The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 2000 Peter Wemm
    3  *
    4  * Redistribution and use in source and binary forms, with or without
    5  * modification, are permitted provided that the following conditions
    6  * are met:
    7  * 1. Redistributions of source code must retain the above copyright
    8  *    notice, this list of conditions and the following disclaimer.
    9  * 2. Redistributions in binary form must reproduce the above copyright
   10  *    notice, this list of conditions and the following disclaimer in the
   11  *    documentation and/or other materials provided with the distribution.
   12  *
   13  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
   14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
   17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   23  * SUCH DAMAGE.
   24  */
   25 
   26 #include <sys/cdefs.h>
   27 __FBSDID("$FreeBSD$");
   28 
   29 #include <sys/param.h>
   30 #include <sys/systm.h>
   31 #include <sys/linker_set.h>
   32 #include <sys/conf.h>
   33 #include <sys/kernel.h>
   34 #include <sys/lock.h>
   35 #include <sys/proc.h>
   36 #include <sys/mutex.h>
   37 #include <sys/mman.h>
   38 #include <sys/sysctl.h>
   39 
   40 #include <vm/vm.h>
   41 #include <vm/vm_object.h>
   42 #include <vm/vm_page.h>
   43 #include <vm/vm_pager.h>
   44 
   45 /* list of phys pager objects */
   46 static struct pagerlst phys_pager_object_list;
   47 /* protect access to phys_pager_object_list */
   48 static struct mtx phys_pager_mtx;
   49 
   50 static void
   51 phys_pager_init(void)
   52 {
   53 
   54         TAILQ_INIT(&phys_pager_object_list);
   55         mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
   56 }
   57 
   58 /*
   59  * MPSAFE
   60  */
   61 static vm_object_t
   62 phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
   63                  vm_ooffset_t foff)
   64 {
   65         vm_object_t object, object1;
   66         vm_pindex_t pindex;
   67 
   68         /*
   69          * Offset should be page aligned.
   70          */
   71         if (foff & PAGE_MASK)
   72                 return (NULL);
   73 
   74         pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
   75 
   76         if (handle != NULL) {
   77                 mtx_lock(&phys_pager_mtx);
   78                 /*
   79                  * Look up pager, creating as necessary.
   80                  */
   81                 object1 = NULL;
   82                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
   83                 if (object == NULL) {
   84                         /*
   85                          * Allocate object and associate it with the pager.
   86                          */
   87                         mtx_unlock(&phys_pager_mtx);
   88                         object1 = vm_object_allocate(OBJT_PHYS, pindex);
   89                         mtx_lock(&phys_pager_mtx);
   90                         object = vm_pager_object_lookup(&phys_pager_object_list,
   91                             handle);
   92                         if (object != NULL) {
   93                                 /*
   94                                  * We raced with other thread while
   95                                  * allocating object.
   96                                  */
   97                                 if (pindex > object->size)
   98                                         object->size = pindex;
   99                         } else {
  100                                 object = object1;
  101                                 object1 = NULL;
  102                                 object->handle = handle;
  103                                 TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
  104                                     pager_object_list);
  105                         }
  106                 } else {
  107                         if (pindex > object->size)
  108                                 object->size = pindex;
  109                 }
  110                 mtx_unlock(&phys_pager_mtx);
  111                 vm_object_deallocate(object1);
  112         } else {
  113                 object = vm_object_allocate(OBJT_PHYS, pindex);
  114         }
  115 
  116         return (object);
  117 }
  118 
  119 /*
  120  * MPSAFE
  121  */
  122 static void
  123 phys_pager_dealloc(vm_object_t object)
  124 {
  125 
  126         if (object->handle != NULL) {
  127                 VM_OBJECT_UNLOCK(object);
  128                 mtx_lock(&phys_pager_mtx);
  129                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
  130                 mtx_unlock(&phys_pager_mtx);
  131                 VM_OBJECT_LOCK(object);
  132         }
  133 }
  134 
  135 /*
  136  * Fill as many pages as vm_fault has allocated for us.
  137  */
  138 static int
  139 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
  140 {
  141         int i;
  142 
  143         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
  144         for (i = 0; i < count; i++) {
  145                 if (m[i]->valid == 0) {
  146                         if ((m[i]->flags & PG_ZERO) == 0)
  147                                 pmap_zero_page(m[i]);
  148                         m[i]->valid = VM_PAGE_BITS_ALL;
  149                 }
  150                 KASSERT(m[i]->valid == VM_PAGE_BITS_ALL,
  151                     ("phys_pager_getpages: partially valid page %p", m[i]));
  152                 m[i]->dirty = 0;
  153                 /* The requested page must remain busy, the others not. */
  154                 if (reqpage != i) {
  155                         m[i]->oflags &= ~VPO_BUSY;
  156                         m[i]->busy = 0;
  157                 }
  158         }
  159         return (VM_PAGER_OK);
  160 }
  161 
  162 static void
  163 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
  164                     int *rtvals)
  165 {
  166 
  167         panic("phys_pager_putpage called");
  168 }
  169 
  170 /*
  171  * Implement a pretty aggressive clustered getpages strategy.  Hint that
  172  * everything in an entire 4MB window should be prefaulted at once.
  173  *
  174  * XXX 4MB (1024 slots per page table page) is convenient for x86,
  175  * but may not be for other arches.
  176  */
  177 #ifndef PHYSCLUSTER
  178 #define PHYSCLUSTER 1024
  179 #endif
  180 static boolean_t
  181 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
  182                    int *after)
  183 {
  184         vm_pindex_t base, end;
  185 
  186         base = pindex & (~(PHYSCLUSTER - 1));
  187         end = base + (PHYSCLUSTER - 1);
  188         if (before != NULL)
  189                 *before = pindex - base;
  190         if (after != NULL)
  191                 *after = end - pindex;
  192         return (TRUE);
  193 }
  194 
  195 struct pagerops physpagerops = {
  196         .pgo_init =     phys_pager_init,
  197         .pgo_alloc =    phys_pager_alloc,
  198         .pgo_dealloc =  phys_pager_dealloc,
  199         .pgo_getpages = phys_pager_getpages,
  200         .pgo_putpages = phys_pager_putpages,
  201         .pgo_haspage =  phys_pager_haspage,
  202 };

Cache object: 17c9a0b6b3e2425c530dce88d86e829f


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