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/linker_set.h>
  32 #include <sys/conf.h>
  33 #include <sys/kernel.h>
  34 #include <sys/lock.h>
  35 #include <sys/proc.h>
  36 #include <sys/mutex.h>
  37 #include <sys/mman.h>
  38 #include <sys/sysctl.h>
  39
  40 #include <vm/vm.h>
  41 #include <vm/vm_object.h>
  42 #include <vm/vm_page.h>
  43 #include <vm/vm_pager.h>
  44
  45 /* list of phys pager objects */
  46 static struct pagerlst phys_pager_object_list;
  47 /* protect access to phys_pager_object_list */
  48 static struct mtx phys_pager_mtx;
  49
  50 static void
  51 phys_pager_init(void)
  52 {
  53
  54         TAILQ_INIT(&phys_pager_object_list);
  55         mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
  56 }
  57
  58 /*
  59  * MPSAFE
  60  */
  61 static vm_object_t
  62 phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
  63     vm_ooffset_t foff, struct ucred *cred)
  64 {
  65         vm_object_t object, object1;
  66         vm_pindex_t pindex;
  67
  68         /*
  69          * Offset should be page aligned.
  70          */
  71         if (foff & PAGE_MASK)
  72                 return (NULL);
  73
  74         pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
  75
  76         if (handle != NULL) {
  77                 mtx_lock(&phys_pager_mtx);
  78                 /*
  79                  * Look up pager, creating as necessary.
  80                  */
  81                 object1 = NULL;
  82                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
  83                 if (object == NULL) {
  84                         /*
  85                          * Allocate object and associate it with the pager.
  86                          */
  87                         mtx_unlock(&phys_pager_mtx);
  88                         object1 = vm_object_allocate(OBJT_PHYS, pindex);
  89                         mtx_lock(&phys_pager_mtx);
  90                         object = vm_pager_object_lookup(&phys_pager_object_list,
  91                             handle);
  92                         if (object != NULL) {
  93                                 /*
  94                                  * We raced with other thread while
  95                                  * allocating object.
  96                                  */
  97                                 if (pindex > object->size)
  98                                         object->size = pindex;
  99                         } else {
 100                                 object = object1;
 101                                 object1 = NULL;
 102                                 object->handle = handle;
 103                                 TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
 104                                     pager_object_list);
 105                         }
 106                 } else {
 107                         if (pindex > object->size)
 108                                 object->size = pindex;
 109                 }
 110                 mtx_unlock(&phys_pager_mtx);
 111                 vm_object_deallocate(object1);
 112         } else {
 113                 object = vm_object_allocate(OBJT_PHYS, pindex);
 114         }
 115
 116         return (object);
 117 }
 118
 119 /*
 120  * MPSAFE
 121  */
 122 static void
 123 phys_pager_dealloc(vm_object_t object)
 124 {
 125
 126         if (object->handle != NULL) {
 127                 VM_OBJECT_UNLOCK(object);
 128                 mtx_lock(&phys_pager_mtx);
 129                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
 130                 mtx_unlock(&phys_pager_mtx);
 131                 VM_OBJECT_LOCK(object);
 132         }
 133 }
 134
 135 /*
 136  * Fill as many pages as vm_fault has allocated for us.
 137  */
 138 static int
 139 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 140 {
 141         int i;
 142
 143         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
 144         for (i = 0; i < count; i++) {
 145                 if (m[i]->valid == 0) {
 146                         if ((m[i]->flags & PG_ZERO) == 0)
 147                                 pmap_zero_page(m[i]);
 148                         m[i]->valid = VM_PAGE_BITS_ALL;
 149                 }
 150                 KASSERT(m[i]->valid == VM_PAGE_BITS_ALL,
 151                     ("phys_pager_getpages: partially valid page %p", m[i]));
 152                 KASSERT(m[i]->dirty == 0,
 153                     ("phys_pager_getpages: dirty page %p", m[i]));
 154                 /* The requested page must remain busy, the others not. */
 155                 if (i == reqpage)
 156                         vm_page_flash(m[i]);
 157                 else
 158                         vm_page_wakeup(m[i]);
 159         }
 160         return (VM_PAGER_OK);
 161 }
 162
 163 static void
 164 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
 165                     int *rtvals)
 166 {
 167
 168         panic("phys_pager_putpage called");
 169 }
 170
 171 /*
 172  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 173  * everything in an entire 4MB window should be prefaulted at once.
 174  *
 175  * XXX 4MB (1024 slots per page table page) is convenient for x86,
 176  * but may not be for other arches.
 177  */
 178 #ifndef PHYSCLUSTER
 179 #define PHYSCLUSTER 1024
 180 #endif
 181 static boolean_t
 182 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 183                    int *after)
 184 {
 185         vm_pindex_t base, end;
 186
 187         base = pindex & (~(PHYSCLUSTER - 1));
 188         end = base + (PHYSCLUSTER - 1);
 189         if (before != NULL)
 190                 *before = pindex - base;
 191         if (after != NULL)
 192                 *after = end - pindex;
 193         return (TRUE);
 194 }
 195
 196 struct pagerops physpagerops = {
 197         .pgo_init =     phys_pager_init,
 198         .pgo_alloc =    phys_pager_alloc,
 199         .pgo_dealloc =  phys_pager_dealloc,
 200         .pgo_getpages = phys_pager_getpages,
 201         .pgo_putpages = phys_pager_putpages,
 202         .pgo_haspage =  phys_pager_haspage,
 203 };