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 /*
  60  * MPSAFE
  61  */
  62 static vm_object_t
  63 phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
  64     vm_ooffset_t foff, struct ucred *cred)
  65 {
  66         vm_object_t object, object1;
  67         vm_pindex_t pindex;
  68
  69         /*
  70          * Offset should be page aligned.
  71          */
  72         if (foff & PAGE_MASK)
  73                 return (NULL);
  74
  75         pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
  76
  77         if (handle != NULL) {
  78                 mtx_lock(&phys_pager_mtx);
  79                 /*
  80                  * Look up pager, creating as necessary.
  81                  */
  82                 object1 = NULL;
  83                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
  84                 if (object == NULL) {
  85                         /*
  86                          * Allocate object and associate it with the pager.
  87                          */
  88                         mtx_unlock(&phys_pager_mtx);
  89                         object1 = vm_object_allocate(OBJT_PHYS, pindex);
  90                         mtx_lock(&phys_pager_mtx);
  91                         object = vm_pager_object_lookup(&phys_pager_object_list,
  92                             handle);
  93                         if (object != NULL) {
  94                                 /*
  95                                  * We raced with other thread while
  96                                  * allocating object.
  97                                  */
  98                                 if (pindex > object->size)
  99                                         object->size = pindex;
 100                         } else {
 101                                 object = object1;
 102                                 object1 = NULL;
 103                                 object->handle = handle;
 104                                 TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
 105                                     pager_object_list);
 106                         }
 107                 } else {
 108                         if (pindex > object->size)
 109                                 object->size = pindex;
 110                 }
 111                 mtx_unlock(&phys_pager_mtx);
 112                 vm_object_deallocate(object1);
 113         } else {
 114                 object = vm_object_allocate(OBJT_PHYS, pindex);
 115         }
 116
 117         return (object);
 118 }
 119
 120 /*
 121  * MPSAFE
 122  */
 123 static void
 124 phys_pager_dealloc(vm_object_t object)
 125 {
 126
 127         if (object->handle != NULL) {
 128                 VM_OBJECT_WUNLOCK(object);
 129                 mtx_lock(&phys_pager_mtx);
 130                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
 131                 mtx_unlock(&phys_pager_mtx);
 132                 VM_OBJECT_WLOCK(object);
 133         }
 134 }
 135
 136 /*
 137  * Fill as many pages as vm_fault has allocated for us.
 138  */
 139 static int
 140 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 141 {
 142         int i;
 143
 144         VM_OBJECT_ASSERT_WLOCKED(object);
 145         for (i = 0; i < count; i++) {
 146                 if (m[i]->valid == 0) {
 147                         if ((m[i]->flags & PG_ZERO) == 0)
 148                                 pmap_zero_page(m[i]);
 149                         m[i]->valid = VM_PAGE_BITS_ALL;
 150                 }
 151                 KASSERT(m[i]->valid == VM_PAGE_BITS_ALL,
 152                     ("phys_pager_getpages: partially valid page %p", m[i]));
 153                 KASSERT(m[i]->dirty == 0,
 154                     ("phys_pager_getpages: dirty page %p", m[i]));
 155                 /* The requested page must remain busy, the others not. */
 156                 if (i == reqpage) {
 157                         vm_page_lock(m[i]);
 158                         vm_page_flash(m[i]);
 159                         vm_page_unlock(m[i]);
 160                 } else
 161                         vm_page_xunbusy(m[i]);
 162         }
 163         return (VM_PAGER_OK);
 164 }
 165
 166 static void
 167 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
 168                     int *rtvals)
 169 {
 170
 171         panic("phys_pager_putpage called");
 172 }
 173
 174 /*
 175  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 176  * everything in an entire 4MB window should be prefaulted at once.
 177  *
 178  * XXX 4MB (1024 slots per page table page) is convenient for x86,
 179  * but may not be for other arches.
 180  */
 181 #ifndef PHYSCLUSTER
 182 #define PHYSCLUSTER 1024
 183 #endif
 184 static boolean_t
 185 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 186                    int *after)
 187 {
 188         vm_pindex_t base, end;
 189
 190         base = pindex & (~(PHYSCLUSTER - 1));
 191         end = base + (PHYSCLUSTER - 1);
 192         if (before != NULL)
 193                 *before = pindex - base;
 194         if (after != NULL)
 195                 *after = end - pindex;
 196         return (TRUE);
 197 }
 198
 199 struct pagerops physpagerops = {
 200         .pgo_init =     phys_pager_init,
 201         .pgo_alloc =    phys_pager_alloc,
 202         .pgo_dealloc =  phys_pager_dealloc,
 203         .pgo_getpages = phys_pager_getpages,
 204         .pgo_putpages = phys_pager_putpages,
 205         .pgo_haspage =  phys_pager_haspage,
 206 };