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_getpages (vm_object_t, vm_page_t *, int, 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, int *,
  66                 int *);
  67
  68 /* list of device pager objects */
  69 static struct pagerlst dev_pager_object_list;
  70 static TAILQ_HEAD(, vm_page) dev_freepages_list;
  71 static MALLOC_DEFINE(M_FICTITIOUS_PAGES, "device-mapped pages", "Device mapped pages");
  72
  73 static vm_page_t dev_pager_getfake (vm_paddr_t);
  74 static void dev_pager_putfake (vm_page_t);
  75
  76 static int dev_pager_alloc_lock, dev_pager_alloc_lock_want;
  77
  78 struct pagerops devicepagerops = {
  79         dev_pager_init,
  80         dev_pager_alloc,
  81         dev_pager_dealloc,
  82         dev_pager_getpages,
  83         dev_pager_putpages,
  84         dev_pager_haspage,
  85         NULL
  86 };
  87
  88 static void
  89 dev_pager_init(void)
  90 {
  91         TAILQ_INIT(&dev_pager_object_list);
  92         TAILQ_INIT(&dev_freepages_list);
  93 }
  94
  95 static vm_object_t
  96 dev_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t foff)
  97 {
  98         cdev_t dev;
  99         vm_object_t object;
 100         unsigned int npages;
 101         vm_offset_t off;
 102
 103         /*
 104          * Make sure this device can be mapped.
 105          */
 106         dev = handle;
 107
 108         /*
 109          * Offset should be page aligned.
 110          */
 111         if (foff & PAGE_MASK)
 112                 return (NULL);
 113
 114         size = round_page(size);
 115
 116         /*
 117          * Check that the specified range of the device allows the desired
 118          * protection.
 119          *
 120          * XXX assumes VM_PROT_* == PROT_*
 121          */
 122         npages = OFF_TO_IDX(size);
 123         for (off = foff; npages--; off += PAGE_SIZE) {
 124                 if (dev_dmmap(dev, off, (int)prot) == -1)
 125                         return (NULL);
 126         }
 127
 128         /*
 129          * Lock to prevent object creation race condition.
 130          */
 131         while (dev_pager_alloc_lock) {
 132                 dev_pager_alloc_lock_want++;
 133                 tsleep(&dev_pager_alloc_lock, 0, "dvpall", 0);
 134                 dev_pager_alloc_lock_want--;
 135         }
 136         dev_pager_alloc_lock = 1;
 137
 138         /*
 139          * Look up pager, creating as necessary.
 140          */
 141         object = vm_pager_object_lookup(&dev_pager_object_list, handle);
 142         if (object == NULL) {
 143                 /*
 144                  * Allocate object and associate it with the pager.
 145                  */
 146                 object = vm_object_allocate(OBJT_DEVICE,
 147                         OFF_TO_IDX(foff + size));
 148                 object->handle = handle;
 149                 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
 150                 TAILQ_INSERT_TAIL(&dev_pager_object_list, object, pager_object_list);
 151         } else {
 152                 /*
 153                  * Gain a reference to the object.
 154                  */
 155                 vm_object_reference(object);
 156                 if (OFF_TO_IDX(foff + size) > object->size)
 157                         object->size = OFF_TO_IDX(foff + size);
 158         }
 159
 160         dev_pager_alloc_lock = 0;
 161         if (dev_pager_alloc_lock_want)
 162                 wakeup(&dev_pager_alloc_lock);
 163
 164         return (object);
 165 }
 166
 167 static void
 168 dev_pager_dealloc(vm_object_t object)
 169 {
 170         vm_page_t m;
 171
 172         TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
 173         /*
 174          * Free up our fake pages.
 175          */
 176         while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
 177                 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
 178                 dev_pager_putfake(m);
 179         }
 180 }
 181
 182 static int
 183 dev_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 184 {
 185         vm_offset_t offset;
 186         vm_paddr_t paddr;
 187         vm_page_t page;
 188         cdev_t dev;
 189         int prot;
 190         int i;
 191
 192         dev = object->handle;
 193         offset = m[reqpage]->pindex;
 194         prot = PROT_READ;       /* XXX should pass in? */
 195
 196         paddr = pmap_phys_address(dev_dmmap(dev, (vm_offset_t) offset << PAGE_SHIFT, prot));
 197         KASSERT(paddr != -1,("dev_pager_getpage: map function returns error"));
 198
 199         if (m[reqpage]->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                 m[reqpage]->phys_addr = paddr;
 205                 m[reqpage]->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(m[reqpage]);
 215                 vm_page_insert(page, object, offset);
 216                 crit_exit();
 217         }
 218         for (i = 0; i < count; i++) {
 219                 if (i != reqpage)
 220                         vm_page_free(m[i]);
 221         }
 222         return (VM_PAGER_OK);
 223 }
 224
 225 static void
 226 dev_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
 227     int *rtvals)
 228 {
 229         panic("dev_pager_putpage called");
 230 }
 231
 232 static boolean_t
 233 dev_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 234     int *after)
 235 {
 236         if (before != NULL)
 237                 *before = 0;
 238         if (after != NULL)
 239                 *after = 0;
 240         return (TRUE);
 241 }
 242
 243 static vm_page_t
 244 dev_pager_getfake(vm_paddr_t paddr)
 245 {
 246         vm_page_t m;
 247
 248         if ((m = TAILQ_FIRST(&dev_freepages_list)) != NULL) {
 249                 TAILQ_REMOVE(&dev_freepages_list, m, pageq);
 250         } else {
 251                 m = kmalloc(sizeof(*m), M_FICTITIOUS_PAGES, M_WAITOK);
 252         }
 253         bzero(m, sizeof(*m));
 254
 255         m->flags = PG_BUSY | PG_FICTITIOUS;
 256         m->valid = VM_PAGE_BITS_ALL;
 257         m->dirty = 0;
 258         m->busy = 0;
 259         m->queue = PQ_NONE;
 260         m->object = NULL;
 261
 262         m->wire_count = 1;
 263         m->hold_count = 0;
 264         m->phys_addr = paddr;
 265
 266         return (m);
 267 }
 268
 269 /*
 270  * Synthesized VM pages must be structurally stable for lockless lookups to
 271  * work properly.
 272  */
 273 static void
 274 dev_pager_putfake(vm_page_t m)
 275 {
 276         if (!(m->flags & PG_FICTITIOUS))
 277                 panic("dev_pager_putfake: bad page");
 278         KKASSERT(m->object == NULL);
 279         TAILQ_INSERT_HEAD(&dev_freepages_list, m, pageq);
 280 }
 281