1/* $NetBSD: uvm_anon.h,v 1.30 2011/08/06 17:25:03 rmind 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 kmutex_t *an_lock; /* Lock for an_ref */
49 union {
50 uintptr_t au_ref; /* Reference count [an_lock] */
51 struct vm_anon *au_link; /* Link for deferred free */
52 } an_u;
53#define an_ref an_u.au_ref
54#define an_link an_u.au_link
55 struct vm_page *an_page; /* If in RAM [an_lock] */
56#if defined(VMSWAP) || 1 /* XXX libkvm */
57 /*
58 * Drum swap slot # (if != 0) [an_lock. also, it is ok to read
59 * an_swslot if we hold an_page PG_BUSY].
60 */
61 int an_swslot;
62#endif
63};
64
65/*
66 * for active vm_anon's the data can be in one of the following state:
67 * [1] in a vm_page with no backing store allocated yet, [2] in a vm_page
68 * with backing store allocated, or [3] paged out to backing store
69 * (no vm_page).
70 *
71 * for pageout in case [2]: if the page has been modified then we must
72 * flush it out to backing store, otherwise we can just dump the
73 * vm_page.
74 */
75
76/*
77 * anons are grouped together in anonymous memory maps, or amaps.
78 * amaps are defined in uvm_amap.h.
79 */
80
81/*
82 * processes reference anonymous virtual memory maps with an anonymous
83 * reference structure:
84 */
85
86struct vm_aref {
87 int ar_pageoff; /* page offset into amap we start */
88 struct vm_amap *ar_amap; /* pointer to amap */
89};
90
91/*
92 * the offset field indicates which part of the amap we are referencing.
93 * locked by vm_map lock.
94 */
95
96#ifdef _KERNEL
97
98/*
99 * prototypes
100 */
101
102struct vm_anon *uvm_analloc(void);
103void uvm_anon_free(struct vm_anon *);
104void uvm_anon_freelst(struct vm_amap *, struct vm_anon *);
105void uvm_anon_init(void);
106struct vm_page *uvm_anon_lockloanpg(struct vm_anon *);
107#if defined(VMSWAP)
108void uvm_anon_dropswap(struct vm_anon *);
109#else /* defined(VMSWAP) */
110#define uvm_anon_dropswap(a) /* nothing */
111#endif /* defined(VMSWAP) */
112void uvm_anon_release(struct vm_anon *);
113bool uvm_anon_pagein(struct vm_amap *, struct vm_anon *);
114#endif /* _KERNEL */
115
116#endif /* _UVM_UVM_ANON_H_ */
117