1/*	$NetBSD: uvm_anon.h,v 1.32 2020/03/20 19:08:54 ad Exp $	*/
2
3/*
4 * Copyright (c) 1997 Charles D. Cranor and Washington University.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#ifndef _UVM_UVM_ANON_H_
29#define _UVM_UVM_ANON_H_
30
31/*
32 * uvm_anon.h
33 */
34
35#if defined(_KERNEL_OPT)
36#include "opt_vmswap.h"
37#endif
38
39/*
40 * anonymous memory management
41 *
42 * anonymous virtual memory is short term virtual memory that goes away
43 * when the processes referencing it go away.    an anonymous page of
44 * virtual memory is described by the following data structure:
45 */
46
47struct vm_anon {
48	krwlock_t		*an_lock;	/* Lock for an_ref */
49	uintptr_t		an_ref;		/* Reference count [an_lock] */
50	struct vm_page		*an_page;	/* If in RAM [an_lock] */
51#if defined(VMSWAP) || 1 /* XXX libkvm */
52	/*
53	 * Drum swap slot # (if != 0) [an_lock.  also, it is ok to read
54	 * an_swslot if we hold an_page PG_BUSY].
55	 */
56	int			an_swslot;
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 */
80
81struct 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
97struct vm_anon *uvm_analloc(void);
98void uvm_anfree(struct vm_anon *);
99void uvm_anon_init(void);
100struct vm_page *uvm_anon_lockloanpg(struct vm_anon *);
101#if defined(VMSWAP)
102void uvm_anon_dropswap(struct vm_anon *);
103#else /* defined(VMSWAP) */
104#define	uvm_anon_dropswap(a)	/* nothing */
105#endif /* defined(VMSWAP) */
106void uvm_anon_release(struct vm_anon *);
107bool uvm_anon_pagein(struct vm_amap *, struct vm_anon *);
108#endif /* _KERNEL */
109
110#endif /* _UVM_UVM_ANON_H_ */
111