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_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 122 {
 123         int i;
 124
 125         crit_enter();
 126         /*
 127          * Fill as many pages as vm_fault has allocated for us.
 128          */
 129         for (i = 0; i < count; i++) {
 130                 if ((m[i]->flags & PG_ZERO) == 0)
 131                         vm_page_zero_fill(m[i]);
 132                 vm_page_flag_set(m[i], PG_ZERO);
 133                 /* Switch off pv_entries */
 134                 vm_page_unmanage(m[i]);
 135                 m[i]->valid = VM_PAGE_BITS_ALL;
 136                 m[i]->dirty = 0;
 137                 /* The requested page must remain busy, the others not. */
 138                 if (reqpage != i) {
 139                         vm_page_flag_clear(m[i], PG_BUSY);
 140                         m[i]->busy = 0;
 141                 }
 142         }
 143         crit_exit();
 144
 145         return (VM_PAGER_OK);
 146 }
 147
 148 static void
 149 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
 150                     int *rtvals)
 151 {
 152
 153         panic("phys_pager_putpage called");
 154 }
 155
 156 /*
 157  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 158  * everything in an entire 4MB window should be prefaulted at once.
 159  *
 160  * XXX 4MB (1024 slots per page table page) is convenient for x86,
 161  * but may not be for other arches.
 162  */
 163 #ifndef PHYSCLUSTER
 164 #define PHYSCLUSTER 1024
 165 #endif
 166 static boolean_t
 167 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 168                    int *after)
 169 {
 170         vm_pindex_t base, end;
 171
 172         base = pindex & (~(PHYSCLUSTER - 1));
 173         end = base + (PHYSCLUSTER - 1);
 174         if (before != NULL)
 175                 *before = pindex - base;
 176         if (after != NULL)
 177                 *after = end - pindex;
 178         return (TRUE);
 179 }
 180
 181 struct pagerops physpagerops = {
 182         phys_pager_init,
 183         phys_pager_alloc,
 184         phys_pager_dealloc,
 185         phys_pager_getpages,
 186         phys_pager_putpages,
 187         phys_pager_haspage,
 188         NULL
 189 };