(ptmp, "uvm_km_get1");
      pps[lcv] = ptmp;
      gotpages++;

    }	/* "for" lcv loop */

    /*
     * step 1b: now we've either done everything needed or we to unlock
     * and do some waiting or I/O.
     */

    UVMHIST_LOG(maphist, "<- done (done=%d)", done, 0,0,0);

    *npagesp = gotpages;
    if (done)
      return(VM_PAGER_OK);		/* bingo! */
    else
      return(VM_PAGER_UNLOCK);		/* EEK!   Need to unlock and I/O */
  }

  /*
   * step 2: get non-resident or busy pages.
   * object is locked.   data structures are unlocked.
   */

  for (lcv = 0, current_offset = offset ; 
       lcv < maxpages ; lcv++, current_offset += PAGE_SIZE) {
    
    /* skip over pages we've already gotten or don't want */
    /* skip over pages we don't _have_ to get */
    if (pps[lcv] != NULL ||
	(lcv != centeridx && (flags & PGO_ALLPAGES) == 0))
      continue;

    /*
     * we have yet to locate the current page (pps[lcv]).   we first
     * look for a page that is already at the current offset.   if we
     * find a page, we check to see if it is busy or released.  if that
     * is the case, then we sleep on the page until it is no longer busy
     * or released and repeat the lookup.    if the page we found is 
     * neither busy nor released, then we busy it (so we own it) and
     * plug it into pps[lcv].   this 'break's the following while loop
     * and indicates we are ready to move on to the next page in the
     * "lcv" loop above.
     *
     * if we exit the while loop with pps[lcv] still set to NULL, then
     * it means that we allocated a new busy/fake/clean page ptmp in the 
     * object and we need to do I/O to fill in the data.
     */

    while (pps[lcv] == NULL) {		/* top of "pps" while loop */
      
      /* look for a current page */
      ptmp = uvm_pagelookup(uobj, current_offset);

      /* nope?   allocate one now (if we can) */
      if (ptmp == NULL) {

	ptmp = uvm_pagealloc(uobj, current_offset, NULL);	/* alloc */

	/* out of RAM? */
	if (ptmp == NULL) {
	  simple_unlock(&uobj->vmobjlock);
	  uvm_wait("kmgetwait1");
	  simple_lock(&uobj->vmobjlock);
	  continue;		/* goto top of pps while loop */
	}

	/* 
	 * got new page ready for I/O.  break pps while loop.  pps[lcv] is
	 * still NULL.
	 */
	break;		
      }

      /* page is there, see if we need to wait on it */
      if ((ptmp->flags & (PG_BUSY|PG_RELEASED)) != 0) {
	ptmp->flags |= PG_WANTED;
	UVM_UNLOCK_AND_WAIT(ptmp,&uobj->vmobjlock,0,"uvn_get",0);
	simple_lock(&uobj->vmobjlock);
	continue;		/* goto top of pps while loop */
      }
      
      /* 
       * if we get here then the page has become resident and unbusy 
       * between steps 1 and 2.  we busy it now (so we own it) and set
       * pps[lcv] (so that we exit the while loop).
       */
      ptmp->flags |= PG_BUSY;	/* we own it, caller must un-busy */
      UVM_PAGE_OWN(ptmp, "uvm_km_get2");
      pps[lcv] = ptmp;
    }

    /*
     * if we own the a valid page at the correct offset, pps[lcv] will
     * point to it.   nothing more to do except go to the next page.
     */

    if (pps[lcv])
      continue;			/* next lcv */

    /*
     * we have a "fake/busy/clean" page that we just allocated.  
     * do the needed "i/o" (in this case that means zero it).
     */

    uvm_pagezero(ptmp);
    ptmp->flags &= ~(PG_FAKE);
    ptmp->wire_count = 1;		/* XXX: prevents pageout attempts */
    pps[lcv] = ptmp;

  }	/* lcv loop */

  /*
   * finally, unlock object and return.
   */

  simple_unlock(&uobj->vmobjlock);
  UVMHIST_LOG(maphist, "<- done (OK)",0,0,0,0);
  return(VM_PAGER_OK);
}

/*
 * uvm_km_init: init kernel maps and objects to reflect reality (i.e.
 * KVM already allocated for text, data, bss, and static data structures).
 *
 * => KVM is defined by VM_MIN_KERNEL_ADDRESS/VM_MAX_KERNEL_ADDRESS.
 *    we assume that [min -> start] has already been allocated and that
 *    "end" is the end.
 */

void uvm_km_init(start, end)

vm_offset_t start, end;

{
  vm_offset_t base = VM_MIN_KERNEL_ADDRESS;

  /*
   * first, init kernel memory objects.
   */

  /* kernel_object: for pageable anonymous kernel memory */
  uvm.kernel_object = uao_create(VM_MAX_KERNEL_ADDRESS -
				 VM_MIN_KERNEL_ADDRESS, UAO_FLAG_KERNOBJ);

  /* kmem_object: for malloc'd memory (always wired) */
  simple_lock_init(&kmem_object_store.vmobjlock);
  kmem_object_store.pgops = &km_pager;
  TAILQ_INIT(&kmem_object_store.memq);
  kmem_object_store.uo_npages = 0;
  kmem_object_store.uo_refs = UVM_OBJ_KERN; 
					/* we are special.  we never die */
  uvmexp.kmem_object = &kmem_object_store;

  /* mb_object: for mbuf memory (always wired) */
  simple_lock_init(&mb_object_store.vmobjlock);
  mb_object_store.pgops = &km_pager;
  TAILQ_INIT(&mb_object_store.memq);
  mb_object_store.uo_npages = 0;
  mb_object_store.uo_refs = UVM_OBJ_KERN; 
					/* we are special.  we never die */
  uvmexp.mb_object = &mb_object_store;

  /*
   * init the map and reserve kernel space before installing.
   */

  uvm_map_setup(&kernel_map_store, base, end, FALSE);
  kernel_map_store.pmap = pmap_kernel();
  if (uvm_map(&kernel_map_store, &base, start - base, NULL, UVM_UNKNOWN_OFFSET,
	      UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE, 
			  UVM_ADV_RANDOM,UVM_FLAG_FIXED)) != KERN_SUCCESS)
    panic("uvm_km_init: could not reserve space for kernel");
  
  /*
   * install!
   */

  kernel_map = &kernel_map_store;
}

/*
 * uvm_km_suballoc: allocate a submap in the kernel map.   once a submap
 * is allocated all references to that area of VM must go through it.  this
 * allows the locking of VAs in kernel_map to be broken up into regions.
 *
 * => if submap is non NULL we use that as the submap, otherwise we
 *	alloc a new map
 */

struct vm_map *uvm_km_suballoc(map, min, max, size, pageable, submap)

struct vm_map *map;
vm_offset_t *min, *max;		/* OUT, OUT */
vm_size_t size;
boolean_t pageable;
struct vm_map *submap;

{
  size = round_page(size);	/* round up to pagesize */

  /*
   * first allocate a blank spot in the parent map
   */

  if (uvm_map(map, min, size, NULL, UVM_UNKNOWN_OFFSET, 
	      UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
			  UVM_ADV_RANDOM, UVM_FLAG_NOMERGE)) != KERN_SUCCESS) {
    panic("uvm_km_suballoc: unable to allocate space in parent map");
  }

  /*
   * set VM bounds (min is filled in by uvm_map)
   */

  *max = *min + size;

  /*
   * add references to pmap and create or init the submap
   */

  pmap_reference(vm_map_pmap(map));
  if (submap == NULL) {
    submap = uvm_map_create(vm_map_pmap(map), *min, *max, pageable);
    if (submap == NULL)
      panic("uvm_km_suballoc: unable to create submap");
  } else {
      uvm_map_setup(submap, *min, *max, pageable);
      submap->pmap = vm_map_pmap(map);
  }

  /*
   * now let uvm_map_submap plug in it...
   */

  if (uvm_map_submap(map, *min, *max, submap) != KERN_SUCCESS)
    panic("uvm_km_suballoc: submap allocation failed");

  return(submap);
}

/*
 * uvm_km_pgremove: remove pages from a kernel uvm_object.
 *
 * => when you unmap a part of anonymous kernel memory you want to toss
 *    the pages right away.    (this gets called from uvm_unmap_...).
 */

#define UKM_HASH_PENALTY 4      /* a guess */

void uvm_km_pgremove(uobj, start, end)

struct uvm_object *uobj;
vm_offset_t start, end;

{
  boolean_t by_list, is_aobj;
  struct vm_page *pp, *ppnext;
  vm_offset_t curoff;
  UVMHIST_FUNC("uvm_km_pgremove"); UVMHIST_CALLED(maphist);

  simple_lock(&uobj->vmobjlock);		/* lock object */

  /* is uobj an aobj? */
  is_aobj = uobj->pgops == &aobj_pager;

  /* choose cheapest traversal */
  by_list = (uobj->uo_npages <=
	     ((end - start) / PAGE_SIZE) * UKM_HASH_PENALTY);
 
  if (by_list)
    goto loop_by_list;

  /* by hash */

  for (curoff = start ; curoff < end ; curoff += PAGE_SIZE) {
    pp = uvm_pagelookup(uobj, curoff);
    if (pp == NULL)
      continue;

    UVMHIST_LOG(maphist,"  page 0x%x, busy=%d", pp,pp->flags & PG_BUSY,0,0);
    /* now do the actual work */
    if (pp->flags & PG_BUSY)
      pp->flags |= PG_RELEASED;	/* owner must check for this when done */
    else {
      pmap_page_protect(PMAP_PGARG(pp), VM_PROT_NONE);

      /*
       * if this kernel object is an aobj, free the swap slot.
       */
      if (is_aobj) {
	int slot = uao_set_swslot(uobj, curoff / PAGE_SIZE, 0);

	if (slot)
	  uvm_swap_free(slot, 1);
      }

      uvm_lock_pageq();
      uvm_pagefree(pp);
      uvm_unlock_pageq();
    }
    /* done */

  }
  simple_unlock(&uobj->vmobjlock);
  return;

loop_by_list:

  for (pp = uobj->memq.tqh_first ; pp != NULL ; pp = ppnext) {

    ppnext = pp->listq.tqe_next;
    if (pp->offset < start || pp->offset >= end) {
      continue;
    }

    UVMHIST_LOG(maphist,"  page 0x%x, busy=%d", pp,pp->flags & PG_BUSY,0,0);
    /* now do the actual work */
    if (pp->flags & PG_BUSY)
      pp->flags |= PG_RELEASED;	/* owner must check for this when done */
    else {
      pmap_page_protect(PMAP_PGARG(pp), VM_PROT_NONE);

      /*
       * if this kernel object is an aobj, free the swap slot.
       */
      if (is_aobj) {
	int slot = uao_set_swslot(uobj, pp->offset / PAGE_SIZE, 0);

	if (slot)
	  uvm_swap_free(slot, 1);
      }

      uvm_lock_pageq();
      uvm_pagefree(pp);
      uvm_unlock_pageq();
    }
    /* done */

  }
  simple_unlock(&uobj->vmobjlock);
  return;
}


/*
 * uvm_km_kmemalloc: lower level kernel memory allocator for malloc()
 *
 * => we map wired memory into the specified map using the obj passed in
 * => NOTE: we can return NULL even if we can wait if there is not enough
 *	free VM space in the map... caller should be prepared to handle
 *	this case.
 * => we return KVA of memory allocated
 * => flags: NOWAIT, VALLOC - just allocate VA, TRYLOCK - fail if we can't
 *	lock the map
 */

vm_offset_t uvm_km_kmemalloc(map, obj, size, flags)

vm_map_t map;
struct uvm_object *obj;
vm_size_t size;
int flags;

{
  vm_offset_t kva, loopva;
  vm_offset_t offset;
  struct vm_page *pg;
  UVMHIST_FUNC("uvm_km_kmemalloc"); UVMHIST_CALLED(maphist);


  UVMHIST_LOG(maphist,"  (map=0x%x, obj=0x%x, size=0x%x, flags=%d)",
	map, obj, size, flags);
#ifdef DIAGNOSTIC
  /* sanity check */
  if (vm_map_pmap(map) != pmap_kernel())
    panic("uvm_km_kmemalloc: invalid map");
#endif

  /*
   * setup for call
   */

  size = round_page(size);
  kva = vm_map_min(map);	/* hint */

  /*
   * allocate some virtual space
   */

  if (uvm_map(map, &kva, size, obj, UVM_UNKNOWN_OFFSET,
	      UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
			  UVM_ADV_RANDOM, (flags & UVM_KMF_TRYLOCK))) 
      != KERN_SUCCESS) {
    UVMHIST_LOG(maphist, "<- done (no VM)",0,0,0,0);
    return(0);
  }

  /*
   * if all we wanted was VA, return now
   */

  if (flags & UVM_KMF_VALLOC) {
    UVMHIST_LOG(maphist,"<- done valloc (kva=0x%x)", kva,0,0,0);
    return(kva);
  }
  /*
   * recover object offset from virtual address
   */

  offset = kva - vm_map_min(map);
  UVMHIST_LOG(maphist, "  kva=0x%x, offset=0x%x", kva, offset,0,0);

  /*
   * now allocate and map in the memory... note that we are the only ones
   * whom should ever get a handle on this area of VM.
   */

  loopva = kva;
  while (size) {
    simple_lock(&obj->vmobjlock);
    pg = uvm_pagealloc(obj, offset, NULL);
    if (pg) {
      pg->flags &= ~PG_BUSY;	/* new page */
      UVM_PAGE_OWN(pg, NULL);

      pg->wire_count = 1;
      uvmexp.wired++;
    }
    simple_unlock(&obj->vmobjlock);
    
    /*
     * out of memory?
     */

    if (pg == NULL) {
      if (flags & UVM_KMF_NOWAIT) {
	uvm_unmap(map, kva, kva + size, 0); /* free everything! */
	return(0);
      } else {
	uvm_wait("km_getwait2");		/* sleep here */
	continue;
      }
    }
    
    /*
     * map it in: note that we call pmap_enter with the map and object
     * unlocked in case we are kmem_map/kmem_object (because if pmap_enter
     * wants to allocate out of kmem_object it will need to lock it itself!)
     */
#if defined(PMAP_NEW)
    pmap_kenter_pa(loopva, VM_PAGE_TO_PHYS(pg), VM_PROT_ALL);
#else
    pmap_enter(map->pmap, loopva, VM_PAGE_TO_PHYS(pg), UVM_PROT_ALL, TRUE);
#endif
    loopva += PAGE_SIZE;
    offset += PAGE_SIZE;
    size -= PAGE_SIZE;
  }

  UVMHIST_LOG(maphist,"<- done (kva=0x%x)", kva,0,0,0);
  return(kva);
}

/*
 * uvm_km_free: free an area of kernel memory
 */

void uvm_km_free(map, addr, size)

vm_map_t map;
vm_offset_t addr;
vm_size_t size;

{
  uvm_unmap(map, trunc_page(addr), round_page(addr+size), 1);
}

/*
 * uvm_km_free_wakeup: free an area of kernel memory and wake up
 * anyone waiting for vm space.
 *
 * => XXX: "wanted" bit + unlock&wait on other end?
 */

void uvm_km_free_wakeup(map, addr, size)

vm_map_t map;
vm_offset_t addr;
vm_size_t size;

{
  vm_map_entry_t dead_entries;

  vm_map_lock(map);
  (void)uvm_unmap_remove(map, trunc_page(addr), round_page(addr+size), 1,
			 &dead_entries);
  thread_wakeup(map);
  vm_map_unlock(map);

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

/*
 * uvm_km_alloc1: allocate wired down memory in the kernel map.
 *
 * => we can sleep if needed
 */

vm_offset_t uvm_km_alloc1(map, size, zeroit)

vm_map_t map;
vm_size_t size;
boolean_t zeroit;

{
  vm_offset_t kva, loopva, offset;
  struct vm_page *pg;
  UVMHIST_FUNC("uvm_km_alloc1"); UVMHIST_CALLED(maphist);

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

#ifdef DIAGNOSTIC
  if (vm_map_pmap(map) != pmap_kernel())
    panic("uvm_km_alloc1");
#endif

  size = round_page(size);
  kva = vm_map_min(map);		/* hint */

  /*
   * allocate some virtual space
   */

  if (uvm_map(map, &kva, size, uvm.kernel_object, UVM_UNKNOWN_OFFSET,
	      UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
			  UVM_ADV_RANDOM, 0)) != KERN_SUCCESS) {
    UVMHIST_LOG(maphist,"<- done (no VM)",0,0,0,0);
    return(0);
  }

  /*
   * recover object offset from virtual address
   */

  offset = kva - vm_map_min(map);
  UVMHIST_LOG(maphist,"  kva=0x%x, offset=0x%x", kva, offset,0,0);

  /*
   * now allocate the memory.  we must be careful about released pages.
   */

  loopva = kva;
  while (size) {
    simple_lock(&uvm.kernel_object->vmobjlock);
    pg = uvm_pagelookup(uvm.kernel_object, offset);

    /* if we found a page in an unallocated region, it must be released */
    if (pg) {
      if ((pg->flags & PG_RELEASED) == 0)
	panic("uvm_km_alloc1: non-released page");
      pg->flags |= PG_WANTED;
      UVM_UNLOCK_AND_WAIT(pg, &uvm.kernel_object->vmobjlock,0,"km_alloc",0);
      continue;   /* retry */
    }
    
    /* allocate ram */
    pg = uvm_pagealloc(uvm.kernel_object, offset, NULL);
    if (pg) {
      pg->flags &= ~PG_BUSY;	/* new page */
      UVM_PAGE_OWN(pg, NULL);
    }
    simple_unlock(&uvm.kernel_object->vmobjlock);
    if (pg == NULL) {
      uvm_wait("km_alloc1w");	/* wait for memory */
      continue;
    }
    
    /* map it in */
#if defined(PMAP_NEW)
    pmap_kenter_pa(loopva, VM_PAGE_TO_PHYS(pg), UVM_PROT_ALL);
#else
    pmap_enter(map->pmap, loopva, VM_PAGE_TO_PHYS(pg), UVM_PROT_ALL, TRUE);
#endif
    loopva += PAGE_SIZE;
    offset += PAGE_SIZE;
    size -= PAGE_SIZE;
  }
  
  /*
   * zero on request (note that "size" is now zero due to the above loop
   * so we need to subtract kva from loopva to reconstruct the size).
   */

  if (zeroit)
    bzero((caddr_t)kva, loopva - kva);

  UVMHIST_LOG(maphist,"<- done (kva=0x%x)", kva,0,0,0);
  return(kva);
}

/*
 * uvm_km_valloc: allocate zero-fill memory in the kernel's address space
 *
 * => memory is not allocated until fault time
 */

vm_offset_t uvm_km_valloc(map, size)

vm_map_t map;
vm_size_t size;

{
  vm_offset_t kva;
  UVMHIST_FUNC("uvm_km_valloc"); UVMHIST_CALLED(maphist);

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

#ifdef DIAGNOSTIC
  if (vm_map_pmap(map) != pmap_kernel())
    panic("uvm_km_valloc");
#endif

  size = round_page(size);
  kva = vm_map_min(map);		/* hint */

  /*
   * allocate some virtual space.   will be demand filled by kernel_object.
   */

  if (uvm_map(map, &kva, size, uvm.kernel_object, UVM_UNKNOWN_OFFSET,
	      UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
			  UVM_ADV_RANDOM, 0)) != KERN_SUCCESS) {
    UVMHIST_LOG(maphist, "<- done (no VM)", 0,0,0,0);
    return(0);
  }

  UVMHIST_LOG(maphist, "<- done (kva=0x%x)", kva,0,0,0);
  return(kva);
}

/*
 * uvm_km_valloc_wait: allocate zero-fill memory in the kernel's address space
 *
 * => memory is not allocated until fault time
 * => if no room in map, wait for space to free, unless requested size
 *    is larger than map (in which case we return 0)
 */

vm_offset_t uvm_km_valloc_wait(map, size)

vm_map_t map;
vm_size_t size;

{
  vm_offset_t kva;
  UVMHIST_FUNC("uvm_km_valloc_wait"); UVMHIST_CALLED(maphist);

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

#ifdef DIAGNOSTIC
  if (vm_map_pmap(map) != pmap_kernel())
    panic("uvm_km_valloc_wait");
#endif

  size = round_page(size);
  if (size > vm_map_max(map) - vm_map_min(map))
    return(0);

  while (1) {
    kva = vm_map_min(map);		/* hint */

    /*
     * allocate some virtual space.   will be demand filled by kernel_object.
     */

    if (uvm_map(map, &kva, size, uvm.kernel_object, UVM_UNKNOWN_OFFSET,
		UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
			    UVM_ADV_RANDOM, 0)) == KERN_SUCCESS){
      UVMHIST_LOG(maphist,"<- done (kva=0x%x)", kva,0,0,0);
      return(kva);
    }

    /*
     * failed.  sleep for a while (on map)
     */

    UVMHIST_LOG(maphist,"<<<sleeping>>>",0,0,0,0);
    tsleep((caddr_t)map, PVM, "vallocwait", 0);
  }
  /*NOTREACHED*/
}