sys/uvm/uvm_anon.h

   1 /*      $NetBSD: uvm_anon.h,v 1.25 2008/01/02 11:49:15 ad Exp $ */
   2
   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  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by Charles D. Cranor and
  19  *      Washington University.
  20  * 4. The name of the author may not be used to endorse or promote products
  21  *    derived from this software without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  25  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  26  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  28  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  29  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  30  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  31  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  32  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  33  */
  34
  35 #ifndef _UVM_UVM_ANON_H_
  36 #define _UVM_UVM_ANON_H_
  37
  38 /*
  39  * uvm_anon.h
  40  */
  41
  42 #if defined(_KERNEL_OPT)
  43 #include "opt_vmswap.h"
  44 #endif
  45
  46 /*
  47  * anonymous memory management
  48  *
  49  * anonymous virtual memory is short term virtual memory that goes away
  50  * when the processes referencing it go away.    an anonymous page of
  51  * virtual memory is described by the following data structure:
  52  */
  53
  54 struct vm_anon {
  55         kmutex_t an_lock;       /* lock for an_ref */
  56         struct vm_page *an_page;/* if in RAM [an_lock] */
  57         int an_ref;             /* reference count [an_lock] */
  58 #if defined(VMSWAP) || 1 /* XXX libkvm */
  59         int an_swslot;          /* drum swap slot # (if != 0)
  60                                    [an_lock.  also, it is ok to read
  61                                    an_swslot if we hold an_page PG_BUSY] */
  62 #endif /* defined(VMSWAP) */
  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
  86 struct 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
 102 struct vm_anon *uvm_analloc(void);
 103 void uvm_anfree(struct vm_anon *);
 104 void uvm_anon_init(void);
 105 struct vm_page *uvm_anon_lockloanpg(struct vm_anon *);
 106 #if defined(VMSWAP)
 107 void uvm_anon_dropswap(struct vm_anon *);
 108 #else /* defined(VMSWAP) */
 109 #define uvm_anon_dropswap(a)    /* nothing */
 110 #endif /* defined(VMSWAP) */
 111 void uvm_anon_release(struct vm_anon *);
 112 bool uvm_anon_pagein(struct vm_anon *);
 113 #endif /* _KERNEL */
 114
 115 #endif /* _UVM_UVM_ANON_H_ */