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

     /*      $NetBSD: uvm_anon.h,v 1.32 2020/03/20 19:08:54 ad 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_
    
    /*
     * uvm_anon.h
     */
    
    #if defined(_KERNEL_OPT)
    #include "opt_vmswap.h"
    #endif
    
    /*
     * 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 {
            krwlock_t               *an_lock;       /* Lock for an_ref */
            uintptr_t               an_ref;         /* Reference count [an_lock] */
            struct vm_page          *an_page;       /* If in RAM [an_lock] */
    #if defined(VMSWAP) || 1 /* XXX libkvm */
            /*
             * Drum swap slot # (if != 0) [an_lock.  also, it is ok to read
             * an_swslot if we hold an_page PG_BUSY].
             */
            int                     an_swslot;
    #endif
    };
    
    /*
     * 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:
     */
    
    struct vm_aref {
            int ar_pageoff;                 /* page offset into amap we start */
            struct vm_amap *ar_amap;        /* pointer to amap */
    };
    
    /*
     * the offset field indicates which part of the amap we are referencing.
     * locked by vm_map lock.
     */
    
    #ifdef _KERNEL
    
    /*
     * prototypes
     */
    
    struct vm_anon *uvm_analloc(void);
    void uvm_anfree(struct vm_anon *);
    void uvm_anon_init(void);
   struct vm_page *uvm_anon_lockloanpg(struct vm_anon *);
   #if defined(VMSWAP)
   void uvm_anon_dropswap(struct vm_anon *);
   #else /* defined(VMSWAP) */
   #define uvm_anon_dropswap(a)    /* nothing */
   #endif /* defined(VMSWAP) */
   void uvm_anon_release(struct vm_anon *);
   bool uvm_anon_pagein(struct vm_amap *, struct vm_anon *);
   #endif /* _KERNEL */
   
   #endif /* _UVM_UVM_ANON_H_ */

Cache object: b3260083718a589c447f5817f168f2ac