sys/vm/phys_pager.c

   1 /*
   2  * Copyright (c) 2000 Peter Wemm
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
  14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
  17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  23  * SUCH DAMAGE.
  24  *
  25  * $FreeBSD: src/sys/vm/phys_pager.c,v 1.3.2.3 2000/12/17 02:05:41 alfred Exp $
  26  * $DragonFly: src/sys/vm/phys_pager.c,v 1.5 2006/03/27 01:54:18 dillon Exp $
  27  */
  28
  29 #include <sys/param.h>
  30 #include <sys/systm.h>
  31 #include <sys/linker_set.h>
  32 #include <sys/conf.h>
  33 #include <sys/mman.h>
  34 #include <sys/sysctl.h>
  35
  36 #include <vm/vm.h>
  37 #include <vm/vm_object.h>
  38 #include <vm/vm_page.h>
  39 #include <vm/vm_pager.h>
  40 #include <vm/vm_zone.h>
  41
  42 #include <sys/thread2.h>
  43
  44 /* list of device pager objects */
  45 static struct pagerlst phys_pager_object_list;
  46
  47 static int phys_pager_alloc_lock, phys_pager_alloc_lock_want;
  48
  49 static void
  50 phys_pager_init(void)
  51 {
  52
  53         TAILQ_INIT(&phys_pager_object_list);
  54 }
  55
  56 static vm_object_t
  57 phys_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t foff)
  58 {
  59         vm_object_t object;
  60
  61         /*
  62          * Offset should be page aligned.
  63          */
  64         if (foff & PAGE_MASK)
  65                 return (NULL);
  66
  67         size = round_page(size);
  68
  69         if (handle != NULL) {
  70                 /*
  71                  * Lock to prevent object creation race condition.
  72                  */
  73                 while (phys_pager_alloc_lock) {
  74                         phys_pager_alloc_lock_want++;
  75                         tsleep(&phys_pager_alloc_lock, 0, "ppall", 0);
  76                         phys_pager_alloc_lock_want--;
  77                 }
  78                 phys_pager_alloc_lock = 1;
  79
  80                 /*
  81                  * Look up pager, creating as necessary.
  82                  */
  83                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
  84                 if (object == NULL) {
  85                         /*
  86                          * Allocate object and associate it with the pager.
  87                          */
  88                         object = vm_object_allocate(OBJT_PHYS,
  89                                 OFF_TO_IDX(foff + size));
  90                         object->handle = handle;
  91                         TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
  92                             pager_object_list);
  93                 } else {
  94                         /*
  95                          * Gain a reference to the object.
  96                          */
  97                         vm_object_reference(object);
  98                         if (OFF_TO_IDX(foff + size) > object->size)
  99                                 object->size = OFF_TO_IDX(foff + size);
 100                 }
 101                 phys_pager_alloc_lock = 0;
 102                 if (phys_pager_alloc_lock_want)
 103                         wakeup(&phys_pager_alloc_lock);
 104         } else {
 105                 object = vm_object_allocate(OBJT_PHYS,
 106                         OFF_TO_IDX(foff + size));
 107         }
 108
 109         return (object);
 110 }
 111
 112 static void
 113 phys_pager_dealloc(vm_object_t object)
 114 {
 115
 116         if (object->handle != NULL)
 117                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
 118 }
 119
 120 static int
 121 phys_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
 122 {
 123         vm_page_t m = *mpp;
 124
 125         crit_enter();
 126         if ((m->flags & PG_ZERO) == 0)
 127                 vm_page_zero_fill(m);
 128         vm_page_flag_set(m, PG_ZERO);
 129         /* Switch off pv_entries */
 130         vm_page_unmanage(m);
 131         m->valid = VM_PAGE_BITS_ALL;
 132         m->dirty = 0;
 133         crit_exit();
 134
 135         return (VM_PAGER_OK);
 136 }
 137
 138 static void
 139 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count,
 140                     boolean_t sync, int *rtvals)
 141 {
 142
 143         panic("phys_pager_putpage called");
 144 }
 145
 146 /*
 147  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 148  * everything in an entire 4MB window should be prefaulted at once.
 149  *
 150  * XXX 4MB (1024 slots per page table page) is convenient for x86,
 151  * but may not be for other arches.
 152  */
 153 #ifndef PHYSCLUSTER
 154 #define PHYSCLUSTER 1024
 155 #endif
 156
 157 static boolean_t
 158 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex)
 159 {
 160         return (TRUE);
 161 }
 162
 163 struct pagerops physpagerops = {
 164         phys_pager_init,
 165         phys_pager_alloc,
 166         phys_pager_dealloc,
 167         phys_pager_getpage,
 168         phys_pager_putpages,
 169         phys_pager_haspage,
 170         NULL
 171 };