sys/vm/device_pager.c

   1 /*
   2  * (MPSAFE)
   3  *
   4  * Copyright (c) 1990 University of Utah.
   5  * Copyright (c) 1991, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * This code is derived from software contributed to Berkeley by
   9  * the Systems Programming Group of the University of Utah Computer
  10  * Science Department.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  *      @(#)device_pager.c      8.1 (Berkeley) 6/11/93
  37  * $FreeBSD: src/sys/vm/device_pager.c,v 1.46.2.1 2000/08/02 21:54:37 peter Exp $
  38  */
  39
  40 #include <sys/param.h>
  41 #include <sys/systm.h>
  42 #include <sys/kernel.h>
  43 #include <sys/conf.h>
  44 #include <sys/mman.h>
  45 #include <sys/device.h>
  46 #include <sys/queue.h>
  47 #include <sys/malloc.h>
  48 #include <sys/thread2.h>
  49 #include <sys/mutex2.h>
  50
  51 #include <vm/vm.h>
  52 #include <vm/vm_object.h>
  53 #include <vm/vm_page.h>
  54 #include <vm/vm_pager.h>
  55 #include <vm/vm_zone.h>
  56
  57 static void dev_pager_dealloc (vm_object_t);
  58 static int dev_pager_getpage (vm_object_t, vm_page_t *, int);
  59 static void dev_pager_putpages (vm_object_t, vm_page_t *, int,
  60                 boolean_t, int *);
  61 static boolean_t dev_pager_haspage (vm_object_t, vm_pindex_t);
  62
  63 /* list of device pager objects */
  64 static TAILQ_HEAD(, vm_page) dev_freepages_list =
  65                 TAILQ_HEAD_INITIALIZER(dev_freepages_list);
  66 static MALLOC_DEFINE(M_FICTITIOUS_PAGES, "device-mapped pages",
  67                 "Device mapped pages");
  68
  69 static vm_page_t dev_pager_getfake (vm_paddr_t);
  70 static void dev_pager_putfake (vm_page_t);
  71
  72 struct pagerops devicepagerops = {
  73         dev_pager_dealloc,
  74         dev_pager_getpage,
  75         dev_pager_putpages,
  76         dev_pager_haspage
  77 };
  78
  79 static struct mtx dev_pager_mtx = MTX_INITIALIZER;
  80
  81 /*
  82  * No requirements.
  83  */
  84 vm_object_t
  85 dev_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t foff)
  86 {
  87         cdev_t dev;
  88         vm_object_t object;
  89         unsigned int npages;
  90         vm_offset_t off;
  91
  92         /*
  93          * Make sure this device can be mapped.
  94          */
  95         dev = handle;
  96
  97         /*
  98          * Offset should be page aligned.
  99          */
 100         if (foff & PAGE_MASK)
 101                 return (NULL);
 102
 103         size = round_page64(size);
 104
 105         /*
 106          * Check that the specified range of the device allows the desired
 107          * protection.
 108          *
 109          * XXX assumes VM_PROT_* == PROT_*
 110          */
 111         npages = OFF_TO_IDX(size);
 112         for (off = foff; npages--; off += PAGE_SIZE) {
 113                 if (dev_dmmap(dev, off, (int)prot) == -1)
 114                         return (NULL);
 115         }
 116
 117         /*
 118          * Look up pager, creating as necessary.
 119          */
 120         mtx_lock(&dev_pager_mtx);
 121         object = dev->si_object;
 122         if (object == NULL) {
 123                 /*
 124                  * Allocate object and associate it with the pager.
 125                  */
 126                 object = vm_object_allocate_hold(OBJT_DEVICE,
 127                                                  OFF_TO_IDX(foff + size));
 128                 object->handle = handle;
 129                 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
 130                 dev->si_object = object;
 131                 vm_object_drop(object);
 132         } else {
 133                 /*
 134                  * Gain a reference to the object.
 135                  */
 136                 vm_object_hold(object);
 137                 vm_object_reference_locked(object);
 138                 if (OFF_TO_IDX(foff + size) > object->size)
 139                         object->size = OFF_TO_IDX(foff + size);
 140                 vm_object_drop(object);
 141         }
 142         mtx_unlock(&dev_pager_mtx);
 143
 144         return (object);
 145 }
 146
 147 /*
 148  * No requirements.
 149  */
 150 static void
 151 dev_pager_dealloc(vm_object_t object)
 152 {
 153         vm_page_t m;
 154         cdev_t dev;
 155
 156         mtx_lock(&dev_pager_mtx);
 157
 158         if ((dev = object->handle) != NULL) {
 159                 KKASSERT(dev->si_object);
 160                 dev->si_object = NULL;
 161         }
 162         KKASSERT(object->swblock_count == 0);
 163
 164         /*
 165          * Free up our fake pages.
 166          */
 167         while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
 168                 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
 169                 dev_pager_putfake(m);
 170         }
 171         mtx_unlock(&dev_pager_mtx);
 172 }
 173
 174 /*
 175  * No requirements.
 176  */
 177 static int
 178 dev_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
 179 {
 180         vm_offset_t offset;
 181         vm_paddr_t paddr;
 182         vm_page_t page;
 183         cdev_t dev;
 184         int prot;
 185
 186         mtx_lock(&dev_pager_mtx);
 187
 188         page = *mpp;
 189         dev = object->handle;
 190         offset = page->pindex;
 191         prot = PROT_READ;       /* XXX should pass in? */
 192
 193         paddr = pmap_phys_address(
 194                     dev_dmmap(dev, offset << PAGE_SHIFT, prot));
 195         KASSERT(paddr != -1,("dev_pager_getpage: map function returns error"));
 196
 197         if (page->flags & PG_FICTITIOUS) {
 198                 /*
 199                  * If the passed in reqpage page is a fake page, update it
 200                  * with the new physical address.
 201                  */
 202                 page->phys_addr = paddr;
 203                 page->valid = VM_PAGE_BITS_ALL;
 204         } else {
 205                 /*
 206                  * Replace the passed in reqpage page with our own fake page
 207                  * and free up all the original pages.
 208                  */
 209                 page = dev_pager_getfake(paddr);
 210                 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist,
 211                                   page, pageq);
 212                 vm_object_hold(object);
 213                 vm_page_free(*mpp);
 214                 if (vm_page_insert(page, object, offset) == FALSE) {
 215                         panic("dev_pager_getpage: page (%p,%ld) exists",
 216                               object, offset);
 217                 }
 218                 vm_object_drop(object);
 219         }
 220         mtx_unlock(&dev_pager_mtx);
 221         return (VM_PAGER_OK);
 222 }
 223
 224 /*
 225  * No requirements.
 226  */
 227 static void
 228 dev_pager_putpages(vm_object_t object, vm_page_t *m,
 229                    int count, boolean_t sync, int *rtvals)
 230 {
 231         panic("dev_pager_putpage called");
 232 }
 233
 234 /*
 235  * No requirements.
 236  */
 237 static boolean_t
 238 dev_pager_haspage(vm_object_t object, vm_pindex_t pindex)
 239 {
 240         return (TRUE);
 241 }
 242
 243 /*
 244  * The caller must hold dev_pager_mtx
 245  */
 246 static vm_page_t
 247 dev_pager_getfake(vm_paddr_t paddr)
 248 {
 249         vm_page_t m;
 250
 251         if ((m = TAILQ_FIRST(&dev_freepages_list)) != NULL) {
 252                 TAILQ_REMOVE(&dev_freepages_list, m, pageq);
 253         } else {
 254                 m = kmalloc(sizeof(*m), M_FICTITIOUS_PAGES, M_WAITOK);
 255         }
 256         bzero(m, sizeof(*m));
 257
 258         m->flags = PG_BUSY | PG_FICTITIOUS;
 259         m->valid = VM_PAGE_BITS_ALL;
 260         m->dirty = 0;
 261         m->busy = 0;
 262         m->queue = PQ_NONE;
 263         m->object = NULL;
 264
 265         m->wire_count = 1;
 266         m->hold_count = 0;
 267         m->phys_addr = paddr;
 268
 269         return (m);
 270 }
 271
 272 /*
 273  * Synthesized VM pages must be structurally stable for lockless lookups to
 274  * work properly.
 275  *
 276  * The caller must hold dev_pager_mtx
 277  */
 278 static void
 279 dev_pager_putfake(vm_page_t m)
 280 {
 281         if (!(m->flags & PG_FICTITIOUS))
 282                 panic("dev_pager_putfake: bad page");
 283         KKASSERT(m->object == NULL);
 284         TAILQ_INSERT_HEAD(&dev_freepages_list, m, pageq);
 285 }
 286