sys/vm/phys_pager.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause
   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 #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 #include <sys/user.h>
  40
  41 #include <vm/vm.h>
  42 #include <vm/vm_param.h>
  43 #include <vm/vm_object.h>
  44 #include <vm/vm_page.h>
  45 #include <vm/vm_pageout.h>
  46 #include <vm/vm_pager.h>
  47
  48 /* list of phys pager objects */
  49 static struct pagerlst phys_pager_object_list;
  50 /* protect access to phys_pager_object_list */
  51 static struct mtx phys_pager_mtx;
  52
  53 static int default_phys_pager_getpages(vm_object_t object, vm_page_t *m,
  54     int count, int *rbehind, int *rahead);
  55 static int default_phys_pager_populate(vm_object_t object, vm_pindex_t pidx,
  56     int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last);
  57 static boolean_t default_phys_pager_haspage(vm_object_t object,
  58     vm_pindex_t pindex, int *before, int *after);
  59 const struct phys_pager_ops default_phys_pg_ops = {
  60         .phys_pg_getpages = default_phys_pager_getpages,
  61         .phys_pg_populate = default_phys_pager_populate,
  62         .phys_pg_haspage = default_phys_pager_haspage,
  63         .phys_pg_ctor = NULL,
  64         .phys_pg_dtor = NULL,
  65 };
  66
  67 static void
  68 phys_pager_init(void)
  69 {
  70
  71         TAILQ_INIT(&phys_pager_object_list);
  72         mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
  73 }
  74
  75 vm_object_t
  76 phys_pager_allocate(void *handle, const struct phys_pager_ops *ops, void *data,
  77     vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff, struct ucred *cred)
  78 {
  79         vm_object_t object, object1;
  80         vm_pindex_t pindex;
  81         bool init;
  82
  83         /*
  84          * Offset should be page aligned.
  85          */
  86         if (foff & PAGE_MASK)
  87                 return (NULL);
  88
  89         pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
  90         init = true;
  91
  92         if (handle != NULL) {
  93                 mtx_lock(&phys_pager_mtx);
  94                 /*
  95                  * Look up pager, creating as necessary.
  96                  */
  97                 object1 = NULL;
  98                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
  99                 if (object == NULL) {
 100                         /*
 101                          * Allocate object and associate it with the pager.
 102                          */
 103                         mtx_unlock(&phys_pager_mtx);
 104                         object1 = vm_object_allocate(OBJT_PHYS, pindex);
 105                         mtx_lock(&phys_pager_mtx);
 106                         object = vm_pager_object_lookup(&phys_pager_object_list,
 107                             handle);
 108                         if (object != NULL) {
 109                                 /*
 110                                  * We raced with other thread while
 111                                  * allocating object.
 112                                  */
 113                                 if (pindex > object->size)
 114                                         object->size = pindex;
 115                                 init = false;
 116                         } else {
 117                                 object = object1;
 118                                 object1 = NULL;
 119                                 object->handle = handle;
 120                                 object->un_pager.phys.ops = ops;
 121                                 object->un_pager.phys.data_ptr = data;
 122                                 if (ops->phys_pg_populate != NULL)
 123                                         vm_object_set_flag(object, OBJ_POPULATE);
 124                                 TAILQ_INSERT_TAIL(&phys_pager_object_list,
 125                                     object, pager_object_list);
 126                         }
 127                 } else {
 128                         if (pindex > object->size)
 129                                 object->size = pindex;
 130                 }
 131                 mtx_unlock(&phys_pager_mtx);
 132                 vm_object_deallocate(object1);
 133         } else {
 134                 object = vm_object_allocate(OBJT_PHYS, pindex);
 135                 object->un_pager.phys.ops = ops;
 136                 object->un_pager.phys.data_ptr = data;
 137                 if (ops->phys_pg_populate != NULL)
 138                         vm_object_set_flag(object, OBJ_POPULATE);
 139         }
 140         if (init && ops->phys_pg_ctor != NULL)
 141                 ops->phys_pg_ctor(object, prot, foff, cred);
 142
 143         return (object);
 144 }
 145
 146 static vm_object_t
 147 phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
 148     vm_ooffset_t foff, struct ucred *ucred)
 149 {
 150         return (phys_pager_allocate(handle, &default_phys_pg_ops, NULL,
 151             size, prot, foff, ucred));
 152 }
 153
 154 static void
 155 phys_pager_dealloc(vm_object_t object)
 156 {
 157
 158         if (object->handle != NULL) {
 159                 VM_OBJECT_WUNLOCK(object);
 160                 mtx_lock(&phys_pager_mtx);
 161                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
 162                 mtx_unlock(&phys_pager_mtx);
 163                 VM_OBJECT_WLOCK(object);
 164         }
 165         object->type = OBJT_DEAD;
 166         if (object->un_pager.phys.ops->phys_pg_dtor != NULL)
 167                 object->un_pager.phys.ops->phys_pg_dtor(object);
 168         object->handle = NULL;
 169 }
 170
 171 /*
 172  * Fill as many pages as vm_fault has allocated for us.
 173  */
 174 static int
 175 default_phys_pager_getpages(vm_object_t object, vm_page_t *m, int count,
 176     int *rbehind, int *rahead)
 177 {
 178         int i;
 179
 180         for (i = 0; i < count; i++) {
 181                 if (vm_page_none_valid(m[i])) {
 182                         if ((m[i]->flags & PG_ZERO) == 0)
 183                                 pmap_zero_page(m[i]);
 184                         vm_page_valid(m[i]);
 185                 }
 186                 KASSERT(vm_page_all_valid(m[i]),
 187                     ("phys_pager_getpages: partially valid page %p", m[i]));
 188                 KASSERT(m[i]->dirty == 0,
 189                     ("phys_pager_getpages: dirty page %p", m[i]));
 190         }
 191         if (rbehind)
 192                 *rbehind = 0;
 193         if (rahead)
 194                 *rahead = 0;
 195         return (VM_PAGER_OK);
 196 }
 197
 198 static int
 199 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
 200     int *rahead)
 201 {
 202         return (object->un_pager.phys.ops->phys_pg_getpages(object, m,
 203             count, rbehind, rahead));
 204 }
 205
 206 /*
 207  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 208  * everything in an entire 4MB window should be prefaulted at once.
 209  *
 210  * 4MB (1024 slots per page table page) is convenient for x86,
 211  * but may not be for other arches.
 212  */
 213 #ifndef PHYSCLUSTER
 214 #define PHYSCLUSTER 1024
 215 #endif
 216 static int phys_pager_cluster = PHYSCLUSTER;
 217 SYSCTL_INT(_vm, OID_AUTO, phys_pager_cluster, CTLFLAG_RWTUN,
 218     &phys_pager_cluster, 0,
 219     "prefault window size for phys pager");
 220
 221 /*
 222  * Max hint to vm_page_alloc() about the further allocation needs
 223  * inside the phys_pager_populate() loop.  The number of bits used to
 224  * implement VM_ALLOC_COUNT() determines the hard limit on this value.
 225  * That limit is currently 65535.
 226  */
 227 #define PHYSALLOC       16
 228
 229 static int
 230 default_phys_pager_populate(vm_object_t object, vm_pindex_t pidx,
 231     int fault_type __unused, vm_prot_t max_prot __unused, vm_pindex_t *first,
 232     vm_pindex_t *last)
 233 {
 234         vm_page_t m;
 235         vm_pindex_t base, end, i;
 236         int ahead;
 237
 238         base = rounddown(pidx, phys_pager_cluster);
 239         end = base + phys_pager_cluster - 1;
 240         if (end >= object->size)
 241                 end = object->size - 1;
 242         if (*first > base)
 243                 base = *first;
 244         if (end > *last)
 245                 end = *last;
 246         *first = base;
 247         *last = end;
 248
 249         for (i = base; i <= end; i++) {
 250                 ahead = MIN(end - i, PHYSALLOC);
 251                 m = vm_page_grab(object, i,
 252                     VM_ALLOC_NORMAL | VM_ALLOC_COUNT(ahead));
 253                 if (!vm_page_all_valid(m))
 254                         vm_page_zero_invalid(m, TRUE);
 255                 KASSERT(m->dirty == 0,
 256                     ("phys_pager_populate: dirty page %p", m));
 257         }
 258         return (VM_PAGER_OK);
 259 }
 260
 261 static int
 262 phys_pager_populate(vm_object_t object, vm_pindex_t pidx, int fault_type,
 263     vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
 264 {
 265         return (object->un_pager.phys.ops->phys_pg_populate(object, pidx,
 266             fault_type, max_prot, first, last));
 267 }
 268
 269 static void
 270 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, int flags,
 271     int *rtvals)
 272 {
 273
 274         panic("phys_pager_putpage called");
 275 }
 276
 277 static boolean_t
 278 default_phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 279     int *after)
 280 {
 281         vm_pindex_t base, end;
 282
 283         base = rounddown(pindex, phys_pager_cluster);
 284         end = base + phys_pager_cluster - 1;
 285         if (before != NULL)
 286                 *before = pindex - base;
 287         if (after != NULL)
 288                 *after = end - pindex;
 289         return (TRUE);
 290 }
 291
 292 static boolean_t
 293 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 294     int *after)
 295 {
 296         return (object->un_pager.phys.ops->phys_pg_haspage(object, pindex,
 297             before, after));
 298 }
 299
 300 const struct pagerops physpagerops = {
 301         .pgo_kvme_type = KVME_TYPE_PHYS,
 302         .pgo_init =     phys_pager_init,
 303         .pgo_alloc =    phys_pager_alloc,
 304         .pgo_dealloc =  phys_pager_dealloc,
 305         .pgo_getpages = phys_pager_getpages,
 306         .pgo_putpages = phys_pager_putpages,
 307         .pgo_haspage =  phys_pager_haspage,
 308         .pgo_populate = phys_pager_populate,
 309 };