sys/vm/phys_pager.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2000 Peter Wemm
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  */
  27
  28 #include <sys/cdefs.h>
  29 __FBSDID("$FreeBSD$");
  30
  31 #include <sys/param.h>
  32 #include <sys/systm.h>
  33 #include <sys/conf.h>
  34 #include <sys/kernel.h>
  35 #include <sys/lock.h>
  36 #include <sys/proc.h>
  37 #include <sys/mutex.h>
  38 #include <sys/mman.h>
  39 #include <sys/rwlock.h>
  40 #include <sys/sysctl.h>
  41
  42 #include <vm/vm.h>
  43 #include <vm/vm_param.h>
  44 #include <vm/vm_object.h>
  45 #include <vm/vm_page.h>
  46 #include <vm/vm_pageout.h>
  47 #include <vm/vm_pager.h>
  48
  49 /* list of phys pager objects */
  50 static struct pagerlst phys_pager_object_list;
  51 /* protect access to phys_pager_object_list */
  52 static struct mtx phys_pager_mtx;
  53
  54 static void
  55 phys_pager_init(void)
  56 {
  57
  58         TAILQ_INIT(&phys_pager_object_list);
  59         mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
  60 }
  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                                 vm_object_set_flag(object, OBJ_POPULATE);
 105                                 TAILQ_INSERT_TAIL(&phys_pager_object_list,
 106                                     object, pager_object_list);
 107                         }
 108                 } else {
 109                         if (pindex > object->size)
 110                                 object->size = pindex;
 111                 }
 112                 mtx_unlock(&phys_pager_mtx);
 113                 vm_object_deallocate(object1);
 114         } else {
 115                 object = vm_object_allocate(OBJT_PHYS, pindex);
 116                 vm_object_set_flag(object, OBJ_POPULATE);
 117         }
 118
 119         return (object);
 120 }
 121
 122 static void
 123 phys_pager_dealloc(vm_object_t object)
 124 {
 125
 126         if (object->handle != NULL) {
 127                 VM_OBJECT_WUNLOCK(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_WLOCK(object);
 132         }
 133         object->handle = NULL;
 134         object->type = OBJT_DEAD;
 135 }
 136
 137 /*
 138  * Fill as many pages as vm_fault has allocated for us.
 139  */
 140 static int
 141 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
 142     int *rahead)
 143 {
 144         int i;
 145
 146         for (i = 0; i < count; i++) {
 147                 if (vm_page_none_valid(m[i])) {
 148                         if ((m[i]->flags & PG_ZERO) == 0)
 149                                 pmap_zero_page(m[i]);
 150                         vm_page_valid(m[i]);
 151                 }
 152                 KASSERT(vm_page_all_valid(m[i]),
 153                     ("phys_pager_getpages: partially valid page %p", m[i]));
 154                 KASSERT(m[i]->dirty == 0,
 155                     ("phys_pager_getpages: dirty page %p", m[i]));
 156         }
 157         if (rbehind)
 158                 *rbehind = 0;
 159         if (rahead)
 160                 *rahead = 0;
 161         return (VM_PAGER_OK);
 162 }
 163
 164 /*
 165  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 166  * everything in an entire 4MB window should be prefaulted at once.
 167  *
 168  * 4MB (1024 slots per page table page) is convenient for x86,
 169  * but may not be for other arches.
 170  */
 171 #ifndef PHYSCLUSTER
 172 #define PHYSCLUSTER 1024
 173 #endif
 174 static int phys_pager_cluster = PHYSCLUSTER;
 175 SYSCTL_INT(_vm, OID_AUTO, phys_pager_cluster, CTLFLAG_RWTUN,
 176     &phys_pager_cluster, 0,
 177     "prefault window size for phys pager");
 178
 179 /*
 180  * Max hint to vm_page_alloc() about the further allocation needs
 181  * inside the phys_pager_populate() loop.  The number of bits used to
 182  * implement VM_ALLOC_COUNT() determines the hard limit on this value.
 183  * That limit is currently 65535.
 184  */
 185 #define PHYSALLOC       16
 186
 187 static int
 188 phys_pager_populate(vm_object_t object, vm_pindex_t pidx,
 189     int fault_type __unused, vm_prot_t max_prot __unused, vm_pindex_t *first,
 190     vm_pindex_t *last)
 191 {
 192         vm_page_t m;
 193         vm_pindex_t base, end, i;
 194         int ahead;
 195
 196         base = rounddown(pidx, phys_pager_cluster);
 197         end = base + phys_pager_cluster - 1;
 198         if (end >= object->size)
 199                 end = object->size - 1;
 200         if (*first > base)
 201                 base = *first;
 202         if (end > *last)
 203                 end = *last;
 204         *first = base;
 205         *last = end;
 206
 207         for (i = base; i <= end; i++) {
 208                 ahead = MIN(end - i, PHYSALLOC);
 209                 m = vm_page_grab(object, i,
 210                     VM_ALLOC_NORMAL | VM_ALLOC_COUNT(ahead));
 211                 if (!vm_page_all_valid(m))
 212                         vm_page_zero_invalid(m, TRUE);
 213                 KASSERT(m->dirty == 0,
 214                     ("phys_pager_populate: dirty page %p", m));
 215         }
 216         return (VM_PAGER_OK);
 217 }
 218
 219 static void
 220 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
 221     int *rtvals)
 222 {
 223
 224         panic("phys_pager_putpage called");
 225 }
 226
 227 static boolean_t
 228 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 229     int *after)
 230 {
 231         vm_pindex_t base, end;
 232
 233         base = rounddown(pindex, phys_pager_cluster);
 234         end = base + phys_pager_cluster - 1;
 235         if (before != NULL)
 236                 *before = pindex - base;
 237         if (after != NULL)
 238                 *after = end - pindex;
 239         return (TRUE);
 240 }
 241
 242 struct pagerops physpagerops = {
 243         .pgo_init =     phys_pager_init,
 244         .pgo_alloc =    phys_pager_alloc,
 245         .pgo_dealloc =  phys_pager_dealloc,
 246         .pgo_getpages = phys_pager_getpages,
 247         .pgo_putpages = phys_pager_putpages,
 248         .pgo_haspage =  phys_pager_haspage,
 249         .pgo_populate = phys_pager_populate,
 250 };