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/vm_kern.c

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    1 /*
    2  * Copyright (c) 1991, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This code is derived from software contributed to Berkeley by
    6  * The Mach Operating System project at Carnegie-Mellon University.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. All advertising materials mentioning features or use of this software
   17  *    must display the following acknowledgement:
   18  *      This product includes software developed by the University of
   19  *      California, Berkeley and its contributors.
   20  * 4. Neither the name of the University nor the names of its contributors
   21  *    may be used to endorse or promote products derived from this software
   22  *    without specific prior written permission.
   23  *
   24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   34  * SUCH DAMAGE.
   35  *
   36  *      from: @(#)vm_kern.c     8.3 (Berkeley) 1/12/94
   37  *
   38  *
   39  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
   40  * All rights reserved.
   41  *
   42  * Authors: Avadis Tevanian, Jr., Michael Wayne Young
   43  *
   44  * Permission to use, copy, modify and distribute this software and
   45  * its documentation is hereby granted, provided that both the copyright
   46  * notice and this permission notice appear in all copies of the
   47  * software, derivative works or modified versions, and any portions
   48  * thereof, and that both notices appear in supporting documentation.
   49  *
   50  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
   51  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
   52  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   53  *
   54  * Carnegie Mellon requests users of this software to return to
   55  *
   56  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   57  *  School of Computer Science
   58  *  Carnegie Mellon University
   59  *  Pittsburgh PA 15213-3890
   60  *
   61  * any improvements or extensions that they make and grant Carnegie the
   62  * rights to redistribute these changes.
   63  *
   64  * $FreeBSD: stable/3/sys/vm/vm_kern.c 50583 1999-08-29 16:33:42Z peter $
   65  */
   66 
   67 /*
   68  *      Kernel memory management.
   69  */
   70 
   71 #include <sys/param.h>
   72 #include <sys/systm.h>
   73 #include <sys/proc.h>
   74 #include <sys/malloc.h>
   75 
   76 #include <vm/vm.h>
   77 #include <vm/vm_param.h>
   78 #include <vm/vm_prot.h>
   79 #include <sys/lock.h>
   80 #include <vm/pmap.h>
   81 #include <vm/vm_map.h>
   82 #include <vm/vm_object.h>
   83 #include <vm/vm_page.h>
   84 #include <vm/vm_pageout.h>
   85 #include <vm/vm_extern.h>
   86 
   87 vm_map_t kernel_map=0;
   88 vm_map_t kmem_map=0;
   89 vm_map_t exec_map=0;
   90 vm_map_t clean_map=0;
   91 vm_map_t u_map=0;
   92 vm_map_t buffer_map=0;
   93 vm_map_t mb_map=0;
   94 int mb_map_full=0;
   95 vm_map_t io_map=0;
   96 vm_map_t phys_map=0;
   97 
   98 /*
   99  *      kmem_alloc_pageable:
  100  *
  101  *      Allocate pageable memory to the kernel's address map.
  102  *      "map" must be kernel_map or a submap of kernel_map.
  103  */
  104 
  105 vm_offset_t
  106 kmem_alloc_pageable(map, size)
  107         vm_map_t map;
  108         register vm_size_t size;
  109 {
  110         vm_offset_t addr;
  111         register int result;
  112 
  113         size = round_page(size);
  114         addr = vm_map_min(map);
  115         result = vm_map_find(map, NULL, (vm_offset_t) 0,
  116             &addr, size, TRUE, VM_PROT_ALL, VM_PROT_ALL, 0);
  117         if (result != KERN_SUCCESS) {
  118                 return (0);
  119         }
  120         return (addr);
  121 }
  122 
  123 /*
  124  *      Allocate wired-down memory in the kernel's address map
  125  *      or a submap.
  126  */
  127 vm_offset_t
  128 kmem_alloc(map, size)
  129         register vm_map_t map;
  130         register vm_size_t size;
  131 {
  132         vm_offset_t addr;
  133         register vm_offset_t offset;
  134         vm_offset_t i;
  135 
  136         size = round_page(size);
  137 
  138         /*
  139          * Use the kernel object for wired-down kernel pages. Assume that no
  140          * region of the kernel object is referenced more than once.
  141          */
  142 
  143         /*
  144          * Locate sufficient space in the map.  This will give us the final
  145          * virtual address for the new memory, and thus will tell us the
  146          * offset within the kernel map.
  147          */
  148         vm_map_lock(map);
  149         if (vm_map_findspace(map, vm_map_min(map), size, &addr)) {
  150                 vm_map_unlock(map);
  151                 return (0);
  152         }
  153         offset = addr - VM_MIN_KERNEL_ADDRESS;
  154         vm_object_reference(kernel_object);
  155         vm_map_insert(map, kernel_object, offset, addr, addr + size,
  156                 VM_PROT_ALL, VM_PROT_ALL, 0);
  157         vm_map_unlock(map);
  158 
  159         /*
  160          * Guarantee that there are pages already in this object before
  161          * calling vm_map_pageable.  This is to prevent the following
  162          * scenario:
  163          *
  164          * 1) Threads have swapped out, so that there is a pager for the
  165          * kernel_object. 2) The kmsg zone is empty, and so we are
  166          * kmem_allocing a new page for it. 3) vm_map_pageable calls vm_fault;
  167          * there is no page, but there is a pager, so we call
  168          * pager_data_request.  But the kmsg zone is empty, so we must
  169          * kmem_alloc. 4) goto 1 5) Even if the kmsg zone is not empty: when
  170          * we get the data back from the pager, it will be (very stale)
  171          * non-zero data.  kmem_alloc is defined to return zero-filled memory.
  172          *
  173          * We're intentionally not activating the pages we allocate to prevent a
  174          * race with page-out.  vm_map_pageable will wire the pages.
  175          */
  176 
  177         for (i = 0; i < size; i += PAGE_SIZE) {
  178                 vm_page_t mem;
  179 
  180                 mem = vm_page_grab(kernel_object, OFF_TO_IDX(offset + i),
  181                                 VM_ALLOC_ZERO | VM_ALLOC_RETRY);
  182                 if ((mem->flags & PG_ZERO) == 0)
  183                         vm_page_zero_fill(mem);
  184                 vm_page_flag_clear(mem, PG_ZERO);
  185                 vm_page_wakeup(mem);
  186                 mem->valid = VM_PAGE_BITS_ALL;
  187         }
  188 
  189         /*
  190          * And finally, mark the data as non-pageable.
  191          */
  192 
  193         (void) vm_map_pageable(map, (vm_offset_t) addr, addr + size, FALSE);
  194 
  195         return (addr);
  196 }
  197 
  198 /*
  199  *      kmem_free:
  200  *
  201  *      Release a region of kernel virtual memory allocated
  202  *      with kmem_alloc, and return the physical pages
  203  *      associated with that region.
  204  */
  205 void
  206 kmem_free(map, addr, size)
  207         vm_map_t map;
  208         register vm_offset_t addr;
  209         vm_size_t size;
  210 {
  211         (void) vm_map_remove(map, trunc_page(addr), round_page(addr + size));
  212 }
  213 
  214 /*
  215  *      kmem_suballoc:
  216  *
  217  *      Allocates a map to manage a subrange
  218  *      of the kernel virtual address space.
  219  *
  220  *      Arguments are as follows:
  221  *
  222  *      parent          Map to take range from
  223  *      size            Size of range to find
  224  *      min, max        Returned endpoints of map
  225  *      pageable        Can the region be paged
  226  */
  227 vm_map_t
  228 kmem_suballoc(parent, min, max, size)
  229         register vm_map_t parent;
  230         vm_offset_t *min, *max;
  231         register vm_size_t size;
  232 {
  233         register int ret;
  234         vm_map_t result;
  235 
  236         size = round_page(size);
  237 
  238         *min = (vm_offset_t) vm_map_min(parent);
  239         ret = vm_map_find(parent, NULL, (vm_offset_t) 0,
  240             min, size, TRUE, VM_PROT_ALL, VM_PROT_ALL, 0);
  241         if (ret != KERN_SUCCESS) {
  242                 printf("kmem_suballoc: bad status return of %d.\n", ret);
  243                 panic("kmem_suballoc");
  244         }
  245         *max = *min + size;
  246         pmap_reference(vm_map_pmap(parent));
  247         result = vm_map_create(vm_map_pmap(parent), *min, *max);
  248         if (result == NULL)
  249                 panic("kmem_suballoc: cannot create submap");
  250         if ((ret = vm_map_submap(parent, *min, *max, result)) != KERN_SUCCESS)
  251                 panic("kmem_suballoc: unable to change range to submap");
  252         return (result);
  253 }
  254 
  255 /*
  256  * Allocate wired-down memory in the kernel's address map for the higher
  257  * level kernel memory allocator (kern/kern_malloc.c).  We cannot use
  258  * kmem_alloc() because we may need to allocate memory at interrupt
  259  * level where we cannot block (canwait == FALSE).
  260  *
  261  * This routine has its own private kernel submap (kmem_map) and object
  262  * (kmem_object).  This, combined with the fact that only malloc uses
  263  * this routine, ensures that we will never block in map or object waits.
  264  *
  265  * Note that this still only works in a uni-processor environment and
  266  * when called at splhigh().
  267  *
  268  * We don't worry about expanding the map (adding entries) since entries
  269  * for wired maps are statically allocated.
  270  */
  271 vm_offset_t
  272 kmem_malloc(map, size, waitflag)
  273         register vm_map_t map;
  274         register vm_size_t size;
  275         boolean_t waitflag;
  276 {
  277         register vm_offset_t offset, i;
  278         vm_map_entry_t entry;
  279         vm_offset_t addr;
  280         vm_page_t m;
  281 
  282         if (map != kmem_map && map != mb_map)
  283                 panic("kmem_malloc: map != {kmem,mb}_map");
  284 
  285         size = round_page(size);
  286         addr = vm_map_min(map);
  287 
  288         /*
  289          * Locate sufficient space in the map.  This will give us the final
  290          * virtual address for the new memory, and thus will tell us the
  291          * offset within the kernel map.
  292          */
  293         vm_map_lock(map);
  294         if (vm_map_findspace(map, vm_map_min(map), size, &addr)) {
  295                 vm_map_unlock(map);
  296                 if (map == mb_map) {
  297                         mb_map_full = TRUE;
  298                         printf("Out of mbuf clusters - adjust NMBCLUSTERS or increase maxusers!\n");
  299                         return (0);
  300                 }
  301                 if (waitflag == M_WAITOK)
  302                         panic("kmem_malloc(%d): kmem_map too small: %d total allocated",
  303                                 size, map->size);
  304                 return (0);
  305         }
  306         offset = addr - VM_MIN_KERNEL_ADDRESS;
  307         vm_object_reference(kmem_object);
  308         vm_map_insert(map, kmem_object, offset, addr, addr + size,
  309                 VM_PROT_ALL, VM_PROT_ALL, 0);
  310 
  311         for (i = 0; i < size; i += PAGE_SIZE) {
  312 retry:
  313                 m = vm_page_alloc(kmem_object, OFF_TO_IDX(offset + i),
  314                         (waitflag == M_NOWAIT) ? VM_ALLOC_INTERRUPT : VM_ALLOC_SYSTEM);
  315 
  316                 /*
  317                  * Ran out of space, free everything up and return. Don't need
  318                  * to lock page queues here as we know that the pages we got
  319                  * aren't on any queues.
  320                  */
  321                 if (m == NULL) {
  322                         if (waitflag == M_WAITOK) {
  323                                 vm_map_unlock(map);
  324                                 VM_WAIT;
  325                                 vm_map_lock(map);
  326                                 goto retry;
  327                         }
  328                         vm_map_delete(map, addr, addr + size);
  329                         vm_map_unlock(map);
  330                         return (0);
  331                 }
  332                 vm_page_flag_clear(m, PG_ZERO);
  333                 m->valid = VM_PAGE_BITS_ALL;
  334         }
  335 
  336         /*
  337          * Mark map entry as non-pageable. Assert: vm_map_insert() will never
  338          * be able to extend the previous entry so there will be a new entry
  339          * exactly corresponding to this address range and it will have
  340          * wired_count == 0.
  341          */
  342         if (!vm_map_lookup_entry(map, addr, &entry) ||
  343             entry->start != addr || entry->end != addr + size ||
  344             entry->wired_count != 0)
  345                 panic("kmem_malloc: entry not found or misaligned");
  346         entry->wired_count = 1;
  347 
  348         vm_map_simplify_entry(map, entry);
  349 
  350         /*
  351          * Loop thru pages, entering them in the pmap. (We cannot add them to
  352          * the wired count without wrapping the vm_page_queue_lock in
  353          * splimp...)
  354          */
  355         for (i = 0; i < size; i += PAGE_SIZE) {
  356                 m = vm_page_lookup(kmem_object, OFF_TO_IDX(offset + i));
  357                 vm_page_wire(m);
  358                 vm_page_wakeup(m);
  359                 pmap_enter(kernel_pmap, addr + i, VM_PAGE_TO_PHYS(m),
  360                         VM_PROT_ALL, 1);
  361                 vm_page_flag_set(m, PG_MAPPED | PG_WRITEABLE | PG_REFERENCED);
  362         }
  363         vm_map_unlock(map);
  364 
  365         return (addr);
  366 }
  367 
  368 /*
  369  *      kmem_alloc_wait
  370  *
  371  *      Allocates pageable memory from a sub-map of the kernel.  If the submap
  372  *      has no room, the caller sleeps waiting for more memory in the submap.
  373  *
  374  */
  375 vm_offset_t
  376 kmem_alloc_wait(map, size)
  377         vm_map_t map;
  378         vm_size_t size;
  379 {
  380         vm_offset_t addr;
  381 
  382         size = round_page(size);
  383 
  384         for (;;) {
  385                 /*
  386                  * To make this work for more than one map, use the map's lock
  387                  * to lock out sleepers/wakers.
  388                  */
  389                 vm_map_lock(map);
  390                 if (vm_map_findspace(map, vm_map_min(map), size, &addr) == 0)
  391                         break;
  392                 /* no space now; see if we can ever get space */
  393                 if (vm_map_max(map) - vm_map_min(map) < size) {
  394                         vm_map_unlock(map);
  395                         return (0);
  396                 }
  397                 vm_map_unlock(map);
  398                 tsleep(map, PVM, "kmaw", 0);
  399         }
  400         vm_map_insert(map, NULL, (vm_offset_t) 0, addr, addr + size, VM_PROT_ALL, VM_PROT_ALL, 0);
  401         vm_map_unlock(map);
  402         return (addr);
  403 }
  404 
  405 /*
  406  *      kmem_free_wakeup
  407  *
  408  *      Returns memory to a submap of the kernel, and wakes up any processes
  409  *      waiting for memory in that map.
  410  */
  411 void
  412 kmem_free_wakeup(map, addr, size)
  413         vm_map_t map;
  414         vm_offset_t addr;
  415         vm_size_t size;
  416 {
  417         vm_map_lock(map);
  418         (void) vm_map_delete(map, trunc_page(addr), round_page(addr + size));
  419         wakeup(map);
  420         vm_map_unlock(map);
  421 }
  422 
  423 /*
  424  * Create the kernel map; insert a mapping covering kernel text, data, bss,
  425  * and all space allocated thus far (`boostrap' data).  The new map will thus
  426  * map the range between VM_MIN_KERNEL_ADDRESS and `start' as allocated, and
  427  * the range between `start' and `end' as free.
  428  */
  429 void
  430 kmem_init(start, end)
  431         vm_offset_t start, end;
  432 {
  433         register vm_map_t m;
  434 
  435         m = vm_map_create(kernel_pmap, VM_MIN_KERNEL_ADDRESS, end);
  436         vm_map_lock(m);
  437         /* N.B.: cannot use kgdb to debug, starting with this assignment ... */
  438         kernel_map = m;
  439         kernel_map->system_map = 1;
  440         (void) vm_map_insert(m, NULL, (vm_offset_t) 0,
  441             VM_MIN_KERNEL_ADDRESS, start, VM_PROT_ALL, VM_PROT_ALL, 0);
  442         /* ... and ending with the completion of the above `insert' */
  443         vm_map_unlock(m);
  444 }

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