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 vm_object_t
  45 phys_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t foff)
  46 {
  47         vm_object_t object;
  48
  49         /*
  50          * Offset should be page aligned.
  51          */
  52         if (foff & PAGE_MASK)
  53                 return (NULL);
  54
  55         size = round_page64(size);
  56
  57         KKASSERT(handle == NULL);
  58 #if 0
  59         if (handle != NULL) {
  60                 /*
  61                  * Lock to prevent object creation race condition.
  62                  */
  63                 while (phys_pager_alloc_lock) {
  64                         phys_pager_alloc_lock_want++;
  65                         tsleep(&phys_pager_alloc_lock, 0, "ppall", 0);
  66                         phys_pager_alloc_lock_want--;
  67                 }
  68                 phys_pager_alloc_lock = 1;
  69
  70                 /*
  71                  * Look up pager, creating as necessary.
  72                  */
  73                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
  74                 if (object == NULL) {
  75                         /*
  76                          * Allocate object and associate it with the pager.
  77                          */
  78                         object = vm_object_allocate(OBJT_PHYS,
  79                                 OFF_TO_IDX(foff + size));
  80                         object->handle = handle;
  81                         TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
  82                             pager_object_list);
  83                 } else {
  84                         /*
  85                          * Gain a reference to the object.
  86                          */
  87                         vm_object_reference(object);
  88                         if (OFF_TO_IDX(foff + size) > object->size)
  89                                 object->size = OFF_TO_IDX(foff + size);
  90                 }
  91                 phys_pager_alloc_lock = 0;
  92                 if (phys_pager_alloc_lock_want)
  93                         wakeup(&phys_pager_alloc_lock);
  94         } else { ... }
  95 #endif
  96         object = vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(foff + size));
  97
  98         return (object);
  99 }
 100
 101 static void
 102 phys_pager_dealloc(vm_object_t object)
 103 {
 104         KKASSERT(object->handle == NULL);
 105         KKASSERT(object->swblock_count == 0);
 106 }
 107
 108 static int
 109 phys_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
 110 {
 111         vm_page_t m = *mpp;
 112
 113         crit_enter();
 114         if ((m->flags & PG_ZERO) == 0)
 115                 vm_page_zero_fill(m);
 116         vm_page_flag_set(m, PG_ZERO);
 117         /* Switch off pv_entries */
 118         vm_page_unmanage(m);
 119         m->valid = VM_PAGE_BITS_ALL;
 120         m->dirty = 0;
 121         crit_exit();
 122
 123         return (VM_PAGER_OK);
 124 }
 125
 126 static void
 127 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count,
 128                     boolean_t sync, int *rtvals)
 129 {
 130
 131         panic("phys_pager_putpage called");
 132 }
 133
 134 /*
 135  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 136  * everything in an entire 4MB window should be prefaulted at once.
 137  *
 138  * XXX 4MB (1024 slots per page table page) is convenient for x86,
 139  * but may not be for other arches.
 140  */
 141 #ifndef PHYSCLUSTER
 142 #define PHYSCLUSTER 1024
 143 #endif
 144
 145 static boolean_t
 146 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex)
 147 {
 148         return (TRUE);
 149 }
 150
 151 struct pagerops physpagerops = {
 152         phys_pager_dealloc,
 153         phys_pager_getpage,
 154         phys_pager_putpages,
 155         phys_pager_haspage
 156 };