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_pageout.h>
  45 #include <vm/vm_pager.h>
  46
  47 /* list of phys pager objects */
  48 static struct pagerlst phys_pager_object_list;
  49 /* protect access to phys_pager_object_list */
  50 static struct mtx phys_pager_mtx;
  51
  52 static void
  53 phys_pager_init(void)
  54 {
  55
  56         TAILQ_INIT(&phys_pager_object_list);
  57         mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
  58 }
  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                                 vm_object_set_flag(object, OBJ_POPULATE);
 103                                 TAILQ_INSERT_TAIL(&phys_pager_object_list,
 104                                     object, 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                 vm_object_set_flag(object, OBJ_POPULATE);
 115         }
 116
 117         return (object);
 118 }
 119
 120 static void
 121 phys_pager_dealloc(vm_object_t object)
 122 {
 123
 124         if (object->handle != NULL) {
 125                 VM_OBJECT_WUNLOCK(object);
 126                 mtx_lock(&phys_pager_mtx);
 127                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
 128                 mtx_unlock(&phys_pager_mtx);
 129                 VM_OBJECT_WLOCK(object);
 130         }
 131         object->handle = NULL;
 132         object->type = OBJT_DEAD;
 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 *rbehind,
 140     int *rahead)
 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         }
 156         if (rbehind)
 157                 *rbehind = 0;
 158         if (rahead)
 159                 *rahead = 0;
 160         return (VM_PAGER_OK);
 161 }
 162
 163 /*
 164  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 165  * everything in an entire 4MB window should be prefaulted at once.
 166  *
 167  * 4MB (1024 slots per page table page) is convenient for x86,
 168  * but may not be for other arches.
 169  */
 170 #ifndef PHYSCLUSTER
 171 #define PHYSCLUSTER 1024
 172 #endif
 173 static int phys_pager_cluster = PHYSCLUSTER;
 174 SYSCTL_INT(_vm, OID_AUTO, phys_pager_cluster, CTLFLAG_RWTUN,
 175     &phys_pager_cluster, 0,
 176     "prefault window size for phys pager");
 177
 178 /*
 179  * Max hint to vm_page_alloc() about the further allocation needs
 180  * inside the phys_pager_populate() loop.  The number of bits used to
 181  * implement VM_ALLOC_COUNT() determines the hard limit on this value.
 182  * That limit is currently 65535.
 183  */
 184 #define PHYSALLOC       16
 185
 186 static int
 187 phys_pager_populate(vm_object_t object, vm_pindex_t pidx,
 188     int fault_type __unused, vm_prot_t max_prot __unused, vm_pindex_t *first,
 189     vm_pindex_t *last)
 190 {
 191         vm_page_t m;
 192         vm_pindex_t base, end, i;
 193         int ahead;
 194
 195         base = rounddown(pidx, phys_pager_cluster);
 196         end = base + phys_pager_cluster - 1;
 197         if (end >= object->size)
 198                 end = object->size - 1;
 199         if (*first > base)
 200                 base = *first;
 201         if (end > *last)
 202                 end = *last;
 203         *first = base;
 204         *last = end;
 205
 206         for (i = base; i <= end; i++) {
 207 retry:
 208                 m = vm_page_lookup(object, i);
 209                 if (m == NULL) {
 210                         ahead = MIN(end - i, PHYSALLOC);
 211                         m = vm_page_alloc(object, i, VM_ALLOC_NORMAL |
 212                             VM_ALLOC_ZERO | VM_ALLOC_WAITFAIL |
 213                             VM_ALLOC_COUNT(ahead));
 214                         if (m == NULL)
 215                                 goto retry;
 216                         if ((m->flags & PG_ZERO) == 0)
 217                                 pmap_zero_page(m);
 218                         m->valid = VM_PAGE_BITS_ALL;
 219                 } else if (vm_page_xbusied(m)) {
 220                         vm_page_lock(m);
 221                         VM_OBJECT_WUNLOCK(object);
 222                         vm_page_busy_sleep(m, "physb", true);
 223                         VM_OBJECT_WLOCK(object);
 224                         goto retry;
 225                 } else {
 226                         vm_page_xbusy(m);
 227                         if (m->valid != VM_PAGE_BITS_ALL)
 228                                 vm_page_zero_invalid(m, TRUE);
 229                 }
 230
 231                 KASSERT(m->valid == VM_PAGE_BITS_ALL,
 232                     ("phys_pager_populate: partially valid page %p", m));
 233                 KASSERT(m->dirty == 0,
 234                     ("phys_pager_populate: dirty page %p", m));
 235         }
 236         return (VM_PAGER_OK);
 237 }
 238
 239 static void
 240 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
 241     int *rtvals)
 242 {
 243
 244         panic("phys_pager_putpage called");
 245 }
 246
 247 static boolean_t
 248 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 249     int *after)
 250 {
 251         vm_pindex_t base, end;
 252
 253         base = rounddown(pindex, phys_pager_cluster);
 254         end = base + phys_pager_cluster - 1;
 255         if (before != NULL)
 256                 *before = pindex - base;
 257         if (after != NULL)
 258                 *after = end - pindex;
 259         return (TRUE);
 260 }
 261
 262 struct pagerops physpagerops = {
 263         .pgo_init =     phys_pager_init,
 264         .pgo_alloc =    phys_pager_alloc,
 265         .pgo_dealloc =  phys_pager_dealloc,
 266         .pgo_getpages = phys_pager_getpages,
 267         .pgo_putpages = phys_pager_putpages,
 268         .pgo_haspage =  phys_pager_haspage,
 269         .pgo_populate = phys_pager_populate,
 270 };