1/* $OpenBSD: uvm_anon.h,v 1.24 2025/12/15 13:02:18 mpi Exp $ */
2/* $NetBSD: uvm_anon.h,v 1.13 2000/12/27 09:17:04 chs Exp $ */
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 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#ifndef _UVM_UVM_ANON_H_
30#define _UVM_UVM_ANON_H_
31
32/*
33 * anonymous memory management
34 *
35 * anonymous virtual memory is short term virtual memory that goes away
36 * when the processes referencing it go away. an anonymous page of
37 * virtual memory is described by the following data structure:
38 */
39
40struct vm_anon {
41 struct rwlock *an_lock;
42
43 struct vm_page *an_page; /* if in RAM */
44 int an_ref; /* reference count */
45
46 /*
47 * Drum swap slot # (if != 0) [if we hold an_page, PG_BUSY]
48 */
49 int an_swslot;
50
51#if defined(MULTIPROCESSOR) && defined(__LP64__)
52 /*
53 * The per-CPU pool caching code requires pool item to be
54 * at least the size of struct pool_cache_item.
55 */
56 long unused;
57#endif
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 * Note that the offset field indicates which part of the amap we are
80 * referencing.
81 * Locked by vm_map lock.
82 */
83
84struct vm_aref {
85 int ar_pageoff; /* page offset into amap we start */
86 struct vm_amap *ar_amap; /* pointer to amap */
87};
88
89#ifdef _KERNEL
90struct vm_anon *uvm_analloc(void);
91void uvm_anfree(struct vm_anon *);
92void uvm_anon_release(struct vm_anon *);
93void uvm_anwait(void);
94void uvm_anon_init(void);
95void uvm_anon_init_percpu(void);
96void uvm_anon_dropswap(struct vm_anon *);
97boolean_t uvm_anon_pagein(struct vm_amap *, struct vm_anon *);
98
99
100#endif /* _KERNEL */
101
102#endif /* _UVM_UVM_ANON_H_ */