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_ */