device_pager.c

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    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: releng/5.0/sys/vm/device_pager.c 99849 2002-07-12 02:55:55Z alc $
   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 }

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FreeBSD/Linux Kernel Cross Reference sys/vm/device_pager.c

FreeBSD/Linux Kernel Cross Reference
sys/vm/device_pager.c