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  * 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: src/sys/vm/device_pager.c,v 1.75.2.1 2005/01/31 23:27:02 imp Exp $");
   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         d_mmap_t *mapfunc;
  107         vm_object_t object;
  108         vm_pindex_t pindex;
  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         pindex = OFF_TO_IDX(foff + size);
  121 
  122         /*
  123          * Make sure this device can be mapped.
  124          */
  125         dev = handle;
  126         mtx_lock(&Giant);
  127         mapfunc = devsw(dev)->d_mmap;
  128         if (mapfunc == NULL || mapfunc == (d_mmap_t *)nullop) {
  129                 printf("obsolete map function %p\n", (void *)mapfunc);
  130                 mtx_unlock(&Giant);
  131                 return (NULL);
  132         }
  133 
  134         /*
  135          * Check that the specified range of the device allows the desired
  136          * protection.
  137          *
  138          * XXX assumes VM_PROT_* == PROT_*
  139          */
  140         npages = OFF_TO_IDX(size);
  141         for (off = foff; npages--; off += PAGE_SIZE)
  142                 if ((*mapfunc)(dev, off, &paddr, (int)prot) != 0) {
  143                         mtx_unlock(&Giant);
  144                         return (NULL);
  145                 }
  146 
  147         /*
  148          * Lock to prevent object creation race condition.
  149          */
  150         sx_xlock(&dev_pager_sx);
  151 
  152         /*
  153          * Look up pager, creating as necessary.
  154          */
  155         object = vm_pager_object_lookup(&dev_pager_object_list, handle);
  156         if (object == NULL) {
  157                 /*
  158                  * Allocate object and associate it with the pager.
  159                  */
  160                 object = vm_object_allocate(OBJT_DEVICE, pindex);
  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 (pindex > object->size)
  172                         object->size = pindex;
  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         struct cdev *dev;
  209         int i, ret;
  210         d_mmap_t *mapfunc;
  211         int prot;
  212 
  213         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
  214         dev = object->handle;
  215         offset = m[reqpage]->pindex;
  216         VM_OBJECT_UNLOCK(object);
  217         mtx_lock(&Giant);
  218         prot = PROT_READ;       /* XXX should pass in? */
  219         mapfunc = devsw(dev)->d_mmap;
  220 
  221         if (mapfunc == NULL || mapfunc == (d_mmap_t *)nullop)
  222                 panic("dev_pager_getpage: no map function");
  223 
  224         ret = (*mapfunc)(dev, (vm_offset_t)offset << PAGE_SHIFT, &paddr, prot);
  225         KASSERT(ret == 0, ("dev_pager_getpage: map function returns error"));
  226         mtx_unlock(&Giant);
  227 
  228         if ((m[reqpage]->flags & PG_FICTITIOUS) != 0) {
  229                 /*
  230                  * If the passed in reqpage page is a fake page, update it with
  231                  * the new physical address.
  232                  */
  233                 VM_OBJECT_LOCK(object);
  234                 dev_pager_updatefake(m[reqpage], paddr);
  235                 if (count > 1) {
  236                         vm_page_lock_queues();
  237                         for (i = 0; i < count; i++) {
  238                                 if (i != reqpage)
  239                                         vm_page_free(m[i]);
  240                         }
  241                         vm_page_unlock_queues();
  242                 }
  243         } else {
  244                 /*
  245                  * Replace the passed in reqpage page with our own fake page and
  246                  * free up the all of the original pages.
  247                  */
  248                 page = dev_pager_getfake(paddr);
  249                 VM_OBJECT_LOCK(object);
  250                 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
  251                 vm_page_lock_queues();
  252                 for (i = 0; i < count; i++)
  253                         vm_page_free(m[i]);
  254                 vm_page_unlock_queues();
  255                 vm_page_insert(page, object, offset);
  256                 m[reqpage] = page;
  257         }
  258 
  259         return (VM_PAGER_OK);
  260 }
  261 
  262 static void
  263 dev_pager_putpages(object, m, count, sync, rtvals)
  264         vm_object_t object;
  265         vm_page_t *m;
  266         int count;
  267         boolean_t sync;
  268         int *rtvals;
  269 {
  270         panic("dev_pager_putpage called");
  271 }
  272 
  273 static boolean_t
  274 dev_pager_haspage(object, pindex, before, after)
  275         vm_object_t object;
  276         vm_pindex_t pindex;
  277         int *before;
  278         int *after;
  279 {
  280         if (before != NULL)
  281                 *before = 0;
  282         if (after != NULL)
  283                 *after = 0;
  284         return (TRUE);
  285 }
  286 
  287 static vm_page_t
  288 dev_pager_getfake(paddr)
  289         vm_paddr_t paddr;
  290 {
  291         vm_page_t m;
  292 
  293         m = uma_zalloc(fakepg_zone, M_WAITOK);
  294 
  295         m->flags = PG_BUSY | PG_FICTITIOUS;
  296         m->valid = VM_PAGE_BITS_ALL;
  297         m->dirty = 0;
  298         m->busy = 0;
  299         m->queue = PQ_NONE;
  300         m->object = NULL;
  301 
  302         m->wire_count = 1;
  303         m->hold_count = 0;
  304         m->phys_addr = paddr;
  305 
  306         return (m);
  307 }
  308 
  309 static void
  310 dev_pager_putfake(m)
  311         vm_page_t m;
  312 {
  313         if (!(m->flags & PG_FICTITIOUS))
  314                 panic("dev_pager_putfake: bad page");
  315         uma_zfree(fakepg_zone, m);
  316 }
  317 
  318 static void
  319 dev_pager_updatefake(m, paddr)
  320         vm_page_t m;
  321         vm_paddr_t paddr;
  322 {
  323         if (!(m->flags & PG_FICTITIOUS))
  324                 panic("dev_pager_updatefake: bad page");
  325         m->phys_addr = paddr;
  326         m->valid = VM_PAGE_BITS_ALL;
  327 }
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FreeBSD/Linux Kernel Cross Reference sys/vm/device_pager.c

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