sys/vm/device_pager.c

   1 /*-
   2  * Copyright (c) 1990 University of Utah.
   3  * Copyright (c) 1991, 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  *
   6  * This code is derived from software contributed to Berkeley by
   7  * the Systems Programming Group of the University of Utah Computer
   8  * Science Department.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 4. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  *      @(#)device_pager.c      8.1 (Berkeley) 6/11/93
  35  */
  36
  37 #include <sys/cdefs.h>
  38 __FBSDID("$FreeBSD$");
  39
  40 #include <sys/param.h>
  41 #include <sys/systm.h>
  42 #include <sys/conf.h>
  43 #include <sys/lock.h>
  44 #include <sys/proc.h>
  45 #include <sys/mutex.h>
  46 #include <sys/mman.h>
  47 #include <sys/sx.h>
  48
  49 #include <vm/vm.h>
  50 #include <vm/vm_object.h>
  51 #include <vm/vm_page.h>
  52 #include <vm/vm_pager.h>
  53 #include <vm/uma.h>
  54
  55 static void dev_pager_init(void);
  56 static vm_object_t dev_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
  57                 vm_ooffset_t);
  58 static void dev_pager_dealloc(vm_object_t);
  59 static int dev_pager_getpages(vm_object_t, vm_page_t *, int, int);
  60 static void dev_pager_putpages(vm_object_t, vm_page_t *, int,
  61                 boolean_t, int *);
  62 static boolean_t dev_pager_haspage(vm_object_t, vm_pindex_t, int *,
  63                 int *);
  64
  65 /* list of device pager objects */
  66 static struct pagerlst dev_pager_object_list;
  67 /* protect list manipulation */
  68 static struct mtx dev_pager_mtx;
  69
  70
  71 static uma_zone_t fakepg_zone;
  72
  73 static vm_page_t dev_pager_getfake(vm_paddr_t);
  74 static void dev_pager_putfake(vm_page_t);
  75 static void dev_pager_updatefake(vm_page_t, vm_paddr_t);
  76
  77 struct pagerops devicepagerops = {
  78         .pgo_init =     dev_pager_init,
  79         .pgo_alloc =    dev_pager_alloc,
  80         .pgo_dealloc =  dev_pager_dealloc,
  81         .pgo_getpages = dev_pager_getpages,
  82         .pgo_putpages = dev_pager_putpages,
  83         .pgo_haspage =  dev_pager_haspage,
  84 };
  85
  86 static void
  87 dev_pager_init()
  88 {
  89         TAILQ_INIT(&dev_pager_object_list);
  90         mtx_init(&dev_pager_mtx, "dev_pager list", NULL, MTX_DEF);
  91         fakepg_zone = uma_zcreate("DP fakepg", sizeof(struct vm_page),
  92             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR,
  93             UMA_ZONE_NOFREE|UMA_ZONE_VM);
  94 }
  95
  96 /*
  97  * MPSAFE
  98  */
  99 static vm_object_t
 100 dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff)
 101 {
 102         struct cdev *dev;
 103         vm_object_t object, object1;
 104         vm_pindex_t pindex;
 105         unsigned int npages;
 106         vm_paddr_t paddr;
 107         vm_offset_t off;
 108         struct cdevsw *csw;
 109
 110         /*
 111          * Offset should be page aligned.
 112          */
 113         if (foff & PAGE_MASK)
 114                 return (NULL);
 115
 116         size = round_page(size);
 117         pindex = OFF_TO_IDX(foff + size);
 118
 119         /*
 120          * Make sure this device can be mapped.
 121          */
 122         dev = handle;
 123         csw = dev_refthread(dev);
 124         if (csw == NULL)
 125                 return (NULL);
 126
 127         /*
 128          * Check that the specified range of the device allows the desired
 129          * protection.
 130          *
 131          * XXX assumes VM_PROT_* == PROT_*
 132          */
 133         npages = OFF_TO_IDX(size);
 134         for (off = foff; npages--; off += PAGE_SIZE)
 135                 if ((*csw->d_mmap)(dev, off, &paddr, (int)prot) != 0) {
 136                         dev_relthread(dev);
 137                         return (NULL);
 138                 }
 139
 140         mtx_lock(&dev_pager_mtx);
 141
 142         /*
 143          * Look up pager, creating as necessary.
 144          */
 145         object1 = NULL;
 146         object = vm_pager_object_lookup(&dev_pager_object_list, handle);
 147         if (object == NULL) {
 148                 /*
 149                  * Allocate object and associate it with the pager.
 150                  */
 151                 mtx_unlock(&dev_pager_mtx);
 152                 object1 = vm_object_allocate(OBJT_DEVICE, pindex);
 153                 mtx_lock(&dev_pager_mtx);
 154                 object = vm_pager_object_lookup(&dev_pager_object_list, handle);
 155                 if (object != NULL) {
 156                         /*
 157                          * We raced with other thread while allocating object.
 158                          */
 159                         if (pindex > object->size)
 160                                 object->size = pindex;
 161                 } else {
 162                         object = object1;
 163                         object1 = NULL;
 164                         object->handle = handle;
 165                         TAILQ_INIT(&object->un_pager.devp.devp_pglist);
 166                         TAILQ_INSERT_TAIL(&dev_pager_object_list, object,
 167                             pager_object_list);
 168                 }
 169         } else {
 170                 if (pindex > object->size)
 171                         object->size = pindex;
 172         }
 173         mtx_unlock(&dev_pager_mtx);
 174         dev_relthread(dev);
 175         vm_object_deallocate(object1);
 176         return (object);
 177 }
 178
 179 static void
 180 dev_pager_dealloc(object)
 181         vm_object_t object;
 182 {
 183         vm_page_t m;
 184
 185         VM_OBJECT_UNLOCK(object);
 186         mtx_lock(&dev_pager_mtx);
 187         TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
 188         mtx_unlock(&dev_pager_mtx);
 189         VM_OBJECT_LOCK(object);
 190         /*
 191          * Free up our fake pages.
 192          */
 193         while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
 194                 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
 195                 dev_pager_putfake(m);
 196         }
 197 }
 198
 199 static int
 200 dev_pager_getpages(object, m, count, reqpage)
 201         vm_object_t object;
 202         vm_page_t *m;
 203         int count;
 204         int reqpage;
 205 {
 206         vm_pindex_t offset;
 207         vm_paddr_t paddr;
 208         vm_page_t page;
 209         struct cdev *dev;
 210         int i, ret;
 211         int prot;
 212         struct cdevsw *csw;
 213
 214         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
 215         dev = object->handle;
 216         offset = m[reqpage]->pindex;
 217         VM_OBJECT_UNLOCK(object);
 218         csw = dev_refthread(dev);
 219         if (csw == NULL)
 220                 panic("dev_pager_getpage: no cdevsw");
 221         prot = PROT_READ;       /* XXX should pass in? */
 222
 223         ret = (*csw->d_mmap)(dev, (vm_offset_t)offset << PAGE_SHIFT, &paddr, prot);
 224         KASSERT(ret == 0, ("dev_pager_getpage: map function returns error"));
 225         dev_relthread(dev);
 226
 227         if ((m[reqpage]->flags & PG_FICTITIOUS) != 0) {
 228                 /*
 229                  * If the passed in reqpage page is a fake page, update it with
 230                  * the new physical address.
 231                  */
 232                 VM_OBJECT_LOCK(object);
 233                 dev_pager_updatefake(m[reqpage], paddr);
 234                 if (count > 1) {
 235                         vm_page_lock_queues();
 236                         for (i = 0; i < count; i++) {
 237                                 if (i != reqpage)
 238                                         vm_page_free(m[i]);
 239                         }
 240                         vm_page_unlock_queues();
 241                 }
 242         } else {
 243                 /*
 244                  * Replace the passed in reqpage page with our own fake page and
 245                  * free up the all of the original pages.
 246                  */
 247                 page = dev_pager_getfake(paddr);
 248                 VM_OBJECT_LOCK(object);
 249                 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
 250                 vm_page_lock_queues();
 251                 for (i = 0; i < count; i++)
 252                         vm_page_free(m[i]);
 253                 vm_page_unlock_queues();
 254                 vm_page_insert(page, object, offset);
 255                 m[reqpage] = page;
 256         }
 257
 258         return (VM_PAGER_OK);
 259 }
 260
 261 static void
 262 dev_pager_putpages(object, m, count, sync, rtvals)
 263         vm_object_t object;
 264         vm_page_t *m;
 265         int count;
 266         boolean_t sync;
 267         int *rtvals;
 268 {
 269         panic("dev_pager_putpage called");
 270 }
 271
 272 static boolean_t
 273 dev_pager_haspage(object, pindex, before, after)
 274         vm_object_t object;
 275         vm_pindex_t pindex;
 276         int *before;
 277         int *after;
 278 {
 279         if (before != NULL)
 280                 *before = 0;
 281         if (after != NULL)
 282                 *after = 0;
 283         return (TRUE);
 284 }
 285
 286 /*
 287  * Instantiate a fictitious page.  Unlike physical memory pages, only
 288  * the machine-independent fields must be initialized.
 289  */
 290 static vm_page_t
 291 dev_pager_getfake(paddr)
 292         vm_paddr_t paddr;
 293 {
 294         vm_page_t m;
 295
 296         m = uma_zalloc(fakepg_zone, M_WAITOK);
 297
 298         m->flags = PG_FICTITIOUS;
 299         m->oflags = VPO_BUSY;
 300         m->valid = VM_PAGE_BITS_ALL;
 301         m->dirty = 0;
 302         m->busy = 0;
 303         m->queue = PQ_NONE;
 304         m->object = NULL;
 305
 306         m->wire_count = 1;
 307         m->hold_count = 0;
 308         m->phys_addr = paddr;
 309
 310         return (m);
 311 }
 312
 313 static void
 314 dev_pager_putfake(m)
 315         vm_page_t m;
 316 {
 317         if (!(m->flags & PG_FICTITIOUS))
 318                 panic("dev_pager_putfake: bad page");
 319         uma_zfree(fakepg_zone, m);
 320 }
 321
 322 static void
 323 dev_pager_updatefake(m, paddr)
 324         vm_page_t m;
 325         vm_paddr_t paddr;
 326 {
 327         if (!(m->flags & PG_FICTITIOUS))
 328                 panic("dev_pager_updatefake: bad page");
 329         m->phys_addr = paddr;
 330         m->valid = VM_PAGE_BITS_ALL;
 331 }