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/5.1/sys/vm/device_pager.c 112569 2003-03-25 00:07:06Z jake $
   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_paddr_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_paddr_t paddr;
  111         vm_offset_t off;
  112 
  113         /*
  114          * Offset should be page aligned.
  115          */
  116         if (foff & PAGE_MASK)
  117                 return (NULL);
  118 
  119         size = round_page(size);
  120 
  121         /*
  122          * Make sure this device can be mapped.
  123          */
  124         dev = handle;
  125         mtx_lock(&Giant);
  126         mapfunc = devsw(dev)->d_mmap;
  127         if (mapfunc == NULL || mapfunc == (d_mmap_t *)nullop) {
  128                 printf("obsolete map function %p\n", (void *)mapfunc);
  129                 mtx_unlock(&Giant);
  130                 return (NULL);
  131         }
  132 
  133         /*
  134          * Check that the specified range of the device allows the desired
  135          * protection.
  136          *
  137          * XXX assumes VM_PROT_* == PROT_*
  138          */
  139         npages = OFF_TO_IDX(size);
  140         for (off = foff; npages--; off += PAGE_SIZE)
  141                 if ((*mapfunc)(dev, off, &paddr, (int)prot) != 0) {
  142                         mtx_unlock(&Giant);
  143                         return (NULL);
  144                 }
  145 
  146         /*
  147          * Lock to prevent object creation race condition.
  148          */
  149         sx_xlock(&dev_pager_sx);
  150 
  151         /*
  152          * Look up pager, creating as necessary.
  153          */
  154         object = vm_pager_object_lookup(&dev_pager_object_list, handle);
  155         if (object == NULL) {
  156                 /*
  157                  * Allocate object and associate it with the pager.
  158                  */
  159                 object = vm_object_allocate(OBJT_DEVICE,
  160                         OFF_TO_IDX(foff + size));
  161                 object->handle = handle;
  162                 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
  163                 mtx_lock(&dev_pager_mtx);
  164                 TAILQ_INSERT_TAIL(&dev_pager_object_list, object, pager_object_list);
  165                 mtx_unlock(&dev_pager_mtx);
  166         } else {
  167                 /*
  168                  * Gain a reference to the object.
  169                  */
  170                 vm_object_reference(object);
  171                 if (OFF_TO_IDX(foff + size) > object->size)
  172                         object->size = OFF_TO_IDX(foff + size);
  173         }
  174 
  175         sx_xunlock(&dev_pager_sx);
  176         mtx_unlock(&Giant);
  177         return (object);
  178 }
  179 
  180 static void
  181 dev_pager_dealloc(object)
  182         vm_object_t object;
  183 {
  184         vm_page_t m;
  185 
  186         mtx_lock(&dev_pager_mtx);
  187         TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
  188         mtx_unlock(&dev_pager_mtx);
  189         /*
  190          * Free up our fake pages.
  191          */
  192         while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
  193                 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
  194                 dev_pager_putfake(m);
  195         }
  196 }
  197 
  198 static int
  199 dev_pager_getpages(object, m, count, reqpage)
  200         vm_object_t object;
  201         vm_page_t *m;
  202         int count;
  203         int reqpage;
  204 {
  205         vm_pindex_t offset;
  206         vm_paddr_t paddr;
  207         vm_page_t page;
  208         dev_t dev;
  209         int i, ret;
  210         d_mmap_t *mapfunc;
  211         int prot;
  212 
  213         mtx_assert(&Giant, MA_OWNED);
  214         dev = object->handle;
  215         offset = m[reqpage]->pindex;
  216         prot = PROT_READ;       /* XXX should pass in? */
  217         mapfunc = devsw(dev)->d_mmap;
  218 
  219         if (mapfunc == NULL || mapfunc == (d_mmap_t *)nullop)
  220                 panic("dev_pager_getpage: no map function");
  221 
  222         ret = (*mapfunc)(dev, (vm_offset_t)offset << PAGE_SHIFT, &paddr, prot);
  223         KASSERT(ret == 0, ("dev_pager_getpage: map function returns error"));
  224         /*
  225          * Replace the passed in reqpage page with our own fake page and
  226          * free up the all of the original pages.
  227          */
  228         page = dev_pager_getfake(paddr);
  229         TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
  230         vm_page_lock_queues();
  231         for (i = 0; i < count; i++)
  232                 vm_page_free(m[i]);
  233         vm_page_unlock_queues();
  234         vm_page_insert(page, object, offset);
  235 
  236         return (VM_PAGER_OK);
  237 }
  238 
  239 static void
  240 dev_pager_putpages(object, m, count, sync, rtvals)
  241         vm_object_t object;
  242         vm_page_t *m;
  243         int count;
  244         boolean_t sync;
  245         int *rtvals;
  246 {
  247         panic("dev_pager_putpage called");
  248 }
  249 
  250 static boolean_t
  251 dev_pager_haspage(object, pindex, before, after)
  252         vm_object_t object;
  253         vm_pindex_t pindex;
  254         int *before;
  255         int *after;
  256 {
  257         if (before != NULL)
  258                 *before = 0;
  259         if (after != NULL)
  260                 *after = 0;
  261         return (TRUE);
  262 }
  263 
  264 static vm_page_t
  265 dev_pager_getfake(paddr)
  266         vm_paddr_t paddr;
  267 {
  268         vm_page_t m;
  269 
  270         m = uma_zalloc(fakepg_zone, M_WAITOK);
  271 
  272         m->flags = PG_BUSY | PG_FICTITIOUS;
  273         m->valid = VM_PAGE_BITS_ALL;
  274         m->dirty = 0;
  275         m->busy = 0;
  276         m->queue = PQ_NONE;
  277         m->object = NULL;
  278 
  279         m->wire_count = 1;
  280         m->hold_count = 0;
  281         m->phys_addr = paddr;
  282 
  283         return (m);
  284 }
  285 
  286 static void
  287 dev_pager_putfake(m)
  288         vm_page_t m;
  289 {
  290         if (!(m->flags & PG_FICTITIOUS))
  291                 panic("dev_pager_putfake: bad page");
  292         uma_zfree(fakepg_zone, m);
  293 }

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

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