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  */
   40 
   41 #include <sys/cdefs.h>
   42 __FBSDID("$FreeBSD: releng/5.2/sys/vm/device_pager.c 120824 2003-10-05 22:23:44Z alc $");
   43 
   44 #include <sys/param.h>
   45 #include <sys/systm.h>
   46 #include <sys/conf.h>
   47 #include <sys/lock.h>
   48 #include <sys/proc.h>
   49 #include <sys/mutex.h>
   50 #include <sys/mman.h>
   51 #include <sys/sx.h>
   52 
   53 #include <vm/vm.h>
   54 #include <vm/vm_object.h>
   55 #include <vm/vm_page.h>
   56 #include <vm/vm_pager.h>
   57 #include <vm/uma.h>
   58 
   59 static void dev_pager_init(void);
   60 static vm_object_t dev_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
   61                 vm_ooffset_t);
   62 static void dev_pager_dealloc(vm_object_t);
   63 static int dev_pager_getpages(vm_object_t, vm_page_t *, int, int);
   64 static void dev_pager_putpages(vm_object_t, vm_page_t *, int, 
   65                 boolean_t, int *);
   66 static boolean_t dev_pager_haspage(vm_object_t, vm_pindex_t, int *,
   67                 int *);
   68 
   69 /* list of device pager objects */
   70 static struct pagerlst dev_pager_object_list;
   71 /* protect against object creation */
   72 static struct sx dev_pager_sx;
   73 /* protect list manipulation */
   74 static struct mtx dev_pager_mtx;
   75 
   76 
   77 static uma_zone_t fakepg_zone;
   78 
   79 static vm_page_t dev_pager_getfake(vm_paddr_t);
   80 static void dev_pager_putfake(vm_page_t);
   81 
   82 struct pagerops devicepagerops = {
   83         .pgo_init =     dev_pager_init,
   84         .pgo_alloc =    dev_pager_alloc,
   85         .pgo_dealloc =  dev_pager_dealloc,
   86         .pgo_getpages = dev_pager_getpages,
   87         .pgo_putpages = dev_pager_putpages,
   88         .pgo_haspage =  dev_pager_haspage,
   89 };
   90 
   91 static void
   92 dev_pager_init()
   93 {
   94         TAILQ_INIT(&dev_pager_object_list);
   95         sx_init(&dev_pager_sx, "dev_pager create");
   96         mtx_init(&dev_pager_mtx, "dev_pager list", NULL, MTX_DEF);
   97         fakepg_zone = uma_zcreate("DP fakepg", sizeof(struct vm_page),
   98             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR,
   99             UMA_ZONE_NOFREE|UMA_ZONE_VM); 
  100 }
  101 
  102 /*
  103  * MPSAFE
  104  */
  105 static vm_object_t
  106 dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff)
  107 {
  108         dev_t dev;
  109         d_mmap_t *mapfunc;
  110         vm_object_t object;
  111         unsigned int npages;
  112         vm_paddr_t paddr;
  113         vm_offset_t off;
  114 
  115         /*
  116          * Offset should be page aligned.
  117          */
  118         if (foff & PAGE_MASK)
  119                 return (NULL);
  120 
  121         size = round_page(size);
  122 
  123         /*
  124          * Make sure this device can be mapped.
  125          */
  126         dev = handle;
  127         mtx_lock(&Giant);
  128         mapfunc = devsw(dev)->d_mmap;
  129         if (mapfunc == NULL || mapfunc == (d_mmap_t *)nullop) {
  130                 printf("obsolete map function %p\n", (void *)mapfunc);
  131                 mtx_unlock(&Giant);
  132                 return (NULL);
  133         }
  134 
  135         /*
  136          * Check that the specified range of the device allows the desired
  137          * protection.
  138          *
  139          * XXX assumes VM_PROT_* == PROT_*
  140          */
  141         npages = OFF_TO_IDX(size);
  142         for (off = foff; npages--; off += PAGE_SIZE)
  143                 if ((*mapfunc)(dev, off, &paddr, (int)prot) != 0) {
  144                         mtx_unlock(&Giant);
  145                         return (NULL);
  146                 }
  147 
  148         /*
  149          * Lock to prevent object creation race condition.
  150          */
  151         sx_xlock(&dev_pager_sx);
  152 
  153         /*
  154          * Look up pager, creating as necessary.
  155          */
  156         object = vm_pager_object_lookup(&dev_pager_object_list, handle);
  157         if (object == NULL) {
  158                 /*
  159                  * Allocate object and associate it with the pager.
  160                  */
  161                 object = vm_object_allocate(OBJT_DEVICE,
  162                         OFF_TO_IDX(foff + size));
  163                 object->handle = handle;
  164                 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
  165                 mtx_lock(&dev_pager_mtx);
  166                 TAILQ_INSERT_TAIL(&dev_pager_object_list, object, pager_object_list);
  167                 mtx_unlock(&dev_pager_mtx);
  168         } else {
  169                 /*
  170                  * Gain a reference to the object.
  171                  */
  172                 vm_object_reference(object);
  173                 if (OFF_TO_IDX(foff + size) > object->size)
  174                         object->size = OFF_TO_IDX(foff + size);
  175         }
  176 
  177         sx_xunlock(&dev_pager_sx);
  178         mtx_unlock(&Giant);
  179         return (object);
  180 }
  181 
  182 static void
  183 dev_pager_dealloc(object)
  184         vm_object_t object;
  185 {
  186         vm_page_t m;
  187 
  188         mtx_lock(&dev_pager_mtx);
  189         TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
  190         mtx_unlock(&dev_pager_mtx);
  191         /*
  192          * Free up our fake pages.
  193          */
  194         while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
  195                 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
  196                 dev_pager_putfake(m);
  197         }
  198 }
  199 
  200 static int
  201 dev_pager_getpages(object, m, count, reqpage)
  202         vm_object_t object;
  203         vm_page_t *m;
  204         int count;
  205         int reqpage;
  206 {
  207         vm_pindex_t offset;
  208         vm_paddr_t paddr;
  209         vm_page_t page;
  210         dev_t dev;
  211         int i, ret;
  212         d_mmap_t *mapfunc;
  213         int prot;
  214 
  215         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
  216         dev = object->handle;
  217         offset = m[reqpage]->pindex;
  218         VM_OBJECT_UNLOCK(object);
  219         prot = PROT_READ;       /* XXX should pass in? */
  220         mapfunc = devsw(dev)->d_mmap;
  221 
  222         if (mapfunc == NULL || mapfunc == (d_mmap_t *)nullop)
  223                 panic("dev_pager_getpage: no map function");
  224 
  225         ret = (*mapfunc)(dev, (vm_offset_t)offset << PAGE_SHIFT, &paddr, prot);
  226         KASSERT(ret == 0, ("dev_pager_getpage: map function returns error"));
  227         /*
  228          * Replace the passed in reqpage page with our own fake page and
  229          * free up the all of the original pages.
  230          */
  231         page = dev_pager_getfake(paddr);
  232         VM_OBJECT_LOCK(object);
  233         TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
  234         vm_page_lock_queues();
  235         for (i = 0; i < count; i++)
  236                 vm_page_free(m[i]);
  237         vm_page_unlock_queues();
  238         vm_page_insert(page, object, offset);
  239         m[reqpage] = page;
  240 
  241         return (VM_PAGER_OK);
  242 }
  243 
  244 static void
  245 dev_pager_putpages(object, m, count, sync, rtvals)
  246         vm_object_t object;
  247         vm_page_t *m;
  248         int count;
  249         boolean_t sync;
  250         int *rtvals;
  251 {
  252         panic("dev_pager_putpage called");
  253 }
  254 
  255 static boolean_t
  256 dev_pager_haspage(object, pindex, before, after)
  257         vm_object_t object;
  258         vm_pindex_t pindex;
  259         int *before;
  260         int *after;
  261 {
  262         if (before != NULL)
  263                 *before = 0;
  264         if (after != NULL)
  265                 *after = 0;
  266         return (TRUE);
  267 }
  268 
  269 static vm_page_t
  270 dev_pager_getfake(paddr)
  271         vm_paddr_t paddr;
  272 {
  273         vm_page_t m;
  274 
  275         m = uma_zalloc(fakepg_zone, M_WAITOK);
  276 
  277         m->flags = PG_BUSY | PG_FICTITIOUS;
  278         m->valid = VM_PAGE_BITS_ALL;
  279         m->dirty = 0;
  280         m->busy = 0;
  281         m->queue = PQ_NONE;
  282         m->object = NULL;
  283 
  284         m->wire_count = 1;
  285         m->hold_count = 0;
  286         m->phys_addr = paddr;
  287 
  288         return (m);
  289 }
  290 
  291 static void
  292 dev_pager_putfake(m)
  293         vm_page_t m;
  294 {
  295         if (!(m->flags & PG_FICTITIOUS))
  296                 panic("dev_pager_putfake: bad page");
  297         uma_zfree(fakepg_zone, m);
  298 }
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FreeBSD/Linux Kernel Cross Reference sys/vm/device_pager.c

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