1/*	$OpenBSD: uvm_anon.h,v 1.22 2021/01/19 13:21:36 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
52/*
53 * for active vm_anon's the data can be in one of the following state:
54 * [1] in a vm_page with no backing store allocated yet, [2] in a vm_page
55 * with backing store allocated, or [3] paged out to backing store
56 * (no vm_page).
57 *
58 * for pageout in case [2]: if the page has been modified then we must
59 * flush it out to backing store, otherwise we can just dump the
60 * vm_page.
61 */
62
63/*
64 * anons are grouped together in anonymous memory maps, or amaps.
65 * amaps are defined in uvm_amap.h.
66 */
67
68/*
69 * processes reference anonymous virtual memory maps with an anonymous
70 * reference structure:
71 * Note that the offset field indicates which part of the amap we are
72 * referencing.
73 * Locked by vm_map lock.
74 */
75
76struct vm_aref {
77	int ar_pageoff;			/* page offset into amap we start */
78	struct vm_amap *ar_amap;	/* pointer to amap */
79};
80
81#ifdef _KERNEL
82struct vm_anon	*uvm_analloc(void);
83void		 uvm_anfree_list(struct vm_anon *, struct pglist *);
84void		 uvm_anon_release(struct vm_anon *);
85void		 uvm_anwait(void);
86void		 uvm_anon_init(void);
87void		 uvm_anon_dropswap(struct vm_anon *);
88boolean_t	 uvm_anon_pagein(struct vm_amap *, struct vm_anon *);
89
90#define		uvm_anfree(an)	uvm_anfree_list((an), NULL)
91
92#endif /* _KERNEL */
93
94#endif /* _UVM_UVM_ANON_H_ */
95