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      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 
     47 struct 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 
     81 struct 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 
     97 struct vm_anon *uvm_analloc(void);
     98 void uvm_anfree(struct vm_anon *);
     99 void uvm_anon_init(void);
    100 struct vm_page *uvm_anon_lockloanpg(struct vm_anon *);
    101 #if defined(VMSWAP)
    102 void uvm_anon_dropswap(struct vm_anon *);
    103 #else /* defined(VMSWAP) */
    104 #define	uvm_anon_dropswap(a)	/* nothing */
    105 #endif /* defined(VMSWAP) */
    106 void uvm_anon_release(struct vm_anon *);
    107 bool uvm_anon_pagein(struct vm_amap *, struct vm_anon *);
    108 #endif /* _KERNEL */
    109 
    110 #endif /* _UVM_UVM_ANON_H_ */
    111