sys/uvm/uvm_anon.h

   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
  47 struct 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
  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_anon_free(struct vm_anon *);
 104 void uvm_anon_freelst(struct vm_amap *, struct vm_anon *);
 105 void uvm_anon_init(void);
 106 struct vm_page *uvm_anon_lockloanpg(struct vm_anon *);
 107 #if defined(VMSWAP)
 108 void uvm_anon_dropswap(struct vm_anon *);
 109 #else /* defined(VMSWAP) */
 110 #define uvm_anon_dropswap(a)    /* nothing */
 111 #endif /* defined(VMSWAP) */
 112 void uvm_anon_release(struct vm_anon *);
 113 bool uvm_anon_pagein(struct vm_amap *, struct vm_anon *);
 114 #endif /* _KERNEL */
 115
 116 #endif /* _UVM_UVM_ANON_H_ */