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 1.4 2004/10/12 19:29:34 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, vm_ooffset_t size, vm_prot_t prot,
  58                  vm_ooffset_t foff)
  59 {
  60         vm_object_t object;
  61
  62         /*
  63          * Offset should be page aligned.
  64          */
  65         if (foff & PAGE_MASK)
  66                 return (NULL);
  67
  68         size = round_page(size);
  69
  70         if (handle != NULL) {
  71                 /*
  72                  * Lock to prevent object creation race condition.
  73                  */
  74                 while (phys_pager_alloc_lock) {
  75                         phys_pager_alloc_lock_want++;
  76                         tsleep(&phys_pager_alloc_lock, 0, "ppall", 0);
  77                         phys_pager_alloc_lock_want--;
  78                 }
  79                 phys_pager_alloc_lock = 1;
  80
  81                 /*
  82                  * Look up pager, creating as necessary.
  83                  */
  84                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
  85                 if (object == NULL) {
  86                         /*
  87                          * Allocate object and associate it with the pager.
  88                          */
  89                         object = vm_object_allocate(OBJT_PHYS,
  90                                 OFF_TO_IDX(foff + size));
  91                         object->handle = handle;
  92                         TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
  93                             pager_object_list);
  94                 } else {
  95                         /*
  96                          * Gain a reference to the object.
  97                          */
  98                         vm_object_reference(object);
  99                         if (OFF_TO_IDX(foff + size) > object->size)
 100                                 object->size = OFF_TO_IDX(foff + size);
 101                 }
 102                 phys_pager_alloc_lock = 0;
 103                 if (phys_pager_alloc_lock_want)
 104                         wakeup(&phys_pager_alloc_lock);
 105         } else {
 106                 object = vm_object_allocate(OBJT_PHYS,
 107                         OFF_TO_IDX(foff + size));
 108         }
 109
 110         return (object);
 111 }
 112
 113 static void
 114 phys_pager_dealloc(vm_object_t object)
 115 {
 116
 117         if (object->handle != NULL)
 118                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
 119 }
 120
 121 static int
 122 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 123 {
 124         int i;
 125
 126         crit_enter();
 127         /*
 128          * Fill as many pages as vm_fault has allocated for us.
 129          */
 130         for (i = 0; i < count; i++) {
 131                 if ((m[i]->flags & PG_ZERO) == 0)
 132                         vm_page_zero_fill(m[i]);
 133                 vm_page_flag_set(m[i], PG_ZERO);
 134                 /* Switch off pv_entries */
 135                 vm_page_unmanage(m[i]);
 136                 m[i]->valid = VM_PAGE_BITS_ALL;
 137                 m[i]->dirty = 0;
 138                 /* The requested page must remain busy, the others not. */
 139                 if (reqpage != i) {
 140                         vm_page_flag_clear(m[i], PG_BUSY);
 141                         m[i]->busy = 0;
 142                 }
 143         }
 144         crit_exit();
 145
 146         return (VM_PAGER_OK);
 147 }
 148
 149 static void
 150 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
 151                     int *rtvals)
 152 {
 153
 154         panic("phys_pager_putpage called");
 155 }
 156
 157 /*
 158  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 159  * everything in an entire 4MB window should be prefaulted at once.
 160  *
 161  * XXX 4MB (1024 slots per page table page) is convenient for x86,
 162  * but may not be for other arches.
 163  */
 164 #ifndef PHYSCLUSTER
 165 #define PHYSCLUSTER 1024
 166 #endif
 167 static boolean_t
 168 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 169                    int *after)
 170 {
 171         vm_pindex_t base, end;
 172
 173         base = pindex & (~(PHYSCLUSTER - 1));
 174         end = base + (PHYSCLUSTER - 1);
 175         if (before != NULL)
 176                 *before = pindex - base;
 177         if (after != NULL)
 178                 *after = end - pindex;
 179         return (TRUE);
 180 }
 181
 182 struct pagerops physpagerops = {
 183         phys_pager_init,
 184         phys_pager_alloc,
 185         phys_pager_dealloc,
 186         phys_pager_getpages,
 187         phys_pager_putpages,
 188         phys_pager_haspage,
 189         NULL
 190 };