1064 lines
27 KiB
C
1064 lines
27 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 1.27 1995/09/03 20:40:41 dyson 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/vnode.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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#include <vm/vm_pager.h>
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#include <vm/vnode_pager.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_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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/*
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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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struct vnode *vp = NULL;
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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_free(m); \
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}
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#define RELEASE_PAGE(m) { \
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PAGE_WAKEUP(m); \
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if ((m->flags & PG_ACTIVE) == 0) vm_page_activate(m); \
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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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vm_object_pip_wakeup(object); \
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if (object != first_object) { \
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FREE_PAGE(first_m); \
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vm_object_pip_wakeup(first_object); \
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} \
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UNLOCK_MAP; \
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if (vp != NULL) VOP_UNLOCK(vp); \
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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 it to begin the
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* search.
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*/
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if ((result = vm_map_lookup(&map, vaddr, fault_type, &entry, &first_object,
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&first_offset, &prot, &wired, &su)) != KERN_SUCCESS) {
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return (result);
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}
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vp = vnode_pager_lock(first_object);
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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 prevent its disposal while we
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* are messing with it. Once we have the reference, the map is free
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* to be diddled. Since objects reference their shadows (and copies),
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* they will stay around as well.
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*/
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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 lock or a busy
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* page in some object to prevent some other process from trying to
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* bring in the same page.
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*
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* Note that we cannot hold any locks during the pager access or when
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* waiting for memory, so we use a busy page then.
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*
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* Note also that we aren't as concerned about more than one thead
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* attempting to pager_data_unlock the same page at once, so we don't
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* hold the page as busy then, but do record the highest unlock value
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* so far. [Unlock requests may also be delivered out of order.]
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*
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* 2) Once we have a busy page, we must remove it from the pageout
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* queues, so that the pageout daemon will not grab it away.
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*
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* 3) To prevent another process from racing us down the shadow chain
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* and entering a new page in the top object before we do, we must
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* keep a busy page in the top object while following the shadow
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* chain.
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*
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* 4) We must increment paging_in_progress on any object for which
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* we have a busy page, to prevent vm_object_collapse from removing
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* the busy page 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, wait for it and
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* then retry.
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*/
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if ((m->flags & PG_BUSY) || m->busy) {
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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) || m->busy) {
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m->flags |= PG_WANTED | PG_REFERENCED;
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cnt.v_intrans++;
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tsleep(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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if ((m->flags & PG_CACHE) &&
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(cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_reserved) {
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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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* Mark page busy for other processes, and the pagedaemon.
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*/
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m->flags |= PG_BUSY;
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if (m->valid && ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) &&
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m->object != kernel_object && m->object != kmem_object) {
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goto readrest;
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}
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break;
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}
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if (((object->type != OBJT_DEFAULT) && (!change_wiring || wired))
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|| (object == first_object)) {
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if (offset >= object->size) {
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UNLOCK_AND_DEALLOCATE;
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return (KERN_PROTECTION_FAILURE);
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}
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#if 0 /* XXX is this really necessary? */
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if (swap_pager_full && !object->backing_object &&
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(object->type == OBJT_DEFAULT ||
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(object->type == OBJT_SWAP &&
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!vm_pager_has_page(object, offset + object->paging_offset, NULL, NULL)))) {
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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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#endif
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/*
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* Allocate a new page for this object/offset pair.
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*/
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m = vm_page_alloc(object, offset,
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vp?VM_ALLOC_NORMAL:(VM_ALLOC_NORMAL|VM_ALLOC_ZERO));
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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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readrest:
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if (object->type != OBJT_DEFAULT && (!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 we find out if any other pages should be paged
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* in at this time this routine checks to see if the
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* pages surrounding this fault reside in the same
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* object as the page for this fault. If they do,
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* then they are faulted in also into the object. The
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* array "marray" returned contains an array of
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* vm_page_t structs where one of them is the
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* vm_page_t passed to the routine. The reqpage
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* return value is the index into the marray for the
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* 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, after
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* 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, marray, faultcount,
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reqpage) : VM_PAGER_FAIL;
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if (rv == VM_PAGER_OK) {
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/*
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* Found the page. Leave it busy while we play
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* with it.
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*/
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/*
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* Relookup in case pager changed page. Pager
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* is responsible for disposition of old page
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* if moved.
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*/
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m = vm_page_lookup(object, offset);
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if( !m) {
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UNLOCK_AND_DEALLOCATE;
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goto RetryFault;
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}
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pmap_clear_modify(VM_PAGE_TO_PHYS(m));
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m->valid = VM_PAGE_BITS_ALL;
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hardfault++;
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break;
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}
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/*
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* Remove the bogus page (which does not exist at this
|
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* object/offset); before doing so, we must get back
|
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* our object lock to preserve our invariant.
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*
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* Also wake up any other process that may want to bring
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* in this page.
|
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*
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* If this is the top-level object, we must leave the
|
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* busy page to prevent another process from rushing
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* past us, and inserting the page in that object at
|
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* the same time that we are.
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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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/*
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* Data outside the range of the pager or an I/O error
|
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*/
|
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/*
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* XXX - the check for kernel_map is a kludge to work
|
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* around having the machine panic on a kernel space
|
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* fault w/ I/O error.
|
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*/
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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!
|
|
*/
|
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}
|
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}
|
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/*
|
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* We get here if the object has default pager (or unwiring) or the
|
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* pager doesn't have the page.
|
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*/
|
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if (object == first_object)
|
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first_m = m;
|
|
|
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/*
|
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* Move on to the next object. Lock the next object before
|
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* unlocking the current one.
|
|
*/
|
|
|
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offset += object->backing_object_offset;
|
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next_object = object->backing_object;
|
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if (next_object == NULL) {
|
|
/*
|
|
* If there's no object left, fill the page in the top
|
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* object with zeros.
|
|
*/
|
|
if (object != first_object) {
|
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vm_object_pip_wakeup(object);
|
|
|
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object = first_object;
|
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offset = first_offset;
|
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m = first_m;
|
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}
|
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first_m = NULL;
|
|
|
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if ((m->flags & PG_ZERO) == 0)
|
|
vm_page_zero_fill(m);
|
|
m->valid = VM_PAGE_BITS_ALL;
|
|
cnt.v_zfod++;
|
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break;
|
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} else {
|
|
if (object != first_object) {
|
|
vm_object_pip_wakeup(object);
|
|
}
|
|
object = next_object;
|
|
object->paging_in_progress++;
|
|
}
|
|
}
|
|
|
|
if ((m->flags & PG_BUSY) == 0)
|
|
panic("vm_fault: not busy after main loop");
|
|
|
|
/*
|
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* PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
|
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* 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->valid = VM_PAGE_BITS_ALL;
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
|
|
if ((m->flags & PG_ACTIVE) == 0)
|
|
vm_page_activate(m);
|
|
vm_page_protect(m, VM_PROT_NONE);
|
|
|
|
/*
|
|
* We no longer need the old page or object.
|
|
*/
|
|
PAGE_WAKEUP(m);
|
|
vm_object_pip_wakeup(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.
|
|
*
|
|
* But we have to play ugly games with
|
|
* paging_in_progress to do that...
|
|
*/
|
|
vm_object_pip_wakeup(object);
|
|
vm_object_collapse(object);
|
|
object->paging_in_progress++;
|
|
} else {
|
|
prot &= ~VM_PROT_WRITE;
|
|
m->flags |= PG_COPYONWRITE;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
|
|
/*
|
|
* To avoid trying to write_lock the map while another process
|
|
* 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);
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
|
|
/*
|
|
* 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).
|
|
*/
|
|
|
|
if (prot & VM_PROT_WRITE) {
|
|
m->flags |= PG_WRITEABLE;
|
|
m->object->flags |= OBJ_WRITEABLE;
|
|
/*
|
|
* If the fault is a write, we know that this page is being
|
|
* written NOW. This will save on the pmap_is_modified() calls
|
|
* later.
|
|
*/
|
|
if (fault_type & VM_PROT_WRITE) {
|
|
m->dirty = VM_PAGE_BITS_ALL;
|
|
}
|
|
}
|
|
|
|
m->flags |= PG_MAPPED|PG_REFERENCED;
|
|
|
|
pmap_enter(map->pmap, vaddr, VM_PAGE_TO_PHYS(m), prot, wired);
|
|
#if 0
|
|
if (change_wiring == 0 && wired == 0)
|
|
pmap_prefault(map->pmap, vaddr, entry, first_object);
|
|
#endif
|
|
|
|
/*
|
|
* If the page is not wired down, then put it where the pageout daemon
|
|
* can find it.
|
|
*/
|
|
if (change_wiring) {
|
|
if (wired)
|
|
vm_page_wire(m);
|
|
else
|
|
vm_page_unwire(m);
|
|
} else {
|
|
if ((m->flags & PG_ACTIVE) == 0)
|
|
vm_page_activate(m);
|
|
}
|
|
|
|
if (curproc && (curproc->p_flag & P_INMEM) && curproc->p_stats) {
|
|
if (hardfault) {
|
|
curproc->p_stats->p_ru.ru_majflt++;
|
|
} else {
|
|
curproc->p_stats->p_ru.ru_minflt++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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) {
|
|
|
|
while( curproc != pageproc &&
|
|
(cnt.v_free_count <= cnt.v_pageout_free_min))
|
|
VM_WAIT;
|
|
|
|
rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE, 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.
|
|
*/
|
|
|
|
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));
|
|
}
|
|
|
|
/*
|
|
* 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(OBJT_DEFAULT,
|
|
(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
|
|
*/
|
|
do {
|
|
dst_m = vm_page_alloc(dst_object, dst_offset, VM_ALLOC_NORMAL);
|
|
if (dst_m == NULL) {
|
|
VM_WAIT;
|
|
}
|
|
} 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.)
|
|
*/
|
|
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...
|
|
*/
|
|
|
|
dst_m->flags |= PG_WRITEABLE;
|
|
dst_m->flags |= PG_MAPPED;
|
|
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_page_activate(dst_m);
|
|
PAGE_WAKEUP(dst_m);
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
* 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 (vm_pager_has_page(object, object->paging_offset + offset, NULL, NULL)) {
|
|
*rtobject = object;
|
|
*rtoffset = offset;
|
|
return 1;
|
|
}
|
|
if (!object->backing_object || (object == *rtobject))
|
|
return 0;
|
|
else {
|
|
offset += object->backing_object_offset;
|
|
object = object->backing_object;
|
|
}
|
|
}
|
|
*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;
|
|
int cbehind, cahead;
|
|
|
|
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,
|
|
object->paging_offset + offset, &cbehind, &cahead))
|
|
return 0;
|
|
|
|
if (object->backing_object == NULL) {
|
|
if (raheada > cahead) {
|
|
raheada = cahead;
|
|
}
|
|
if (rbehind > cbehind) {
|
|
rbehind = cbehind;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* try to do any readahead that we might have free pages for.
|
|
*/
|
|
rahead = raheada;
|
|
if ((rahead + rbehind) > ((cnt.v_free_count + cnt.v_cache_count) - 2*cnt.v_free_reserved)) {
|
|
rahead = ((cnt.v_free_count + cnt.v_cache_count) - 2*cnt.v_free_reserved) / 2;
|
|
rbehind = rahead;
|
|
if (!rahead)
|
|
pagedaemon_wakeup();
|
|
}
|
|
/*
|
|
* 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 (toffset < offset) {
|
|
if (rbehind * NBPG > offset)
|
|
rbehind = offset / NBPG;
|
|
startoffset = offset - rbehind * NBPG;
|
|
while (toffset >= startoffset) {
|
|
rtobject = object;
|
|
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;
|
|
}
|
|
} else {
|
|
startoffset = offset;
|
|
}
|
|
|
|
/*
|
|
* 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) {
|
|
rtobject = object;
|
|
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_cache_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, VM_ALLOC_NORMAL);
|
|
if (rtm == NULL)
|
|
break;
|
|
} 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 < treqpage) {
|
|
for (i = 0; i < size; i++) {
|
|
if (i != treqpage && marray[i])
|
|
FREE_PAGE(marray[i]);
|
|
}
|
|
*reqpage = 0;
|
|
marray[0] = m;
|
|
return 1;
|
|
}
|
|
|
|
size = i;
|
|
*reqpage = treqpage;
|
|
return size;
|
|
}
|
|
*reqpage = 0;
|
|
marray[0] = m;
|
|
return 1;
|
|
}
|