LCOM1920-T02G10

/*        $NetBSD: uvm_anon.h,v 1.30 2011/08/06 17:25:03 rmind 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 {

        kmutex_t                *an_lock;        /* Lock for an_ref */

        union {

                uintptr_t        au_ref;                /* Reference count [an_lock] */

                struct vm_anon        *au_link;        /* Link for deferred free */

        } an_u;

#define        an_ref        an_u.au_ref

#define        an_link        an_u.au_link

        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_anon_free(struct vm_anon *);

void uvm_anon_freelst(struct vm_amap *, 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_ */