1325 lines
32 KiB
C
1325 lines
32 KiB
C
/*
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* Copyright (c) 1994 John S. Dyson
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* All rights reserved.
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* Copyright (c) 1994 David Greenman
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* All rights reserved.
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*
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*
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* This code is derived from software contributed to Berkeley by
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* The Mach Operating System project at Carnegie-Mellon University.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94
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*
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*
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* Copyright (c) 1987, 1990 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Authors: Avadis Tevanian, Jr., Michael Wayne Young
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*
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* $Id: vm_fault.c,v 1.11 1994/10/23 06:15:03 davidg Exp $
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*/
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/*
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* Page fault handling module.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/proc.h>
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#include <sys/resource.h>
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#include <sys/signalvar.h>
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#include <sys/resourcevar.h>
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#include <vm/vm.h>
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#include <vm/vm_page.h>
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#include <vm/vm_pageout.h>
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#include <vm/vm_kern.h>
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int vm_fault_additional_pages __P((vm_object_t, vm_offset_t, vm_page_t, int, int, vm_page_t *, int *));
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#define VM_FAULT_READ_AHEAD 4
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#define VM_FAULT_READ_AHEAD_MIN 1
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#define VM_FAULT_READ_BEHIND 3
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#define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1)
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extern int swap_pager_full;
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extern int vm_pageout_proc_limit;
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/*
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* vm_fault:
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*
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* Handle a page fault occuring at the given address,
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* requiring the given permissions, in the map specified.
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* If successful, the page is inserted into the
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* associated physical map.
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*
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* NOTE: the given address should be truncated to the
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* proper page address.
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*
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* KERN_SUCCESS is returned if the page fault is handled; otherwise,
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* a standard error specifying why the fault is fatal is returned.
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*
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*
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* The map in question must be referenced, and remains so.
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* Caller may hold no locks.
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*/
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int
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vm_fault(map, vaddr, fault_type, change_wiring)
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vm_map_t map;
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vm_offset_t vaddr;
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vm_prot_t fault_type;
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boolean_t change_wiring;
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{
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vm_object_t first_object;
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vm_offset_t first_offset;
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vm_map_entry_t entry;
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register vm_object_t object;
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register vm_offset_t offset;
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vm_page_t m;
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vm_page_t first_m;
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vm_prot_t prot;
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int result;
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boolean_t wired;
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boolean_t su;
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boolean_t lookup_still_valid;
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boolean_t page_exists;
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vm_page_t old_m;
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vm_object_t next_object;
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vm_page_t marray[VM_FAULT_READ];
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int spl;
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int hardfault=0;
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cnt.v_vm_faults++; /* needs lock XXX */
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/*
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* Recovery actions
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*/
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#define FREE_PAGE(m) { \
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PAGE_WAKEUP(m); \
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vm_page_lock_queues(); \
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vm_page_free(m); \
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vm_page_unlock_queues(); \
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}
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#define RELEASE_PAGE(m) { \
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PAGE_WAKEUP(m); \
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vm_page_lock_queues(); \
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vm_page_activate(m); \
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vm_page_unlock_queues(); \
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}
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#define UNLOCK_MAP { \
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if (lookup_still_valid) { \
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vm_map_lookup_done(map, entry); \
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lookup_still_valid = FALSE; \
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} \
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}
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#define UNLOCK_THINGS { \
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object->paging_in_progress--; \
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if (object->paging_in_progress == 0) \
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wakeup((caddr_t)object); \
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vm_object_unlock(object); \
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if (object != first_object) { \
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vm_object_lock(first_object); \
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FREE_PAGE(first_m); \
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first_object->paging_in_progress--; \
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if (first_object->paging_in_progress == 0) \
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wakeup((caddr_t)first_object); \
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vm_object_unlock(first_object); \
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} \
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UNLOCK_MAP; \
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}
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#define UNLOCK_AND_DEALLOCATE { \
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UNLOCK_THINGS; \
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vm_object_deallocate(first_object); \
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}
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RetryFault: ;
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/*
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* Find the backing store object and offset into
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* it to begin the search.
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*/
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if ((result = vm_map_lookup(&map, vaddr, fault_type, &entry,
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&first_object, &first_offset,
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&prot, &wired, &su)) != KERN_SUCCESS) {
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return(result);
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}
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lookup_still_valid = TRUE;
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if (wired)
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fault_type = prot;
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first_m = NULL;
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/*
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* Make a reference to this object to
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* prevent its disposal while we are messing with
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* it. Once we have the reference, the map is free
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* to be diddled. Since objects reference their
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* shadows (and copies), they will stay around as well.
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*/
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vm_object_lock(first_object);
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first_object->ref_count++;
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first_object->paging_in_progress++;
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/*
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* INVARIANTS (through entire routine):
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*
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* 1) At all times, we must either have the object
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* lock or a busy page in some object to prevent
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* some other thread from trying to bring in
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* the same page.
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*
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* Note that we cannot hold any locks during the
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* pager access or when waiting for memory, so
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* we use a busy page then.
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*
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* Note also that we aren't as concerned about
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* more than one thead attempting to pager_data_unlock
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* the same page at once, so we don't hold the page
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* as busy then, but do record the highest unlock
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* value so far. [Unlock requests may also be delivered
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* out of order.]
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*
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* 2) Once we have a busy page, we must remove it from
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* the pageout queues, so that the pageout daemon
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* will not grab it away.
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*
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* 3) To prevent another thread from racing us down the
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* shadow chain and entering a new page in the top
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* object before we do, we must keep a busy page in
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* the top object while following the shadow chain.
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*
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* 4) We must increment paging_in_progress on any object
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* for which we have a busy page, to prevent
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* vm_object_collapse from removing the busy page
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* without our noticing.
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*/
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/*
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* Search for the page at object/offset.
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*/
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object = first_object;
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offset = first_offset;
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/*
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* See whether this page is resident
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*/
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while (TRUE) {
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m = vm_page_lookup(object, offset);
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if (m != NULL) {
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/*
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* If the page is being brought in,
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* wait for it and then retry.
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*/
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if (m->flags & (PG_BUSY|PG_VMIO)) {
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int s;
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UNLOCK_THINGS;
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s = splhigh();
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if (m->flags & (PG_BUSY|PG_VMIO)) {
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m->flags |= PG_WANTED;
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cnt.v_intrans++;
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tsleep((caddr_t)m,PSWP,"vmpfw",0);
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}
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splx(s);
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vm_object_deallocate(first_object);
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goto RetryFault;
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}
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/*
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* Remove the page from the pageout daemon's
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* reach while we play with it.
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*/
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vm_page_lock_queues();
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spl = splhigh();
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if (m->flags & PG_INACTIVE) {
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TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq);
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m->flags &= ~PG_INACTIVE;
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cnt.v_inactive_count--;
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cnt.v_reactivated++;
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}
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if (m->flags & PG_ACTIVE) {
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TAILQ_REMOVE(&vm_page_queue_active, m, pageq);
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m->flags &= ~PG_ACTIVE;
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cnt.v_active_count--;
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}
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splx(spl);
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vm_page_unlock_queues();
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/*
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* Mark page busy for other threads.
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*/
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m->flags |= PG_BUSY;
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break;
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}
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if (((object->pager != NULL) &&
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(!change_wiring || wired))
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|| (object == first_object)) {
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#if 0
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if (curproc && (vaddr < VM_MAXUSER_ADDRESS) &&
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(curproc->p_rlimit[RLIMIT_RSS].rlim_max <
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curproc->p_vmspace->vm_pmap.pm_stats.resident_count * NBPG)) {
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UNLOCK_AND_DEALLOCATE;
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vm_fault_free_pages(curproc);
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goto RetryFault;
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}
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#endif
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if (swap_pager_full && !object->shadow && (!object->pager ||
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(object->pager && object->pager->pg_type == PG_SWAP &&
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!vm_pager_has_page(object->pager, offset+object->paging_offset)))) {
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if (vaddr < VM_MAXUSER_ADDRESS && curproc && curproc->p_pid >= 48) /* XXX */ {
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printf("Process %lu killed by vm_fault -- out of swap\n", (u_long)curproc->p_pid);
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psignal(curproc, SIGKILL);
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curproc->p_estcpu = 0;
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curproc->p_nice = PRIO_MIN;
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resetpriority(curproc);
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}
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}
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/*
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* Allocate a new page for this object/offset
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* pair.
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*/
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m = vm_page_alloc(object, offset);
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if (m == NULL) {
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UNLOCK_AND_DEALLOCATE;
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VM_WAIT;
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goto RetryFault;
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}
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}
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if (object->pager != NULL && (!change_wiring || wired)) {
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int rv;
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int faultcount;
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int reqpage;
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/*
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* Now that we have a busy page, we can
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* release the object lock.
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*/
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vm_object_unlock(object);
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/*
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* now we find out if any other pages should
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* be paged in at this time
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* this routine checks to see if the pages surrounding this fault
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* reside in the same object as the page for this fault. If
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* they do, then they are faulted in also into the
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* object. The array "marray" returned contains an array of
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* vm_page_t structs where one of them is the vm_page_t passed to
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* the routine. The reqpage return value is the index into the
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* marray for the vm_page_t passed to the routine.
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*/
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faultcount = vm_fault_additional_pages(
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first_object, first_offset,
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m, VM_FAULT_READ_BEHIND, VM_FAULT_READ_AHEAD,
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marray, &reqpage);
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/*
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* Call the pager to retrieve the data, if any,
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* after releasing the lock on the map.
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*/
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UNLOCK_MAP;
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rv = faultcount ?
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vm_pager_get_pages(object->pager,
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marray, faultcount, reqpage, TRUE): VM_PAGER_FAIL;
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if (rv == VM_PAGER_OK) {
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/*
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* Found the page.
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* Leave it busy while we play with it.
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*/
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vm_object_lock(object);
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/*
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* Relookup in case pager changed page.
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* Pager is responsible for disposition
|
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* of old page if moved.
|
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*/
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m = vm_page_lookup(object, offset);
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m->flags &= ~PG_FAKE;
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pmap_clear_modify(VM_PAGE_TO_PHYS(m));
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hardfault++;
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break;
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}
|
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|
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/*
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* Remove the bogus page (which does not
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* exist at this object/offset); before
|
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* doing so, we must get back our object
|
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* lock to preserve our invariant.
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*
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* Also wake up any other thread that may want
|
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* to bring in this page.
|
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*
|
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* If this is the top-level object, we must
|
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* leave the busy page to prevent another
|
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* thread from rushing past us, and inserting
|
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* the page in that object at the same time
|
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* that we are.
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*/
|
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|
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if (rv == VM_PAGER_ERROR)
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printf("vm_fault: pager input (probably hardware) error, PID %d failure\n",
|
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curproc->p_pid);
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vm_object_lock(object);
|
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/*
|
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* Data outside the range of the pager or an I/O error
|
|
*/
|
|
/*
|
|
* XXX - the check for kernel_map is a kludge to work around
|
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* having the machine panic on a kernel space fault w/ I/O error.
|
|
*/
|
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if (((map != kernel_map) && (rv == VM_PAGER_ERROR)) || (rv == VM_PAGER_BAD)) {
|
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FREE_PAGE(m);
|
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UNLOCK_AND_DEALLOCATE;
|
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return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE);
|
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}
|
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if (object != first_object) {
|
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FREE_PAGE(m);
|
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/*
|
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* XXX - we cannot just fall out at this
|
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* point, m has been freed and is invalid!
|
|
*/
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We get here if the object has no pager (or unwiring)
|
|
* or the pager doesn't have the page.
|
|
*/
|
|
if (object == first_object)
|
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first_m = m;
|
|
|
|
/*
|
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* Move on to the next object. Lock the next
|
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* object before unlocking the current one.
|
|
*/
|
|
|
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offset += object->shadow_offset;
|
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next_object = object->shadow;
|
|
if (next_object == NULL) {
|
|
/*
|
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* If there's no object left, fill the page
|
|
* in the top object with zeros.
|
|
*/
|
|
if (object != first_object) {
|
|
object->paging_in_progress--;
|
|
if (object->paging_in_progress == 0)
|
|
wakeup((caddr_t) object);
|
|
vm_object_unlock(object);
|
|
|
|
object = first_object;
|
|
offset = first_offset;
|
|
m = first_m;
|
|
vm_object_lock(object);
|
|
}
|
|
first_m = NULL;
|
|
|
|
vm_page_zero_fill(m);
|
|
cnt.v_zfod++;
|
|
m->flags &= ~PG_FAKE;
|
|
break;
|
|
}
|
|
else {
|
|
vm_object_lock(next_object);
|
|
if (object != first_object) {
|
|
object->paging_in_progress--;
|
|
if (object->paging_in_progress == 0)
|
|
wakeup((caddr_t) object);
|
|
}
|
|
vm_object_unlock(object);
|
|
object = next_object;
|
|
object->paging_in_progress++;
|
|
}
|
|
}
|
|
|
|
if ((m->flags & (PG_ACTIVE|PG_INACTIVE) != 0) ||
|
|
(m->flags & PG_BUSY) == 0)
|
|
panic("vm_fault: absent or active or inactive or not busy after main loop");
|
|
|
|
/*
|
|
* PAGE HAS BEEN FOUND.
|
|
* [Loop invariant still holds -- the object lock
|
|
* is held.]
|
|
*/
|
|
|
|
old_m = m; /* save page that would be copied */
|
|
|
|
/*
|
|
* If the page is being written, but isn't
|
|
* already owned by the top-level object,
|
|
* we have to copy it into a new page owned
|
|
* by the top-level object.
|
|
*/
|
|
|
|
if (object != first_object) {
|
|
/*
|
|
* We only really need to copy if we
|
|
* want to write it.
|
|
*/
|
|
|
|
if (fault_type & VM_PROT_WRITE) {
|
|
|
|
/*
|
|
* If we try to collapse first_object at this
|
|
* point, we may deadlock when we try to get
|
|
* the lock on an intermediate object (since we
|
|
* have the bottom object locked). We can't
|
|
* unlock the bottom object, because the page
|
|
* we found may move (by collapse) if we do.
|
|
*
|
|
* Instead, we first copy the page. Then, when
|
|
* we have no more use for the bottom object,
|
|
* we unlock it and try to collapse.
|
|
*
|
|
* Note that we copy the page even if we didn't
|
|
* need to... that's the breaks.
|
|
*/
|
|
|
|
/*
|
|
* We already have an empty page in
|
|
* first_object - use it.
|
|
*/
|
|
|
|
vm_page_copy(m, first_m);
|
|
first_m->flags &= ~PG_FAKE;
|
|
|
|
/*
|
|
* If another map is truly sharing this
|
|
* page with us, we have to flush all
|
|
* uses of the original page, since we
|
|
* can't distinguish those which want the
|
|
* original from those which need the
|
|
* new copy.
|
|
*
|
|
* XXX If we know that only one map has
|
|
* access to this page, then we could
|
|
* avoid the pmap_page_protect() call.
|
|
*/
|
|
|
|
vm_page_lock_queues();
|
|
|
|
vm_page_activate(m);
|
|
pmap_page_protect(VM_PAGE_TO_PHYS(m), VM_PROT_NONE);
|
|
if ((m->flags & PG_CLEAN) == 0)
|
|
m->flags |= PG_LAUNDRY;
|
|
vm_page_unlock_queues();
|
|
|
|
/*
|
|
* We no longer need the old page or object.
|
|
*/
|
|
PAGE_WAKEUP(m);
|
|
object->paging_in_progress--;
|
|
if (object->paging_in_progress == 0)
|
|
wakeup((caddr_t) object);
|
|
vm_object_unlock(object);
|
|
|
|
/*
|
|
* Only use the new page below...
|
|
*/
|
|
|
|
cnt.v_cow_faults++;
|
|
m = first_m;
|
|
object = first_object;
|
|
offset = first_offset;
|
|
|
|
/*
|
|
* Now that we've gotten the copy out of the
|
|
* way, let's try to collapse the top object.
|
|
*/
|
|
vm_object_lock(object);
|
|
/*
|
|
* But we have to play ugly games with
|
|
* paging_in_progress to do that...
|
|
*/
|
|
object->paging_in_progress--;
|
|
if (object->paging_in_progress == 0)
|
|
wakeup((caddr_t) object);
|
|
vm_object_collapse(object);
|
|
object->paging_in_progress++;
|
|
}
|
|
else {
|
|
prot &= ~VM_PROT_WRITE;
|
|
m->flags |= PG_COPYONWRITE;
|
|
}
|
|
}
|
|
|
|
if (m->flags & (PG_ACTIVE|PG_INACTIVE))
|
|
panic("vm_fault: active or inactive before copy object handling");
|
|
|
|
/*
|
|
* If the page is being written, but hasn't been
|
|
* copied to the copy-object, we have to copy it there.
|
|
*/
|
|
RetryCopy:
|
|
if (first_object->copy != NULL) {
|
|
vm_object_t copy_object = first_object->copy;
|
|
vm_offset_t copy_offset;
|
|
vm_page_t copy_m;
|
|
|
|
/*
|
|
* We only need to copy if we want to write it.
|
|
*/
|
|
if ((fault_type & VM_PROT_WRITE) == 0) {
|
|
prot &= ~VM_PROT_WRITE;
|
|
m->flags |= PG_COPYONWRITE;
|
|
}
|
|
else {
|
|
/*
|
|
* Try to get the lock on the copy_object.
|
|
*/
|
|
if (!vm_object_lock_try(copy_object)) {
|
|
vm_object_unlock(object);
|
|
/* should spin a bit here... */
|
|
vm_object_lock(object);
|
|
goto RetryCopy;
|
|
}
|
|
|
|
/*
|
|
* Make another reference to the copy-object,
|
|
* to keep it from disappearing during the
|
|
* copy.
|
|
*/
|
|
copy_object->ref_count++;
|
|
|
|
/*
|
|
* Does the page exist in the copy?
|
|
*/
|
|
copy_offset = first_offset
|
|
- copy_object->shadow_offset;
|
|
copy_m = vm_page_lookup(copy_object, copy_offset);
|
|
page_exists = (copy_m != NULL);
|
|
if (page_exists) {
|
|
if (copy_m->flags & (PG_BUSY|PG_VMIO)) {
|
|
/*
|
|
* If the page is being brought
|
|
* in, wait for it and then retry.
|
|
*/
|
|
RELEASE_PAGE(m);
|
|
copy_object->ref_count--;
|
|
vm_object_unlock(copy_object);
|
|
UNLOCK_THINGS;
|
|
spl = splhigh();
|
|
if( copy_m->flags & (PG_BUSY|PG_VMIO)) {
|
|
copy_m->flags |= PG_WANTED;
|
|
tsleep((caddr_t)copy_m,PSWP,"vmpfwc",0);
|
|
}
|
|
splx(spl);
|
|
vm_object_deallocate(first_object);
|
|
goto RetryFault;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If the page is not in memory (in the object)
|
|
* and the object has a pager, we have to check
|
|
* if the pager has the data in secondary
|
|
* storage.
|
|
*/
|
|
if (!page_exists) {
|
|
|
|
/*
|
|
* If we don't allocate a (blank) page
|
|
* here... another thread could try
|
|
* to page it in, allocate a page, and
|
|
* then block on the busy page in its
|
|
* shadow (first_object). Then we'd
|
|
* trip over the busy page after we
|
|
* found that the copy_object's pager
|
|
* doesn't have the page...
|
|
*/
|
|
copy_m = vm_page_alloc(copy_object, copy_offset);
|
|
if (copy_m == NULL) {
|
|
/*
|
|
* Wait for a page, then retry.
|
|
*/
|
|
RELEASE_PAGE(m);
|
|
copy_object->ref_count--;
|
|
vm_object_unlock(copy_object);
|
|
UNLOCK_AND_DEALLOCATE;
|
|
VM_WAIT;
|
|
goto RetryFault;
|
|
}
|
|
|
|
if (copy_object->pager != NULL) {
|
|
vm_object_unlock(object);
|
|
vm_object_unlock(copy_object);
|
|
UNLOCK_MAP;
|
|
|
|
page_exists = vm_pager_has_page(
|
|
copy_object->pager,
|
|
(copy_offset + copy_object->paging_offset));
|
|
|
|
vm_object_lock(copy_object);
|
|
|
|
/*
|
|
* Since the map is unlocked, someone
|
|
* else could have copied this object
|
|
* and put a different copy_object
|
|
* between the two. Or, the last
|
|
* reference to the copy-object (other
|
|
* than the one we have) may have
|
|
* disappeared - if that has happened,
|
|
* we don't need to make the copy.
|
|
*/
|
|
if (copy_object->shadow != object ||
|
|
copy_object->ref_count == 1) {
|
|
/*
|
|
* Gaah... start over!
|
|
*/
|
|
FREE_PAGE(copy_m);
|
|
vm_object_unlock(copy_object);
|
|
vm_object_deallocate(copy_object);
|
|
/* may block */
|
|
vm_object_lock(object);
|
|
goto RetryCopy;
|
|
}
|
|
vm_object_lock(object);
|
|
|
|
if (page_exists) {
|
|
/*
|
|
* We didn't need the page
|
|
*/
|
|
FREE_PAGE(copy_m);
|
|
}
|
|
}
|
|
}
|
|
if (!page_exists) {
|
|
/*
|
|
* Must copy page into copy-object.
|
|
*/
|
|
vm_page_copy(m, copy_m);
|
|
copy_m->flags &= ~PG_FAKE;
|
|
|
|
/*
|
|
* Things to remember:
|
|
* 1. The copied page must be marked 'dirty'
|
|
* so it will be paged out to the copy
|
|
* object.
|
|
* 2. If the old page was in use by any users
|
|
* of the copy-object, it must be removed
|
|
* from all pmaps. (We can't know which
|
|
* pmaps use it.)
|
|
*/
|
|
vm_page_lock_queues();
|
|
|
|
vm_page_activate(old_m);
|
|
|
|
|
|
pmap_page_protect(VM_PAGE_TO_PHYS(old_m),
|
|
VM_PROT_NONE);
|
|
if ((old_m->flags & PG_CLEAN) == 0)
|
|
old_m->flags |= PG_LAUNDRY;
|
|
copy_m->flags &= ~PG_CLEAN;
|
|
vm_page_activate(copy_m);
|
|
vm_page_unlock_queues();
|
|
|
|
PAGE_WAKEUP(copy_m);
|
|
}
|
|
/*
|
|
* The reference count on copy_object must be
|
|
* at least 2: one for our extra reference,
|
|
* and at least one from the outside world
|
|
* (we checked that when we last locked
|
|
* copy_object).
|
|
*/
|
|
copy_object->ref_count--;
|
|
vm_object_unlock(copy_object);
|
|
m->flags &= ~PG_COPYONWRITE;
|
|
}
|
|
}
|
|
|
|
if (m->flags & (PG_ACTIVE | PG_INACTIVE))
|
|
panic("vm_fault: active or inactive before retrying lookup");
|
|
|
|
/*
|
|
* We must verify that the maps have not changed
|
|
* since our last lookup.
|
|
*/
|
|
|
|
if (!lookup_still_valid) {
|
|
vm_object_t retry_object;
|
|
vm_offset_t retry_offset;
|
|
vm_prot_t retry_prot;
|
|
|
|
/*
|
|
* Since map entries may be pageable, make sure we can
|
|
* take a page fault on them.
|
|
*/
|
|
vm_object_unlock(object);
|
|
|
|
/*
|
|
* To avoid trying to write_lock the map while another
|
|
* thread has it read_locked (in vm_map_pageable), we
|
|
* do not try for write permission. If the page is
|
|
* still writable, we will get write permission. If it
|
|
* is not, or has been marked needs_copy, we enter the
|
|
* mapping without write permission, and will merely
|
|
* take another fault.
|
|
*/
|
|
result = vm_map_lookup(&map, vaddr,
|
|
fault_type & ~VM_PROT_WRITE, &entry,
|
|
&retry_object, &retry_offset, &retry_prot,
|
|
&wired, &su);
|
|
|
|
vm_object_lock(object);
|
|
|
|
/*
|
|
* If we don't need the page any longer, put it on the
|
|
* active list (the easiest thing to do here). If no
|
|
* one needs it, pageout will grab it eventually.
|
|
*/
|
|
|
|
if (result != KERN_SUCCESS) {
|
|
RELEASE_PAGE(m);
|
|
UNLOCK_AND_DEALLOCATE;
|
|
return(result);
|
|
}
|
|
|
|
lookup_still_valid = TRUE;
|
|
|
|
if ((retry_object != first_object) ||
|
|
(retry_offset != first_offset)) {
|
|
RELEASE_PAGE(m);
|
|
UNLOCK_AND_DEALLOCATE;
|
|
goto RetryFault;
|
|
}
|
|
|
|
/*
|
|
* Check whether the protection has changed or the object
|
|
* has been copied while we left the map unlocked.
|
|
* Changing from read to write permission is OK - we leave
|
|
* the page write-protected, and catch the write fault.
|
|
* Changing from write to read permission means that we
|
|
* can't mark the page write-enabled after all.
|
|
*/
|
|
prot &= retry_prot;
|
|
if (m->flags & PG_COPYONWRITE)
|
|
prot &= ~VM_PROT_WRITE;
|
|
}
|
|
|
|
/*
|
|
* (the various bits we're fiddling with here are locked by
|
|
* the object's lock)
|
|
*/
|
|
|
|
/* XXX This distorts the meaning of the copy_on_write bit */
|
|
|
|
if (prot & VM_PROT_WRITE)
|
|
m->flags &= ~PG_COPYONWRITE;
|
|
|
|
/*
|
|
* It's critically important that a wired-down page be faulted
|
|
* only once in each map for which it is wired.
|
|
*/
|
|
|
|
if (m->flags & (PG_ACTIVE | PG_INACTIVE))
|
|
panic("vm_fault: active or inactive before pmap_enter");
|
|
|
|
vm_object_unlock(object);
|
|
|
|
/*
|
|
* Put this page into the physical map.
|
|
* We had to do the unlock above because pmap_enter
|
|
* may cause other faults. We don't put the
|
|
* page back on the active queue until later so
|
|
* that the page-out daemon won't find us (yet).
|
|
*/
|
|
|
|
pmap_enter(map->pmap, vaddr, VM_PAGE_TO_PHYS(m), prot, wired);
|
|
|
|
/*
|
|
* If the page is not wired down, then put it where the
|
|
* pageout daemon can find it.
|
|
*/
|
|
vm_object_lock(object);
|
|
vm_page_lock_queues();
|
|
if (change_wiring) {
|
|
if (wired)
|
|
vm_page_wire(m);
|
|
else
|
|
vm_page_unwire(m);
|
|
}
|
|
else {
|
|
vm_page_activate(m);
|
|
}
|
|
|
|
if( curproc && curproc->p_stats) {
|
|
if (hardfault) {
|
|
curproc->p_stats->p_ru.ru_majflt++;
|
|
} else {
|
|
curproc->p_stats->p_ru.ru_minflt++;
|
|
}
|
|
}
|
|
|
|
vm_page_unlock_queues();
|
|
|
|
/*
|
|
* Unlock everything, and return
|
|
*/
|
|
|
|
PAGE_WAKEUP(m);
|
|
UNLOCK_AND_DEALLOCATE;
|
|
|
|
return(KERN_SUCCESS);
|
|
|
|
}
|
|
|
|
/*
|
|
* vm_fault_wire:
|
|
*
|
|
* Wire down a range of virtual addresses in a map.
|
|
*/
|
|
int
|
|
vm_fault_wire(map, start, end)
|
|
vm_map_t map;
|
|
vm_offset_t start, end;
|
|
{
|
|
|
|
register vm_offset_t va;
|
|
register pmap_t pmap;
|
|
int rv;
|
|
|
|
pmap = vm_map_pmap(map);
|
|
|
|
/*
|
|
* Inform the physical mapping system that the
|
|
* range of addresses may not fault, so that
|
|
* page tables and such can be locked down as well.
|
|
*/
|
|
|
|
pmap_pageable(pmap, start, end, FALSE);
|
|
|
|
/*
|
|
* We simulate a fault to get the page and enter it
|
|
* in the physical map.
|
|
*/
|
|
|
|
for (va = start; va < end; va += PAGE_SIZE) {
|
|
rv = vm_fault(map, va, VM_PROT_NONE, TRUE);
|
|
if (rv) {
|
|
if (va != start)
|
|
vm_fault_unwire(map, start, va);
|
|
return(rv);
|
|
}
|
|
}
|
|
return(KERN_SUCCESS);
|
|
}
|
|
|
|
|
|
/*
|
|
* vm_fault_unwire:
|
|
*
|
|
* Unwire a range of virtual addresses in a map.
|
|
*/
|
|
void
|
|
vm_fault_unwire(map, start, end)
|
|
vm_map_t map;
|
|
vm_offset_t start, end;
|
|
{
|
|
|
|
register vm_offset_t va, pa;
|
|
register pmap_t pmap;
|
|
|
|
pmap = vm_map_pmap(map);
|
|
|
|
/*
|
|
* Since the pages are wired down, we must be able to
|
|
* get their mappings from the physical map system.
|
|
*/
|
|
|
|
vm_page_lock_queues();
|
|
|
|
for (va = start; va < end; va += PAGE_SIZE) {
|
|
pa = pmap_extract(pmap, va);
|
|
if (pa == (vm_offset_t) 0) {
|
|
panic("unwire: page not in pmap");
|
|
}
|
|
pmap_change_wiring(pmap, va, FALSE);
|
|
vm_page_unwire(PHYS_TO_VM_PAGE(pa));
|
|
}
|
|
vm_page_unlock_queues();
|
|
|
|
/*
|
|
* Inform the physical mapping system that the range
|
|
* of addresses may fault, so that page tables and
|
|
* such may be unwired themselves.
|
|
*/
|
|
|
|
pmap_pageable(pmap, start, end, TRUE);
|
|
|
|
}
|
|
|
|
/*
|
|
* Routine:
|
|
* vm_fault_copy_entry
|
|
* Function:
|
|
* Copy all of the pages from a wired-down map entry to another.
|
|
*
|
|
* In/out conditions:
|
|
* The source and destination maps must be locked for write.
|
|
* The source map entry must be wired down (or be a sharing map
|
|
* entry corresponding to a main map entry that is wired down).
|
|
*/
|
|
|
|
void
|
|
vm_fault_copy_entry(dst_map, src_map, dst_entry, src_entry)
|
|
vm_map_t dst_map;
|
|
vm_map_t src_map;
|
|
vm_map_entry_t dst_entry;
|
|
vm_map_entry_t src_entry;
|
|
{
|
|
vm_object_t dst_object;
|
|
vm_object_t src_object;
|
|
vm_offset_t dst_offset;
|
|
vm_offset_t src_offset;
|
|
vm_prot_t prot;
|
|
vm_offset_t vaddr;
|
|
vm_page_t dst_m;
|
|
vm_page_t src_m;
|
|
|
|
#ifdef lint
|
|
src_map++;
|
|
#endif lint
|
|
|
|
src_object = src_entry->object.vm_object;
|
|
src_offset = src_entry->offset;
|
|
|
|
/*
|
|
* Create the top-level object for the destination entry.
|
|
* (Doesn't actually shadow anything - we copy the pages
|
|
* directly.)
|
|
*/
|
|
dst_object = vm_object_allocate(
|
|
(vm_size_t) (dst_entry->end - dst_entry->start));
|
|
|
|
dst_entry->object.vm_object = dst_object;
|
|
dst_entry->offset = 0;
|
|
|
|
prot = dst_entry->max_protection;
|
|
|
|
/*
|
|
* Loop through all of the pages in the entry's range, copying
|
|
* each one from the source object (it should be there) to the
|
|
* destination object.
|
|
*/
|
|
for (vaddr = dst_entry->start, dst_offset = 0;
|
|
vaddr < dst_entry->end;
|
|
vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) {
|
|
|
|
/*
|
|
* Allocate a page in the destination object
|
|
*/
|
|
vm_object_lock(dst_object);
|
|
do {
|
|
dst_m = vm_page_alloc(dst_object, dst_offset);
|
|
if (dst_m == NULL) {
|
|
vm_object_unlock(dst_object);
|
|
VM_WAIT;
|
|
vm_object_lock(dst_object);
|
|
}
|
|
} while (dst_m == NULL);
|
|
|
|
/*
|
|
* Find the page in the source object, and copy it in.
|
|
* (Because the source is wired down, the page will be
|
|
* in memory.)
|
|
*/
|
|
vm_object_lock(src_object);
|
|
src_m = vm_page_lookup(src_object, dst_offset + src_offset);
|
|
if (src_m == NULL)
|
|
panic("vm_fault_copy_wired: page missing");
|
|
|
|
vm_page_copy(src_m, dst_m);
|
|
|
|
/*
|
|
* Enter it in the pmap...
|
|
*/
|
|
vm_object_unlock(src_object);
|
|
vm_object_unlock(dst_object);
|
|
|
|
pmap_enter(dst_map->pmap, vaddr, VM_PAGE_TO_PHYS(dst_m),
|
|
prot, FALSE);
|
|
|
|
/*
|
|
* Mark it no longer busy, and put it on the active list.
|
|
*/
|
|
vm_object_lock(dst_object);
|
|
vm_page_lock_queues();
|
|
vm_page_activate(dst_m);
|
|
vm_page_unlock_queues();
|
|
PAGE_WAKEUP(dst_m);
|
|
vm_object_unlock(dst_object);
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
* looks page up in shadow chain
|
|
*/
|
|
|
|
int
|
|
vm_fault_page_lookup(object, offset, rtobject, rtoffset, rtm)
|
|
vm_object_t object;
|
|
vm_offset_t offset;
|
|
vm_object_t *rtobject;
|
|
vm_offset_t *rtoffset;
|
|
vm_page_t *rtm;
|
|
{
|
|
vm_page_t m;
|
|
|
|
*rtm = 0;
|
|
*rtobject = 0;
|
|
*rtoffset = 0;
|
|
|
|
|
|
while (!(m=vm_page_lookup(object, offset))) {
|
|
if (object->pager) {
|
|
if (vm_pager_has_page(object->pager, object->paging_offset+offset)) {
|
|
*rtobject = object;
|
|
*rtoffset = offset;
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
if (!object->shadow)
|
|
return 0;
|
|
else {
|
|
offset += object->shadow_offset;
|
|
object = object->shadow;
|
|
}
|
|
}
|
|
*rtobject = object;
|
|
*rtoffset = offset;
|
|
*rtm = m;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* This routine checks around the requested page for other pages that
|
|
* might be able to be faulted in.
|
|
*
|
|
* Inputs:
|
|
* first_object, first_offset, m, rbehind, rahead
|
|
*
|
|
* Outputs:
|
|
* marray (array of vm_page_t), reqpage (index of requested page)
|
|
*
|
|
* Return value:
|
|
* number of pages in marray
|
|
*/
|
|
int
|
|
vm_fault_additional_pages(first_object, first_offset, m, rbehind, raheada, marray, reqpage)
|
|
vm_object_t first_object;
|
|
vm_offset_t first_offset;
|
|
vm_page_t m;
|
|
int rbehind;
|
|
int raheada;
|
|
vm_page_t *marray;
|
|
int *reqpage;
|
|
{
|
|
int i;
|
|
vm_object_t object;
|
|
vm_offset_t offset, startoffset, endoffset, toffset, size;
|
|
vm_object_t rtobject;
|
|
vm_page_t rtm;
|
|
vm_offset_t rtoffset;
|
|
vm_offset_t offsetdiff;
|
|
int rahead;
|
|
int treqpage;
|
|
|
|
object = m->object;
|
|
offset = m->offset;
|
|
|
|
offsetdiff = offset - first_offset;
|
|
|
|
/*
|
|
* if the requested page is not available, then give up now
|
|
*/
|
|
|
|
if (!vm_pager_has_page(object->pager, object->paging_offset+offset))
|
|
return 0;
|
|
|
|
/*
|
|
* if there is no getmulti routine for this pager, then just allow
|
|
* one page to be read.
|
|
*/
|
|
/*
|
|
if (!object->pager->pg_ops->pgo_getpages) {
|
|
*reqpage = 0;
|
|
marray[0] = m;
|
|
return 1;
|
|
}
|
|
*/
|
|
|
|
/*
|
|
* try to do any readahead that we might have free pages for.
|
|
*/
|
|
rahead = raheada;
|
|
if (rahead > (cnt.v_free_count - cnt.v_free_reserved)) {
|
|
rahead = cnt.v_free_count - cnt.v_free_reserved;
|
|
rbehind = 0;
|
|
}
|
|
|
|
if (cnt.v_free_count < cnt.v_free_min) {
|
|
if (rahead > VM_FAULT_READ_AHEAD_MIN)
|
|
rahead = VM_FAULT_READ_AHEAD_MIN;
|
|
rbehind = 0;
|
|
}
|
|
|
|
/*
|
|
* if we don't have any free pages, then just read one page.
|
|
*/
|
|
if (rahead <= 0) {
|
|
*reqpage = 0;
|
|
marray[0] = m;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* scan backward for the read behind pages --
|
|
* in memory or on disk not in same object
|
|
*/
|
|
toffset = offset - NBPG;
|
|
if( rbehind*NBPG > offset)
|
|
rbehind = offset / NBPG;
|
|
startoffset = offset - rbehind*NBPG;
|
|
while (toffset >= startoffset) {
|
|
if (!vm_fault_page_lookup(first_object, toffset - offsetdiff, &rtobject, &rtoffset, &rtm) ||
|
|
rtm != 0 || rtobject != object) {
|
|
startoffset = toffset + NBPG;
|
|
break;
|
|
}
|
|
if( toffset == 0)
|
|
break;
|
|
toffset -= NBPG;
|
|
}
|
|
|
|
/*
|
|
* scan forward for the read ahead pages --
|
|
* in memory or on disk not in same object
|
|
*/
|
|
toffset = offset + NBPG;
|
|
endoffset = offset + (rahead+1)*NBPG;
|
|
while (toffset < object->size && toffset < endoffset) {
|
|
if (!vm_fault_page_lookup(first_object, toffset - offsetdiff, &rtobject, &rtoffset, &rtm) ||
|
|
rtm != 0 || rtobject != object) {
|
|
break;
|
|
}
|
|
toffset += NBPG;
|
|
}
|
|
endoffset = toffset;
|
|
|
|
/* calculate number of bytes of pages */
|
|
size = (endoffset - startoffset) / NBPG;
|
|
|
|
/* calculate the page offset of the required page */
|
|
treqpage = (offset - startoffset) / NBPG;
|
|
|
|
/* see if we have space (again) */
|
|
if (cnt.v_free_count >= cnt.v_free_reserved + size) {
|
|
bzero(marray, (rahead + rbehind + 1) * sizeof(vm_page_t));
|
|
/*
|
|
* get our pages and don't block for them
|
|
*/
|
|
for (i = 0; i < size; i++) {
|
|
if (i != treqpage)
|
|
rtm = vm_page_alloc(object, startoffset + i * NBPG);
|
|
else
|
|
rtm = m;
|
|
marray[i] = rtm;
|
|
}
|
|
|
|
for (i = 0; i < size; i++) {
|
|
if (marray[i] == 0)
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* if we could not get our block of pages, then
|
|
* free the readahead/readbehind pages.
|
|
*/
|
|
if (i < size) {
|
|
for (i = 0; i < size; i++) {
|
|
if (i != treqpage && marray[i])
|
|
FREE_PAGE(marray[i]);
|
|
}
|
|
*reqpage = 0;
|
|
marray[0] = m;
|
|
return 1;
|
|
}
|
|
|
|
*reqpage = treqpage;
|
|
return size;
|
|
}
|
|
*reqpage = 0;
|
|
marray[0] = m;
|
|
return 1;
|
|
}
|
|
|