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uvm_anon.h revision 1.18 
      1 /*	$NetBSD: uvm_anon.h,v 1.18 2005/05/11 13:02:25 yamt Exp $	*/
      2 
      3 /*
      4  *
      5  * Copyright (c) 1997 Charles D. Cranor and Washington University.
      6  * All rights reserved.
      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 Charles D. Cranor and
     19  *      Washington University.
     20  * 4. The name of the author may not be used to endorse or promote products
     21  *    derived from this software without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     25  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     26  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     27  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     28  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     29  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     30  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     31  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     32  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     33  */
     34 
     35 #ifndef _UVM_UVM_ANON_H_
     36 #define _UVM_UVM_ANON_H_
     37 
     38 /*
     39  * uvm_anon.h
     40  */
     41 
     42 /*
     43  * anonymous memory management
     44  *
     45  * anonymous virtual memory is short term virtual memory that goes away
     46  * when the processes referencing it go away.    an anonymous page of
     47  * virtual memory is described by the following data structure:
     48  */
     49 
     50 struct vm_anon {
     51 	int an_ref;			/* reference count [an_lock] */
     52 	struct simplelock an_lock;	/* lock for an_ref */
     53 	struct vm_page *an_page;/* if in RAM [an_lock] */
     54 	int an_swslot;		/* drum swap slot # (if != 0)
     55 				   [an_lock.  also, it is ok to read
     56 				   an_swslot if we hold an_page PG_BUSY] */
     57 };
     58 
     59 /*
     60  * for active vm_anon's the data can be in one of the following state:
     61  * [1] in a vm_page with no backing store allocated yet, [2] in a vm_page
     62  * with backing store allocated, or [3] paged out to backing store
     63  * (no vm_page).
     64  *
     65  * for pageout in case [2]: if the page has been modified then we must
     66  * flush it out to backing store, otherwise we can just dump the
     67  * vm_page.
     68  */
     69 
     70 /*
     71  * anons are grouped together in anonymous memory maps, or amaps.
     72  * amaps are defined in uvm_amap.h.
     73  */
     74 
     75 /*
     76  * processes reference anonymous virtual memory maps with an anonymous
     77  * reference structure:
     78  */
     79 
     80 struct vm_aref {
     81 	int ar_pageoff;			/* page offset into amap we start */
     82 	struct vm_amap *ar_amap;	/* pointer to amap */
     83 };
     84 
     85 /*
     86  * the offset field indicates which part of the amap we are referencing.
     87  * locked by vm_map lock.
     88  */
     89 
     90 #ifdef _KERNEL
     91 
     92 /*
     93  * prototypes
     94  */
     95 
     96 struct vm_anon *uvm_analloc(void);
     97 void uvm_anfree(struct vm_anon *);
     98 void uvm_anon_init(void);
     99 struct vm_page *uvm_anon_lockloanpg(struct vm_anon *);
    100 void uvm_anon_dropswap(struct vm_anon *);
    101 void uvm_anon_release(struct vm_anon *);
    102 boolean_t uvm_anon_pagein(struct vm_anon *);
    103 #endif /* _KERNEL */
    104 
    105 #endif /* _UVM_UVM_ANON_H_ */
    106