FreeBSD/Linux Kernel Cross Reference
sys/uvm/uvm_km.c

     /*      $NetBSD: uvm_km.c,v 1.77.2.1 2005/12/06 20:00:12 riz Exp $      */
     
     /*
      * Copyright (c) 1997 Charles D. Cranor and Washington University.
      * Copyright (c) 1991, 1993, The Regents of the University of California.
      *
      * All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
     * The Mach Operating System project at Carnegie-Mellon University.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by Charles D. Cranor,
     *      Washington University, the University of California, Berkeley and
     *      its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)vm_kern.c   8.3 (Berkeley) 1/12/94
     * from: Id: uvm_km.c,v 1.1.2.14 1998/02/06 05:19:27 chs Exp
     *
     *
     * Copyright (c) 1987, 1990 Carnegie-Mellon University.
     * All rights reserved.
     *
     * Permission to use, copy, modify and distribute this software and
     * its documentation is hereby granted, provided that both the copyright
     * notice and this permission notice appear in all copies of the
     * software, derivative works or modified versions, and any portions
     * thereof, and that both notices appear in supporting documentation.
     *
     * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
     * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     *
     * Carnegie Mellon requests users of this software to return to
     *
     *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
     *  School of Computer Science
     *  Carnegie Mellon University
     *  Pittsburgh PA 15213-3890
     *
     * any improvements or extensions that they make and grant Carnegie the
     * rights to redistribute these changes.
     */
    
    /*
     * uvm_km.c: handle kernel memory allocation and management
     */
    
    /*
     * overview of kernel memory management:
     *
     * the kernel virtual address space is mapped by "kernel_map."   kernel_map
     * starts at VM_MIN_KERNEL_ADDRESS and goes to VM_MAX_KERNEL_ADDRESS.
     * note that VM_MIN_KERNEL_ADDRESS is equal to vm_map_min(kernel_map).
     *
     * the kernel_map has several "submaps."   submaps can only appear in
     * the kernel_map (user processes can't use them).   submaps "take over"
     * the management of a sub-range of the kernel's address space.  submaps
     * are typically allocated at boot time and are never released.   kernel
     * virtual address space that is mapped by a submap is locked by the
     * submap's lock -- not the kernel_map's lock.
     *
     * thus, the useful feature of submaps is that they allow us to break
     * up the locking and protection of the kernel address space into smaller
     * chunks.
     *
     * the vm system has several standard kernel submaps, including:
     *   kmem_map => contains only wired kernel memory for the kernel
     *              malloc.   *** access to kmem_map must be protected
     *              by splvm() because we are allowed to call malloc()
     *              at interrupt time ***
     *   mb_map => memory for large mbufs,  *** protected by splvm ***
     *   pager_map => used to map "buf" structures into kernel space
     *   exec_map => used during exec to handle exec args
     *   etc...
    *
    * the kernel allocates its private memory out of special uvm_objects whose
    * reference count is set to UVM_OBJ_KERN (thus indicating that the objects
    * are "special" and never die).   all kernel objects should be thought of
    * as large, fixed-sized, sparsely populated uvm_objects.   each kernel
    * object is equal to the size of kernel virtual address space (i.e. the
    * value "VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS").
    *
    * most kernel private memory lives in kernel_object.   the only exception
    * to this is for memory that belongs to submaps that must be protected
    * by splvm().  pages in these submaps are not assigned to an object.
    *
    * note that just because a kernel object spans the entire kernel virutal
    * address space doesn't mean that it has to be mapped into the entire space.
    * large chunks of a kernel object's space go unused either because
    * that area of kernel VM is unmapped, or there is some other type of
    * object mapped into that range (e.g. a vnode).    for submap's kernel
    * objects, the only part of the object that can ever be populated is the
    * offsets that are managed by the submap.
    *
    * note that the "offset" in a kernel object is always the kernel virtual
    * address minus the VM_MIN_KERNEL_ADDRESS (aka vm_map_min(kernel_map)).
    * example:
    *   suppose VM_MIN_KERNEL_ADDRESS is 0xf8000000 and the kernel does a
    *   uvm_km_alloc(kernel_map, PAGE_SIZE) [allocate 1 wired down page in the
    *   kernel map].    if uvm_km_alloc returns virtual address 0xf8235000,
    *   then that means that the page at offset 0x235000 in kernel_object is
    *   mapped at 0xf8235000.
    *
    * kernel object have one other special property: when the kernel virtual
    * memory mapping them is unmapped, the backing memory in the object is
    * freed right away.   this is done with the uvm_km_pgremove() function.
    * this has to be done because there is no backing store for kernel pages
    * and no need to save them after they are no longer referenced.
    */
   
   #include <sys/cdefs.h>
   __KERNEL_RCSID(0, "$NetBSD: uvm_km.c,v 1.77.2.1 2005/12/06 20:00:12 riz Exp $");
   
   #include "opt_uvmhist.h"
   
   #include <sys/param.h>
   #include <sys/malloc.h>
   #include <sys/systm.h>
   #include <sys/proc.h>
   #include <sys/pool.h>
   
   #include <uvm/uvm.h>
   
   /*
    * global data structures
    */
   
   struct vm_map *kernel_map = NULL;
   
   /*
    * local data structues
    */
   
   static struct vm_map_kernel     kernel_map_store;
   static struct vm_map_entry      kernel_first_mapent_store;
   
   #if !defined(PMAP_MAP_POOLPAGE)
   
   /*
    * kva cache
    *
    * XXX maybe it's better to do this at the uvm_map layer.
    */
   
   #define KM_VACACHE_SIZE (32 * PAGE_SIZE) /* XXX tune */
   
   static void *km_vacache_alloc(struct pool *, int);
   static void km_vacache_free(struct pool *, void *);
   static void km_vacache_init(struct vm_map *, const char *, size_t);
   
   /* XXX */
   #define KM_VACACHE_POOL_TO_MAP(pp) \
           ((struct vm_map *)((char *)(pp) - \
               offsetof(struct vm_map_kernel, vmk_vacache)))
   
   static void *
   km_vacache_alloc(struct pool *pp, int flags)
   {
           vaddr_t va;
           size_t size;
           struct vm_map *map;
   #if defined(DEBUG)
           vaddr_t loopva;
   #endif
           size = pp->pr_alloc->pa_pagesz;
   
           map = KM_VACACHE_POOL_TO_MAP(pp);
   
           va = vm_map_min(map); /* hint */
           if (uvm_map(map, &va, size, NULL, UVM_UNKNOWN_OFFSET, size,
               UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
               UVM_ADV_RANDOM, UVM_FLAG_QUANTUM |
               ((flags & PR_WAITOK) ? 0 : UVM_FLAG_TRYLOCK | UVM_FLAG_NOWAIT))))
                   return NULL;
   
   #if defined(DEBUG)
           for (loopva = va; loopva < va + size; loopva += PAGE_SIZE) {
                   if (pmap_extract(pmap_kernel(), loopva, NULL))
                           panic("km_vacache_free: has mapping");
           }
   #endif
   
           return (void *)va;
   }
   
   static void
   km_vacache_free(struct pool *pp, void *v)
   {
           vaddr_t va = (vaddr_t)v;
           size_t size = pp->pr_alloc->pa_pagesz;
           struct vm_map *map;
   #if defined(DEBUG)
           vaddr_t loopva;
   
           for (loopva = va; loopva < va + size; loopva += PAGE_SIZE) {
                   if (pmap_extract(pmap_kernel(), loopva, NULL))
                           panic("km_vacache_free: has mapping");
           }
   #endif
           map = KM_VACACHE_POOL_TO_MAP(pp);
           uvm_unmap1(map, va, va + size, UVM_FLAG_QUANTUM);
   }
   
   /*
    * km_vacache_init: initialize kva cache.
    */
   
   static void
   km_vacache_init(struct vm_map *map, const char *name, size_t size)
   {
           struct vm_map_kernel *vmk;
           struct pool *pp;
           struct pool_allocator *pa;
   
           KASSERT(VM_MAP_IS_KERNEL(map));
           KASSERT(size < (vm_map_max(map) - vm_map_min(map)) / 2); /* sanity */
   
           vmk = vm_map_to_kernel(map);
           pp = &vmk->vmk_vacache;
           pa = &vmk->vmk_vacache_allocator;
           memset(pa, 0, sizeof(*pa));
           pa->pa_alloc = km_vacache_alloc;
           pa->pa_free = km_vacache_free;
           pa->pa_pagesz = (unsigned int)size;
           pool_init(pp, PAGE_SIZE, 0, 0, PR_NOTOUCH | PR_RECURSIVE, name, pa);
   
           /* XXX for now.. */
           pool_sethiwat(pp, 0);
   }
   
   void
   uvm_km_vacache_init(struct vm_map *map, const char *name, size_t size)
   {
   
           map->flags |= VM_MAP_VACACHE;
           if (size == 0)
                   size = KM_VACACHE_SIZE;
           km_vacache_init(map, name, size);
   }
   
   #else /* !defined(PMAP_MAP_POOLPAGE) */
   
   void
   uvm_km_vacache_init(struct vm_map *map, const char *name, size_t size)
   {
   
           /* nothing */
   }
   
   #endif /* !defined(PMAP_MAP_POOLPAGE) */
   
   /*
    * 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)
           vaddr_t start, end;
   {
           vaddr_t base = VM_MIN_KERNEL_ADDRESS;
   
           /*
            * next, init kernel memory objects.
            */
   
           /* kernel_object: for pageable anonymous kernel memory */
           uao_init();
           uvm.kernel_object = uao_create(VM_MAX_KERNEL_ADDRESS -
                                    VM_MIN_KERNEL_ADDRESS, UAO_FLAG_KERNOBJ);
   
           /*
            * init the map and reserve any space that might already
            * have been allocated kernel space before installing.
            */
   
           uvm_map_setup_kernel(&kernel_map_store, base, end, VM_MAP_PAGEABLE);
           kernel_map_store.vmk_map.pmap = pmap_kernel();
           if (start != base) {
                   int error;
                   struct uvm_map_args args;
   
                   error = uvm_map_prepare(&kernel_map_store.vmk_map,
                       base, start - base,
                       NULL, UVM_UNKNOWN_OFFSET, 0,
                       UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
                                   UVM_ADV_RANDOM, UVM_FLAG_FIXED), &args);
                   if (!error) {
                           kernel_first_mapent_store.flags =
                               UVM_MAP_KERNEL | UVM_MAP_FIRST;
                           error = uvm_map_enter(&kernel_map_store.vmk_map, &args,
                               &kernel_first_mapent_store);
                   }
   
                   if (error)
                           panic(
                               "uvm_km_init: could not reserve space for kernel");
           }
   
           /*
            * install!
            */
   
           kernel_map = &kernel_map_store.vmk_map;
           uvm_km_vacache_init(kernel_map, "kvakernel", 0);
   }
   
   /*
    * 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 `fixed' is true, *min specifies where the region described
    *      by the submap must start
    * => 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, flags, fixed, submap)
           struct vm_map *map;
           vaddr_t *min, *max;             /* IN/OUT, OUT */
           vsize_t size;
           int flags;
           boolean_t fixed;
           struct vm_map_kernel *submap;
   {
           int mapflags = UVM_FLAG_NOMERGE | (fixed ? UVM_FLAG_FIXED : 0);
   
           KASSERT(vm_map_pmap(map) == pmap_kernel());
   
           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, 0,
               UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
               UVM_ADV_RANDOM, mapflags)) != 0) {
                  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 = malloc(sizeof(*submap), M_VMMAP, M_WAITOK);
                   if (submap == NULL)
                           panic("uvm_km_suballoc: unable to create submap");
           }
           uvm_map_setup_kernel(submap, *min, *max, flags);
           submap->vmk_map.pmap = vm_map_pmap(map);
   
           /*
            * now let uvm_map_submap plug in it...
            */
   
           if (uvm_map_submap(map, *min, *max, &submap->vmk_map) != 0)
                   panic("uvm_km_suballoc: submap allocation failed");
   
           return(&submap->vmk_map);
   }
   
   /*
    * 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_...).
    */
   
   void
   uvm_km_pgremove(uobj, start, end)
           struct uvm_object *uobj;
           vaddr_t start, end;
   {
           struct vm_page *pg;
           voff_t curoff, nextoff;
           int swpgonlydelta = 0;
           UVMHIST_FUNC("uvm_km_pgremove"); UVMHIST_CALLED(maphist);
   
           KASSERT(uobj->pgops == &aobj_pager);
           simple_lock(&uobj->vmobjlock);
   
           for (curoff = start; curoff < end; curoff = nextoff) {
                   nextoff = curoff + PAGE_SIZE;
                   pg = uvm_pagelookup(uobj, curoff);
                   if (pg != NULL && pg->flags & PG_BUSY) {
                           pg->flags |= PG_WANTED;
                           UVM_UNLOCK_AND_WAIT(pg, &uobj->vmobjlock, 0,
                                       "km_pgrm", 0);
                           simple_lock(&uobj->vmobjlock);
                           nextoff = curoff;
                           continue;
                   }
   
                   /*
                    * free the swap slot, then the page.
                    */
   
                   if (pg == NULL &&
                       uao_find_swslot(uobj, curoff >> PAGE_SHIFT) > 0) {
                           swpgonlydelta++;
                   }
                   uao_dropswap(uobj, curoff >> PAGE_SHIFT);
                   if (pg != NULL) {
                           uvm_lock_pageq();
                           uvm_pagefree(pg);
                           uvm_unlock_pageq();
                   }
           }
           simple_unlock(&uobj->vmobjlock);
   
           if (swpgonlydelta > 0) {
                   simple_lock(&uvm.swap_data_lock);
                   KASSERT(uvmexp.swpgonly >= swpgonlydelta);
                   uvmexp.swpgonly -= swpgonlydelta;
                   simple_unlock(&uvm.swap_data_lock);
           }
   }
   
   
   /*
    * uvm_km_pgremove_intrsafe: like uvm_km_pgremove(), but for "intrsafe"
    *    maps
    *
    * => when you unmap a part of anonymous kernel memory you want to toss
    *    the pages right away.    (this is called from uvm_unmap_...).
    * => none of the pages will ever be busy, and none of them will ever
    *    be on the active or inactive queues (because they have no object).
    */
   
   void
   uvm_km_pgremove_intrsafe(start, end)
           vaddr_t start, end;
   {
           struct vm_page *pg;
           paddr_t pa;
           UVMHIST_FUNC("uvm_km_pgremove_intrsafe"); UVMHIST_CALLED(maphist);
   
           for (; start < end; start += PAGE_SIZE) {
                   if (!pmap_extract(pmap_kernel(), start, &pa)) {
                           continue;
                   }
                   pg = PHYS_TO_VM_PAGE(pa);
                   KASSERT(pg);
                   KASSERT(pg->uobject == NULL && pg->uanon == NULL);
                   uvm_pagefree(pg);
           }
   }
   
   
   /*
    * 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
    * => align,prefer - passed on to uvm_map()
    * => flags: NOWAIT, VALLOC - just allocate VA, TRYLOCK - fail if we can't
    *      lock the map
    */
   
   vaddr_t
   uvm_km_kmemalloc1(map, obj, size, align, prefer, flags)
           struct vm_map *map;
           struct uvm_object *obj;
           vsize_t size;
           vsize_t align;
           voff_t prefer;
           int flags;
   {
           vaddr_t kva, loopva;
           vaddr_t offset;
           vsize_t loopsize;
           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);
           KASSERT(vm_map_pmap(map) == pmap_kernel());
   
           /*
            * setup for call
            */
   
           size = round_page(size);
           kva = vm_map_min(map);  /* hint */
   
           /*
            * allocate some virtual space
            */
   
           if (__predict_false(uvm_map(map, &kva, size, obj, prefer, align,
                   UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
                               UVM_ADV_RANDOM,
                               (flags & (UVM_KMF_TRYLOCK | UVM_KMF_NOWAIT))
                               | UVM_FLAG_QUANTUM))
                           != 0)) {
                   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(kernel_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;
           loopsize = size;
           while (loopsize) {
                   if (obj) {
                           simple_lock(&obj->vmobjlock);
                   }
                   pg = uvm_pagealloc(obj, offset, NULL, UVM_PGA_USERESERVE);
                   if (__predict_true(pg != NULL)) {
                           pg->flags &= ~PG_BUSY;  /* new page */
                           UVM_PAGE_OWN(pg, NULL);
                   }
                   if (obj) {
                           simple_unlock(&obj->vmobjlock);
                   }
   
                   /*
                    * out of memory?
                    */
   
                   if (__predict_false(pg == NULL)) {
                           if ((flags & UVM_KMF_NOWAIT) ||
                               ((flags & UVM_KMF_CANFAIL) && uvm_swapisfull())) {
                                   /* free everything! */
                                   uvm_unmap1(map, kva, kva + size,
                                       UVM_FLAG_QUANTUM);
                                   return (0);
                           } else {
                                   uvm_wait("km_getwait2");        /* sleep here */
                                   continue;
                           }
                   }
   
                   /*
                    * map it in
                    */
   
                   if (obj == NULL) {
                           pmap_kenter_pa(loopva, VM_PAGE_TO_PHYS(pg),
                               VM_PROT_READ | VM_PROT_WRITE);
                   } else {
                           pmap_enter(map->pmap, loopva, VM_PAGE_TO_PHYS(pg),
                               UVM_PROT_ALL,
                               PMAP_WIRED | VM_PROT_READ | VM_PROT_WRITE);
                   }
                   loopva += PAGE_SIZE;
                   offset += PAGE_SIZE;
                   loopsize -= PAGE_SIZE;
           }
   
           pmap_update(pmap_kernel());
   
           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)
           struct vm_map *map;
           vaddr_t addr;
           vsize_t size;
   {
           uvm_unmap1(map, trunc_page(addr), round_page(addr+size),
               UVM_FLAG_QUANTUM);
   }
   
   /*
    * uvm_km_alloc1: allocate wired down memory in the kernel map.
    *
    * => we can sleep if needed
    */
   
   vaddr_t
   uvm_km_alloc1(map, size, zeroit)
           struct vm_map *map;
           vsize_t size;
           boolean_t zeroit;
   {
           vaddr_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);
           KASSERT(vm_map_pmap(map) == pmap_kernel());
   
           size = round_page(size);
           kva = vm_map_min(map);          /* hint */
   
           /*
            * allocate some virtual space
            */
   
           if (__predict_false(uvm_map(map, &kva, size, uvm.kernel_object,
                 UVM_UNKNOWN_OFFSET, 0, UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL,
                                                 UVM_INH_NONE, UVM_ADV_RANDOM,
                                                 UVM_FLAG_QUANTUM)) != 0)) {
                   UVMHIST_LOG(maphist,"<- done (no VM)",0,0,0,0);
                   return(0);
           }
   
           /*
            * recover object offset from virtual address
            */
   
           offset = kva - vm_map_min(kernel_map);
           UVMHIST_LOG(maphist,"  kva=0x%x, offset=0x%x", kva, offset,0,0);
   
           /*
            * now allocate the memory.
            */
   
           loopva = kva;
           while (size) {
                   simple_lock(&uvm.kernel_object->vmobjlock);
                   KASSERT(uvm_pagelookup(uvm.kernel_object, offset) == NULL);
                   pg = uvm_pagealloc(uvm.kernel_object, offset, NULL, 0);
                   if (pg) {
                           pg->flags &= ~PG_BUSY;
                           UVM_PAGE_OWN(pg, NULL);
                   }
                   simple_unlock(&uvm.kernel_object->vmobjlock);
                   if (pg == NULL) {
                           uvm_wait("km_alloc1w");
                           continue;
                   }
                   pmap_enter(map->pmap, loopva, VM_PAGE_TO_PHYS(pg),
                       UVM_PROT_ALL, PMAP_WIRED | VM_PROT_READ | VM_PROT_WRITE);
                   loopva += PAGE_SIZE;
                   offset += PAGE_SIZE;
                   size -= PAGE_SIZE;
           }
           pmap_update(map->pmap);
   
           /*
            * 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)
                   memset((caddr_t)kva, 0, loopva - kva);
           UVMHIST_LOG(maphist,"<- done (kva=0x%x)", kva,0,0,0);
           return(kva);
   }
   
   /*
    * uvm_km_valloc1: allocate zero-fill memory in the kernel's address space
    *
    * => memory is not allocated until fault time
    * => the align, prefer and flags parameters are passed on to uvm_map().
    *
    * Note: this function is also the backend for these macros:
    *      uvm_km_valloc
    *      uvm_km_valloc_wait
    *      uvm_km_valloc_prefer
    *      uvm_km_valloc_prefer_wait
    *      uvm_km_valloc_align
    */
   
   vaddr_t
   uvm_km_valloc1(map, size, align, prefer, flags)
           struct vm_map *map;
           vsize_t size;
           vsize_t align;
           voff_t prefer;
           uvm_flag_t flags;
   {
           vaddr_t kva;
           int error;
           UVMHIST_FUNC("uvm_km_valloc1"); UVMHIST_CALLED(maphist);
   
           UVMHIST_LOG(maphist, "(map=0x%x, size=0x%x, align=0x%x, prefer=0x%x)",
                       map, size, align, prefer);
   
           KASSERT(vm_map_pmap(map) == pmap_kernel());
   
           size = round_page(size);
           /*
            * Check if requested size is larger than the map, in which
            * case we can't succeed.
            */
           if (size > vm_map_max(map) - vm_map_min(map))
                   return (0);
   
           flags |= UVM_FLAG_QUANTUM;
           if ((flags & UVM_KMF_NOWAIT) == 0) /* XXX */
                   flags |= UVM_FLAG_WAITVA;  /* XXX */
   
           kva = vm_map_min(map);          /* hint */
   
           /*
            * allocate some virtual space.   will be demand filled
            * by kernel_object.
            */
   
           error = uvm_map(map, &kva, size, uvm.kernel_object,
               prefer, align, UVM_MAPFLAG(UVM_PROT_ALL,
               UVM_PROT_ALL, UVM_INH_NONE, UVM_ADV_RANDOM, flags));
   
           KASSERT(error == 0 || (flags & UVM_KMF_NOWAIT) != 0);
   
           if (error) {
                   return 0;
           }
   
           UVMHIST_LOG(maphist,"<- done (kva=0x%x)", kva,0,0,0);
   
           return (kva);
   }
   
   /* Function definitions for binary compatibility */
   vaddr_t
   uvm_km_kmemalloc(struct vm_map *map, struct uvm_object *obj,
                    vsize_t sz, int flags)
   {
           return uvm_km_kmemalloc1(map, obj, sz, 0, UVM_UNKNOWN_OFFSET, flags);
   }
   
   vaddr_t uvm_km_valloc(struct vm_map *map, vsize_t sz)
   {
           return uvm_km_valloc1(map, sz, 0, UVM_UNKNOWN_OFFSET, UVM_KMF_NOWAIT);
   }
   
   vaddr_t uvm_km_valloc_align(struct vm_map *map, vsize_t sz, vsize_t align)
   {
           return uvm_km_valloc1(map, sz, align, UVM_UNKNOWN_OFFSET, UVM_KMF_NOWAIT);
   }
   
   vaddr_t uvm_km_valloc_prefer_wait(struct vm_map *map, vsize_t sz, voff_t prefer)
   {
           return uvm_km_valloc1(map, sz, 0, prefer, 0);
   }
   
   vaddr_t uvm_km_valloc_wait(struct vm_map *map, vsize_t sz)
   {
           return uvm_km_valloc1(map, sz, 0, UVM_UNKNOWN_OFFSET, 0);
   }
   
   /* Sanity; must specify both or none. */
   #if (defined(PMAP_MAP_POOLPAGE) || defined(PMAP_UNMAP_POOLPAGE)) && \
       (!defined(PMAP_MAP_POOLPAGE) || !defined(PMAP_UNMAP_POOLPAGE))
   #error Must specify MAP and UNMAP together.
   #endif
   
   /*
    * uvm_km_alloc_poolpage: allocate a page for the pool allocator
    *
    * => if the pmap specifies an alternate mapping method, we use it.
    */
   
   /* ARGSUSED */
   vaddr_t
   uvm_km_alloc_poolpage_cache(map, obj, waitok)
           struct vm_map *map;
           struct uvm_object *obj;
           boolean_t waitok;
   {
   #if defined(PMAP_MAP_POOLPAGE)
           return uvm_km_alloc_poolpage1(map, obj, waitok);
   #else
           struct vm_page *pg;
           struct pool *pp = &vm_map_to_kernel(map)->vmk_vacache;
           vaddr_t va;
           int s = 0xdeadbeaf; /* XXX: gcc */
           const boolean_t intrsafe = (map->flags & VM_MAP_INTRSAFE) != 0;
   
           if ((map->flags & VM_MAP_VACACHE) == 0)
                   return uvm_km_alloc_poolpage1(map, obj, waitok);
   
           if (intrsafe)
                   s = splvm();
           va = (vaddr_t)pool_get(pp, waitok ? PR_WAITOK : PR_NOWAIT);
           if (intrsafe)
                   splx(s);
           if (va == 0)
                   return 0;
           KASSERT(!pmap_extract(pmap_kernel(), va, NULL));
   again:
           pg = uvm_pagealloc(NULL, 0, NULL, UVM_PGA_USERESERVE);
           if (__predict_false(pg == NULL)) {
                   if (waitok) {
                           uvm_wait("plpg");
                           goto again;
                   } else {
                           if (intrsafe)
                                   s = splvm();
                           pool_put(pp, (void *)va);
                           if (intrsafe)
                                   splx(s);
                           return 0;
                   }
           }
           pmap_kenter_pa(va, VM_PAGE_TO_PHYS(pg),
               VM_PROT_READ|VM_PROT_WRITE);
           pmap_update(pmap_kernel());
   
           return va;
   #endif /* PMAP_MAP_POOLPAGE */
   }
   
   vaddr_t
   uvm_km_alloc_poolpage1(map, obj, waitok)
           struct vm_map *map;
           struct uvm_object *obj;
           boolean_t waitok;
   {
   #if defined(PMAP_MAP_POOLPAGE)
           struct vm_page *pg;
           vaddr_t va;
   
    again:
           pg = uvm_pagealloc(NULL, 0, NULL, UVM_PGA_USERESERVE);
           if (__predict_false(pg == NULL)) {
                   if (waitok) {
                           uvm_wait("plpg");
                           goto again;
                   } else
                           return (0);
           }
           va = PMAP_MAP_POOLPAGE(VM_PAGE_TO_PHYS(pg));
           if (__predict_false(va == 0))
                   uvm_pagefree(pg);
           return (va);
   #else
           vaddr_t va;
           int s = 0xdeadbeaf; /* XXX: gcc */
           const boolean_t intrsafe = (map->flags & VM_MAP_INTRSAFE) != 0;
   
           if (intrsafe)
                   s = splvm();
           va = uvm_km_kmemalloc(map, obj, PAGE_SIZE,
               waitok ? 0 : UVM_KMF_NOWAIT | UVM_KMF_TRYLOCK);
           if (intrsafe)
                   splx(s);
           return (va);
   #endif /* PMAP_MAP_POOLPAGE */
   }
   
   /*
    * uvm_km_free_poolpage: free a previously allocated pool page
    *
    * => if the pmap specifies an alternate unmapping method, we use it.
    */
   
   /* ARGSUSED */
   void
   uvm_km_free_poolpage_cache(map, addr)
           struct vm_map *map;
           vaddr_t addr;
   {
   #if defined(PMAP_UNMAP_POOLPAGE)
           uvm_km_free_poolpage1(map, addr);
   #else
           struct pool *pp;
           int s = 0xdeadbeaf; /* XXX: gcc */
           const boolean_t intrsafe = (map->flags & VM_MAP_INTRSAFE) != 0;
   
           if ((map->flags & VM_MAP_VACACHE) == 0) {
                   uvm_km_free_poolpage1(map, addr);
                   return;
           }
   
           KASSERT(pmap_extract(pmap_kernel(), addr, NULL));
           uvm_km_pgremove_intrsafe(addr, addr + PAGE_SIZE);
           pmap_kremove(addr, PAGE_SIZE);
   #if defined(DEBUG)
           pmap_update(pmap_kernel());
   #endif
           KASSERT(!pmap_extract(pmap_kernel(), addr, NULL));
           pp = &vm_map_to_kernel(map)->vmk_vacache;
           if (intrsafe)
                   s = splvm();
           pool_put(pp, (void *)addr);
           if (intrsafe)
                   splx(s);
   #endif
   }
   
   /* ARGSUSED */
   void
   uvm_km_free_poolpage1(map, addr)
           struct vm_map *map;
           vaddr_t addr;
   {
   #if defined(PMAP_UNMAP_POOLPAGE)
           paddr_t pa;
   
           pa = PMAP_UNMAP_POOLPAGE(addr);
           uvm_pagefree(PHYS_TO_VM_PAGE(pa));
   #else
           int s = 0xdeadbeaf; /* XXX: gcc */
           const boolean_t intrsafe = (map->flags & VM_MAP_INTRSAFE) != 0;
   
           if (intrsafe)
                   s = splvm();
           uvm_km_free(map, addr, PAGE_SIZE);
           if (intrsafe)
                   splx(s);
   #endif /* PMAP_UNMAP_POOLPAGE */
   }

Cache object: 13ce0f520bb4c1c560c9e48f679a329b