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
  26 #include <sys/cdefs.h>
  27 __FBSDID("$FreeBSD$");
  28
  29 #include <sys/param.h>
  30 #include <sys/systm.h>
  31 #include <sys/conf.h>
  32 #include <sys/kernel.h>
  33 #include <sys/lock.h>
  34 #include <sys/proc.h>
  35 #include <sys/mutex.h>
  36 #include <sys/mman.h>
  37 #include <sys/rwlock.h>
  38 #include <sys/sysctl.h>
  39
  40 #include <vm/vm.h>
  41 #include <vm/vm_param.h>
  42 #include <vm/vm_object.h>
  43 #include <vm/vm_page.h>
  44 #include <vm/vm_pager.h>
  45
  46 /* list of phys pager objects */
  47 static struct pagerlst phys_pager_object_list;
  48 /* protect access to phys_pager_object_list */
  49 static struct mtx phys_pager_mtx;
  50
  51 static void
  52 phys_pager_init(void)
  53 {
  54
  55         TAILQ_INIT(&phys_pager_object_list);
  56         mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
  57 }
  58
  59 static vm_object_t
  60 phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
  61     vm_ooffset_t foff, struct ucred *cred)
  62 {
  63         vm_object_t object, object1;
  64         vm_pindex_t pindex;
  65
  66         /*
  67          * Offset should be page aligned.
  68          */
  69         if (foff & PAGE_MASK)
  70                 return (NULL);
  71
  72         pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
  73
  74         if (handle != NULL) {
  75                 mtx_lock(&phys_pager_mtx);
  76                 /*
  77                  * Look up pager, creating as necessary.
  78                  */
  79                 object1 = NULL;
  80                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
  81                 if (object == NULL) {
  82                         /*
  83                          * Allocate object and associate it with the pager.
  84                          */
  85                         mtx_unlock(&phys_pager_mtx);
  86                         object1 = vm_object_allocate(OBJT_PHYS, pindex);
  87                         mtx_lock(&phys_pager_mtx);
  88                         object = vm_pager_object_lookup(&phys_pager_object_list,
  89                             handle);
  90                         if (object != NULL) {
  91                                 /*
  92                                  * We raced with other thread while
  93                                  * allocating object.
  94                                  */
  95                                 if (pindex > object->size)
  96                                         object->size = pindex;
  97                         } else {
  98                                 object = object1;
  99                                 object1 = NULL;
 100                                 object->handle = handle;
 101                                 TAILQ_INSERT_TAIL(&phys_pager_object_list,
 102                                     object, pager_object_list);
 103                         }
 104                 } else {
 105                         if (pindex > object->size)
 106                                 object->size = pindex;
 107                 }
 108                 mtx_unlock(&phys_pager_mtx);
 109                 vm_object_deallocate(object1);
 110         } else {
 111                 object = vm_object_allocate(OBJT_PHYS, pindex);
 112         }
 113
 114         return (object);
 115 }
 116
 117 static void
 118 phys_pager_dealloc(vm_object_t object)
 119 {
 120
 121         if (object->handle != NULL) {
 122                 VM_OBJECT_WUNLOCK(object);
 123                 mtx_lock(&phys_pager_mtx);
 124                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
 125                 mtx_unlock(&phys_pager_mtx);
 126                 VM_OBJECT_WLOCK(object);
 127         }
 128         object->handle = NULL;
 129         object->type = OBJT_DEAD;
 130 }
 131
 132 /*
 133  * Fill as many pages as vm_fault has allocated for us.
 134  */
 135 static int
 136 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 137 {
 138         int i;
 139
 140         VM_OBJECT_ASSERT_WLOCKED(object);
 141         for (i = 0; i < count; i++) {
 142                 if (m[i]->valid == 0) {
 143                         if ((m[i]->flags & PG_ZERO) == 0)
 144                                 pmap_zero_page(m[i]);
 145                         m[i]->valid = VM_PAGE_BITS_ALL;
 146                 }
 147                 KASSERT(m[i]->valid == VM_PAGE_BITS_ALL,
 148                     ("phys_pager_getpages: partially valid page %p", m[i]));
 149                 KASSERT(m[i]->dirty == 0,
 150                     ("phys_pager_getpages: dirty page %p", m[i]));
 151                 /* The requested page must remain busy, the others not. */
 152                 if (i == reqpage) {
 153                         vm_page_lock(m[i]);
 154                         vm_page_flash(m[i]);
 155                         vm_page_unlock(m[i]);
 156                 } else
 157                         vm_page_xunbusy(m[i]);
 158         }
 159         return (VM_PAGER_OK);
 160 }
 161
 162 static void
 163 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
 164     int *rtvals)
 165 {
 166
 167         panic("phys_pager_putpage called");
 168 }
 169
 170 /*
 171  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 172  * everything in an entire 4MB window should be prefaulted at once.
 173  *
 174  * XXX 4MB (1024 slots per page table page) is convenient for x86,
 175  * but may not be for other arches.
 176  */
 177 #ifndef PHYSCLUSTER
 178 #define PHYSCLUSTER 1024
 179 #endif
 180 static boolean_t
 181 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 182     int *after)
 183 {
 184         vm_pindex_t base, end;
 185
 186         base = pindex & (~(PHYSCLUSTER - 1));
 187         end = base + (PHYSCLUSTER - 1);
 188         if (before != NULL)
 189                 *before = pindex - base;
 190         if (after != NULL)
 191                 *after = end - pindex;
 192         return (TRUE);
 193 }
 194
 195 struct pagerops physpagerops = {
 196         .pgo_init =     phys_pager_init,
 197         .pgo_alloc =    phys_pager_alloc,
 198         .pgo_dealloc =  phys_pager_dealloc,
 199         .pgo_getpages = phys_pager_getpages,
 200         .pgo_putpages = phys_pager_putpages,
 201         .pgo_haspage =  phys_pager_haspage,
 202 };