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  */
  27
  28 #include <sys/param.h>
  29 #include <sys/systm.h>
  30 #include <sys/linker_set.h>
  31 #include <sys/conf.h>
  32 #include <sys/mman.h>
  33 #include <sys/sysctl.h>
  34
  35 #include <vm/vm.h>
  36 #include <vm/vm_object.h>
  37 #include <vm/vm_page.h>
  38 #include <vm/vm_pager.h>
  39 #include <vm/vm_zone.h>
  40
  41 /* list of device pager objects */
  42 static struct pagerlst phys_pager_object_list;
  43
  44 static int phys_pager_alloc_lock, phys_pager_alloc_lock_want;
  45
  46 static void
  47 phys_pager_init(void)
  48 {
  49
  50         TAILQ_INIT(&phys_pager_object_list);
  51 }
  52
  53 static vm_object_t
  54 phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
  55                  vm_ooffset_t foff)
  56 {
  57         vm_object_t object;
  58
  59         /*
  60          * Offset should be page aligned.
  61          */
  62         if (foff & PAGE_MASK)
  63                 return (NULL);
  64
  65         size = round_page(size);
  66
  67         if (handle != NULL) {
  68                 /*
  69                  * Lock to prevent object creation race condition.
  70                  */
  71                 while (phys_pager_alloc_lock) {
  72                         phys_pager_alloc_lock_want++;
  73                         tsleep(&phys_pager_alloc_lock, PVM, "ppall", 0);
  74                         phys_pager_alloc_lock_want--;
  75                 }
  76                 phys_pager_alloc_lock = 1;
  77
  78                 /*
  79                  * Look up pager, creating as necessary.
  80                  */
  81                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
  82                 if (object == NULL) {
  83                         /*
  84                          * Allocate object and associate it with the pager.
  85                          */
  86                         object = vm_object_allocate(OBJT_PHYS,
  87                                 OFF_TO_IDX(foff + size));
  88                         object->handle = handle;
  89                         TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
  90                             pager_object_list);
  91                 } else {
  92                         /*
  93                          * Gain a reference to the object.
  94                          */
  95                         vm_object_reference(object);
  96                         if (OFF_TO_IDX(foff + size) > object->size)
  97                                 object->size = OFF_TO_IDX(foff + size);
  98                 }
  99                 phys_pager_alloc_lock = 0;
 100                 if (phys_pager_alloc_lock_want)
 101                         wakeup(&phys_pager_alloc_lock);
 102         } else {
 103                 object = vm_object_allocate(OBJT_PHYS,
 104                         OFF_TO_IDX(foff + size));
 105         }
 106
 107         return (object);
 108 }
 109
 110 static void
 111 phys_pager_dealloc(vm_object_t object)
 112 {
 113
 114         if (object->handle != NULL)
 115                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
 116 }
 117
 118 static int
 119 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 120 {
 121         int i, s;
 122
 123         s = splvm();
 124         /*
 125          * Fill as many pages as vm_fault has allocated for us.
 126          */
 127         for (i = 0; i < count; i++) {
 128                 if ((m[i]->flags & PG_ZERO) == 0)
 129                         vm_page_zero_fill(m[i]);
 130                 vm_page_flag_set(m[i], PG_ZERO);
 131                 /* Switch off pv_entries */
 132                 vm_page_unmanage(m[i]);
 133                 m[i]->valid = VM_PAGE_BITS_ALL;
 134                 m[i]->dirty = 0;
 135                 /* The requested page must remain busy, the others not. */
 136                 if (reqpage != i) {
 137                         vm_page_flag_clear(m[i], PG_BUSY);
 138                         m[i]->busy = 0;
 139                 }
 140         }
 141         splx(s);
 142
 143         return (VM_PAGER_OK);
 144 }
 145
 146 static void
 147 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
 148                     int *rtvals)
 149 {
 150
 151         panic("phys_pager_putpage called");
 152 }
 153
 154 /*
 155  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 156  * everything in an entire 4MB window should be prefaulted at once.
 157  *
 158  * XXX 4MB (1024 slots per page table page) is convenient for x86,
 159  * but may not be for other arches.
 160  */
 161 #ifndef PHYSCLUSTER
 162 #define PHYSCLUSTER 1024
 163 #endif
 164 static boolean_t
 165 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 166                    int *after)
 167 {
 168         vm_pindex_t base, end;
 169
 170         base = pindex & (~(PHYSCLUSTER - 1));
 171         end = base + (PHYSCLUSTER - 1);
 172         if (before != NULL)
 173                 *before = pindex - base;
 174         if (after != NULL)
 175                 *after = end - pindex;
 176         return (TRUE);
 177 }
 178
 179 struct pagerops physpagerops = {
 180         phys_pager_init,
 181         phys_pager_alloc,
 182         phys_pager_dealloc,
 183         phys_pager_getpages,
 184         phys_pager_putpages,
 185         phys_pager_haspage,
 186         NULL
 187 };