151 lines
5.5 KiB
C
151 lines
5.5 KiB
C
/* $NetBSD: uvm_anon.h,v 1.8 1998/11/20 19:37:06 chuck Exp $ */
|
|
|
|
/*
|
|
* XXXCDC: "ROUGH DRAFT" QUALITY UVM PRE-RELEASE FILE!
|
|
* >>>USE AT YOUR OWN RISK, WORK IS NOT FINISHED<<<
|
|
*/
|
|
/*
|
|
*
|
|
* 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.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by Charles D. Cranor and
|
|
* Washington University.
|
|
* 4. The name of the author may not be used to endorse or promote products
|
|
* derived from this software without specific prior written permission.
|
|
*
|
|
* 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.
|
|
*
|
|
* from: Id: uvm_anon.h,v 1.1.2.4 1998/01/04 22:43:39 chuck Exp
|
|
*/
|
|
|
|
#ifndef _UVM_UVM_ANON_H_
|
|
#define _UVM_UVM_ANON_H_
|
|
|
|
/*
|
|
* 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 {
|
|
int an_ref; /* reference count [an_lock] */
|
|
simple_lock_data_t an_lock; /* lock for an_ref */
|
|
union {
|
|
struct vm_anon *an_nxt; /* if on free list [afreelock] */
|
|
struct vm_page *an_page;/* if in RAM [an_lock] */
|
|
} u;
|
|
int an_swslot; /* drum swap slot # (if != 0)
|
|
[an_lock. also, it is ok to read
|
|
an_swslot if we hold an_page PG_BUSY] */
|
|
};
|
|
|
|
/*
|
|
* a pool of vm_anon data structures is allocated and put on a global
|
|
* free list at boot time. vm_anon's on the free list use "an_nxt" as
|
|
* a pointer to the next item on the free list. 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.
|
|
*/
|
|
|
|
/*
|
|
* anonymous virtual memory pages (vm_anon's) live in anonymous memory
|
|
* maps. anonymous memory maps can be shared between processes.
|
|
* different subsets of an anonymous memory map can be referenced by
|
|
* processes (see below). an anonymous map is described by the following
|
|
* data structure:
|
|
*/
|
|
|
|
#define VM_AMAP_PPREF /* use a per-page reference count for split
|
|
vm_map_entry_t's. */
|
|
|
|
struct vm_amap {
|
|
simple_lock_data_t am_l; /* simple lock [locks all vm_amap fields] */
|
|
int am_ref; /* reference count */
|
|
int am_flags; /* flags */
|
|
int am_maxslot; /* max # of slots allocated */
|
|
int am_nslot; /* # of slots currently in map ( <= maxslot) */
|
|
int am_nused; /* # of slots currently in use */
|
|
int *am_slots; /* contig array of active slots */
|
|
int *am_bckptr; /* back pointer array to am_slots */
|
|
struct vm_anon **am_anon; /* array of anonymous pages */
|
|
#ifdef VM_AMAP_PPREF
|
|
int *am_ppref; /* per page reference count (if !NULL) */
|
|
#endif
|
|
};
|
|
|
|
#define AMAP_SHARED 0x1 /* am_flags: shared amap */
|
|
#define AMAP_REFALL 0x2 /* flag to amap_ref() */
|
|
|
|
/*
|
|
* note that am_slots, am_bckptr, and am_anon are arrays. this allows
|
|
* fast lookup of pages based on their virual address at the expense of
|
|
* some extra memory. [XXX: for memory starved systems provide alternate
|
|
* functions?]
|
|
*
|
|
* 4 slot/page example, with slots 1 and 3 in use:
|
|
* ("D/C" == don't care what the value is)
|
|
*
|
|
* 0 1 2 3
|
|
* am_anon: NULL, anon0, NULL, anon1 (actual pointers to anons)
|
|
* am_bckptr: D/C, 1, D/C, 0 (points to am_slots entry)
|
|
*
|
|
* am_slots: 3, 1, D/C, D/C (says slots 3 and 1 are in use)
|
|
*
|
|
* note that am_bckptr is D/C if the slot in am_anon is set to NULL.
|
|
* to find the entry in am_slots for an anon, look at am_bckptr[slot],
|
|
* thus the entry for slot 3 in am_slots[] is at am_slots[am_bckptr[3]].
|
|
* in general, if am_anon[X] is non-NULL, then the following must be
|
|
* true: am_slots[am_bckptr[X]] == X
|
|
*
|
|
* note that am_slots is always contig-packed.
|
|
*/
|
|
|
|
/*
|
|
* processes reference anonymous virtual memory maps with an anonymous
|
|
* reference structure:
|
|
*/
|
|
|
|
struct vm_aref {
|
|
int ar_slotoff; /* slot 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.
|
|
*/
|
|
|
|
|
|
#endif /* _UVM_UVM_ANON_H_ */
|