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uvm_anon.h revision 1.26.4.1 
      1 /*	$NetBSD: uvm_anon.h,v 1.26.4.1 2010/03/17 06:03:17 rmind 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 #if defined(_KERNEL_OPT)
     43 #include "opt_vmswap.h"
     44 #endif
     45 
     46 /*
     47  * anonymous memory management
     48  *
     49  * anonymous virtual memory is short term virtual memory that goes away
     50  * when the processes referencing it go away.    an anonymous page of
     51  * virtual memory is described by the following data structure:
     52  */
     53 
     54 struct vm_anon {
     55 	kmutex_t		*an_lock;	/* Lock for an_ref */
     56 	union {
     57 		uintptr_t	au_ref;		/* Reference count [an_lock] */
     58 		struct vm_anon	*au_link;	/* Link for deferred free */
     59 	} an_u;
     60 #define	an_ref	an_u.au_ref
     61 #define	an_link	an_u.au_link
     62 	struct vm_page		*an_page;	/* If in RAM [an_lock] */
     63 #if defined(VMSWAP) || 1 /* XXX libkvm */
     64 	/*
     65 	 * Drum swap slot # (if != 0) [an_lock.  also, it is ok to read
     66 	 * an_swslot if we hold an_page PG_BUSY].
     67 	 */
     68 	int			an_swslot;
     69 #endif
     70 };
     71 
     72 /*
     73  * for active vm_anon's the data can be in one of the following state:
     74  * [1] in a vm_page with no backing store allocated yet, [2] in a vm_page
     75  * with backing store allocated, or [3] paged out to backing store
     76  * (no vm_page).
     77  *
     78  * for pageout in case [2]: if the page has been modified then we must
     79  * flush it out to backing store, otherwise we can just dump the
     80  * vm_page.
     81  */
     82 
     83 /*
     84  * anons are grouped together in anonymous memory maps, or amaps.
     85  * amaps are defined in uvm_amap.h.
     86  */
     87 
     88 /*
     89  * processes reference anonymous virtual memory maps with an anonymous
     90  * reference structure:
     91  */
     92 
     93 struct vm_aref {
     94 	int ar_pageoff;			/* page offset into amap we start */
     95 	struct vm_amap *ar_amap;	/* pointer to amap */
     96 };
     97 
     98 /*
     99  * the offset field indicates which part of the amap we are referencing.
    100  * locked by vm_map lock.
    101  */
    102 
    103 #ifdef _KERNEL
    104 
    105 /*
    106  * prototypes
    107  */
    108 
    109 struct vm_anon *uvm_analloc(void);
    110 void uvm_anfree(struct vm_anon *);
    111 void uvm_anon_init(void);
    112 struct vm_page *uvm_anon_lockloanpg(struct vm_anon *);
    113 #if defined(VMSWAP)
    114 void uvm_anon_dropswap(struct vm_anon *);
    115 #else /* defined(VMSWAP) */
    116 #define	uvm_anon_dropswap(a)	/* nothing */
    117 #endif /* defined(VMSWAP) */
    118 void uvm_anon_release(struct vm_anon *);
    119 bool uvm_anon_pagein(struct vm_anon *);
    120 #endif /* _KERNEL */
    121 
    122 #endif /* _UVM_UVM_ANON_H_ */
    123