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_dealloc (vm_object_t);
  60 static int dev_pager_getpage (vm_object_t, vm_page_t *, int);
  61 static void dev_pager_putpages (vm_object_t, vm_page_t *, int,
  62                 boolean_t, int *);
  63 static boolean_t dev_pager_haspage (vm_object_t, vm_pindex_t);
  64
  65 /* list of device pager objects */
  66 static TAILQ_HEAD(, vm_page) dev_freepages_list =
  67                 TAILQ_HEAD_INITIALIZER(dev_freepages_list);
  68 static MALLOC_DEFINE(M_FICTITIOUS_PAGES, "device-mapped pages", "Device mapped pages");
  69
  70 static vm_page_t dev_pager_getfake (vm_paddr_t);
  71 static void dev_pager_putfake (vm_page_t);
  72
  73 static int dev_pager_alloc_lock, dev_pager_alloc_lock_want;
  74
  75 struct pagerops devicepagerops = {
  76         dev_pager_dealloc,
  77         dev_pager_getpage,
  78         dev_pager_putpages,
  79         dev_pager_haspage
  80 };
  81
  82 vm_object_t
  83 dev_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t foff)
  84 {
  85         cdev_t dev;
  86         vm_object_t object;
  87         unsigned int npages;
  88         vm_offset_t off;
  89
  90         /*
  91          * Make sure this device can be mapped.
  92          */
  93         dev = handle;
  94
  95         /*
  96          * Offset should be page aligned.
  97          */
  98         if (foff & PAGE_MASK)
  99                 return (NULL);
 100
 101         size = round_page64(size);
 102
 103         /*
 104          * Check that the specified range of the device allows the desired
 105          * protection.
 106          *
 107          * XXX assumes VM_PROT_* == PROT_*
 108          */
 109         npages = OFF_TO_IDX(size);
 110         for (off = foff; npages--; off += PAGE_SIZE) {
 111                 if (dev_dmmap(dev, off, (int)prot) == -1)
 112                         return (NULL);
 113         }
 114
 115         /*
 116          * Lock to prevent object creation race condition.
 117          */
 118         while (dev_pager_alloc_lock) {
 119                 dev_pager_alloc_lock_want++;
 120                 tsleep(&dev_pager_alloc_lock, 0, "dvpall", 0);
 121                 dev_pager_alloc_lock_want--;
 122         }
 123         dev_pager_alloc_lock = 1;
 124
 125         /*
 126          * Look up pager, creating as necessary.
 127          */
 128         object = dev->si_object;
 129         if (object == NULL) {
 130                 /*
 131                  * Allocate object and associate it with the pager.
 132                  */
 133                 object = vm_object_allocate(OBJT_DEVICE,
 134                         OFF_TO_IDX(foff + size));
 135                 object->handle = handle;
 136                 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
 137                 dev->si_object = object;
 138         } else {
 139                 /*
 140                  * Gain a reference to the object.
 141                  */
 142                 vm_object_reference(object);
 143                 if (OFF_TO_IDX(foff + size) > object->size)
 144                         object->size = OFF_TO_IDX(foff + size);
 145         }
 146
 147         dev_pager_alloc_lock = 0;
 148         if (dev_pager_alloc_lock_want)
 149                 wakeup(&dev_pager_alloc_lock);
 150
 151         return (object);
 152 }
 153
 154 static void
 155 dev_pager_dealloc(vm_object_t object)
 156 {
 157         vm_page_t m;
 158         cdev_t dev;
 159
 160         if ((dev = object->handle) != NULL) {
 161                 KKASSERT(dev->si_object);
 162                 dev->si_object = NULL;
 163         }
 164         KKASSERT(object->swblock_count == 0);
 165
 166         /*
 167          * Free up our fake pages.
 168          */
 169         while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
 170                 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
 171                 dev_pager_putfake(m);
 172         }
 173 }
 174
 175 static int
 176 dev_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
 177 {
 178         vm_offset_t offset;
 179         vm_paddr_t paddr;
 180         vm_page_t page;
 181         cdev_t dev;
 182         int prot;
 183
 184         page = *mpp;
 185         dev = object->handle;
 186         offset = page->pindex;
 187         prot = PROT_READ;       /* XXX should pass in? */
 188
 189         paddr = pmap_phys_address(
 190                     dev_dmmap(dev, (vm_offset_t)offset << PAGE_SHIFT, prot));
 191         KASSERT(paddr != -1,("dev_pager_getpage: map function returns error"));
 192
 193         if (page->flags & PG_FICTITIOUS) {
 194                 /*
 195                  * If the passed in reqpage page is a fake page, update it
 196                  * with the new physical address.
 197                  */
 198                 page->phys_addr = paddr;
 199                 page->valid = VM_PAGE_BITS_ALL;
 200         } else {
 201                 /*
 202                  * Replace the passed in reqpage page with our own fake page
 203                  * and free up all the original pages.
 204                  */
 205                 page = dev_pager_getfake(paddr);
 206                 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
 207                 crit_enter();
 208                 vm_page_free(*mpp);
 209                 vm_page_insert(page, object, offset);
 210                 crit_exit();
 211         }
 212         return (VM_PAGER_OK);
 213 }
 214
 215 static void
 216 dev_pager_putpages(vm_object_t object, vm_page_t *m,
 217                    int count, boolean_t sync, int *rtvals)
 218 {
 219         panic("dev_pager_putpage called");
 220 }
 221
 222 static boolean_t
 223 dev_pager_haspage(vm_object_t object, vm_pindex_t pindex)
 224 {
 225         return (TRUE);
 226 }
 227
 228 static vm_page_t
 229 dev_pager_getfake(vm_paddr_t paddr)
 230 {
 231         vm_page_t m;
 232
 233         if ((m = TAILQ_FIRST(&dev_freepages_list)) != NULL) {
 234                 TAILQ_REMOVE(&dev_freepages_list, m, pageq);
 235         } else {
 236                 m = kmalloc(sizeof(*m), M_FICTITIOUS_PAGES, M_WAITOK);
 237         }
 238         bzero(m, sizeof(*m));
 239
 240         m->flags = PG_BUSY | PG_FICTITIOUS;
 241         m->valid = VM_PAGE_BITS_ALL;
 242         m->dirty = 0;
 243         m->busy = 0;
 244         m->queue = PQ_NONE;
 245         m->object = NULL;
 246
 247         m->wire_count = 1;
 248         m->hold_count = 0;
 249         m->phys_addr = paddr;
 250
 251         return (m);
 252 }
 253
 254 /*
 255  * Synthesized VM pages must be structurally stable for lockless lookups to
 256  * work properly.
 257  */
 258 static void
 259 dev_pager_putfake(vm_page_t m)
 260 {
 261         if (!(m->flags & PG_FICTITIOUS))
 262                 panic("dev_pager_putfake: bad page");
 263         KKASSERT(m->object == NULL);
 264         TAILQ_INSERT_HEAD(&dev_freepages_list, m, pageq);
 265 }
 266