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_ */