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  * 3. All advertising materials mentioning features or use of this software
  19  *    must display the following acknowledgement:
  20  *      This product includes software developed by the University of
  21  *      California, Berkeley and its contributors.
  22  * 4. Neither the name of the University nor the names of its contributors
  23  *    may be used to endorse or promote products derived from this software
  24  *    without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36  * SUCH DAMAGE.
  37  *
  38  *      @(#)device_pager.c      8.1 (Berkeley) 6/11/93
  39  * $FreeBSD: src/sys/vm/device_pager.c,v 1.46.2.1 2000/08/02 21:54:37 peter Exp $
  40  * $DragonFly: src/sys/vm/device_pager.c,v 1.13 2008/01/21 10:25:18 corecode Exp $
  41  */
  42
  43 #include <sys/param.h>
  44 #include <sys/systm.h>
  45 #include <sys/kernel.h>
  46 #include <sys/conf.h>
  47 #include <sys/mman.h>
  48 #include <sys/device.h>
  49 #include <sys/queue.h>
  50 #include <sys/malloc.h>
  51 #include <sys/thread2.h>
  52
  53 #include <vm/vm.h>
  54 #include <vm/vm_object.h>
  55 #include <vm/vm_page.h>
  56 #include <vm/vm_pager.h>
  57 #include <vm/vm_zone.h>
  58
  59 static void dev_pager_init (void);
  60 static vm_object_t dev_pager_alloc (void *, off_t, vm_prot_t, off_t);
  61 static void dev_pager_dealloc (vm_object_t);
  62 static int dev_pager_getpage (vm_object_t, vm_page_t *, int);
  63 static void dev_pager_putpages (vm_object_t, vm_page_t *, int,
  64                 boolean_t, int *);
  65 static boolean_t dev_pager_haspage (vm_object_t, vm_pindex_t);
  66
  67 /* list of device pager objects */
  68 static TAILQ_HEAD(, vm_page) dev_freepages_list;
  69 static MALLOC_DEFINE(M_FICTITIOUS_PAGES, "device-mapped pages", "Device mapped pages");
  70
  71 static vm_page_t dev_pager_getfake (vm_paddr_t);
  72 static void dev_pager_putfake (vm_page_t);
  73
  74 static int dev_pager_alloc_lock, dev_pager_alloc_lock_want;
  75
  76 struct pagerops devicepagerops = {
  77         dev_pager_init,
  78         dev_pager_alloc,
  79         dev_pager_dealloc,
  80         dev_pager_getpage,
  81         dev_pager_putpages,
  82         dev_pager_haspage,
  83         NULL
  84 };
  85
  86 static void
  87 dev_pager_init(void)
  88 {
  89         TAILQ_INIT(&dev_freepages_list);
  90 }
  91
  92 static vm_object_t
  93 dev_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t foff)
  94 {
  95         cdev_t dev;
  96         vm_object_t object;
  97         unsigned int npages;
  98         vm_offset_t off;
  99
 100         /*
 101          * Make sure this device can be mapped.
 102          */
 103         dev = handle;
 104
 105         /*
 106          * Offset should be page aligned.
 107          */
 108         if (foff & PAGE_MASK)
 109                 return (NULL);
 110
 111         size = round_page(size);
 112
 113         /*
 114          * Check that the specified range of the device allows the desired
 115          * protection.
 116          *
 117          * XXX assumes VM_PROT_* == PROT_*
 118          */
 119         npages = OFF_TO_IDX(size);
 120         for (off = foff; npages--; off += PAGE_SIZE) {
 121                 if (dev_dmmap(dev, off, (int)prot) == -1)
 122                         return (NULL);
 123         }
 124
 125         /*
 126          * Lock to prevent object creation race condition.
 127          */
 128         while (dev_pager_alloc_lock) {
 129                 dev_pager_alloc_lock_want++;
 130                 tsleep(&dev_pager_alloc_lock, 0, "dvpall", 0);
 131                 dev_pager_alloc_lock_want--;
 132         }
 133         dev_pager_alloc_lock = 1;
 134
 135         /*
 136          * Look up pager, creating as necessary.
 137          */
 138         object = dev->si_object;
 139         if (object == NULL) {
 140                 /*
 141                  * Allocate object and associate it with the pager.
 142                  */
 143                 object = vm_object_allocate(OBJT_DEVICE,
 144                         OFF_TO_IDX(foff + size));
 145                 object->handle = handle;
 146                 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
 147                 dev->si_object = object;
 148         } else {
 149                 /*
 150                  * Gain a reference to the object.
 151                  */
 152                 vm_object_reference(object);
 153                 if (OFF_TO_IDX(foff + size) > object->size)
 154                         object->size = OFF_TO_IDX(foff + size);
 155         }
 156
 157         dev_pager_alloc_lock = 0;
 158         if (dev_pager_alloc_lock_want)
 159                 wakeup(&dev_pager_alloc_lock);
 160
 161         return (object);
 162 }
 163
 164 static void
 165 dev_pager_dealloc(vm_object_t object)
 166 {
 167         vm_page_t m;
 168         cdev_t dev;
 169
 170         if ((dev = object->handle) != NULL) {
 171                 KKASSERT(dev->si_object);
 172                 dev->si_object = NULL;
 173         }
 174
 175         /*
 176          * Free up our fake pages.
 177          */
 178         while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
 179                 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
 180                 dev_pager_putfake(m);
 181         }
 182 }
 183
 184 static int
 185 dev_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
 186 {
 187         vm_offset_t offset;
 188         vm_paddr_t paddr;
 189         vm_page_t page;
 190         cdev_t dev;
 191         int prot;
 192
 193         page = *mpp;
 194         dev = object->handle;
 195         offset = page->pindex;
 196         prot = PROT_READ;       /* XXX should pass in? */
 197
 198         paddr = pmap_phys_address(
 199                     dev_dmmap(dev, (vm_offset_t)offset << PAGE_SHIFT, prot));
 200         KASSERT(paddr != -1,("dev_pager_getpage: map function returns error"));
 201
 202         if (page->flags & PG_FICTITIOUS) {
 203                 /*
 204                  * If the passed in reqpage page is a fake page, update it
 205                  * with the new physical address.
 206                  */
 207                 page->phys_addr = paddr;
 208                 page->valid = VM_PAGE_BITS_ALL;
 209         } else {
 210                 /*
 211                  * Replace the passed in reqpage page with our own fake page
 212                  * and free up all the original pages.
 213                  */
 214                 page = dev_pager_getfake(paddr);
 215                 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
 216                 crit_enter();
 217                 vm_page_free(*mpp);
 218                 vm_page_insert(page, object, offset);
 219                 crit_exit();
 220         }
 221         return (VM_PAGER_OK);
 222 }
 223
 224 static void
 225 dev_pager_putpages(vm_object_t object, vm_page_t *m,
 226                    int count, boolean_t sync, int *rtvals)
 227 {
 228         panic("dev_pager_putpage called");
 229 }
 230
 231 static boolean_t
 232 dev_pager_haspage(vm_object_t object, vm_pindex_t pindex)
 233 {
 234         return (TRUE);
 235 }
 236
 237 static vm_page_t
 238 dev_pager_getfake(vm_paddr_t paddr)
 239 {
 240         vm_page_t m;
 241
 242         if ((m = TAILQ_FIRST(&dev_freepages_list)) != NULL) {
 243                 TAILQ_REMOVE(&dev_freepages_list, m, pageq);
 244         } else {
 245                 m = kmalloc(sizeof(*m), M_FICTITIOUS_PAGES, M_WAITOK);
 246         }
 247         bzero(m, sizeof(*m));
 248
 249         m->flags = PG_BUSY | PG_FICTITIOUS;
 250         m->valid = VM_PAGE_BITS_ALL;
 251         m->dirty = 0;
 252         m->busy = 0;
 253         m->queue = PQ_NONE;
 254         m->object = NULL;
 255
 256         m->wire_count = 1;
 257         m->hold_count = 0;
 258         m->phys_addr = paddr;
 259
 260         return (m);
 261 }
 262
 263 /*
 264  * Synthesized VM pages must be structurally stable for lockless lookups to
 265  * work properly.
 266  */
 267 static void
 268 dev_pager_putfake(vm_page_t m)
 269 {
 270         if (!(m->flags & PG_FICTITIOUS))
 271                 panic("dev_pager_putfake: bad page");
 272         KKASSERT(m->object == NULL);
 273         TAILQ_INSERT_HEAD(&dev_freepages_list, m, pageq);
 274 }
 275