1 /* $OpenBSD: uvm_anon.h,v 1.11 2002/03/14 01:27:18 millert Exp $ */ 2 /* $NetBSD: uvm_anon.h,v 1.13 2000/12/27 09:17:04 chs Exp $ */ 3 4 /* 5 * 6 * Copyright (c) 1997 Charles D. Cranor and Washington University. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by Charles D. Cranor and 20 * Washington University. 21 * 4. The name of the author may not be used to endorse or promote products 22 * derived from this software without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36 #ifndef _UVM_UVM_ANON_H_ 37 #define _UVM_UVM_ANON_H_ 38 39 /* 40 * uvm_anon.h 41 */ 42 43 /* 44 * anonymous memory management 45 * 46 * anonymous virtual memory is short term virtual memory that goes away 47 * when the processes referencing it go away. an anonymous page of 48 * virtual memory is described by the following data structure: 49 */ 50 51 struct vm_anon { 52 int an_ref; /* reference count [an_lock] */ 53 simple_lock_data_t an_lock; /* lock for an_ref */ 54 union { 55 struct vm_anon *an_nxt; /* if on free list [afreelock] */ 56 struct vm_page *an_page;/* if in RAM [an_lock] */ 57 } u; 58 int an_swslot; /* drum swap slot # (if != 0) 59 [an_lock. also, it is ok to read 60 an_swslot if we hold an_page PG_BUSY] */ 61 }; 62 63 /* 64 * a pool of vm_anon data structures is allocated and put on a global 65 * free list at boot time. vm_anon's on the free list use "an_nxt" as 66 * a pointer to the next item on the free list. for active vm_anon's 67 * the data can be in one of the following state: [1] in a vm_page 68 * with no backing store allocated yet, [2] in a vm_page with backing 69 * store allocated, or [3] paged out to backing store (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 int uvm_anon_add(int); 106 void uvm_anon_remove(int); 107 struct vm_page *uvm_anon_lockloanpg(struct vm_anon *); 108 void uvm_anon_dropswap(struct vm_anon *); 109 boolean_t anon_swap_off(int, int); 110 #endif /* _KERNEL */ 111 112 #endif /* _UVM_UVM_ANON_H_ */ 113