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

     /*
      * Copyright (c) 1991, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
      * The Mach Operating System project at Carnegie-Mellon University.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      from: @(#)vm_kern.c     8.3 (Berkeley) 1/12/94
     *
     *
     * Copyright (c) 1987, 1990 Carnegie-Mellon University.
     * All rights reserved.
     *
     * Authors: Avadis Tevanian, Jr., Michael Wayne Young
     *
     * Permission to use, copy, modify and distribute this software and
     * its documentation is hereby granted, provided that both the copyright
     * notice and this permission notice appear in all copies of the
     * software, derivative works or modified versions, and any portions
     * thereof, and that both notices appear in supporting documentation.
     *
     * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
     * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     *
     * Carnegie Mellon requests users of this software to return to
     *
     *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
     *  School of Computer Science
     *  Carnegie Mellon University
     *  Pittsburgh PA 15213-3890
     *
     * any improvements or extensions that they make and grant Carnegie the
     * rights to redistribute these changes.
     *
     * $FreeBSD$
     */
    
    /*
     *      Kernel memory management.
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/proc.h>
    #include <sys/malloc.h>
    
    #include <vm/vm.h>
    #include <vm/vm_param.h>
    #include <sys/lock.h>
    #include <vm/pmap.h>
    #include <vm/vm_map.h>
    #include <vm/vm_object.h>
    #include <vm/vm_page.h>
    #include <vm/vm_pageout.h>
    #include <vm/vm_extern.h>
    
    vm_map_t kernel_map=0;
    vm_map_t kmem_map=0;
    vm_map_t exec_map=0;
    vm_map_t clean_map=0;
    vm_map_t buffer_map=0;
    vm_map_t mb_map=0;
    int mb_map_full=0;
    
    /*
     *      kmem_alloc_pageable:
     *
     *      Allocate pageable memory to the kernel's address map.
     *      "map" must be kernel_map or a submap of kernel_map.
     */
   
   vm_offset_t
   kmem_alloc_pageable(map, size)
           vm_map_t map;
           register vm_size_t size;
   {
           vm_offset_t addr;
           register int result;
   
           size = round_page(size);
           addr = vm_map_min(map);
           result = vm_map_find(map, NULL, (vm_offset_t) 0,
               &addr, size, TRUE, VM_PROT_ALL, VM_PROT_ALL, 0);
           if (result != KERN_SUCCESS) {
                   return (0);
           }
           return (addr);
   }
   
   /*
    *      kmem_alloc_nofault:
    *
    *      Same as kmem_alloc_pageable, except that it create a nofault entry.
    */
   
   vm_offset_t
   kmem_alloc_nofault(map, size)
           vm_map_t map;
           register vm_size_t size;
   {
           vm_offset_t addr;
           register int result;
   
           size = round_page(size);
           addr = vm_map_min(map);
           result = vm_map_find(map, NULL, (vm_offset_t) 0,
               &addr, size, TRUE, VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
           if (result != KERN_SUCCESS) {
                   return (0);
           }
           return (addr);
   }
   
   /*
    *      Allocate wired-down memory in the kernel's address map
    *      or a submap.
    */
   vm_offset_t
   kmem_alloc(map, size)
           register vm_map_t map;
           register vm_size_t size;
   {
           vm_offset_t addr;
           register vm_offset_t offset;
           vm_offset_t i;
   
           size = round_page(size);
   
           /*
            * Use the kernel object for wired-down kernel pages. Assume that no
            * region of the kernel object is referenced more than once.
            */
   
           /*
            * Locate sufficient space in the map.  This will give us the final
            * virtual address for the new memory, and thus will tell us the
            * offset within the kernel map.
            */
           vm_map_lock(map);
           if (vm_map_findspace(map, vm_map_min(map), size, &addr)) {
                   vm_map_unlock(map);
                   return (0);
           }
           offset = addr - VM_MIN_KERNEL_ADDRESS;
           vm_object_reference(kernel_object);
           vm_map_insert(map, kernel_object, offset, addr, addr + size,
                   VM_PROT_ALL, VM_PROT_ALL, 0);
           vm_map_unlock(map);
   
           /*
            * Guarantee that there are pages already in this object before
            * calling vm_map_pageable.  This is to prevent the following
            * scenario:
            *
            * 1) Threads have swapped out, so that there is a pager for the
            * kernel_object. 2) The kmsg zone is empty, and so we are
            * kmem_allocing a new page for it. 3) vm_map_pageable calls vm_fault;
            * there is no page, but there is a pager, so we call
            * pager_data_request.  But the kmsg zone is empty, so we must
            * kmem_alloc. 4) goto 1 5) Even if the kmsg zone is not empty: when
            * we get the data back from the pager, it will be (very stale)
            * non-zero data.  kmem_alloc is defined to return zero-filled memory.
            *
            * We're intentionally not activating the pages we allocate to prevent a
            * race with page-out.  vm_map_pageable will wire the pages.
            */
   
           for (i = 0; i < size; i += PAGE_SIZE) {
                   vm_page_t mem;
   
                   mem = vm_page_grab(kernel_object, OFF_TO_IDX(offset + i),
                                   VM_ALLOC_ZERO | VM_ALLOC_RETRY);
                   if ((mem->flags & PG_ZERO) == 0)
                           vm_page_zero_fill(mem);
                   mem->valid = VM_PAGE_BITS_ALL;
                   vm_page_flag_clear(mem, PG_ZERO);
                   vm_page_wakeup(mem);
           }
   
           /*
            * And finally, mark the data as non-pageable.
            */
   
           (void) vm_map_pageable(map, (vm_offset_t) addr, addr + size, FALSE);
   
           return (addr);
   }
   
   /*
    *      kmem_free:
    *
    *      Release a region of kernel virtual memory allocated
    *      with kmem_alloc, and return the physical pages
    *      associated with that region.
    *
    *      This routine may not block on kernel maps.
    */
   void
   kmem_free(map, addr, size)
           vm_map_t map;
           register vm_offset_t addr;
           vm_size_t size;
   {
           (void) vm_map_remove(map, trunc_page(addr), round_page(addr + size));
   }
   
   /*
    *      kmem_suballoc:
    *
    *      Allocates a map to manage a subrange
    *      of the kernel virtual address space.
    *
    *      Arguments are as follows:
    *
    *      parent          Map to take range from
    *      size            Size of range to find
    *      min, max        Returned endpoints of map
    *      pageable        Can the region be paged
    */
   vm_map_t
   kmem_suballoc(parent, min, max, size)
           register vm_map_t parent;
           vm_offset_t *min, *max;
           register vm_size_t size;
   {
           register int ret;
           vm_map_t result;
   
           size = round_page(size);
   
           *min = (vm_offset_t) vm_map_min(parent);
           ret = vm_map_find(parent, NULL, (vm_offset_t) 0,
               min, size, TRUE, VM_PROT_ALL, VM_PROT_ALL, 0);
           if (ret != KERN_SUCCESS) {
                   printf("kmem_suballoc: bad status return of %d.\n", ret);
                   panic("kmem_suballoc");
           }
           *max = *min + size;
           result = vm_map_create(vm_map_pmap(parent), *min, *max);
           if (result == NULL)
                   panic("kmem_suballoc: cannot create submap");
           if ((ret = vm_map_submap(parent, *min, *max, result)) != KERN_SUCCESS)
                   panic("kmem_suballoc: unable to change range to submap");
           return (result);
   }
   
   /*
    *      kmem_malloc:
    *
    *      Allocate wired-down memory in the kernel's address map for the higher
    *      level kernel memory allocator (kern/kern_malloc.c).  We cannot use
    *      kmem_alloc() because we may need to allocate memory at interrupt
    *      level where we cannot block (canwait == FALSE).
    *
    *      This routine has its own private kernel submap (kmem_map) and object
    *      (kmem_object).  This, combined with the fact that only malloc uses
    *      this routine, ensures that we will never block in map or object waits.
    *
    *      Note that this still only works in a uni-processor environment and
    *      when called at splhigh().
    *
    *      We don't worry about expanding the map (adding entries) since entries
    *      for wired maps are statically allocated.
    *
    *      NOTE:  This routine is not supposed to block if M_NOWAIT is set, but
    *      I have not verified that it actually does not block.
    */
   vm_offset_t
   kmem_malloc(map, size, flags)
           register vm_map_t map;
           register vm_size_t size;
           int flags;
   {
           register vm_offset_t offset, i;
           vm_map_entry_t entry;
           vm_offset_t addr;
           vm_page_t m;
   
           if (map != kmem_map && map != mb_map)
                   panic("kmem_malloc: map != {kmem,mb}_map");
   
           size = round_page(size);
           addr = vm_map_min(map);
   
           /*
            * Locate sufficient space in the map.  This will give us the final
            * virtual address for the new memory, and thus will tell us the
            * offset within the kernel map.
            */
           vm_map_lock(map);
           if (vm_map_findspace(map, vm_map_min(map), size, &addr)) {
                   vm_map_unlock(map);
                   if (map == mb_map) {
                           mb_map_full = TRUE;
                           printf("Out of mbuf clusters - adjust NMBCLUSTERS or increase maxusers!\n");
                           return (0);
                   }
                   if ((flags & M_NOWAIT) == 0)
                           panic("kmem_malloc(%ld): kmem_map too small: %ld total allocated",
                                   (long)size, (long)map->size);
                   return (0);
           }
           offset = addr - VM_MIN_KERNEL_ADDRESS;
           vm_object_reference(kmem_object);
           vm_map_insert(map, kmem_object, offset, addr, addr + size,
                   VM_PROT_ALL, VM_PROT_ALL, 0);
   
           for (i = 0; i < size; i += PAGE_SIZE) {
                   /*
                    * Note: if M_NOWAIT specified alone, allocate from 
                    * interrupt-safe queues only (just the free list).  If 
                    * M_ASLEEP or M_USE_RESERVE is also specified, we can also
                    * allocate from the cache.  Neither of the latter two
                    * flags may be specified from an interrupt since interrupts
                    * are not allowed to mess with the cache queue.
                    */
   retry:
                   m = vm_page_alloc(kmem_object, OFF_TO_IDX(offset + i),
                       ((flags & (M_NOWAIT|M_ASLEEP|M_USE_RESERVE)) == M_NOWAIT) ?
                           VM_ALLOC_INTERRUPT : 
                           VM_ALLOC_SYSTEM);
   
                   /*
                    * Ran out of space, free everything up and return. Don't need
                    * to lock page queues here as we know that the pages we got
                    * aren't on any queues.
                    */
                   if (m == NULL) {
                           if ((flags & M_NOWAIT) == 0) {
                                   vm_map_unlock(map);
                                   VM_WAIT;
                                   vm_map_lock(map);
                                   goto retry;
                           }
                           /* 
                            * Free the pages before removing the map entry.
                            * They are already marked busy.  Calling
                            * vm_map_delete before the pages has been freed or
                            * unbusied will cause a deadlock.
                            */
                           while (i != 0) {
                                   i -= PAGE_SIZE;
                                   m = vm_page_lookup(kmem_object,
                                                      OFF_TO_IDX(offset + i));
                                   vm_page_free(m);
                           }
                           vm_map_delete(map, addr, addr + size);
                           vm_map_unlock(map);
                           if (flags & M_ASLEEP) {
                                   VM_AWAIT;
                           }
                           return (0);
                   }
                   vm_page_flag_clear(m, PG_ZERO);
                   m->valid = VM_PAGE_BITS_ALL;
           }
   
           /*
            * Mark map entry as non-pageable. Assert: vm_map_insert() will never
            * be able to extend the previous entry so there will be a new entry
            * exactly corresponding to this address range and it will have
            * wired_count == 0.
            */
           if (!vm_map_lookup_entry(map, addr, &entry) ||
               entry->start != addr || entry->end != addr + size ||
               entry->wired_count != 0)
                   panic("kmem_malloc: entry not found or misaligned");
           entry->wired_count = 1;
   
           vm_map_simplify_entry(map, entry);
   
           /*
            * Loop thru pages, entering them in the pmap. (We cannot add them to
            * the wired count without wrapping the vm_page_queue_lock in
            * splimp...)
            */
           for (i = 0; i < size; i += PAGE_SIZE) {
                   m = vm_page_lookup(kmem_object, OFF_TO_IDX(offset + i));
                   vm_page_wire(m);
                   vm_page_wakeup(m);
                   /*
                    * Because this is kernel_pmap, this call will not block.
                    */
                   pmap_enter(kernel_pmap, addr + i, m, VM_PROT_ALL, 1);
                   vm_page_flag_set(m, PG_MAPPED | PG_WRITEABLE | PG_REFERENCED);
           }
           vm_map_unlock(map);
   
           return (addr);
   }
   
   /*
    *      kmem_alloc_wait:
    *
    *      Allocates pageable memory from a sub-map of the kernel.  If the submap
    *      has no room, the caller sleeps waiting for more memory in the submap.
    *
    *      This routine may block.
    */
   
   vm_offset_t
   kmem_alloc_wait(map, size)
           vm_map_t map;
           vm_size_t size;
   {
           vm_offset_t addr;
   
           size = round_page(size);
   
           for (;;) {
                   /*
                    * To make this work for more than one map, use the map's lock
                    * to lock out sleepers/wakers.
                    */
                   vm_map_lock(map);
                   if (vm_map_findspace(map, vm_map_min(map), size, &addr) == 0)
                           break;
                   /* no space now; see if we can ever get space */
                   if (vm_map_max(map) - vm_map_min(map) < size) {
                           vm_map_unlock(map);
                           return (0);
                   }
                   vm_map_unlock(map);
                   tsleep(map, PVM, "kmaw", 0);
           }
           vm_map_insert(map, NULL, (vm_offset_t) 0, addr, addr + size, VM_PROT_ALL, VM_PROT_ALL, 0);
           vm_map_unlock(map);
           return (addr);
   }
   
   /*
    *      kmem_free_wakeup:
    *
    *      Returns memory to a submap of the kernel, and wakes up any processes
    *      waiting for memory in that map.
    */
   void
   kmem_free_wakeup(map, addr, size)
           vm_map_t map;
           vm_offset_t addr;
           vm_size_t size;
   {
           vm_map_lock(map);
           (void) vm_map_delete(map, trunc_page(addr), round_page(addr + size));
           wakeup(map);
           vm_map_unlock(map);
   }
   
   /*
    *      kmem_init:
    *
    *      Create the kernel map; insert a mapping covering kernel text, 
    *      data, bss, and all space allocated thus far (`boostrap' data).  The 
    *      new map will thus map the range between VM_MIN_KERNEL_ADDRESS and 
    *      `start' as allocated, and the range between `start' and `end' as free.
    */
   
   void
   kmem_init(start, end)
           vm_offset_t start, end;
   {
           register vm_map_t m;
   
           m = vm_map_create(kernel_pmap, VM_MIN_KERNEL_ADDRESS, end);
           vm_map_lock(m);
           /* N.B.: cannot use kgdb to debug, starting with this assignment ... */
           kernel_map = m;
           kernel_map->system_map = 1;
           (void) vm_map_insert(m, NULL, (vm_offset_t) 0,
               VM_MIN_KERNEL_ADDRESS, start, VM_PROT_ALL, VM_PROT_ALL, 0);
           /* ... and ending with the completion of the above `insert' */
           vm_map_unlock(m);
   }
   

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