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/conf.h>
   32 #include <sys/kernel.h>
   33 #include <sys/lock.h>
   34 #include <sys/proc.h>
   35 #include <sys/mutex.h>
   36 #include <sys/mman.h>
   37 #include <sys/sysctl.h>
   38 
   39 #include <vm/vm.h>
   40 #include <vm/vm_object.h>
   41 #include <vm/vm_page.h>
   42 #include <vm/vm_pager.h>
   43 
   44 /* list of phys pager objects */
   45 static struct pagerlst phys_pager_object_list;
   46 /* protect access to phys_pager_object_list */
   47 static struct mtx phys_pager_mtx;
   48 
   49 static void
   50 phys_pager_init(void)
   51 {
   52 
   53         TAILQ_INIT(&phys_pager_object_list);
   54         mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
   55 }
   56 
   57 /*
   58  * MPSAFE
   59  */
   60 static vm_object_t
   61 phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
   62     vm_ooffset_t foff, struct ucred *cred)
   63 {
   64         vm_object_t object, object1;
   65         vm_pindex_t pindex;
   66 
   67         /*
   68          * Offset should be page aligned.
   69          */
   70         if (foff & PAGE_MASK)
   71                 return (NULL);
   72 
   73         pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
   74 
   75         if (handle != NULL) {
   76                 mtx_lock(&phys_pager_mtx);
   77                 /*
   78                  * Look up pager, creating as necessary.
   79                  */
   80                 object1 = NULL;
   81                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
   82                 if (object == NULL) {
   83                         /*
   84                          * Allocate object and associate it with the pager.
   85                          */
   86                         mtx_unlock(&phys_pager_mtx);
   87                         object1 = vm_object_allocate(OBJT_PHYS, pindex);
   88                         mtx_lock(&phys_pager_mtx);
   89                         object = vm_pager_object_lookup(&phys_pager_object_list,
   90                             handle);
   91                         if (object != NULL) {
   92                                 /*
   93                                  * We raced with other thread while
   94                                  * allocating object.
   95                                  */
   96                                 if (pindex > object->size)
   97                                         object->size = pindex;
   98                         } else {
   99                                 object = object1;
  100                                 object1 = NULL;
  101                                 object->handle = handle;
  102                                 TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
  103                                     pager_object_list);
  104                         }
  105                 } else {
  106                         if (pindex > object->size)
  107                                 object->size = pindex;
  108                 }
  109                 mtx_unlock(&phys_pager_mtx);
  110                 vm_object_deallocate(object1);
  111         } else {
  112                 object = vm_object_allocate(OBJT_PHYS, pindex);
  113         }
  114 
  115         return (object);
  116 }
  117 
  118 /*
  119  * MPSAFE
  120  */
  121 static void
  122 phys_pager_dealloc(vm_object_t object)
  123 {
  124 
  125         if (object->handle != NULL) {
  126                 VM_OBJECT_UNLOCK(object);
  127                 mtx_lock(&phys_pager_mtx);
  128                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
  129                 mtx_unlock(&phys_pager_mtx);
  130                 VM_OBJECT_LOCK(object);
  131         }
  132         object->handle = NULL;
  133         object->type = OBJT_DEAD;
  134 }
  135 
  136 /*
  137  * Fill as many pages as vm_fault has allocated for us.
  138  */
  139 static int
  140 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
  141 {
  142         int i;
  143 
  144         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
  145         for (i = 0; i < count; i++) {
  146                 if (m[i]->valid == 0) {
  147                         if ((m[i]->flags & PG_ZERO) == 0)
  148                                 pmap_zero_page(m[i]);
  149                         m[i]->valid = VM_PAGE_BITS_ALL;
  150                 }
  151                 KASSERT(m[i]->valid == VM_PAGE_BITS_ALL,
  152                     ("phys_pager_getpages: partially valid page %p", m[i]));
  153                 KASSERT(m[i]->dirty == 0,
  154                     ("phys_pager_getpages: dirty page %p", m[i]));
  155                 /* The requested page must remain busy, the others not. */
  156                 if (i == reqpage)
  157                         vm_page_flash(m[i]);
  158                 else
  159                         vm_page_wakeup(m[i]);
  160         }
  161         return (VM_PAGER_OK);
  162 }
  163 
  164 static void
  165 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
  166                     int *rtvals)
  167 {
  168 
  169         panic("phys_pager_putpage called");
  170 }
  171 
  172 /*
  173  * Implement a pretty aggressive clustered getpages strategy.  Hint that
  174  * everything in an entire 4MB window should be prefaulted at once.
  175  *
  176  * XXX 4MB (1024 slots per page table page) is convenient for x86,
  177  * but may not be for other arches.
  178  */
  179 #ifndef PHYSCLUSTER
  180 #define PHYSCLUSTER 1024
  181 #endif
  182 static boolean_t
  183 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
  184                    int *after)
  185 {
  186         vm_pindex_t base, end;
  187 
  188         base = pindex & (~(PHYSCLUSTER - 1));
  189         end = base + (PHYSCLUSTER - 1);
  190         if (before != NULL)
  191                 *before = pindex - base;
  192         if (after != NULL)
  193                 *after = end - pindex;
  194         return (TRUE);
  195 }
  196 
  197 struct pagerops physpagerops = {
  198         .pgo_init =     phys_pager_init,
  199         .pgo_alloc =    phys_pager_alloc,
  200         .pgo_dealloc =  phys_pager_dealloc,
  201         .pgo_getpages = phys_pager_getpages,
  202         .pgo_putpages = phys_pager_putpages,
  203         .pgo_haspage =  phys_pager_haspage,
  204 };

Cache object: 3ad62097391e9b0fef6f6a447c8df848


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