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. All advertising materials mentioning features or use of this software
  21  *    must display the following acknowledgement:
  22  *      This product includes software developed by the University of
  23  *      California, Berkeley and its contributors.
  24  * 4. Neither the name of the University nor the names of its contributors
  25  *    may be used to endorse or promote products derived from this software
  26  *    without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  38  * SUCH DAMAGE.
  39  *
  40  *      @(#)device_pager.c      8.1 (Berkeley) 6/11/93
  41  * $FreeBSD: src/sys/vm/device_pager.c,v 1.46.2.1 2000/08/02 21:54:37 peter Exp $
  42  */
  43
  44 #include <sys/param.h>
  45 #include <sys/systm.h>
  46 #include <sys/kernel.h>
  47 #include <sys/conf.h>
  48 #include <sys/mman.h>
  49 #include <sys/device.h>
  50 #include <sys/queue.h>
  51 #include <sys/malloc.h>
  52 #include <sys/thread2.h>
  53 #include <sys/mutex2.h>
  54
  55 #include <vm/vm.h>
  56 #include <vm/vm_object.h>
  57 #include <vm/vm_page.h>
  58 #include <vm/vm_pager.h>
  59 #include <vm/vm_zone.h>
  60
  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                 TAILQ_HEAD_INITIALIZER(dev_freepages_list);
  70 static MALLOC_DEFINE(M_FICTITIOUS_PAGES, "device-mapped pages",
  71                 "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 struct pagerops devicepagerops = {
  77         dev_pager_dealloc,
  78         dev_pager_getpage,
  79         dev_pager_putpages,
  80         dev_pager_haspage
  81 };
  82
  83 static struct mtx dev_pager_mtx = MTX_INITIALIZER;
  84
  85 /*
  86  * No requirements.
  87  */
  88 vm_object_t
  89 dev_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t foff)
  90 {
  91         cdev_t dev;
  92         vm_object_t object;
  93         unsigned int npages;
  94         vm_offset_t off;
  95
  96         /*
  97          * Make sure this device can be mapped.
  98          */
  99         dev = handle;
 100
 101         /*
 102          * Offset should be page aligned.
 103          */
 104         if (foff & PAGE_MASK)
 105                 return (NULL);
 106
 107         size = round_page64(size);
 108
 109         /*
 110          * Check that the specified range of the device allows the desired
 111          * protection.
 112          *
 113          * XXX assumes VM_PROT_* == PROT_*
 114          */
 115         npages = OFF_TO_IDX(size);
 116         for (off = foff; npages--; off += PAGE_SIZE) {
 117                 if (dev_dmmap(dev, off, (int)prot) == -1)
 118                         return (NULL);
 119         }
 120
 121         /*
 122          * Look up pager, creating as necessary.
 123          */
 124         mtx_lock(&dev_pager_mtx);
 125         object = dev->si_object;
 126         if (object == NULL) {
 127                 /*
 128                  * Allocate object and associate it with the pager.
 129                  */
 130                 object = vm_object_allocate_hold(OBJT_DEVICE,
 131                                                  OFF_TO_IDX(foff + size));
 132                 object->handle = handle;
 133                 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
 134                 dev->si_object = object;
 135                 vm_object_drop(object);
 136         } else {
 137                 /*
 138                  * Gain a reference to the object.
 139                  */
 140                 vm_object_hold(object);
 141                 vm_object_reference_locked(object);
 142                 if (OFF_TO_IDX(foff + size) > object->size)
 143                         object->size = OFF_TO_IDX(foff + size);
 144                 vm_object_drop(object);
 145         }
 146         mtx_unlock(&dev_pager_mtx);
 147
 148         return (object);
 149 }
 150
 151 /*
 152  * No requirements.
 153  */
 154 static void
 155 dev_pager_dealloc(vm_object_t object)
 156 {
 157         vm_page_t m;
 158         cdev_t dev;
 159
 160         mtx_lock(&dev_pager_mtx);
 161
 162         if ((dev = object->handle) != NULL) {
 163                 KKASSERT(dev->si_object);
 164                 dev->si_object = NULL;
 165         }
 166         KKASSERT(object->swblock_count == 0);
 167
 168         /*
 169          * Free up our fake pages.
 170          */
 171         while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
 172                 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
 173                 dev_pager_putfake(m);
 174         }
 175         mtx_unlock(&dev_pager_mtx);
 176 }
 177
 178 /*
 179  * No requirements.
 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         mtx_lock(&dev_pager_mtx);
 191
 192         page = *mpp;
 193         dev = object->handle;
 194         offset = page->pindex;
 195         prot = PROT_READ;       /* XXX should pass in? */
 196
 197         paddr = pmap_phys_address(
 198                     dev_dmmap(dev, (vm_offset_t)offset << PAGE_SHIFT, prot));
 199         KASSERT(paddr != -1,("dev_pager_getpage: map function returns error"));
 200
 201         if (page->flags & PG_FICTITIOUS) {
 202                 /*
 203                  * If the passed in reqpage page is a fake page, update it
 204                  * with the new physical address.
 205                  */
 206                 page->phys_addr = paddr;
 207                 page->valid = VM_PAGE_BITS_ALL;
 208         } else {
 209                 /*
 210                  * Replace the passed in reqpage page with our own fake page
 211                  * and free up all the original pages.
 212                  */
 213                 page = dev_pager_getfake(paddr);
 214                 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist,
 215                                   page, pageq);
 216                 vm_object_hold(object);
 217                 vm_page_free(*mpp);
 218                 if (vm_page_insert(page, object, offset) == FALSE) {
 219                         panic("dev_pager_getpage: page (%p,%ld) exists",
 220                               object, offset);
 221                 }
 222                 vm_object_drop(object);
 223         }
 224         mtx_unlock(&dev_pager_mtx);
 225         return (VM_PAGER_OK);
 226 }
 227
 228 /*
 229  * No requirements.
 230  */
 231 static void
 232 dev_pager_putpages(vm_object_t object, vm_page_t *m,
 233                    int count, boolean_t sync, int *rtvals)
 234 {
 235         panic("dev_pager_putpage called");
 236 }
 237
 238 /*
 239  * No requirements.
 240  */
 241 static boolean_t
 242 dev_pager_haspage(vm_object_t object, vm_pindex_t pindex)
 243 {
 244         return (TRUE);
 245 }
 246
 247 /*
 248  * The caller must hold dev_pager_mtx
 249  */
 250 static vm_page_t
 251 dev_pager_getfake(vm_paddr_t paddr)
 252 {
 253         vm_page_t m;
 254
 255         if ((m = TAILQ_FIRST(&dev_freepages_list)) != NULL) {
 256                 TAILQ_REMOVE(&dev_freepages_list, m, pageq);
 257         } else {
 258                 m = kmalloc(sizeof(*m), M_FICTITIOUS_PAGES, M_WAITOK);
 259         }
 260         bzero(m, sizeof(*m));
 261
 262         m->flags = PG_BUSY | PG_FICTITIOUS;
 263         m->valid = VM_PAGE_BITS_ALL;
 264         m->dirty = 0;
 265         m->busy = 0;
 266         m->queue = PQ_NONE;
 267         m->object = NULL;
 268
 269         m->wire_count = 1;
 270         m->hold_count = 0;
 271         m->phys_addr = paddr;
 272
 273         return (m);
 274 }
 275
 276 /*
 277  * Synthesized VM pages must be structurally stable for lockless lookups to
 278  * work properly.
 279  *
 280  * The caller must hold dev_pager_mtx
 281  */
 282 static void
 283 dev_pager_putfake(vm_page_t m)
 284 {
 285         if (!(m->flags & PG_FICTITIOUS))
 286                 panic("dev_pager_putfake: bad page");
 287         KKASSERT(m->object == NULL);
 288         TAILQ_INSERT_HEAD(&dev_freepages_list, m, pageq);
 289 }
 290