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/sysctl.h>
  38
  39 #include <vm/vm.h>
  40 #include <vm/vm_object.h>
  41 #include <vm/vm_page.h>
  42 #include <vm/vm_pager.h>
  43
  44 /* list of phys pager objects */
  45 static struct pagerlst phys_pager_object_list;
  46 /* protect access to phys_pager_object_list */
  47 static struct mtx phys_pager_mtx;
  48
  49 static void
  50 phys_pager_init(void)
  51 {
  52
  53         TAILQ_INIT(&phys_pager_object_list);
  54         mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
  55 }
  56
  57 /*
  58  * MPSAFE
  59  */
  60 static vm_object_t
  61 phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
  62     vm_ooffset_t foff, struct ucred *cred)
  63 {
  64         vm_object_t object, object1;
  65         vm_pindex_t pindex;
  66
  67         /*
  68          * Offset should be page aligned.
  69          */
  70         if (foff & PAGE_MASK)
  71                 return (NULL);
  72
  73         pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
  74
  75         if (handle != NULL) {
  76                 mtx_lock(&phys_pager_mtx);
  77                 /*
  78                  * Look up pager, creating as necessary.
  79                  */
  80                 object1 = NULL;
  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                         mtx_unlock(&phys_pager_mtx);
  87                         object1 = vm_object_allocate(OBJT_PHYS, pindex);
  88                         mtx_lock(&phys_pager_mtx);
  89                         object = vm_pager_object_lookup(&phys_pager_object_list,
  90                             handle);
  91                         if (object != NULL) {
  92                                 /*
  93                                  * We raced with other thread while
  94                                  * allocating object.
  95                                  */
  96                                 if (pindex > object->size)
  97                                         object->size = pindex;
  98                         } else {
  99                                 object = object1;
 100                                 object1 = NULL;
 101                                 object->handle = handle;
 102                                 TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
 103                                     pager_object_list);
 104                         }
 105                 } else {
 106                         if (pindex > object->size)
 107                                 object->size = pindex;
 108                 }
 109                 mtx_unlock(&phys_pager_mtx);
 110                 vm_object_deallocate(object1);
 111         } else {
 112                 object = vm_object_allocate(OBJT_PHYS, pindex);
 113         }
 114
 115         return (object);
 116 }
 117
 118 /*
 119  * MPSAFE
 120  */
 121 static void
 122 phys_pager_dealloc(vm_object_t object)
 123 {
 124
 125         if (object->handle != NULL) {
 126                 VM_OBJECT_UNLOCK(object);
 127                 mtx_lock(&phys_pager_mtx);
 128                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
 129                 mtx_unlock(&phys_pager_mtx);
 130                 VM_OBJECT_LOCK(object);
 131         }
 132 }
 133
 134 /*
 135  * Fill as many pages as vm_fault has allocated for us.
 136  */
 137 static int
 138 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 139 {
 140         int i;
 141
 142         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
 143         for (i = 0; i < count; i++) {
 144                 if (m[i]->valid == 0) {
 145                         if ((m[i]->flags & PG_ZERO) == 0)
 146                                 pmap_zero_page(m[i]);
 147                         m[i]->valid = VM_PAGE_BITS_ALL;
 148                 }
 149                 KASSERT(m[i]->valid == VM_PAGE_BITS_ALL,
 150                     ("phys_pager_getpages: partially valid page %p", m[i]));
 151                 KASSERT(m[i]->dirty == 0,
 152                     ("phys_pager_getpages: dirty page %p", m[i]));
 153                 /* The requested page must remain busy, the others not. */
 154                 if (i == reqpage)
 155                         vm_page_flash(m[i]);
 156                 else
 157                         vm_page_wakeup(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 };