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 struct pagerlst dev_pager_object_list;
  69 static TAILQ_HEAD(, vm_page) dev_freepages_list;
  70 static MALLOC_DEFINE(M_FICTITIOUS_PAGES, "device-mapped pages", "Device mapped pages");
  71
  72 static vm_page_t dev_pager_getfake (vm_paddr_t);
  73 static void dev_pager_putfake (vm_page_t);
  74
  75 static int dev_pager_alloc_lock, dev_pager_alloc_lock_want;
  76
  77 struct pagerops devicepagerops = {
  78         dev_pager_init,
  79         dev_pager_alloc,
  80         dev_pager_dealloc,
  81         dev_pager_getpage,
  82         dev_pager_putpages,
  83         dev_pager_haspage,
  84         NULL
  85 };
  86
  87 static void
  88 dev_pager_init(void)
  89 {
  90         TAILQ_INIT(&dev_pager_object_list);
  91         TAILQ_INIT(&dev_freepages_list);
  92 }
  93
  94 static vm_object_t
  95 dev_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t foff)
  96 {
  97         cdev_t dev;
  98         vm_object_t object;
  99         unsigned int npages;
 100         vm_offset_t off;
 101
 102         /*
 103          * Make sure this device can be mapped.
 104          */
 105         dev = handle;
 106
 107         /*
 108          * Offset should be page aligned.
 109          */
 110         if (foff & PAGE_MASK)
 111                 return (NULL);
 112
 113         size = round_page(size);
 114
 115         /*
 116          * Check that the specified range of the device allows the desired
 117          * protection.
 118          *
 119          * XXX assumes VM_PROT_* == PROT_*
 120          */
 121         npages = OFF_TO_IDX(size);
 122         for (off = foff; npages--; off += PAGE_SIZE) {
 123                 if (dev_dmmap(dev, off, (int)prot) == -1)
 124                         return (NULL);
 125         }
 126
 127         /*
 128          * Lock to prevent object creation race condition.
 129          */
 130         while (dev_pager_alloc_lock) {
 131                 dev_pager_alloc_lock_want++;
 132                 tsleep(&dev_pager_alloc_lock, 0, "dvpall", 0);
 133                 dev_pager_alloc_lock_want--;
 134         }
 135         dev_pager_alloc_lock = 1;
 136
 137         /*
 138          * Look up pager, creating as necessary.
 139          */
 140         object = vm_pager_object_lookup(&dev_pager_object_list, handle);
 141         if (object == NULL) {
 142                 /*
 143                  * Allocate object and associate it with the pager.
 144                  */
 145                 object = vm_object_allocate(OBJT_DEVICE,
 146                         OFF_TO_IDX(foff + size));
 147                 object->handle = handle;
 148                 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
 149                 TAILQ_INSERT_TAIL(&dev_pager_object_list, object, pager_object_list);
 150         } else {
 151                 /*
 152                  * Gain a reference to the object.
 153                  */
 154                 vm_object_reference(object);
 155                 if (OFF_TO_IDX(foff + size) > object->size)
 156                         object->size = OFF_TO_IDX(foff + size);
 157         }
 158
 159         dev_pager_alloc_lock = 0;
 160         if (dev_pager_alloc_lock_want)
 161                 wakeup(&dev_pager_alloc_lock);
 162
 163         return (object);
 164 }
 165
 166 static void
 167 dev_pager_dealloc(vm_object_t object)
 168 {
 169         vm_page_t m;
 170
 171         TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
 172         /*
 173          * Free up our fake pages.
 174          */
 175         while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
 176                 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
 177                 dev_pager_putfake(m);
 178         }
 179 }
 180
 181 static int
 182 dev_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
 183 {
 184         vm_offset_t offset;
 185         vm_paddr_t paddr;
 186         vm_page_t page;
 187         cdev_t dev;
 188         int prot;
 189
 190         page = *mpp;
 191         dev = object->handle;
 192         offset = page->pindex;
 193         prot = PROT_READ;       /* XXX should pass in? */
 194
 195         paddr = pmap_phys_address(
 196                     dev_dmmap(dev, (vm_offset_t)offset << PAGE_SHIFT, prot));
 197         KASSERT(paddr != -1,("dev_pager_getpage: map function returns error"));
 198
 199         if (page->flags & PG_FICTITIOUS) {
 200                 /*
 201                  * If the passed in reqpage page is a fake page, update it
 202                  * with the new physical address.
 203                  */
 204                 page->phys_addr = paddr;
 205                 page->valid = VM_PAGE_BITS_ALL;
 206         } else {
 207                 /*
 208                  * Replace the passed in reqpage page with our own fake page
 209                  * and free up all the original pages.
 210                  */
 211                 page = dev_pager_getfake(paddr);
 212                 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
 213                 crit_enter();
 214                 vm_page_free(*mpp);
 215                 vm_page_insert(page, object, offset);
 216                 crit_exit();
 217         }
 218         return (VM_PAGER_OK);
 219 }
 220
 221 static void
 222 dev_pager_putpages(vm_object_t object, vm_page_t *m,
 223                    int count, boolean_t sync, int *rtvals)
 224 {
 225         panic("dev_pager_putpage called");
 226 }
 227
 228 static boolean_t
 229 dev_pager_haspage(vm_object_t object, vm_pindex_t pindex)
 230 {
 231         return (TRUE);
 232 }
 233
 234 static vm_page_t
 235 dev_pager_getfake(vm_paddr_t paddr)
 236 {
 237         vm_page_t m;
 238
 239         if ((m = TAILQ_FIRST(&dev_freepages_list)) != NULL) {
 240                 TAILQ_REMOVE(&dev_freepages_list, m, pageq);
 241         } else {
 242                 m = kmalloc(sizeof(*m), M_FICTITIOUS_PAGES, M_WAITOK);
 243         }
 244         bzero(m, sizeof(*m));
 245
 246         m->flags = PG_BUSY | PG_FICTITIOUS;
 247         m->valid = VM_PAGE_BITS_ALL;
 248         m->dirty = 0;
 249         m->busy = 0;
 250         m->queue = PQ_NONE;
 251         m->object = NULL;
 252
 253         m->wire_count = 1;
 254         m->hold_count = 0;
 255         m->phys_addr = paddr;
 256
 257         return (m);
 258 }
 259
 260 /*
 261  * Synthesized VM pages must be structurally stable for lockless lookups to
 262  * work properly.
 263  */
 264 static void
 265 dev_pager_putfake(vm_page_t m)
 266 {
 267         if (!(m->flags & PG_FICTITIOUS))
 268                 panic("dev_pager_putfake: bad page");
 269         KKASSERT(m->object == NULL);
 270         TAILQ_INSERT_HEAD(&dev_freepages_list, m, pageq);
 271 }
 272