1 /* $OpenBSD: uvm_anon.h,v 1.20 2016/05/08 11:52:32 stefan Exp $ */ 2 /* $NetBSD: uvm_anon.h,v 1.13 2000/12/27 09:17:04 chs Exp $ */ 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 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #ifndef _UVM_UVM_ANON_H_ 30 #define _UVM_UVM_ANON_H_ 31 32 /* 33 * anonymous memory management 34 * 35 * anonymous virtual memory is short term virtual memory that goes away 36 * when the processes referencing it go away. an anonymous page of 37 * virtual memory is described by the following data structure: 38 */ 39 40 struct vm_anon { 41 struct vm_page *an_page; /* if in RAM */ 42 int an_ref; /* reference count */ 43 44 /* 45 * Drum swap slot # (if != 0) [if we hold an_page, PG_BUSY] 46 */ 47 int an_swslot; 48 }; 49 50 /* 51 * for active vm_anon's the data can be in one of the following state: 52 * [1] in a vm_page with no backing store allocated yet, [2] in a vm_page 53 * with backing store allocated, or [3] paged out to backing store 54 * (no vm_page). 55 * 56 * for pageout in case [2]: if the page has been modified then we must 57 * flush it out to backing store, otherwise we can just dump the 58 * vm_page. 59 */ 60 61 /* 62 * anons are grouped together in anonymous memory maps, or amaps. 63 * amaps are defined in uvm_amap.h. 64 */ 65 66 /* 67 * processes reference anonymous virtual memory maps with an anonymous 68 * reference structure: 69 * Note that the offset field indicates which part of the amap we are 70 * referencing. 71 * Locked by vm_map lock. 72 */ 73 74 struct vm_aref { 75 int ar_pageoff; /* page offset into amap we start */ 76 struct vm_amap *ar_amap; /* pointer to amap */ 77 }; 78 79 #ifdef _KERNEL 80 struct vm_anon *uvm_analloc(void); 81 void uvm_anfree(struct vm_anon *); 82 void uvm_anwait(void); 83 void uvm_anon_init(void); 84 void uvm_anon_dropswap(struct vm_anon *); 85 boolean_t uvm_anon_pagein(struct vm_anon *); 86 #endif /* _KERNEL */ 87 88 #endif /* _UVM_UVM_ANON_H_ */ 89