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: releng/10.3/sys/vm/phys_pager.c 284100 2015-06-06 20:37:40Z jhb $");
   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/rwlock.h>
   38 #include <sys/sysctl.h>
   39 
   40 #include <vm/vm.h>
   41 #include <vm/vm_param.h>
   42 #include <vm/vm_object.h>
   43 #include <vm/vm_page.h>
   44 #include <vm/vm_pager.h>
   45 
   46 /* list of phys pager objects */
   47 static struct pagerlst phys_pager_object_list;
   48 /* protect access to phys_pager_object_list */
   49 static struct mtx phys_pager_mtx;
   50 
   51 static void
   52 phys_pager_init(void)
   53 {
   54 
   55         TAILQ_INIT(&phys_pager_object_list);
   56         mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
   57 }
   58 
   59 /*
   60  * MPSAFE
   61  */
   62 static vm_object_t
   63 phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
   64     vm_ooffset_t foff, struct ucred *cred)
   65 {
   66         vm_object_t object, object1;
   67         vm_pindex_t pindex;
   68 
   69         /*
   70          * Offset should be page aligned.
   71          */
   72         if (foff & PAGE_MASK)
   73                 return (NULL);
   74 
   75         pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
   76 
   77         if (handle != NULL) {
   78                 mtx_lock(&phys_pager_mtx);
   79                 /*
   80                  * Look up pager, creating as necessary.
   81                  */
   82                 object1 = NULL;
   83                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
   84                 if (object == NULL) {
   85                         /*
   86                          * Allocate object and associate it with the pager.
   87                          */
   88                         mtx_unlock(&phys_pager_mtx);
   89                         object1 = vm_object_allocate(OBJT_PHYS, pindex);
   90                         mtx_lock(&phys_pager_mtx);
   91                         object = vm_pager_object_lookup(&phys_pager_object_list,
   92                             handle);
   93                         if (object != NULL) {
   94                                 /*
   95                                  * We raced with other thread while
   96                                  * allocating object.
   97                                  */
   98                                 if (pindex > object->size)
   99                                         object->size = pindex;
  100                         } else {
  101                                 object = object1;
  102                                 object1 = NULL;
  103                                 object->handle = handle;
  104                                 TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
  105                                     pager_object_list);
  106                         }
  107                 } else {
  108                         if (pindex > object->size)
  109                                 object->size = pindex;
  110                 }
  111                 mtx_unlock(&phys_pager_mtx);
  112                 vm_object_deallocate(object1);
  113         } else {
  114                 object = vm_object_allocate(OBJT_PHYS, pindex);
  115         }
  116 
  117         return (object);
  118 }
  119 
  120 /*
  121  * MPSAFE
  122  */
  123 static void
  124 phys_pager_dealloc(vm_object_t object)
  125 {
  126 
  127         if (object->handle != NULL) {
  128                 VM_OBJECT_WUNLOCK(object);
  129                 mtx_lock(&phys_pager_mtx);
  130                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
  131                 mtx_unlock(&phys_pager_mtx);
  132                 VM_OBJECT_WLOCK(object);
  133         }
  134         object->handle = NULL;
  135         object->type = OBJT_DEAD;
  136 }
  137 
  138 /*
  139  * Fill as many pages as vm_fault has allocated for us.
  140  */
  141 static int
  142 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
  143 {
  144         int i;
  145 
  146         VM_OBJECT_ASSERT_WLOCKED(object);
  147         for (i = 0; i < count; i++) {
  148                 if (m[i]->valid == 0) {
  149                         if ((m[i]->flags & PG_ZERO) == 0)
  150                                 pmap_zero_page(m[i]);
  151                         m[i]->valid = VM_PAGE_BITS_ALL;
  152                 }
  153                 KASSERT(m[i]->valid == VM_PAGE_BITS_ALL,
  154                     ("phys_pager_getpages: partially valid page %p", m[i]));
  155                 KASSERT(m[i]->dirty == 0,
  156                     ("phys_pager_getpages: dirty page %p", m[i]));
  157                 /* The requested page must remain busy, the others not. */
  158                 if (i == reqpage) {
  159                         vm_page_lock(m[i]);
  160                         vm_page_flash(m[i]);
  161                         vm_page_unlock(m[i]);
  162                 } else
  163                         vm_page_xunbusy(m[i]);
  164         }
  165         return (VM_PAGER_OK);
  166 }
  167 
  168 static void
  169 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
  170                     int *rtvals)
  171 {
  172 
  173         panic("phys_pager_putpage called");
  174 }
  175 
  176 /*
  177  * Implement a pretty aggressive clustered getpages strategy.  Hint that
  178  * everything in an entire 4MB window should be prefaulted at once.
  179  *
  180  * XXX 4MB (1024 slots per page table page) is convenient for x86,
  181  * but may not be for other arches.
  182  */
  183 #ifndef PHYSCLUSTER
  184 #define PHYSCLUSTER 1024
  185 #endif
  186 static boolean_t
  187 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
  188                    int *after)
  189 {
  190         vm_pindex_t base, end;
  191 
  192         base = pindex & (~(PHYSCLUSTER - 1));
  193         end = base + (PHYSCLUSTER - 1);
  194         if (before != NULL)
  195                 *before = pindex - base;
  196         if (after != NULL)
  197                 *after = end - pindex;
  198         return (TRUE);
  199 }
  200 
  201 struct pagerops physpagerops = {
  202         .pgo_init =     phys_pager_init,
  203         .pgo_alloc =    phys_pager_alloc,
  204         .pgo_dealloc =  phys_pager_dealloc,
  205         .pgo_getpages = phys_pager_getpages,
  206         .pgo_putpages = phys_pager_putpages,
  207         .pgo_haspage =  phys_pager_haspage,
  208 };

Cache object: 5ae612f14e8e8fcc596d24bc9c81bd98


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