1 /* $NetBSD: uvm_anon.h,v 1.32 2020/03/20 19:08:54 ad 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 krwlock_t *an_lock; /* Lock for an_ref */ 49 uintptr_t an_ref; /* Reference count [an_lock] */ 50 struct vm_page *an_page; /* If in RAM [an_lock] */ 51 #if defined(VMSWAP) || 1 /* XXX libkvm */ 52 /* 53 * Drum swap slot # (if != 0) [an_lock. also, it is ok to read 54 * an_swslot if we hold an_page PG_BUSY]. 55 */ 56 int an_swslot; 57 #endif 58 }; 59 60 /* 61 * for active vm_anon's the data can be in one of the following state: 62 * [1] in a vm_page with no backing store allocated yet, [2] in a vm_page 63 * with backing store allocated, or [3] paged out to backing store 64 * (no vm_page). 65 * 66 * for pageout in case [2]: if the page has been modified then we must 67 * flush it out to backing store, otherwise we can just dump the 68 * vm_page. 69 */ 70 71 /* 72 * anons are grouped together in anonymous memory maps, or amaps. 73 * amaps are defined in uvm_amap.h. 74 */ 75 76 /* 77 * processes reference anonymous virtual memory maps with an anonymous 78 * reference structure: 79 */ 80 81 struct vm_aref { 82 int ar_pageoff; /* page offset into amap we start */ 83 struct vm_amap *ar_amap; /* pointer to amap */ 84 }; 85 86 /* 87 * the offset field indicates which part of the amap we are referencing. 88 * locked by vm_map lock. 89 */ 90 91 #ifdef _KERNEL 92 93 /* 94 * prototypes 95 */ 96 97 struct vm_anon *uvm_analloc(void); 98 void uvm_anfree(struct vm_anon *); 99 void uvm_anon_init(void); 100 struct vm_page *uvm_anon_lockloanpg(struct vm_anon *); 101 #if defined(VMSWAP) 102 void uvm_anon_dropswap(struct vm_anon *); 103 #else /* defined(VMSWAP) */ 104 #define uvm_anon_dropswap(a) /* nothing */ 105 #endif /* defined(VMSWAP) */ 106 void uvm_anon_release(struct vm_anon *); 107 bool uvm_anon_pagein(struct vm_amap *, struct vm_anon *); 108 #endif /* _KERNEL */ 109 110 #endif /* _UVM_UVM_ANON_H_ */ 111