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/6.4/sys/vm/phys_pager.c 173517 2007-11-10 11:23:01Z remko $");
   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 /* prevent concurrant creation races */
   46 static int phys_pager_alloc_lock;
   47 /* list of phys pager objects */
   48 static struct pagerlst phys_pager_object_list;
   49 /* protect access to phys_pager_object_list */
   50 static struct mtx phys_pager_mtx;
   51 
   52 static void
   53 phys_pager_init(void)
   54 {
   55 
   56         TAILQ_INIT(&phys_pager_object_list);
   57         mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
   58 }
   59 
   60 /*
   61  * MPSAFE
   62  */
   63 static vm_object_t
   64 phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
   65                  vm_ooffset_t foff)
   66 {
   67         vm_object_t object;
   68         vm_pindex_t pindex;
   69 
   70         /*
   71          * Offset should be page aligned.
   72          */
   73         if (foff & PAGE_MASK)
   74                 return (NULL);
   75 
   76         pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
   77 
   78         if (handle != NULL) {
   79                 mtx_lock(&Giant);
   80                 /*
   81                  * Lock to prevent object creation race condition.
   82                  */
   83                 while (phys_pager_alloc_lock) {
   84                         phys_pager_alloc_lock = -1;
   85                         tsleep(&phys_pager_alloc_lock, PVM, "phyalc", 0);
   86                 }
   87                 phys_pager_alloc_lock = 1;
   88 
   89                 /*
   90                  * Look up pager, creating as necessary.
   91                  */
   92                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
   93                 if (object == NULL) {
   94                         /*
   95                          * Allocate object and associate it with the pager.
   96                          */
   97                         object = vm_object_allocate(OBJT_PHYS, pindex);
   98                         object->handle = handle;
   99                         mtx_lock(&phys_pager_mtx);
  100                         TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
  101                             pager_object_list);
  102                         mtx_unlock(&phys_pager_mtx);
  103                 } else {
  104                         /*
  105                          * Gain a reference to the object.
  106                          */
  107                         vm_object_reference(object);
  108                         if (pindex > object->size)
  109                                 object->size = pindex;
  110                 }
  111                 if (phys_pager_alloc_lock == -1)
  112                         wakeup(&phys_pager_alloc_lock);
  113                 phys_pager_alloc_lock = 0;
  114                 mtx_unlock(&Giant);
  115         } else {
  116                 object = vm_object_allocate(OBJT_PHYS, pindex);
  117         }
  118 
  119         return (object);
  120 }
  121 
  122 /*
  123  * MPSAFE
  124  */
  125 static void
  126 phys_pager_dealloc(vm_object_t object)
  127 {
  128 
  129         if (object->handle != NULL) {
  130                 mtx_lock(&phys_pager_mtx);
  131                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
  132                 mtx_unlock(&phys_pager_mtx);
  133         }
  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         }
  154         vm_page_lock_queues();
  155         for (i = 0; i < count; i++) {
  156                 /* Switch off pv_entries */
  157                 vm_page_unmanage(m[i]);
  158                 m[i]->dirty = 0;
  159                 /* The requested page must remain busy, the others not. */
  160                 if (reqpage != i) {
  161                         vm_page_flag_clear(m[i], PG_BUSY);
  162                         m[i]->busy = 0;
  163                 }
  164         }
  165         vm_page_unlock_queues();
  166         return (VM_PAGER_OK);
  167 }
  168 
  169 static void
  170 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
  171                     int *rtvals)
  172 {
  173 
  174         panic("phys_pager_putpage called");
  175 }
  176 
  177 /*
  178  * Implement a pretty aggressive clustered getpages strategy.  Hint that
  179  * everything in an entire 4MB window should be prefaulted at once.
  180  *
  181  * XXX 4MB (1024 slots per page table page) is convenient for x86,
  182  * but may not be for other arches.
  183  */
  184 #ifndef PHYSCLUSTER
  185 #define PHYSCLUSTER 1024
  186 #endif
  187 static boolean_t
  188 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
  189                    int *after)
  190 {
  191         vm_pindex_t base, end;
  192 
  193         base = pindex & (~(PHYSCLUSTER - 1));
  194         end = base + (PHYSCLUSTER - 1);
  195         if (before != NULL)
  196                 *before = pindex - base;
  197         if (after != NULL)
  198                 *after = end - pindex;
  199         return (TRUE);
  200 }
  201 
  202 struct pagerops physpagerops = {
  203         .pgo_init =     phys_pager_init,
  204         .pgo_alloc =    phys_pager_alloc,
  205         .pgo_dealloc =  phys_pager_dealloc,
  206         .pgo_getpages = phys_pager_getpages,
  207         .pgo_putpages = phys_pager_putpages,
  208         .pgo_haspage =  phys_pager_haspage,
  209 };

Cache object: 4b96ff79d8bb3a1ccff62815834d3eca


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