1 /* $NetBSD: uvm_anon.h,v 1.15 2001/05/26 16:32:46 chs 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 /* 43 * anonymous memory management 44 * 45 * anonymous virtual memory is short term virtual memory that goes away 46 * when the processes referencing it go away. an anonymous page of 47 * virtual memory is described by the following data structure: 48 */ 49 50 struct vm_anon { 51 int an_ref; /* reference count [an_lock] */ 52 struct simplelock an_lock; /* lock for an_ref */ 53 union { 54 struct vm_anon *an_nxt; /* if on free list [afreelock] */ 55 struct vm_page *an_page;/* if in RAM [an_lock] */ 56 } u; 57 int an_swslot; /* drum swap slot # (if != 0) 58 [an_lock. also, it is ok to read 59 an_swslot if we hold an_page PG_BUSY] */ 60 }; 61 62 /* 63 * a pool of vm_anon data structures is allocated and put on a global 64 * free list at boot time. vm_anon's on the free list use "an_nxt" as 65 * a pointer to the next item on the free list. for active vm_anon's 66 * the data can be in one of the following state: [1] in a vm_page 67 * with no backing store allocated yet, [2] in a vm_page with backing 68 * store allocated, or [3] paged out to backing store (no vm_page). 69 * 70 * for pageout in case [2]: if the page has been modified then we must 71 * flush it out to backing store, otherwise we can just dump the 72 * vm_page. 73 */ 74 75 /* 76 * anons are grouped together in anonymous memory maps, or amaps. 77 * amaps are defined in uvm_amap.h. 78 */ 79 80 /* 81 * processes reference anonymous virtual memory maps with an anonymous 82 * reference structure: 83 */ 84 85 struct vm_aref { 86 int ar_pageoff; /* page offset into amap we start */ 87 struct vm_amap *ar_amap; /* pointer to amap */ 88 }; 89 90 /* 91 * the offset field indicates which part of the amap we are referencing. 92 * locked by vm_map lock. 93 */ 94 95 #ifdef _KERNEL 96 97 /* 98 * prototypes 99 */ 100 101 struct vm_anon *uvm_analloc __P((void)); 102 void uvm_anfree __P((struct vm_anon *)); 103 void uvm_anon_init __P((void)); 104 int uvm_anon_add __P((int)); 105 void uvm_anon_remove __P((int)); 106 struct vm_page *uvm_anon_lockloanpg __P((struct vm_anon *)); 107 void uvm_anon_dropswap __P((struct vm_anon *)); 108 boolean_t anon_swap_off __P((int, int)); 109 #endif /* _KERNEL */ 110 111 #endif /* _UVM_UVM_ANON_H_ */ 112