xref: /openbsd-src/sys/uvm/uvm_anon.h (revision 2b0358df1d88d06ef4139321dd05bd5e05d91eaf)
1 /*	$OpenBSD: uvm_anon.h,v 1.14 2007/06/18 21:51:15 pedro Exp $	*/
2 /*	$NetBSD: uvm_anon.h,v 1.13 2000/12/27 09:17:04 chs Exp $	*/
3 
4 /*
5  *
6  * Copyright (c) 1997 Charles D. Cranor and Washington University.
7  * All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. All advertising materials mentioning features or use of this software
18  *    must display the following acknowledgement:
19  *      This product includes software developed by Charles D. Cranor and
20  *      Washington University.
21  * 4. The name of the author may not be used to endorse or promote products
22  *    derived from this software without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
28  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
29  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
33  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34  */
35 
36 #ifndef _UVM_UVM_ANON_H_
37 #define _UVM_UVM_ANON_H_
38 
39 /*
40  * uvm_anon.h
41  */
42 
43 /*
44  * anonymous memory management
45  *
46  * anonymous virtual memory is short term virtual memory that goes away
47  * when the processes referencing it go away.    an anonymous page of
48  * virtual memory is described by the following data structure:
49  */
50 
51 struct vm_anon {
52 	struct vm_page *an_page;	/* if in RAM [an_lock] */
53 	int an_ref;			/* reference count [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 	simple_lock_data_t an_lock;	/* lock for an_ref */
58 };
59 
60 /*
61  * for active vm_anon's the data can be in one of the following state:
62  * [1] in a vm_page with no backing store allocated yet, [2] in a vm_page
63  * with backing store allocated, or [3] paged out to backing store
64  * (no vm_page).
65  *
66  * for pageout in case [2]: if the page has been modified then we must
67  * flush it out to backing store, otherwise we can just dump the
68  * vm_page.
69  */
70 
71 /*
72  * anons are grouped together in anonymous memory maps, or amaps.
73  * amaps are defined in uvm_amap.h.
74  */
75 
76 /*
77  * processes reference anonymous virtual memory maps with an anonymous
78  * reference structure:
79  */
80 
81 struct vm_aref {
82 	int ar_pageoff;			/* page offset into amap we start */
83 	struct vm_amap *ar_amap;	/* pointer to amap */
84 };
85 
86 /*
87  * the offset field indicates which part of the amap we are referencing.
88  * locked by vm_map lock.
89  */
90 
91 #ifdef _KERNEL
92 
93 /*
94  * prototypes
95  */
96 
97 struct vm_anon *uvm_analloc(void);
98 void uvm_anfree(struct vm_anon *);
99 void uvm_anon_init(void);
100 struct vm_page *uvm_anon_lockloanpg(struct vm_anon *);
101 void uvm_anon_dropswap(struct vm_anon *);
102 boolean_t uvm_anon_pagein(struct vm_anon *);
103 #endif /* _KERNEL */
104 
105 #endif /* _UVM_UVM_ANON_H_ */
106