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         object->handle = NULL;
 133         object->type = OBJT_DEAD;
 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_LOCK_ASSERT(object, MA_OWNED);
 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_flash(m[i]);
 158                 else
 159                         vm_page_wakeup(m[i]);
 160         }
 161         return (VM_PAGER_OK);
 162 }
 163
 164 static void
 165 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
 166                     int *rtvals)
 167 {
 168
 169         panic("phys_pager_putpage called");
 170 }
 171
 172 /*
 173  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 174  * everything in an entire 4MB window should be prefaulted at once.
 175  *
 176  * XXX 4MB (1024 slots per page table page) is convenient for x86,
 177  * but may not be for other arches.
 178  */
 179 #ifndef PHYSCLUSTER
 180 #define PHYSCLUSTER 1024
 181 #endif
 182 static boolean_t
 183 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 184                    int *after)
 185 {
 186         vm_pindex_t base, end;
 187
 188         base = pindex & (~(PHYSCLUSTER - 1));
 189         end = base + (PHYSCLUSTER - 1);
 190         if (before != NULL)
 191                 *before = pindex - base;
 192         if (after != NULL)
 193                 *after = end - pindex;
 194         return (TRUE);
 195 }
 196
 197 struct pagerops physpagerops = {
 198         .pgo_init =     phys_pager_init,
 199         .pgo_alloc =    phys_pager_alloc,
 200         .pgo_dealloc =  phys_pager_dealloc,
 201         .pgo_getpages = phys_pager_getpages,
 202         .pgo_putpages = phys_pager_putpages,
 203         .pgo_haspage =  phys_pager_haspage,
 204 };