1179a1717e
Differential Revision discusses the benefits of this change.) Add a function, vm_reserv_to_superpage(), that returns the superpage containing the specified base page. Reviewed by: kib, markj Tested by: pho MFC after: 10 days Differential Revision: https://reviews.freebsd.org/D11556
1749 lines
50 KiB
C
1749 lines
50 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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/*
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* Page fault handling module.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_ktrace.h"
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#include "opt_vm.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mman.h>
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#include <sys/proc.h>
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#include <sys/racct.h>
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#include <sys/resourcevar.h>
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#include <sys/rwlock.h>
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#include <sys/sysctl.h>
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#include <sys/vmmeter.h>
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#include <sys/vnode.h>
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#ifdef KTRACE
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#include <sys/ktrace.h>
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#endif
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#include <vm/vm.h>
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#include <vm/vm_param.h>
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#include <vm/pmap.h>
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#include <vm/vm_map.h>
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#include <vm/vm_object.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/vm_extern.h>
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#include <vm/vm_reserv.h>
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#define PFBAK 4
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#define PFFOR 4
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#define VM_FAULT_READ_DEFAULT (1 + VM_FAULT_READ_AHEAD_INIT)
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#define VM_FAULT_READ_MAX (1 + VM_FAULT_READ_AHEAD_MAX)
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#define VM_FAULT_DONTNEED_MIN 1048576
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struct faultstate {
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vm_page_t m;
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vm_object_t object;
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vm_pindex_t pindex;
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vm_page_t first_m;
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vm_object_t first_object;
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vm_pindex_t first_pindex;
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vm_map_t map;
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vm_map_entry_t entry;
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int map_generation;
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bool lookup_still_valid;
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struct vnode *vp;
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};
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static void vm_fault_dontneed(const struct faultstate *fs, vm_offset_t vaddr,
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int ahead);
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static void vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra,
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int backward, int forward);
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static inline void
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release_page(struct faultstate *fs)
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{
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vm_page_xunbusy(fs->m);
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vm_page_lock(fs->m);
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vm_page_deactivate(fs->m);
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vm_page_unlock(fs->m);
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fs->m = NULL;
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}
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static inline void
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unlock_map(struct faultstate *fs)
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{
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if (fs->lookup_still_valid) {
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vm_map_lookup_done(fs->map, fs->entry);
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fs->lookup_still_valid = false;
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}
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}
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static void
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unlock_vp(struct faultstate *fs)
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{
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if (fs->vp != NULL) {
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vput(fs->vp);
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fs->vp = NULL;
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}
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}
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static void
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unlock_and_deallocate(struct faultstate *fs)
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{
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vm_object_pip_wakeup(fs->object);
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VM_OBJECT_WUNLOCK(fs->object);
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if (fs->object != fs->first_object) {
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VM_OBJECT_WLOCK(fs->first_object);
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vm_page_lock(fs->first_m);
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vm_page_free(fs->first_m);
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vm_page_unlock(fs->first_m);
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vm_object_pip_wakeup(fs->first_object);
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VM_OBJECT_WUNLOCK(fs->first_object);
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fs->first_m = NULL;
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}
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vm_object_deallocate(fs->first_object);
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unlock_map(fs);
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unlock_vp(fs);
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}
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static void
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vm_fault_dirty(vm_map_entry_t entry, vm_page_t m, vm_prot_t prot,
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vm_prot_t fault_type, int fault_flags, bool set_wd)
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{
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bool need_dirty;
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if (((prot & VM_PROT_WRITE) == 0 &&
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(fault_flags & VM_FAULT_DIRTY) == 0) ||
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(m->oflags & VPO_UNMANAGED) != 0)
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return;
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VM_OBJECT_ASSERT_LOCKED(m->object);
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need_dirty = ((fault_type & VM_PROT_WRITE) != 0 &&
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(fault_flags & VM_FAULT_WIRE) == 0) ||
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(fault_flags & VM_FAULT_DIRTY) != 0;
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if (set_wd)
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vm_object_set_writeable_dirty(m->object);
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else
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/*
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* If two callers of vm_fault_dirty() with set_wd ==
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* FALSE, one for the map entry with MAP_ENTRY_NOSYNC
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* flag set, other with flag clear, race, it is
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* possible for the no-NOSYNC thread to see m->dirty
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* != 0 and not clear VPO_NOSYNC. Take vm_page lock
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* around manipulation of VPO_NOSYNC and
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* vm_page_dirty() call, to avoid the race and keep
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* m->oflags consistent.
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*/
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vm_page_lock(m);
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/*
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* If this is a NOSYNC mmap we do not want to set VPO_NOSYNC
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* if the page is already dirty to prevent data written with
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* the expectation of being synced from not being synced.
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* Likewise if this entry does not request NOSYNC then make
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* sure the page isn't marked NOSYNC. Applications sharing
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* data should use the same flags to avoid ping ponging.
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*/
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if ((entry->eflags & MAP_ENTRY_NOSYNC) != 0) {
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if (m->dirty == 0) {
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m->oflags |= VPO_NOSYNC;
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}
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} else {
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m->oflags &= ~VPO_NOSYNC;
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}
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/*
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* If the fault is a write, we know that this page is being
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* written NOW so dirty it explicitly to save on
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* pmap_is_modified() calls later.
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*
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* Also tell the backing pager, if any, that it should remove
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* any swap backing since the page is now dirty.
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*/
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if (need_dirty)
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vm_page_dirty(m);
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if (!set_wd)
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vm_page_unlock(m);
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if (need_dirty)
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vm_pager_page_unswapped(m);
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}
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static void
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vm_fault_fill_hold(vm_page_t *m_hold, vm_page_t m)
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{
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if (m_hold != NULL) {
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*m_hold = m;
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vm_page_lock(m);
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vm_page_hold(m);
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vm_page_unlock(m);
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}
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}
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/*
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* Unlocks fs.first_object and fs.map on success.
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*/
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static int
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vm_fault_soft_fast(struct faultstate *fs, vm_offset_t vaddr, vm_prot_t prot,
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int fault_type, int fault_flags, boolean_t wired, vm_page_t *m_hold)
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{
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vm_page_t m, m_map;
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#if defined(__amd64__) && VM_NRESERVLEVEL > 0
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vm_page_t m_super;
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#endif
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int flags, psind, rv;
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MPASS(fs->vp == NULL);
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m = vm_page_lookup(fs->first_object, fs->first_pindex);
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/* A busy page can be mapped for read|execute access. */
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if (m == NULL || ((prot & VM_PROT_WRITE) != 0 &&
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vm_page_busied(m)) || m->valid != VM_PAGE_BITS_ALL)
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return (KERN_FAILURE);
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m_map = m;
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psind = 0;
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#if defined(__amd64__) && VM_NRESERVLEVEL > 0
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if ((m->flags & PG_FICTITIOUS) == 0 &&
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(m_super = vm_reserv_to_superpage(m)) != NULL &&
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rounddown2(vaddr, pagesizes[m_super->psind]) >= fs->entry->start &&
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roundup2(vaddr + 1, pagesizes[m_super->psind]) <= fs->entry->end &&
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(vaddr & (pagesizes[m_super->psind] - 1)) == (VM_PAGE_TO_PHYS(m) &
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(pagesizes[m_super->psind] - 1)) &&
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pmap_ps_enabled(fs->map->pmap)) {
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flags = PS_ALL_VALID;
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if ((prot & VM_PROT_WRITE) != 0) {
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/*
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* Create a superpage mapping allowing write access
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* only if none of the constituent pages are busy and
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* all of them are already dirty (except possibly for
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* the page that was faulted on).
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*/
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flags |= PS_NONE_BUSY;
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if ((fs->first_object->flags & OBJ_UNMANAGED) == 0)
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flags |= PS_ALL_DIRTY;
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}
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if (vm_page_ps_test(m_super, flags, m)) {
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m_map = m_super;
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psind = m_super->psind;
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vaddr = rounddown2(vaddr, pagesizes[psind]);
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/* Preset the modified bit for dirty superpages. */
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if ((flags & PS_ALL_DIRTY) != 0)
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fault_type |= VM_PROT_WRITE;
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}
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}
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#endif
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rv = pmap_enter(fs->map->pmap, vaddr, m_map, prot, fault_type |
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PMAP_ENTER_NOSLEEP | (wired ? PMAP_ENTER_WIRED : 0), psind);
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if (rv != KERN_SUCCESS)
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return (rv);
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vm_fault_fill_hold(m_hold, m);
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vm_fault_dirty(fs->entry, m, prot, fault_type, fault_flags, false);
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VM_OBJECT_RUNLOCK(fs->first_object);
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if (psind == 0 && !wired)
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vm_fault_prefault(fs, vaddr, PFBAK, PFFOR);
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vm_map_lookup_done(fs->map, fs->entry);
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curthread->td_ru.ru_minflt++;
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return (KERN_SUCCESS);
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}
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static void
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vm_fault_restore_map_lock(struct faultstate *fs)
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{
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VM_OBJECT_ASSERT_WLOCKED(fs->first_object);
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MPASS(fs->first_object->paging_in_progress > 0);
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if (!vm_map_trylock_read(fs->map)) {
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VM_OBJECT_WUNLOCK(fs->first_object);
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vm_map_lock_read(fs->map);
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VM_OBJECT_WLOCK(fs->first_object);
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}
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fs->lookup_still_valid = true;
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}
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static void
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vm_fault_populate_check_page(vm_page_t m)
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{
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/*
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* Check each page to ensure that the pager is obeying the
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* interface: the page must be installed in the object, fully
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* valid, and exclusively busied.
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*/
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MPASS(m != NULL);
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MPASS(m->valid == VM_PAGE_BITS_ALL);
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MPASS(vm_page_xbusied(m));
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}
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static void
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vm_fault_populate_cleanup(vm_object_t object, vm_pindex_t first,
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vm_pindex_t last)
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{
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vm_page_t m;
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vm_pindex_t pidx;
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VM_OBJECT_ASSERT_WLOCKED(object);
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MPASS(first <= last);
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for (pidx = first, m = vm_page_lookup(object, pidx);
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pidx <= last; pidx++, m = vm_page_next(m)) {
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vm_fault_populate_check_page(m);
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vm_page_lock(m);
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vm_page_deactivate(m);
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vm_page_unlock(m);
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vm_page_xunbusy(m);
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}
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}
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static int
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vm_fault_populate(struct faultstate *fs, vm_offset_t vaddr, vm_prot_t prot,
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int fault_type, int fault_flags, boolean_t wired, vm_page_t *m_hold)
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{
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vm_page_t m;
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vm_pindex_t map_first, map_last, pager_first, pager_last, pidx;
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int rv;
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MPASS(fs->object == fs->first_object);
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VM_OBJECT_ASSERT_WLOCKED(fs->first_object);
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MPASS(fs->first_object->paging_in_progress > 0);
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MPASS(fs->first_object->backing_object == NULL);
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MPASS(fs->lookup_still_valid);
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pager_first = OFF_TO_IDX(fs->entry->offset);
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pager_last = pager_first + atop(fs->entry->end - fs->entry->start) - 1;
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unlock_map(fs);
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unlock_vp(fs);
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/*
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* Call the pager (driver) populate() method.
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*
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* There is no guarantee that the method will be called again
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* if the current fault is for read, and a future fault is
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* for write. Report the entry's maximum allowed protection
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* to the driver.
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*/
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rv = vm_pager_populate(fs->first_object, fs->first_pindex,
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fault_type, fs->entry->max_protection, &pager_first, &pager_last);
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VM_OBJECT_ASSERT_WLOCKED(fs->first_object);
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if (rv == VM_PAGER_BAD) {
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/*
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* VM_PAGER_BAD is the backdoor for a pager to request
|
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* normal fault handling.
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*/
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vm_fault_restore_map_lock(fs);
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if (fs->map->timestamp != fs->map_generation)
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return (KERN_RESOURCE_SHORTAGE); /* RetryFault */
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return (KERN_NOT_RECEIVER);
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}
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if (rv != VM_PAGER_OK)
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return (KERN_FAILURE); /* AKA SIGSEGV */
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|
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/* Ensure that the driver is obeying the interface. */
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MPASS(pager_first <= pager_last);
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MPASS(fs->first_pindex <= pager_last);
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MPASS(fs->first_pindex >= pager_first);
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MPASS(pager_last < fs->first_object->size);
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vm_fault_restore_map_lock(fs);
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if (fs->map->timestamp != fs->map_generation) {
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vm_fault_populate_cleanup(fs->first_object, pager_first,
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pager_last);
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return (KERN_RESOURCE_SHORTAGE); /* RetryFault */
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}
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|
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/*
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* The map is unchanged after our last unlock. Process the fault.
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*
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* The range [pager_first, pager_last] that is given to the
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* pager is only a hint. The pager may populate any range
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* within the object that includes the requested page index.
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* In case the pager expanded the range, clip it to fit into
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* the map entry.
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*/
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map_first = OFF_TO_IDX(fs->entry->offset);
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if (map_first > pager_first) {
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vm_fault_populate_cleanup(fs->first_object, pager_first,
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map_first - 1);
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pager_first = map_first;
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}
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map_last = map_first + atop(fs->entry->end - fs->entry->start) - 1;
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if (map_last < pager_last) {
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vm_fault_populate_cleanup(fs->first_object, map_last + 1,
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pager_last);
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pager_last = map_last;
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}
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for (pidx = pager_first, m = vm_page_lookup(fs->first_object, pidx);
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pidx <= pager_last; pidx++, m = vm_page_next(m)) {
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vm_fault_populate_check_page(m);
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vm_fault_dirty(fs->entry, m, prot, fault_type, fault_flags,
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true);
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VM_OBJECT_WUNLOCK(fs->first_object);
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pmap_enter(fs->map->pmap, fs->entry->start + IDX_TO_OFF(pidx) -
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fs->entry->offset, m, prot, fault_type | (wired ?
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PMAP_ENTER_WIRED : 0), 0);
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VM_OBJECT_WLOCK(fs->first_object);
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if (pidx == fs->first_pindex)
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vm_fault_fill_hold(m_hold, m);
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vm_page_lock(m);
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if ((fault_flags & VM_FAULT_WIRE) != 0) {
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KASSERT(wired, ("VM_FAULT_WIRE && !wired"));
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vm_page_wire(m);
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} else {
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vm_page_activate(m);
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}
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vm_page_unlock(m);
|
|
vm_page_xunbusy(m);
|
|
}
|
|
curthread->td_ru.ru_majflt++;
|
|
return (KERN_SUCCESS);
|
|
}
|
|
|
|
/*
|
|
* vm_fault:
|
|
*
|
|
* Handle a page fault occurring at the given address,
|
|
* requiring the given permissions, in the map specified.
|
|
* If successful, the page is inserted into the
|
|
* associated physical map.
|
|
*
|
|
* NOTE: the given address should be truncated to the
|
|
* proper page address.
|
|
*
|
|
* KERN_SUCCESS is returned if the page fault is handled; otherwise,
|
|
* a standard error specifying why the fault is fatal is returned.
|
|
*
|
|
* The map in question must be referenced, and remains so.
|
|
* Caller may hold no locks.
|
|
*/
|
|
int
|
|
vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
|
|
int fault_flags)
|
|
{
|
|
struct thread *td;
|
|
int result;
|
|
|
|
td = curthread;
|
|
if ((td->td_pflags & TDP_NOFAULTING) != 0)
|
|
return (KERN_PROTECTION_FAILURE);
|
|
#ifdef KTRACE
|
|
if (map != kernel_map && KTRPOINT(td, KTR_FAULT))
|
|
ktrfault(vaddr, fault_type);
|
|
#endif
|
|
result = vm_fault_hold(map, trunc_page(vaddr), fault_type, fault_flags,
|
|
NULL);
|
|
#ifdef KTRACE
|
|
if (map != kernel_map && KTRPOINT(td, KTR_FAULTEND))
|
|
ktrfaultend(result);
|
|
#endif
|
|
return (result);
|
|
}
|
|
|
|
int
|
|
vm_fault_hold(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
|
|
int fault_flags, vm_page_t *m_hold)
|
|
{
|
|
struct faultstate fs;
|
|
struct vnode *vp;
|
|
vm_object_t next_object, retry_object;
|
|
vm_offset_t e_end, e_start;
|
|
vm_pindex_t retry_pindex;
|
|
vm_prot_t prot, retry_prot;
|
|
int ahead, alloc_req, behind, cluster_offset, error, era, faultcount;
|
|
int locked, nera, result, rv;
|
|
u_char behavior;
|
|
boolean_t wired; /* Passed by reference. */
|
|
bool dead, hardfault, is_first_object_locked;
|
|
|
|
VM_CNT_INC(v_vm_faults);
|
|
fs.vp = NULL;
|
|
faultcount = 0;
|
|
nera = -1;
|
|
hardfault = false;
|
|
|
|
RetryFault:;
|
|
|
|
/*
|
|
* Find the backing store object and offset into it to begin the
|
|
* search.
|
|
*/
|
|
fs.map = map;
|
|
result = vm_map_lookup(&fs.map, vaddr, fault_type |
|
|
VM_PROT_FAULT_LOOKUP, &fs.entry, &fs.first_object,
|
|
&fs.first_pindex, &prot, &wired);
|
|
if (result != KERN_SUCCESS) {
|
|
unlock_vp(&fs);
|
|
return (result);
|
|
}
|
|
|
|
fs.map_generation = fs.map->timestamp;
|
|
|
|
if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
|
|
panic("%s: fault on nofault entry, addr: %#lx",
|
|
__func__, (u_long)vaddr);
|
|
}
|
|
|
|
if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION &&
|
|
fs.entry->wiring_thread != curthread) {
|
|
vm_map_unlock_read(fs.map);
|
|
vm_map_lock(fs.map);
|
|
if (vm_map_lookup_entry(fs.map, vaddr, &fs.entry) &&
|
|
(fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) {
|
|
unlock_vp(&fs);
|
|
fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP;
|
|
vm_map_unlock_and_wait(fs.map, 0);
|
|
} else
|
|
vm_map_unlock(fs.map);
|
|
goto RetryFault;
|
|
}
|
|
|
|
MPASS((fs.entry->eflags & MAP_ENTRY_GUARD) == 0);
|
|
|
|
if (wired)
|
|
fault_type = prot | (fault_type & VM_PROT_COPY);
|
|
else
|
|
KASSERT((fault_flags & VM_FAULT_WIRE) == 0,
|
|
("!wired && VM_FAULT_WIRE"));
|
|
|
|
/*
|
|
* Try to avoid lock contention on the top-level object through
|
|
* special-case handling of some types of page faults, specifically,
|
|
* those that are both (1) mapping an existing page from the top-
|
|
* level object and (2) not having to mark that object as containing
|
|
* dirty pages. Under these conditions, a read lock on the top-level
|
|
* object suffices, allowing multiple page faults of a similar type to
|
|
* run in parallel on the same top-level object.
|
|
*/
|
|
if (fs.vp == NULL /* avoid locked vnode leak */ &&
|
|
(fault_flags & (VM_FAULT_WIRE | VM_FAULT_DIRTY)) == 0 &&
|
|
/* avoid calling vm_object_set_writeable_dirty() */
|
|
((prot & VM_PROT_WRITE) == 0 ||
|
|
(fs.first_object->type != OBJT_VNODE &&
|
|
(fs.first_object->flags & OBJ_TMPFS_NODE) == 0) ||
|
|
(fs.first_object->flags & OBJ_MIGHTBEDIRTY) != 0)) {
|
|
VM_OBJECT_RLOCK(fs.first_object);
|
|
if ((prot & VM_PROT_WRITE) == 0 ||
|
|
(fs.first_object->type != OBJT_VNODE &&
|
|
(fs.first_object->flags & OBJ_TMPFS_NODE) == 0) ||
|
|
(fs.first_object->flags & OBJ_MIGHTBEDIRTY) != 0) {
|
|
rv = vm_fault_soft_fast(&fs, vaddr, prot, fault_type,
|
|
fault_flags, wired, m_hold);
|
|
if (rv == KERN_SUCCESS)
|
|
return (rv);
|
|
}
|
|
if (!VM_OBJECT_TRYUPGRADE(fs.first_object)) {
|
|
VM_OBJECT_RUNLOCK(fs.first_object);
|
|
VM_OBJECT_WLOCK(fs.first_object);
|
|
}
|
|
} else {
|
|
VM_OBJECT_WLOCK(fs.first_object);
|
|
}
|
|
|
|
/*
|
|
* Make a reference to this object to prevent its disposal while we
|
|
* are messing with it. Once we have the reference, the map is free
|
|
* to be diddled. Since objects reference their shadows (and copies),
|
|
* they will stay around as well.
|
|
*
|
|
* Bump the paging-in-progress count to prevent size changes (e.g.
|
|
* truncation operations) during I/O.
|
|
*/
|
|
vm_object_reference_locked(fs.first_object);
|
|
vm_object_pip_add(fs.first_object, 1);
|
|
|
|
fs.lookup_still_valid = true;
|
|
|
|
fs.first_m = NULL;
|
|
|
|
/*
|
|
* Search for the page at object/offset.
|
|
*/
|
|
fs.object = fs.first_object;
|
|
fs.pindex = fs.first_pindex;
|
|
while (TRUE) {
|
|
/*
|
|
* If the object is marked for imminent termination,
|
|
* we retry here, since the collapse pass has raced
|
|
* with us. Otherwise, if we see terminally dead
|
|
* object, return fail.
|
|
*/
|
|
if ((fs.object->flags & OBJ_DEAD) != 0) {
|
|
dead = fs.object->type == OBJT_DEAD;
|
|
unlock_and_deallocate(&fs);
|
|
if (dead)
|
|
return (KERN_PROTECTION_FAILURE);
|
|
pause("vmf_de", 1);
|
|
goto RetryFault;
|
|
}
|
|
|
|
/*
|
|
* See if page is resident
|
|
*/
|
|
fs.m = vm_page_lookup(fs.object, fs.pindex);
|
|
if (fs.m != NULL) {
|
|
/*
|
|
* Wait/Retry if the page is busy. We have to do this
|
|
* if the page is either exclusive or shared busy
|
|
* because the vm_pager may be using read busy for
|
|
* pageouts (and even pageins if it is the vnode
|
|
* pager), and we could end up trying to pagein and
|
|
* pageout the same page simultaneously.
|
|
*
|
|
* We can theoretically allow the busy case on a read
|
|
* fault if the page is marked valid, but since such
|
|
* pages are typically already pmap'd, putting that
|
|
* special case in might be more effort then it is
|
|
* worth. We cannot under any circumstances mess
|
|
* around with a shared busied page except, perhaps,
|
|
* to pmap it.
|
|
*/
|
|
if (vm_page_busied(fs.m)) {
|
|
/*
|
|
* Reference the page before unlocking and
|
|
* sleeping so that the page daemon is less
|
|
* likely to reclaim it.
|
|
*/
|
|
vm_page_aflag_set(fs.m, PGA_REFERENCED);
|
|
if (fs.object != fs.first_object) {
|
|
if (!VM_OBJECT_TRYWLOCK(
|
|
fs.first_object)) {
|
|
VM_OBJECT_WUNLOCK(fs.object);
|
|
VM_OBJECT_WLOCK(fs.first_object);
|
|
VM_OBJECT_WLOCK(fs.object);
|
|
}
|
|
vm_page_lock(fs.first_m);
|
|
vm_page_free(fs.first_m);
|
|
vm_page_unlock(fs.first_m);
|
|
vm_object_pip_wakeup(fs.first_object);
|
|
VM_OBJECT_WUNLOCK(fs.first_object);
|
|
fs.first_m = NULL;
|
|
}
|
|
unlock_map(&fs);
|
|
if (fs.m == vm_page_lookup(fs.object,
|
|
fs.pindex)) {
|
|
vm_page_sleep_if_busy(fs.m, "vmpfw");
|
|
}
|
|
vm_object_pip_wakeup(fs.object);
|
|
VM_OBJECT_WUNLOCK(fs.object);
|
|
VM_CNT_INC(v_intrans);
|
|
vm_object_deallocate(fs.first_object);
|
|
goto RetryFault;
|
|
}
|
|
vm_page_lock(fs.m);
|
|
vm_page_remque(fs.m);
|
|
vm_page_unlock(fs.m);
|
|
|
|
/*
|
|
* Mark page busy for other processes, and the
|
|
* pagedaemon. If it still isn't completely valid
|
|
* (readable), jump to readrest, else break-out ( we
|
|
* found the page ).
|
|
*/
|
|
vm_page_xbusy(fs.m);
|
|
if (fs.m->valid != VM_PAGE_BITS_ALL)
|
|
goto readrest;
|
|
break;
|
|
}
|
|
KASSERT(fs.m == NULL, ("fs.m should be NULL, not %p", fs.m));
|
|
|
|
/*
|
|
* Page is not resident. If the pager might contain the page
|
|
* or this is the beginning of the search, allocate a new
|
|
* page. (Default objects are zero-fill, so there is no real
|
|
* pager for them.)
|
|
*/
|
|
if (fs.object->type != OBJT_DEFAULT ||
|
|
fs.object == fs.first_object) {
|
|
if (fs.pindex >= fs.object->size) {
|
|
unlock_and_deallocate(&fs);
|
|
return (KERN_PROTECTION_FAILURE);
|
|
}
|
|
|
|
if (fs.object == fs.first_object &&
|
|
(fs.first_object->flags & OBJ_POPULATE) != 0 &&
|
|
fs.first_object->shadow_count == 0) {
|
|
rv = vm_fault_populate(&fs, vaddr, prot,
|
|
fault_type, fault_flags, wired, m_hold);
|
|
switch (rv) {
|
|
case KERN_SUCCESS:
|
|
case KERN_FAILURE:
|
|
unlock_and_deallocate(&fs);
|
|
return (rv);
|
|
case KERN_RESOURCE_SHORTAGE:
|
|
unlock_and_deallocate(&fs);
|
|
goto RetryFault;
|
|
case KERN_NOT_RECEIVER:
|
|
/*
|
|
* Pager's populate() method
|
|
* returned VM_PAGER_BAD.
|
|
*/
|
|
break;
|
|
default:
|
|
panic("inconsistent return codes");
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocate a new page for this object/offset pair.
|
|
*
|
|
* Unlocked read of the p_flag is harmless. At
|
|
* worst, the P_KILLED might be not observed
|
|
* there, and allocation can fail, causing
|
|
* restart and new reading of the p_flag.
|
|
*/
|
|
if (!vm_page_count_severe() || P_KILLED(curproc)) {
|
|
#if VM_NRESERVLEVEL > 0
|
|
vm_object_color(fs.object, atop(vaddr) -
|
|
fs.pindex);
|
|
#endif
|
|
alloc_req = P_KILLED(curproc) ?
|
|
VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL;
|
|
if (fs.object->type != OBJT_VNODE &&
|
|
fs.object->backing_object == NULL)
|
|
alloc_req |= VM_ALLOC_ZERO;
|
|
fs.m = vm_page_alloc(fs.object, fs.pindex,
|
|
alloc_req);
|
|
}
|
|
if (fs.m == NULL) {
|
|
unlock_and_deallocate(&fs);
|
|
VM_WAITPFAULT;
|
|
goto RetryFault;
|
|
}
|
|
}
|
|
|
|
readrest:
|
|
/*
|
|
* At this point, we have either allocated a new page or found
|
|
* an existing page that is only partially valid.
|
|
*
|
|
* We hold a reference on the current object and the page is
|
|
* exclusive busied.
|
|
*/
|
|
|
|
/*
|
|
* If the pager for the current object might have the page,
|
|
* then determine the number of additional pages to read and
|
|
* potentially reprioritize previously read pages for earlier
|
|
* reclamation. These operations should only be performed
|
|
* once per page fault. Even if the current pager doesn't
|
|
* have the page, the number of additional pages to read will
|
|
* apply to subsequent objects in the shadow chain.
|
|
*/
|
|
if (fs.object->type != OBJT_DEFAULT && nera == -1 &&
|
|
!P_KILLED(curproc)) {
|
|
KASSERT(fs.lookup_still_valid, ("map unlocked"));
|
|
era = fs.entry->read_ahead;
|
|
behavior = vm_map_entry_behavior(fs.entry);
|
|
if (behavior == MAP_ENTRY_BEHAV_RANDOM) {
|
|
nera = 0;
|
|
} else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) {
|
|
nera = VM_FAULT_READ_AHEAD_MAX;
|
|
if (vaddr == fs.entry->next_read)
|
|
vm_fault_dontneed(&fs, vaddr, nera);
|
|
} else if (vaddr == fs.entry->next_read) {
|
|
/*
|
|
* This is a sequential fault. Arithmetically
|
|
* increase the requested number of pages in
|
|
* the read-ahead window. The requested
|
|
* number of pages is "# of sequential faults
|
|
* x (read ahead min + 1) + read ahead min"
|
|
*/
|
|
nera = VM_FAULT_READ_AHEAD_MIN;
|
|
if (era > 0) {
|
|
nera += era + 1;
|
|
if (nera > VM_FAULT_READ_AHEAD_MAX)
|
|
nera = VM_FAULT_READ_AHEAD_MAX;
|
|
}
|
|
if (era == VM_FAULT_READ_AHEAD_MAX)
|
|
vm_fault_dontneed(&fs, vaddr, nera);
|
|
} else {
|
|
/*
|
|
* This is a non-sequential fault.
|
|
*/
|
|
nera = 0;
|
|
}
|
|
if (era != nera) {
|
|
/*
|
|
* A read lock on the map suffices to update
|
|
* the read ahead count safely.
|
|
*/
|
|
fs.entry->read_ahead = nera;
|
|
}
|
|
|
|
/*
|
|
* Prepare for unlocking the map. Save the map
|
|
* entry's start and end addresses, which are used to
|
|
* optimize the size of the pager operation below.
|
|
* Even if the map entry's addresses change after
|
|
* unlocking the map, using the saved addresses is
|
|
* safe.
|
|
*/
|
|
e_start = fs.entry->start;
|
|
e_end = fs.entry->end;
|
|
}
|
|
|
|
/*
|
|
* Call the pager to retrieve the page if there is a chance
|
|
* that the pager has it, and potentially retrieve additional
|
|
* pages at the same time.
|
|
*/
|
|
if (fs.object->type != OBJT_DEFAULT) {
|
|
/*
|
|
* Release the map lock before locking the vnode or
|
|
* sleeping in the pager. (If the current object has
|
|
* a shadow, then an earlier iteration of this loop
|
|
* may have already unlocked the map.)
|
|
*/
|
|
unlock_map(&fs);
|
|
|
|
if (fs.object->type == OBJT_VNODE &&
|
|
(vp = fs.object->handle) != fs.vp) {
|
|
/*
|
|
* Perform an unlock in case the desired vnode
|
|
* changed while the map was unlocked during a
|
|
* retry.
|
|
*/
|
|
unlock_vp(&fs);
|
|
|
|
locked = VOP_ISLOCKED(vp);
|
|
if (locked != LK_EXCLUSIVE)
|
|
locked = LK_SHARED;
|
|
|
|
/*
|
|
* We must not sleep acquiring the vnode lock
|
|
* while we have the page exclusive busied or
|
|
* the object's paging-in-progress count
|
|
* incremented. Otherwise, we could deadlock.
|
|
*/
|
|
error = vget(vp, locked | LK_CANRECURSE |
|
|
LK_NOWAIT, curthread);
|
|
if (error != 0) {
|
|
vhold(vp);
|
|
release_page(&fs);
|
|
unlock_and_deallocate(&fs);
|
|
error = vget(vp, locked | LK_RETRY |
|
|
LK_CANRECURSE, curthread);
|
|
vdrop(vp);
|
|
fs.vp = vp;
|
|
KASSERT(error == 0,
|
|
("vm_fault: vget failed"));
|
|
goto RetryFault;
|
|
}
|
|
fs.vp = vp;
|
|
}
|
|
KASSERT(fs.vp == NULL || !fs.map->system_map,
|
|
("vm_fault: vnode-backed object mapped by system map"));
|
|
|
|
/*
|
|
* Page in the requested page and hint the pager,
|
|
* that it may bring up surrounding pages.
|
|
*/
|
|
if (nera == -1 || behavior == MAP_ENTRY_BEHAV_RANDOM ||
|
|
P_KILLED(curproc)) {
|
|
behind = 0;
|
|
ahead = 0;
|
|
} else {
|
|
/* Is this a sequential fault? */
|
|
if (nera > 0) {
|
|
behind = 0;
|
|
ahead = nera;
|
|
} else {
|
|
/*
|
|
* Request a cluster of pages that is
|
|
* aligned to a VM_FAULT_READ_DEFAULT
|
|
* page offset boundary within the
|
|
* object. Alignment to a page offset
|
|
* boundary is more likely to coincide
|
|
* with the underlying file system
|
|
* block than alignment to a virtual
|
|
* address boundary.
|
|
*/
|
|
cluster_offset = fs.pindex %
|
|
VM_FAULT_READ_DEFAULT;
|
|
behind = ulmin(cluster_offset,
|
|
atop(vaddr - e_start));
|
|
ahead = VM_FAULT_READ_DEFAULT - 1 -
|
|
cluster_offset;
|
|
}
|
|
ahead = ulmin(ahead, atop(e_end - vaddr) - 1);
|
|
}
|
|
rv = vm_pager_get_pages(fs.object, &fs.m, 1,
|
|
&behind, &ahead);
|
|
if (rv == VM_PAGER_OK) {
|
|
faultcount = behind + 1 + ahead;
|
|
hardfault = true;
|
|
break; /* break to PAGE HAS BEEN FOUND */
|
|
}
|
|
if (rv == VM_PAGER_ERROR)
|
|
printf("vm_fault: pager read error, pid %d (%s)\n",
|
|
curproc->p_pid, curproc->p_comm);
|
|
|
|
/*
|
|
* If an I/O error occurred or the requested page was
|
|
* outside the range of the pager, clean up and return
|
|
* an error.
|
|
*/
|
|
if (rv == VM_PAGER_ERROR || rv == VM_PAGER_BAD) {
|
|
vm_page_lock(fs.m);
|
|
if (fs.m->wire_count == 0)
|
|
vm_page_free(fs.m);
|
|
else
|
|
vm_page_xunbusy_maybelocked(fs.m);
|
|
vm_page_unlock(fs.m);
|
|
fs.m = NULL;
|
|
unlock_and_deallocate(&fs);
|
|
return (rv == VM_PAGER_ERROR ? KERN_FAILURE :
|
|
KERN_PROTECTION_FAILURE);
|
|
}
|
|
|
|
/*
|
|
* The requested page does not exist at this object/
|
|
* offset. Remove the invalid page from the object,
|
|
* waking up anyone waiting for it, and continue on to
|
|
* the next object. However, if this is the top-level
|
|
* object, we must leave the busy page in place to
|
|
* prevent another process from rushing past us, and
|
|
* inserting the page in that object at the same time
|
|
* that we are.
|
|
*/
|
|
if (fs.object != fs.first_object) {
|
|
vm_page_lock(fs.m);
|
|
if (fs.m->wire_count == 0)
|
|
vm_page_free(fs.m);
|
|
else
|
|
vm_page_xunbusy_maybelocked(fs.m);
|
|
vm_page_unlock(fs.m);
|
|
fs.m = NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We get here if the object has default pager (or unwiring)
|
|
* or the pager doesn't have the page.
|
|
*/
|
|
if (fs.object == fs.first_object)
|
|
fs.first_m = fs.m;
|
|
|
|
/*
|
|
* Move on to the next object. Lock the next object before
|
|
* unlocking the current one.
|
|
*/
|
|
next_object = fs.object->backing_object;
|
|
if (next_object == NULL) {
|
|
/*
|
|
* If there's no object left, fill the page in the top
|
|
* object with zeros.
|
|
*/
|
|
if (fs.object != fs.first_object) {
|
|
vm_object_pip_wakeup(fs.object);
|
|
VM_OBJECT_WUNLOCK(fs.object);
|
|
|
|
fs.object = fs.first_object;
|
|
fs.pindex = fs.first_pindex;
|
|
fs.m = fs.first_m;
|
|
VM_OBJECT_WLOCK(fs.object);
|
|
}
|
|
fs.first_m = NULL;
|
|
|
|
/*
|
|
* Zero the page if necessary and mark it valid.
|
|
*/
|
|
if ((fs.m->flags & PG_ZERO) == 0) {
|
|
pmap_zero_page(fs.m);
|
|
} else {
|
|
VM_CNT_INC(v_ozfod);
|
|
}
|
|
VM_CNT_INC(v_zfod);
|
|
fs.m->valid = VM_PAGE_BITS_ALL;
|
|
/* Don't try to prefault neighboring pages. */
|
|
faultcount = 1;
|
|
break; /* break to PAGE HAS BEEN FOUND */
|
|
} else {
|
|
KASSERT(fs.object != next_object,
|
|
("object loop %p", next_object));
|
|
VM_OBJECT_WLOCK(next_object);
|
|
vm_object_pip_add(next_object, 1);
|
|
if (fs.object != fs.first_object)
|
|
vm_object_pip_wakeup(fs.object);
|
|
fs.pindex +=
|
|
OFF_TO_IDX(fs.object->backing_object_offset);
|
|
VM_OBJECT_WUNLOCK(fs.object);
|
|
fs.object = next_object;
|
|
}
|
|
}
|
|
|
|
vm_page_assert_xbusied(fs.m);
|
|
|
|
/*
|
|
* PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
|
|
* is held.]
|
|
*/
|
|
|
|
/*
|
|
* 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 (fs.object != fs.first_object) {
|
|
/*
|
|
* We only really need to copy if we want to write it.
|
|
*/
|
|
if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) {
|
|
/*
|
|
* This allows pages to be virtually copied from a
|
|
* backing_object into the first_object, where the
|
|
* backing object has no other refs to it, and cannot
|
|
* gain any more refs. Instead of a bcopy, we just
|
|
* move the page from the backing object to the
|
|
* first object. Note that we must mark the page
|
|
* dirty in the first object so that it will go out
|
|
* to swap when needed.
|
|
*/
|
|
is_first_object_locked = false;
|
|
if (
|
|
/*
|
|
* Only one shadow object
|
|
*/
|
|
(fs.object->shadow_count == 1) &&
|
|
/*
|
|
* No COW refs, except us
|
|
*/
|
|
(fs.object->ref_count == 1) &&
|
|
/*
|
|
* No one else can look this object up
|
|
*/
|
|
(fs.object->handle == NULL) &&
|
|
/*
|
|
* No other ways to look the object up
|
|
*/
|
|
((fs.object->type == OBJT_DEFAULT) ||
|
|
(fs.object->type == OBJT_SWAP)) &&
|
|
(is_first_object_locked = VM_OBJECT_TRYWLOCK(fs.first_object)) &&
|
|
/*
|
|
* We don't chase down the shadow chain
|
|
*/
|
|
fs.object == fs.first_object->backing_object) {
|
|
vm_page_lock(fs.m);
|
|
vm_page_remove(fs.m);
|
|
vm_page_unlock(fs.m);
|
|
vm_page_lock(fs.first_m);
|
|
vm_page_replace_checked(fs.m, fs.first_object,
|
|
fs.first_pindex, fs.first_m);
|
|
vm_page_free(fs.first_m);
|
|
vm_page_unlock(fs.first_m);
|
|
vm_page_dirty(fs.m);
|
|
#if VM_NRESERVLEVEL > 0
|
|
/*
|
|
* Rename the reservation.
|
|
*/
|
|
vm_reserv_rename(fs.m, fs.first_object,
|
|
fs.object, OFF_TO_IDX(
|
|
fs.first_object->backing_object_offset));
|
|
#endif
|
|
/*
|
|
* Removing the page from the backing object
|
|
* unbusied it.
|
|
*/
|
|
vm_page_xbusy(fs.m);
|
|
fs.first_m = fs.m;
|
|
fs.m = NULL;
|
|
VM_CNT_INC(v_cow_optim);
|
|
} else {
|
|
/*
|
|
* Oh, well, lets copy it.
|
|
*/
|
|
pmap_copy_page(fs.m, fs.first_m);
|
|
fs.first_m->valid = VM_PAGE_BITS_ALL;
|
|
if (wired && (fault_flags &
|
|
VM_FAULT_WIRE) == 0) {
|
|
vm_page_lock(fs.first_m);
|
|
vm_page_wire(fs.first_m);
|
|
vm_page_unlock(fs.first_m);
|
|
|
|
vm_page_lock(fs.m);
|
|
vm_page_unwire(fs.m, PQ_INACTIVE);
|
|
vm_page_unlock(fs.m);
|
|
}
|
|
/*
|
|
* We no longer need the old page or object.
|
|
*/
|
|
release_page(&fs);
|
|
}
|
|
/*
|
|
* fs.object != fs.first_object due to above
|
|
* conditional
|
|
*/
|
|
vm_object_pip_wakeup(fs.object);
|
|
VM_OBJECT_WUNLOCK(fs.object);
|
|
/*
|
|
* Only use the new page below...
|
|
*/
|
|
fs.object = fs.first_object;
|
|
fs.pindex = fs.first_pindex;
|
|
fs.m = fs.first_m;
|
|
if (!is_first_object_locked)
|
|
VM_OBJECT_WLOCK(fs.object);
|
|
VM_CNT_INC(v_cow_faults);
|
|
curthread->td_cow++;
|
|
} else {
|
|
prot &= ~VM_PROT_WRITE;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We must verify that the maps have not changed since our last
|
|
* lookup.
|
|
*/
|
|
if (!fs.lookup_still_valid) {
|
|
if (!vm_map_trylock_read(fs.map)) {
|
|
release_page(&fs);
|
|
unlock_and_deallocate(&fs);
|
|
goto RetryFault;
|
|
}
|
|
fs.lookup_still_valid = true;
|
|
if (fs.map->timestamp != fs.map_generation) {
|
|
result = vm_map_lookup_locked(&fs.map, vaddr, fault_type,
|
|
&fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired);
|
|
|
|
/*
|
|
* If we don't need the page any longer, put it on the inactive
|
|
* list (the easiest thing to do here). If no one needs it,
|
|
* pageout will grab it eventually.
|
|
*/
|
|
if (result != KERN_SUCCESS) {
|
|
release_page(&fs);
|
|
unlock_and_deallocate(&fs);
|
|
|
|
/*
|
|
* If retry of map lookup would have blocked then
|
|
* retry fault from start.
|
|
*/
|
|
if (result == KERN_FAILURE)
|
|
goto RetryFault;
|
|
return (result);
|
|
}
|
|
if ((retry_object != fs.first_object) ||
|
|
(retry_pindex != fs.first_pindex)) {
|
|
release_page(&fs);
|
|
unlock_and_deallocate(&fs);
|
|
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 the page was filled by a pager, save the virtual address that
|
|
* should be faulted on next under a sequential access pattern to the
|
|
* map entry. A read lock on the map suffices to update this address
|
|
* safely.
|
|
*/
|
|
if (hardfault)
|
|
fs.entry->next_read = vaddr + ptoa(ahead) + PAGE_SIZE;
|
|
|
|
vm_fault_dirty(fs.entry, fs.m, prot, fault_type, fault_flags, true);
|
|
vm_page_assert_xbusied(fs.m);
|
|
|
|
/*
|
|
* Page must be completely valid or it is not fit to
|
|
* map into user space. vm_pager_get_pages() ensures this.
|
|
*/
|
|
KASSERT(fs.m->valid == VM_PAGE_BITS_ALL,
|
|
("vm_fault: page %p partially invalid", fs.m));
|
|
VM_OBJECT_WUNLOCK(fs.object);
|
|
|
|
/*
|
|
* Put this page into the physical map. We had to do the unlock above
|
|
* because pmap_enter() may sleep. We don't put the page
|
|
* back on the active queue until later so that the pageout daemon
|
|
* won't find it (yet).
|
|
*/
|
|
pmap_enter(fs.map->pmap, vaddr, fs.m, prot,
|
|
fault_type | (wired ? PMAP_ENTER_WIRED : 0), 0);
|
|
if (faultcount != 1 && (fault_flags & VM_FAULT_WIRE) == 0 &&
|
|
wired == 0)
|
|
vm_fault_prefault(&fs, vaddr,
|
|
faultcount > 0 ? behind : PFBAK,
|
|
faultcount > 0 ? ahead : PFFOR);
|
|
VM_OBJECT_WLOCK(fs.object);
|
|
vm_page_lock(fs.m);
|
|
|
|
/*
|
|
* If the page is not wired down, then put it where the pageout daemon
|
|
* can find it.
|
|
*/
|
|
if ((fault_flags & VM_FAULT_WIRE) != 0) {
|
|
KASSERT(wired, ("VM_FAULT_WIRE && !wired"));
|
|
vm_page_wire(fs.m);
|
|
} else
|
|
vm_page_activate(fs.m);
|
|
if (m_hold != NULL) {
|
|
*m_hold = fs.m;
|
|
vm_page_hold(fs.m);
|
|
}
|
|
vm_page_unlock(fs.m);
|
|
vm_page_xunbusy(fs.m);
|
|
|
|
/*
|
|
* Unlock everything, and return
|
|
*/
|
|
unlock_and_deallocate(&fs);
|
|
if (hardfault) {
|
|
VM_CNT_INC(v_io_faults);
|
|
curthread->td_ru.ru_majflt++;
|
|
#ifdef RACCT
|
|
if (racct_enable && fs.object->type == OBJT_VNODE) {
|
|
PROC_LOCK(curproc);
|
|
if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) {
|
|
racct_add_force(curproc, RACCT_WRITEBPS,
|
|
PAGE_SIZE + behind * PAGE_SIZE);
|
|
racct_add_force(curproc, RACCT_WRITEIOPS, 1);
|
|
} else {
|
|
racct_add_force(curproc, RACCT_READBPS,
|
|
PAGE_SIZE + ahead * PAGE_SIZE);
|
|
racct_add_force(curproc, RACCT_READIOPS, 1);
|
|
}
|
|
PROC_UNLOCK(curproc);
|
|
}
|
|
#endif
|
|
} else
|
|
curthread->td_ru.ru_minflt++;
|
|
|
|
return (KERN_SUCCESS);
|
|
}
|
|
|
|
/*
|
|
* Speed up the reclamation of pages that precede the faulting pindex within
|
|
* the first object of the shadow chain. Essentially, perform the equivalent
|
|
* to madvise(..., MADV_DONTNEED) on a large cluster of pages that precedes
|
|
* the faulting pindex by the cluster size when the pages read by vm_fault()
|
|
* cross a cluster-size boundary. The cluster size is the greater of the
|
|
* smallest superpage size and VM_FAULT_DONTNEED_MIN.
|
|
*
|
|
* When "fs->first_object" is a shadow object, the pages in the backing object
|
|
* that precede the faulting pindex are deactivated by vm_fault(). So, this
|
|
* function must only be concerned with pages in the first object.
|
|
*/
|
|
static void
|
|
vm_fault_dontneed(const struct faultstate *fs, vm_offset_t vaddr, int ahead)
|
|
{
|
|
vm_map_entry_t entry;
|
|
vm_object_t first_object, object;
|
|
vm_offset_t end, start;
|
|
vm_page_t m, m_next;
|
|
vm_pindex_t pend, pstart;
|
|
vm_size_t size;
|
|
|
|
object = fs->object;
|
|
VM_OBJECT_ASSERT_WLOCKED(object);
|
|
first_object = fs->first_object;
|
|
if (first_object != object) {
|
|
if (!VM_OBJECT_TRYWLOCK(first_object)) {
|
|
VM_OBJECT_WUNLOCK(object);
|
|
VM_OBJECT_WLOCK(first_object);
|
|
VM_OBJECT_WLOCK(object);
|
|
}
|
|
}
|
|
/* Neither fictitious nor unmanaged pages can be reclaimed. */
|
|
if ((first_object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0) {
|
|
size = VM_FAULT_DONTNEED_MIN;
|
|
if (MAXPAGESIZES > 1 && size < pagesizes[1])
|
|
size = pagesizes[1];
|
|
end = rounddown2(vaddr, size);
|
|
if (vaddr - end >= size - PAGE_SIZE - ptoa(ahead) &&
|
|
(entry = fs->entry)->start < end) {
|
|
if (end - entry->start < size)
|
|
start = entry->start;
|
|
else
|
|
start = end - size;
|
|
pmap_advise(fs->map->pmap, start, end, MADV_DONTNEED);
|
|
pstart = OFF_TO_IDX(entry->offset) + atop(start -
|
|
entry->start);
|
|
m_next = vm_page_find_least(first_object, pstart);
|
|
pend = OFF_TO_IDX(entry->offset) + atop(end -
|
|
entry->start);
|
|
while ((m = m_next) != NULL && m->pindex < pend) {
|
|
m_next = TAILQ_NEXT(m, listq);
|
|
if (m->valid != VM_PAGE_BITS_ALL ||
|
|
vm_page_busied(m))
|
|
continue;
|
|
|
|
/*
|
|
* Don't clear PGA_REFERENCED, since it would
|
|
* likely represent a reference by a different
|
|
* process.
|
|
*
|
|
* Typically, at this point, prefetched pages
|
|
* are still in the inactive queue. Only
|
|
* pages that triggered page faults are in the
|
|
* active queue.
|
|
*/
|
|
vm_page_lock(m);
|
|
vm_page_deactivate(m);
|
|
vm_page_unlock(m);
|
|
}
|
|
}
|
|
}
|
|
if (first_object != object)
|
|
VM_OBJECT_WUNLOCK(first_object);
|
|
}
|
|
|
|
/*
|
|
* vm_fault_prefault provides a quick way of clustering
|
|
* pagefaults into a processes address space. It is a "cousin"
|
|
* of vm_map_pmap_enter, except it runs at page fault time instead
|
|
* of mmap time.
|
|
*/
|
|
static void
|
|
vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra,
|
|
int backward, int forward)
|
|
{
|
|
pmap_t pmap;
|
|
vm_map_entry_t entry;
|
|
vm_object_t backing_object, lobject;
|
|
vm_offset_t addr, starta;
|
|
vm_pindex_t pindex;
|
|
vm_page_t m;
|
|
int i;
|
|
|
|
pmap = fs->map->pmap;
|
|
if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace))
|
|
return;
|
|
|
|
entry = fs->entry;
|
|
|
|
if (addra < backward * PAGE_SIZE) {
|
|
starta = entry->start;
|
|
} else {
|
|
starta = addra - backward * PAGE_SIZE;
|
|
if (starta < entry->start)
|
|
starta = entry->start;
|
|
}
|
|
|
|
/*
|
|
* Generate the sequence of virtual addresses that are candidates for
|
|
* prefaulting in an outward spiral from the faulting virtual address,
|
|
* "addra". Specifically, the sequence is "addra - PAGE_SIZE", "addra
|
|
* + PAGE_SIZE", "addra - 2 * PAGE_SIZE", "addra + 2 * PAGE_SIZE", ...
|
|
* If the candidate address doesn't have a backing physical page, then
|
|
* the loop immediately terminates.
|
|
*/
|
|
for (i = 0; i < 2 * imax(backward, forward); i++) {
|
|
addr = addra + ((i >> 1) + 1) * ((i & 1) == 0 ? -PAGE_SIZE :
|
|
PAGE_SIZE);
|
|
if (addr > addra + forward * PAGE_SIZE)
|
|
addr = 0;
|
|
|
|
if (addr < starta || addr >= entry->end)
|
|
continue;
|
|
|
|
if (!pmap_is_prefaultable(pmap, addr))
|
|
continue;
|
|
|
|
pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
|
|
lobject = entry->object.vm_object;
|
|
VM_OBJECT_RLOCK(lobject);
|
|
while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
|
|
lobject->type == OBJT_DEFAULT &&
|
|
(backing_object = lobject->backing_object) != NULL) {
|
|
KASSERT((lobject->backing_object_offset & PAGE_MASK) ==
|
|
0, ("vm_fault_prefault: unaligned object offset"));
|
|
pindex += lobject->backing_object_offset >> PAGE_SHIFT;
|
|
VM_OBJECT_RLOCK(backing_object);
|
|
VM_OBJECT_RUNLOCK(lobject);
|
|
lobject = backing_object;
|
|
}
|
|
if (m == NULL) {
|
|
VM_OBJECT_RUNLOCK(lobject);
|
|
break;
|
|
}
|
|
if (m->valid == VM_PAGE_BITS_ALL &&
|
|
(m->flags & PG_FICTITIOUS) == 0)
|
|
pmap_enter_quick(pmap, addr, m, entry->protection);
|
|
VM_OBJECT_RUNLOCK(lobject);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Hold each of the physical pages that are mapped by the specified range of
|
|
* virtual addresses, ["addr", "addr" + "len"), if those mappings are valid
|
|
* and allow the specified types of access, "prot". If all of the implied
|
|
* pages are successfully held, then the number of held pages is returned
|
|
* together with pointers to those pages in the array "ma". However, if any
|
|
* of the pages cannot be held, -1 is returned.
|
|
*/
|
|
int
|
|
vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len,
|
|
vm_prot_t prot, vm_page_t *ma, int max_count)
|
|
{
|
|
vm_offset_t end, va;
|
|
vm_page_t *mp;
|
|
int count;
|
|
boolean_t pmap_failed;
|
|
|
|
if (len == 0)
|
|
return (0);
|
|
end = round_page(addr + len);
|
|
addr = trunc_page(addr);
|
|
|
|
/*
|
|
* Check for illegal addresses.
|
|
*/
|
|
if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map))
|
|
return (-1);
|
|
|
|
if (atop(end - addr) > max_count)
|
|
panic("vm_fault_quick_hold_pages: count > max_count");
|
|
count = atop(end - addr);
|
|
|
|
/*
|
|
* Most likely, the physical pages are resident in the pmap, so it is
|
|
* faster to try pmap_extract_and_hold() first.
|
|
*/
|
|
pmap_failed = FALSE;
|
|
for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) {
|
|
*mp = pmap_extract_and_hold(map->pmap, va, prot);
|
|
if (*mp == NULL)
|
|
pmap_failed = TRUE;
|
|
else if ((prot & VM_PROT_WRITE) != 0 &&
|
|
(*mp)->dirty != VM_PAGE_BITS_ALL) {
|
|
/*
|
|
* Explicitly dirty the physical page. Otherwise, the
|
|
* caller's changes may go unnoticed because they are
|
|
* performed through an unmanaged mapping or by a DMA
|
|
* operation.
|
|
*
|
|
* The object lock is not held here.
|
|
* See vm_page_clear_dirty_mask().
|
|
*/
|
|
vm_page_dirty(*mp);
|
|
}
|
|
}
|
|
if (pmap_failed) {
|
|
/*
|
|
* One or more pages could not be held by the pmap. Either no
|
|
* page was mapped at the specified virtual address or that
|
|
* mapping had insufficient permissions. Attempt to fault in
|
|
* and hold these pages.
|
|
*/
|
|
for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE)
|
|
if (*mp == NULL && vm_fault_hold(map, va, prot,
|
|
VM_FAULT_NORMAL, mp) != KERN_SUCCESS)
|
|
goto error;
|
|
}
|
|
return (count);
|
|
error:
|
|
for (mp = ma; mp < ma + count; mp++)
|
|
if (*mp != NULL) {
|
|
vm_page_lock(*mp);
|
|
vm_page_unhold(*mp);
|
|
vm_page_unlock(*mp);
|
|
}
|
|
return (-1);
|
|
}
|
|
|
|
/*
|
|
* Routine:
|
|
* vm_fault_copy_entry
|
|
* Function:
|
|
* Create new shadow object backing dst_entry with private copy of
|
|
* all underlying pages. When src_entry is equal to dst_entry,
|
|
* function implements COW for wired-down map entry. Otherwise,
|
|
* it forks wired entry into dst_map.
|
|
*
|
|
* 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(vm_map_t dst_map, vm_map_t src_map,
|
|
vm_map_entry_t dst_entry, vm_map_entry_t src_entry,
|
|
vm_ooffset_t *fork_charge)
|
|
{
|
|
vm_object_t backing_object, dst_object, object, src_object;
|
|
vm_pindex_t dst_pindex, pindex, src_pindex;
|
|
vm_prot_t access, prot;
|
|
vm_offset_t vaddr;
|
|
vm_page_t dst_m;
|
|
vm_page_t src_m;
|
|
boolean_t upgrade;
|
|
|
|
#ifdef lint
|
|
src_map++;
|
|
#endif /* lint */
|
|
|
|
upgrade = src_entry == dst_entry;
|
|
access = prot = dst_entry->protection;
|
|
|
|
src_object = src_entry->object.vm_object;
|
|
src_pindex = OFF_TO_IDX(src_entry->offset);
|
|
|
|
if (upgrade && (dst_entry->eflags & MAP_ENTRY_NEEDS_COPY) == 0) {
|
|
dst_object = src_object;
|
|
vm_object_reference(dst_object);
|
|
} else {
|
|
/*
|
|
* 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,
|
|
atop(dst_entry->end - dst_entry->start));
|
|
#if VM_NRESERVLEVEL > 0
|
|
dst_object->flags |= OBJ_COLORED;
|
|
dst_object->pg_color = atop(dst_entry->start);
|
|
#endif
|
|
}
|
|
|
|
VM_OBJECT_WLOCK(dst_object);
|
|
KASSERT(upgrade || dst_entry->object.vm_object == NULL,
|
|
("vm_fault_copy_entry: vm_object not NULL"));
|
|
if (src_object != dst_object) {
|
|
dst_entry->object.vm_object = dst_object;
|
|
dst_entry->offset = 0;
|
|
dst_object->charge = dst_entry->end - dst_entry->start;
|
|
}
|
|
if (fork_charge != NULL) {
|
|
KASSERT(dst_entry->cred == NULL,
|
|
("vm_fault_copy_entry: leaked swp charge"));
|
|
dst_object->cred = curthread->td_ucred;
|
|
crhold(dst_object->cred);
|
|
*fork_charge += dst_object->charge;
|
|
} else if (dst_object->cred == NULL) {
|
|
KASSERT(dst_entry->cred != NULL, ("no cred for entry %p",
|
|
dst_entry));
|
|
dst_object->cred = dst_entry->cred;
|
|
dst_entry->cred = NULL;
|
|
}
|
|
|
|
/*
|
|
* If not an upgrade, then enter the mappings in the pmap as
|
|
* read and/or execute accesses. Otherwise, enter them as
|
|
* write accesses.
|
|
*
|
|
* A writeable large page mapping is only created if all of
|
|
* the constituent small page mappings are modified. Marking
|
|
* PTEs as modified on inception allows promotion to happen
|
|
* without taking potentially large number of soft faults.
|
|
*/
|
|
if (!upgrade)
|
|
access &= ~VM_PROT_WRITE;
|
|
|
|
/*
|
|
* Loop through all of the virtual pages within the entry's
|
|
* range, copying each page from the source object to the
|
|
* destination object. Since the source is wired, those pages
|
|
* must exist. In contrast, the destination is pageable.
|
|
* Since the destination object does share any backing storage
|
|
* with the source object, all of its pages must be dirtied,
|
|
* regardless of whether they can be written.
|
|
*/
|
|
for (vaddr = dst_entry->start, dst_pindex = 0;
|
|
vaddr < dst_entry->end;
|
|
vaddr += PAGE_SIZE, dst_pindex++) {
|
|
again:
|
|
/*
|
|
* Find the page in the source object, and copy it in.
|
|
* Because the source is wired down, the page will be
|
|
* in memory.
|
|
*/
|
|
if (src_object != dst_object)
|
|
VM_OBJECT_RLOCK(src_object);
|
|
object = src_object;
|
|
pindex = src_pindex + dst_pindex;
|
|
while ((src_m = vm_page_lookup(object, pindex)) == NULL &&
|
|
(backing_object = object->backing_object) != NULL) {
|
|
/*
|
|
* Unless the source mapping is read-only or
|
|
* it is presently being upgraded from
|
|
* read-only, the first object in the shadow
|
|
* chain should provide all of the pages. In
|
|
* other words, this loop body should never be
|
|
* executed when the source mapping is already
|
|
* read/write.
|
|
*/
|
|
KASSERT((src_entry->protection & VM_PROT_WRITE) == 0 ||
|
|
upgrade,
|
|
("vm_fault_copy_entry: main object missing page"));
|
|
|
|
VM_OBJECT_RLOCK(backing_object);
|
|
pindex += OFF_TO_IDX(object->backing_object_offset);
|
|
if (object != dst_object)
|
|
VM_OBJECT_RUNLOCK(object);
|
|
object = backing_object;
|
|
}
|
|
KASSERT(src_m != NULL, ("vm_fault_copy_entry: page missing"));
|
|
|
|
if (object != dst_object) {
|
|
/*
|
|
* Allocate a page in the destination object.
|
|
*/
|
|
dst_m = vm_page_alloc(dst_object, (src_object ==
|
|
dst_object ? src_pindex : 0) + dst_pindex,
|
|
VM_ALLOC_NORMAL);
|
|
if (dst_m == NULL) {
|
|
VM_OBJECT_WUNLOCK(dst_object);
|
|
VM_OBJECT_RUNLOCK(object);
|
|
VM_WAIT;
|
|
VM_OBJECT_WLOCK(dst_object);
|
|
goto again;
|
|
}
|
|
pmap_copy_page(src_m, dst_m);
|
|
VM_OBJECT_RUNLOCK(object);
|
|
dst_m->valid = VM_PAGE_BITS_ALL;
|
|
dst_m->dirty = VM_PAGE_BITS_ALL;
|
|
} else {
|
|
dst_m = src_m;
|
|
if (vm_page_sleep_if_busy(dst_m, "fltupg"))
|
|
goto again;
|
|
vm_page_xbusy(dst_m);
|
|
KASSERT(dst_m->valid == VM_PAGE_BITS_ALL,
|
|
("invalid dst page %p", dst_m));
|
|
}
|
|
VM_OBJECT_WUNLOCK(dst_object);
|
|
|
|
/*
|
|
* Enter it in the pmap. If a wired, copy-on-write
|
|
* mapping is being replaced by a write-enabled
|
|
* mapping, then wire that new mapping.
|
|
*/
|
|
pmap_enter(dst_map->pmap, vaddr, dst_m, prot,
|
|
access | (upgrade ? PMAP_ENTER_WIRED : 0), 0);
|
|
|
|
/*
|
|
* Mark it no longer busy, and put it on the active list.
|
|
*/
|
|
VM_OBJECT_WLOCK(dst_object);
|
|
|
|
if (upgrade) {
|
|
if (src_m != dst_m) {
|
|
vm_page_lock(src_m);
|
|
vm_page_unwire(src_m, PQ_INACTIVE);
|
|
vm_page_unlock(src_m);
|
|
vm_page_lock(dst_m);
|
|
vm_page_wire(dst_m);
|
|
vm_page_unlock(dst_m);
|
|
} else {
|
|
KASSERT(dst_m->wire_count > 0,
|
|
("dst_m %p is not wired", dst_m));
|
|
}
|
|
} else {
|
|
vm_page_lock(dst_m);
|
|
vm_page_activate(dst_m);
|
|
vm_page_unlock(dst_m);
|
|
}
|
|
vm_page_xunbusy(dst_m);
|
|
}
|
|
VM_OBJECT_WUNLOCK(dst_object);
|
|
if (upgrade) {
|
|
dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY);
|
|
vm_object_deallocate(src_object);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Block entry into the machine-independent layer's page fault handler by
|
|
* the calling thread. Subsequent calls to vm_fault() by that thread will
|
|
* return KERN_PROTECTION_FAILURE. Enable machine-dependent handling of
|
|
* spurious page faults.
|
|
*/
|
|
int
|
|
vm_fault_disable_pagefaults(void)
|
|
{
|
|
|
|
return (curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR));
|
|
}
|
|
|
|
void
|
|
vm_fault_enable_pagefaults(int save)
|
|
{
|
|
|
|
curthread_pflags_restore(save);
|
|
}
|