FreeBSD/Linux Kernel Cross Reference
sys/uvm/uvm_anon.h

     /*      $OpenBSD: uvm_anon.h,v 1.22 2021/01/19 13:21:36 mpi Exp $       */
     /*      $NetBSD: uvm_anon.h,v 1.13 2000/12/27 09:17:04 chs Exp $        */
     
     /*
      * Copyright (c) 1997 Charles D. Cranor and Washington University.
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     */
    
    #ifndef _UVM_UVM_ANON_H_
    #define _UVM_UVM_ANON_H_
    
    /*
     * anonymous memory management
     *
     * anonymous virtual memory is short term virtual memory that goes away
     * when the processes referencing it go away.    an anonymous page of
     * virtual memory is described by the following data structure:
     */
    
    struct vm_anon {
            struct rwlock *an_lock;
    
            struct vm_page *an_page;        /* if in RAM */
            int an_ref;                     /* reference count */
    
            /*
             * Drum swap slot # (if != 0) [if we hold an_page, PG_BUSY]
             */
            int an_swslot;
    };
    
    /*
     * for active vm_anon's the data can be in one of the following state:
     * [1] in a vm_page with no backing store allocated yet, [2] in a vm_page
     * with backing store allocated, or [3] paged out to backing store
     * (no vm_page).
     *
     * for pageout in case [2]: if the page has been modified then we must
     * flush it out to backing store, otherwise we can just dump the
     * vm_page.
     */
    
    /*
     * anons are grouped together in anonymous memory maps, or amaps.
     * amaps are defined in uvm_amap.h.
     */
    
    /*
     * processes reference anonymous virtual memory maps with an anonymous 
     * reference structure:
     * Note that the offset field indicates which part of the amap we are
     * referencing.
     * Locked by vm_map lock.
     */
    
    struct vm_aref {
            int ar_pageoff;                 /* page offset into amap we start */
            struct vm_amap *ar_amap;        /* pointer to amap */
    };
    
    #ifdef _KERNEL
    struct vm_anon  *uvm_analloc(void);
    void             uvm_anfree_list(struct vm_anon *, struct pglist *);
    void             uvm_anon_release(struct vm_anon *);
    void             uvm_anwait(void);
    void             uvm_anon_init(void);
    void             uvm_anon_dropswap(struct vm_anon *);
    boolean_t        uvm_anon_pagein(struct vm_amap *, struct vm_anon *);
    
    #define         uvm_anfree(an)  uvm_anfree_list((an), NULL)
    
    #endif /* _KERNEL */
    
    #endif /* _UVM_UVM_ANON_H_ */

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