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 static void
  45 phys_pager_init(void)
  46 {
  47 }
  48
  49 static vm_object_t
  50 phys_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t foff)
  51 {
  52         vm_object_t object;
  53
  54         /*
  55          * Offset should be page aligned.
  56          */
  57         if (foff & PAGE_MASK)
  58                 return (NULL);
  59
  60         size = round_page(size);
  61
  62         KKASSERT(handle == NULL);
  63 #if 0
  64         if (handle != NULL) {
  65                 /*
  66                  * Lock to prevent object creation race condition.
  67                  */
  68                 while (phys_pager_alloc_lock) {
  69                         phys_pager_alloc_lock_want++;
  70                         tsleep(&phys_pager_alloc_lock, 0, "ppall", 0);
  71                         phys_pager_alloc_lock_want--;
  72                 }
  73                 phys_pager_alloc_lock = 1;
  74
  75                 /*
  76                  * Look up pager, creating as necessary.
  77                  */
  78                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
  79                 if (object == NULL) {
  80                         /*
  81                          * Allocate object and associate it with the pager.
  82                          */
  83                         object = vm_object_allocate(OBJT_PHYS,
  84                                 OFF_TO_IDX(foff + size));
  85                         object->handle = handle;
  86                         TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
  87                             pager_object_list);
  88                 } else {
  89                         /*
  90                          * Gain a reference to the object.
  91                          */
  92                         vm_object_reference(object);
  93                         if (OFF_TO_IDX(foff + size) > object->size)
  94                                 object->size = OFF_TO_IDX(foff + size);
  95                 }
  96                 phys_pager_alloc_lock = 0;
  97                 if (phys_pager_alloc_lock_want)
  98                         wakeup(&phys_pager_alloc_lock);
  99         } else { ... }
 100 #endif
 101         object = vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(foff + size));
 102
 103         return (object);
 104 }
 105
 106 static void
 107 phys_pager_dealloc(vm_object_t object)
 108 {
 109         KKASSERT(object->handle == NULL);
 110 }
 111
 112 static int
 113 phys_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
 114 {
 115         vm_page_t m = *mpp;
 116
 117         crit_enter();
 118         if ((m->flags & PG_ZERO) == 0)
 119                 vm_page_zero_fill(m);
 120         vm_page_flag_set(m, PG_ZERO);
 121         /* Switch off pv_entries */
 122         vm_page_unmanage(m);
 123         m->valid = VM_PAGE_BITS_ALL;
 124         m->dirty = 0;
 125         crit_exit();
 126
 127         return (VM_PAGER_OK);
 128 }
 129
 130 static void
 131 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count,
 132                     boolean_t sync, int *rtvals)
 133 {
 134
 135         panic("phys_pager_putpage called");
 136 }
 137
 138 /*
 139  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 140  * everything in an entire 4MB window should be prefaulted at once.
 141  *
 142  * XXX 4MB (1024 slots per page table page) is convenient for x86,
 143  * but may not be for other arches.
 144  */
 145 #ifndef PHYSCLUSTER
 146 #define PHYSCLUSTER 1024
 147 #endif
 148
 149 static boolean_t
 150 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex)
 151 {
 152         return (TRUE);
 153 }
 154
 155 struct pagerops physpagerops = {
 156         phys_pager_init,
 157         phys_pager_alloc,
 158         phys_pager_dealloc,
 159         phys_pager_getpage,
 160         phys_pager_putpages,
 161         phys_pager_haspage,
 162         NULL
 163 };