1 /* $NetBSD: uvm_anon.h,v 1.27 2011/02/02 15:13:34 chuck 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 struct vm_page *an_page;/* if in RAM [an_lock] */ 50 int an_ref; /* reference count [an_lock] */ 51 #if defined(VMSWAP) || 1 /* XXX libkvm */ 52 int an_swslot; /* drum swap slot # (if != 0) 53 [an_lock. also, it is ok to read 54 an_swslot if we hold an_page PG_BUSY] */ 55 #endif /* defined(VMSWAP) */ 56 }; 57 58 /* 59 * for active vm_anon's the data can be in one of the following state: 60 * [1] in a vm_page with no backing store allocated yet, [2] in a vm_page 61 * with backing store allocated, or [3] paged out to backing store 62 * (no vm_page). 63 * 64 * for pageout in case [2]: if the page has been modified then we must 65 * flush it out to backing store, otherwise we can just dump the 66 * vm_page. 67 */ 68 69 /* 70 * anons are grouped together in anonymous memory maps, or amaps. 71 * amaps are defined in uvm_amap.h. 72 */ 73 74 /* 75 * processes reference anonymous virtual memory maps with an anonymous 76 * reference structure: 77 */ 78 79 struct vm_aref { 80 int ar_pageoff; /* page offset into amap we start */ 81 struct vm_amap *ar_amap; /* pointer to amap */ 82 }; 83 84 /* 85 * the offset field indicates which part of the amap we are referencing. 86 * locked by vm_map lock. 87 */ 88 89 #ifdef _KERNEL 90 91 /* 92 * prototypes 93 */ 94 95 struct vm_anon *uvm_analloc(void); 96 void uvm_anfree(struct vm_anon *); 97 void uvm_anon_init(void); 98 struct vm_page *uvm_anon_lockloanpg(struct vm_anon *); 99 #if defined(VMSWAP) 100 void uvm_anon_dropswap(struct vm_anon *); 101 #else /* defined(VMSWAP) */ 102 #define uvm_anon_dropswap(a) /* nothing */ 103 #endif /* defined(VMSWAP) */ 104 void uvm_anon_release(struct vm_anon *); 105 bool uvm_anon_pagein(struct vm_anon *); 106 #endif /* _KERNEL */ 107 108 #endif /* _UVM_UVM_ANON_H_ */ 109