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uvm_anon.h revision 1.25.10.1 
      1 /*	$NetBSD: uvm_anon.h,v 1.25.10.1 2009/06/20 07:20:38 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 #if defined(_KERNEL_OPT)
     43 #include "opt_vmswap.h"
     44 #endif
     45 
     46 /*
     47  * anonymous memory management
     48  *
     49  * anonymous virtual memory is short term virtual memory that goes away
     50  * when the processes referencing it go away.    an anonymous page of
     51  * virtual memory is described by the following data structure:
     52  */
     53 
     54 struct vm_anon {
     55 	kmutex_t an_lock;	/* lock for an_ref */
     56 	struct vm_page *an_page;/* if in RAM [an_lock] */
     57 	int an_ref;		/* reference count [an_lock] */
     58 #if defined(VMSWAP) || 1 /* XXX libkvm */
     59 	int an_swslot;		/* drum swap slot # (if != 0)
     60 				   [an_lock.  also, it is ok to read
     61 				   an_swslot if we hold an_page PG_BUSY] */
     62 #endif /* defined(VMSWAP) */
     63 };
     64 
     65 /*
     66  * for active vm_anon's the data can be in one of the following state:
     67  * [1] in a vm_page with no backing store allocated yet, [2] in a vm_page
     68  * with backing store allocated, or [3] paged out to backing store
     69  * (no vm_page).
     70  *
     71  * for pageout in case [2]: if the page has been modified then we must
     72  * flush it out to backing store, otherwise we can just dump the
     73  * vm_page.
     74  */
     75 
     76 /*
     77  * anons are grouped together in anonymous memory maps, or amaps.
     78  * amaps are defined in uvm_amap.h.
     79  */
     80 
     81 /*
     82  * processes reference anonymous virtual memory maps with an anonymous
     83  * reference structure:
     84  */
     85 
     86 struct vm_aref {
     87 	int ar_pageoff;			/* page offset into amap we start */
     88 	struct vm_amap *ar_amap;	/* pointer to amap */
     89 };
     90 
     91 /*
     92  * the offset field indicates which part of the amap we are referencing.
     93  * locked by vm_map lock.
     94  */
     95 
     96 #ifdef _KERNEL
     97 
     98 /*
     99  * prototypes
    100  */
    101 
    102 struct vm_anon *uvm_analloc(void);
    103 void uvm_anfree(struct vm_anon *);
    104 void uvm_anon_init(void);
    105 struct vm_page *uvm_anon_lockloanpg(struct vm_anon *);
    106 #if defined(VMSWAP)
    107 void uvm_anon_dropswap(struct vm_anon *);
    108 #else /* defined(VMSWAP) */
    109 #define	uvm_anon_dropswap(a)	/* nothing */
    110 #endif /* defined(VMSWAP) */
    111 void uvm_anon_release(struct vm_anon *);
    112 bool uvm_anon_pagein(struct vm_anon *);
    113 #endif /* _KERNEL */
    114 
    115 #endif /* _UVM_UVM_ANON_H_ */
    116