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  * $FreeBSD$
  40  */
  41
  42 #include <sys/param.h>
  43 #include <sys/systm.h>
  44 #include <sys/conf.h>
  45 #include <sys/lock.h>
  46 #include <sys/proc.h>
  47 #include <sys/mutex.h>
  48 #include <sys/mman.h>
  49 #include <sys/sx.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/uma.h>
  56
  57 static void dev_pager_init(void);
  58 static vm_object_t dev_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
  59                 vm_ooffset_t);
  60 static void dev_pager_dealloc(vm_object_t);
  61 static int dev_pager_getpages(vm_object_t, vm_page_t *, int, int);
  62 static void dev_pager_putpages(vm_object_t, vm_page_t *, int,
  63                 boolean_t, int *);
  64 static boolean_t dev_pager_haspage(vm_object_t, vm_pindex_t, int *,
  65                 int *);
  66
  67 /* list of device pager objects */
  68 static struct pagerlst dev_pager_object_list;
  69 /* protect against object creation */
  70 static struct sx dev_pager_sx;
  71 /* protect list manipulation */
  72 static struct mtx dev_pager_mtx;
  73
  74
  75 static uma_zone_t fakepg_zone;
  76
  77 static vm_page_t dev_pager_getfake(vm_offset_t);
  78 static void dev_pager_putfake(vm_page_t);
  79
  80 struct pagerops devicepagerops = {
  81         dev_pager_init,
  82         dev_pager_alloc,
  83         dev_pager_dealloc,
  84         dev_pager_getpages,
  85         dev_pager_putpages,
  86         dev_pager_haspage,
  87         NULL
  88 };
  89
  90 static void
  91 dev_pager_init()
  92 {
  93         TAILQ_INIT(&dev_pager_object_list);
  94         sx_init(&dev_pager_sx, "dev_pager create");
  95         mtx_init(&dev_pager_mtx, "dev_pager list", NULL, MTX_DEF);
  96         fakepg_zone = uma_zcreate("DP fakepg", sizeof(struct vm_page),
  97             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  98 }
  99
 100 /*
 101  * MPSAFE
 102  */
 103 static vm_object_t
 104 dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff)
 105 {
 106         dev_t dev;
 107         d_mmap_t *mapfunc;
 108         vm_object_t object;
 109         unsigned int npages;
 110         vm_offset_t off;
 111
 112         /*
 113          * Offset should be page aligned.
 114          */
 115         if (foff & PAGE_MASK)
 116                 return (NULL);
 117
 118         size = round_page(size);
 119
 120         /*
 121          * Make sure this device can be mapped.
 122          */
 123         dev = handle;
 124         mtx_lock(&Giant);
 125         mapfunc = devsw(dev)->d_mmap;
 126         if (mapfunc == NULL || mapfunc == (d_mmap_t *)nullop) {
 127                 printf("obsolete map function %p\n", (void *)mapfunc);
 128                 mtx_unlock(&Giant);
 129                 return (NULL);
 130         }
 131
 132         /*
 133          * Check that the specified range of the device allows the desired
 134          * protection.
 135          *
 136          * XXX assumes VM_PROT_* == PROT_*
 137          */
 138         npages = OFF_TO_IDX(size);
 139         for (off = foff; npages--; off += PAGE_SIZE)
 140                 if ((*mapfunc)(dev, off, (int) prot) == -1) {
 141                         mtx_unlock(&Giant);
 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,
 159                         OFF_TO_IDX(foff + size));
 160                 object->handle = handle;
 161                 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
 162                 mtx_lock(&dev_pager_mtx);
 163                 TAILQ_INSERT_TAIL(&dev_pager_object_list, object, pager_object_list);
 164                 mtx_unlock(&dev_pager_mtx);
 165         } else {
 166                 /*
 167                  * Gain a reference to the object.
 168                  */
 169                 vm_object_reference(object);
 170                 if (OFF_TO_IDX(foff + size) > object->size)
 171                         object->size = OFF_TO_IDX(foff + size);
 172         }
 173
 174         sx_xunlock(&dev_pager_sx);
 175         mtx_unlock(&Giant);
 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_offset_t paddr;
 206         vm_page_t page;
 207         dev_t dev;
 208         int i;
 209         d_mmap_t *mapfunc;
 210         int prot;
 211
 212         mtx_assert(&Giant, MA_OWNED);
 213         dev = object->handle;
 214         offset = m[reqpage]->pindex;
 215         prot = PROT_READ;       /* XXX should pass in? */
 216         mapfunc = devsw(dev)->d_mmap;
 217
 218         if (mapfunc == NULL || mapfunc == (d_mmap_t *)nullop)
 219                 panic("dev_pager_getpage: no map function");
 220
 221         paddr = pmap_phys_address((*mapfunc) (dev, (vm_offset_t) offset << PAGE_SHIFT, prot));
 222         KASSERT(paddr != -1,("dev_pager_getpage: map function returns error"));
 223         /*
 224          * Replace the passed in reqpage page with our own fake page and free up the
 225          * all of the original pages.
 226          */
 227         page = dev_pager_getfake(paddr);
 228         TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
 229         vm_page_lock_queues();
 230         for (i = 0; i < count; i++)
 231                 vm_page_free(m[i]);
 232         vm_page_unlock_queues();
 233         vm_page_insert(page, object, offset);
 234
 235         return (VM_PAGER_OK);
 236 }
 237
 238 static void
 239 dev_pager_putpages(object, m, count, sync, rtvals)
 240         vm_object_t object;
 241         vm_page_t *m;
 242         int count;
 243         boolean_t sync;
 244         int *rtvals;
 245 {
 246         panic("dev_pager_putpage called");
 247 }
 248
 249 static boolean_t
 250 dev_pager_haspage(object, pindex, before, after)
 251         vm_object_t object;
 252         vm_pindex_t pindex;
 253         int *before;
 254         int *after;
 255 {
 256         if (before != NULL)
 257                 *before = 0;
 258         if (after != NULL)
 259                 *after = 0;
 260         return (TRUE);
 261 }
 262
 263 static vm_page_t
 264 dev_pager_getfake(paddr)
 265         vm_offset_t paddr;
 266 {
 267         vm_page_t m;
 268
 269         m = uma_zalloc(fakepg_zone, M_WAITOK);
 270
 271         m->flags = PG_BUSY | PG_FICTITIOUS;
 272         m->valid = VM_PAGE_BITS_ALL;
 273         m->dirty = 0;
 274         m->busy = 0;
 275         m->queue = PQ_NONE;
 276         m->object = NULL;
 277
 278         m->wire_count = 1;
 279         m->hold_count = 0;
 280         m->phys_addr = paddr;
 281
 282         return (m);
 283 }
 284
 285 static void
 286 dev_pager_putfake(m)
 287         vm_page_t m;
 288 {
 289         if (!(m->flags & PG_FICTITIOUS))
 290                 panic("dev_pager_putfake: bad page");
 291         uma_zfree(fakepg_zone, m);
 292 }