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  * 4. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  *      @(#)device_pager.c      8.1 (Berkeley) 6/11/93
  35  */
  36
  37 #include <sys/cdefs.h>
  38 __FBSDID("$FreeBSD$");
  39
  40 #include <sys/param.h>
  41 #include <sys/systm.h>
  42 #include <sys/conf.h>
  43 #include <sys/lock.h>
  44 #include <sys/proc.h>
  45 #include <sys/mutex.h>
  46 #include <sys/mman.h>
  47 #include <sys/sx.h>
  48
  49 #include <vm/vm.h>
  50 #include <vm/vm_object.h>
  51 #include <vm/vm_page.h>
  52 #include <vm/vm_pager.h>
  53 #include <vm/uma.h>
  54
  55 static void dev_pager_init(void);
  56 static vm_object_t dev_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
  57                 vm_ooffset_t);
  58 static void dev_pager_dealloc(vm_object_t);
  59 static int dev_pager_getpages(vm_object_t, vm_page_t *, int, int);
  60 static void dev_pager_putpages(vm_object_t, vm_page_t *, int,
  61                 boolean_t, int *);
  62 static boolean_t dev_pager_haspage(vm_object_t, vm_pindex_t, int *,
  63                 int *);
  64
  65 /* list of device pager objects */
  66 static struct pagerlst dev_pager_object_list;
  67 /* protect against object creation */
  68 static struct sx dev_pager_sx;
  69 /* protect list manipulation */
  70 static struct mtx dev_pager_mtx;
  71
  72
  73 static uma_zone_t fakepg_zone;
  74
  75 static vm_page_t dev_pager_getfake(vm_paddr_t);
  76 static void dev_pager_putfake(vm_page_t);
  77 static void dev_pager_updatefake(vm_page_t, vm_paddr_t);
  78
  79 struct pagerops devicepagerops = {
  80         .pgo_init =     dev_pager_init,
  81         .pgo_alloc =    dev_pager_alloc,
  82         .pgo_dealloc =  dev_pager_dealloc,
  83         .pgo_getpages = dev_pager_getpages,
  84         .pgo_putpages = dev_pager_putpages,
  85         .pgo_haspage =  dev_pager_haspage,
  86 };
  87
  88 static void
  89 dev_pager_init()
  90 {
  91         TAILQ_INIT(&dev_pager_object_list);
  92         sx_init(&dev_pager_sx, "dev_pager create");
  93         mtx_init(&dev_pager_mtx, "dev_pager list", NULL, MTX_DEF);
  94         fakepg_zone = uma_zcreate("DP fakepg", sizeof(struct vm_page),
  95             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR,
  96             UMA_ZONE_NOFREE|UMA_ZONE_VM);
  97 }
  98
  99 /*
 100  * MPSAFE
 101  */
 102 static vm_object_t
 103 dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff)
 104 {
 105         struct cdev *dev;
 106         vm_object_t object;
 107         vm_pindex_t pindex;
 108         unsigned int npages;
 109         vm_paddr_t paddr;
 110         vm_offset_t off;
 111         struct cdevsw *csw;
 112
 113         /*
 114          * Offset should be page aligned.
 115          */
 116         if (foff & PAGE_MASK)
 117                 return (NULL);
 118
 119         size = round_page(size);
 120         pindex = OFF_TO_IDX(foff + size);
 121
 122         /*
 123          * Make sure this device can be mapped.
 124          */
 125         dev = handle;
 126         csw = dev_refthread(dev);
 127         if (csw == NULL)
 128                 return (NULL);
 129         mtx_lock(&Giant);
 130
 131         /*
 132          * Check that the specified range of the device allows the desired
 133          * protection.
 134          *
 135          * XXX assumes VM_PROT_* == PROT_*
 136          */
 137         npages = OFF_TO_IDX(size);
 138         for (off = foff; npages--; off += PAGE_SIZE)
 139                 if ((*csw->d_mmap)(dev, off, &paddr, (int)prot) != 0) {
 140                         mtx_unlock(&Giant);
 141                         dev_relthread(dev);
 142                         return (NULL);
 143                 }
 144
 145         /*
 146          * Lock to prevent object creation race condition.
 147          */
 148         sx_xlock(&dev_pager_sx);
 149
 150         /*
 151          * Look up pager, creating as necessary.
 152          */
 153         object = vm_pager_object_lookup(&dev_pager_object_list, handle);
 154         if (object == NULL) {
 155                 /*
 156                  * Allocate object and associate it with the pager.
 157                  */
 158                 object = vm_object_allocate(OBJT_DEVICE, pindex);
 159                 object->handle = handle;
 160                 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
 161                 mtx_lock(&dev_pager_mtx);
 162                 TAILQ_INSERT_TAIL(&dev_pager_object_list, object, pager_object_list);
 163                 mtx_unlock(&dev_pager_mtx);
 164         } else {
 165                 /*
 166                  * Gain a reference to the object.
 167                  */
 168                 vm_object_reference(object);
 169                 if (pindex > object->size)
 170                         object->size = pindex;
 171         }
 172
 173         sx_xunlock(&dev_pager_sx);
 174         mtx_unlock(&Giant);
 175         dev_relthread(dev);
 176         return (object);
 177 }
 178
 179 static void
 180 dev_pager_dealloc(object)
 181         vm_object_t object;
 182 {
 183         vm_page_t m;
 184
 185         mtx_lock(&dev_pager_mtx);
 186         TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
 187         mtx_unlock(&dev_pager_mtx);
 188         /*
 189          * Free up our fake pages.
 190          */
 191         while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
 192                 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
 193                 dev_pager_putfake(m);
 194         }
 195 }
 196
 197 static int
 198 dev_pager_getpages(object, m, count, reqpage)
 199         vm_object_t object;
 200         vm_page_t *m;
 201         int count;
 202         int reqpage;
 203 {
 204         vm_pindex_t offset;
 205         vm_paddr_t paddr;
 206         vm_page_t page;
 207         struct cdev *dev;
 208         int i, ret;
 209         int prot;
 210         struct cdevsw *csw;
 211
 212         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
 213         dev = object->handle;
 214         offset = m[reqpage]->pindex;
 215         VM_OBJECT_UNLOCK(object);
 216         csw = dev_refthread(dev);
 217         if (csw == NULL)
 218                 panic("dev_pager_getpage: no cdevsw");
 219         mtx_lock(&Giant);
 220         prot = PROT_READ;       /* XXX should pass in? */
 221
 222         ret = (*csw->d_mmap)(dev, (vm_offset_t)offset << PAGE_SHIFT, &paddr, prot);
 223         KASSERT(ret == 0, ("dev_pager_getpage: map function returns error"));
 224         mtx_unlock(&Giant);
 225         dev_relthread(dev);
 226
 227         if ((m[reqpage]->flags & PG_FICTITIOUS) != 0) {
 228                 /*
 229                  * If the passed in reqpage page is a fake page, update it with
 230                  * the new physical address.
 231                  */
 232                 VM_OBJECT_LOCK(object);
 233                 dev_pager_updatefake(m[reqpage], paddr);
 234                 if (count > 1) {
 235                         vm_page_lock_queues();
 236                         for (i = 0; i < count; i++) {
 237                                 if (i != reqpage)
 238                                         vm_page_free(m[i]);
 239                         }
 240                         vm_page_unlock_queues();
 241                 }
 242         } else {
 243                 /*
 244                  * Replace the passed in reqpage page with our own fake page and
 245                  * free up the all of the original pages.
 246                  */
 247                 page = dev_pager_getfake(paddr);
 248                 VM_OBJECT_LOCK(object);
 249                 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
 250                 vm_page_lock_queues();
 251                 for (i = 0; i < count; i++)
 252                         vm_page_free(m[i]);
 253                 vm_page_unlock_queues();
 254                 vm_page_insert(page, object, offset);
 255                 m[reqpage] = page;
 256         }
 257
 258         return (VM_PAGER_OK);
 259 }
 260
 261 static void
 262 dev_pager_putpages(object, m, count, sync, rtvals)
 263         vm_object_t object;
 264         vm_page_t *m;
 265         int count;
 266         boolean_t sync;
 267         int *rtvals;
 268 {
 269         panic("dev_pager_putpage called");
 270 }
 271
 272 static boolean_t
 273 dev_pager_haspage(object, pindex, before, after)
 274         vm_object_t object;
 275         vm_pindex_t pindex;
 276         int *before;
 277         int *after;
 278 {
 279         if (before != NULL)
 280                 *before = 0;
 281         if (after != NULL)
 282                 *after = 0;
 283         return (TRUE);
 284 }
 285
 286 /*
 287  * Instantiate a fictitious page.  Unlike physical memory pages, only
 288  * the machine-independent fields must be initialized.
 289  */
 290 static vm_page_t
 291 dev_pager_getfake(paddr)
 292         vm_paddr_t paddr;
 293 {
 294         vm_page_t m;
 295
 296         m = uma_zalloc(fakepg_zone, M_WAITOK);
 297
 298         m->flags = PG_FICTITIOUS;
 299         m->oflags = VPO_BUSY;
 300         m->valid = VM_PAGE_BITS_ALL;
 301         m->dirty = 0;
 302         m->busy = 0;
 303         m->queue = PQ_NONE;
 304         m->object = NULL;
 305
 306         m->wire_count = 1;
 307         m->hold_count = 0;
 308         m->phys_addr = paddr;
 309
 310         return (m);
 311 }
 312
 313 static void
 314 dev_pager_putfake(m)
 315         vm_page_t m;
 316 {
 317         if (!(m->flags & PG_FICTITIOUS))
 318                 panic("dev_pager_putfake: bad page");
 319         uma_zfree(fakepg_zone, m);
 320 }
 321
 322 static void
 323 dev_pager_updatefake(m, paddr)
 324         vm_page_t m;
 325         vm_paddr_t paddr;
 326 {
 327         if (!(m->flags & PG_FICTITIOUS))
 328                 panic("dev_pager_updatefake: bad page");
 329         m->phys_addr = paddr;
 330         m->valid = VM_PAGE_BITS_ALL;
 331 }