725441f69b
sleepable scan, iteration over the shadow chain looking for a page could find an OBJ_DEAD object. Such state of the mapping is only transient, the dead object will be terminated and removed from the chain shortly. We must not return KERN_PROTECTION_FAILURE unless the object type is changed to OBJT_DEAD in the chain, indicating that paging on this address is really impossible. Returning KERN_PROTECTION_FAILURE prematurely causes spurious SIGSEGV delivered to processes, or kernel accesses to UVA spuriously failing with EFAULT. If the object with OBJ_DEAD flag is found, only return KERN_PROTECTION_FAILURE when object type is already OBJT_DEAD. Otherwise, sleep a tick and retry the fault handling. Ideally, we would wait until the OBJ_DEAD flag is resolved, e.g. by waiting until the paging on this object is finished. But to do so, we need to reference the dead object, while vm_object_collapse() insists on owning the final reference on the collapsed object. This could be fixed by e.g. changing the assert to shared reference release between vm_fault() and vm_object_collapse(), but it seems to be too much complications for rare boundary condition. PR: 204426 Tested by: pho Reviewed by: alc Sponsored by: The FreeBSD Foundation X-Differential revision: https://reviews.freebsd.org/D6085 MFC after: 2 weeks Approved by: re (gjb)
1458 lines
42 KiB
C
1458 lines
42 KiB
C
/*-
|
|
* Copyright (c) 1991, 1993
|
|
* The Regents of the University of California. All rights reserved.
|
|
* Copyright (c) 1994 John S. Dyson
|
|
* All rights reserved.
|
|
* Copyright (c) 1994 David Greenman
|
|
* All rights reserved.
|
|
*
|
|
*
|
|
* This code is derived from software contributed to Berkeley by
|
|
* The Mach Operating System project at Carnegie-Mellon University.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* 4. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94
|
|
*
|
|
*
|
|
* Copyright (c) 1987, 1990 Carnegie-Mellon University.
|
|
* All rights reserved.
|
|
*
|
|
* Authors: Avadis Tevanian, Jr., Michael Wayne Young
|
|
*
|
|
* Permission to use, copy, modify and distribute this software and
|
|
* its documentation is hereby granted, provided that both the copyright
|
|
* notice and this permission notice appear in all copies of the
|
|
* software, derivative works or modified versions, and any portions
|
|
* thereof, and that both notices appear in supporting documentation.
|
|
*
|
|
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
|
|
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
|
|
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
|
|
*
|
|
* Carnegie Mellon requests users of this software to return to
|
|
*
|
|
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
|
|
* School of Computer Science
|
|
* Carnegie Mellon University
|
|
* Pittsburgh PA 15213-3890
|
|
*
|
|
* any improvements or extensions that they make and grant Carnegie the
|
|
* rights to redistribute these changes.
|
|
*/
|
|
|
|
/*
|
|
* Page fault handling module.
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
__FBSDID("$FreeBSD$");
|
|
|
|
#include "opt_ktrace.h"
|
|
#include "opt_vm.h"
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/lock.h>
|
|
#include <sys/mman.h>
|
|
#include <sys/proc.h>
|
|
#include <sys/racct.h>
|
|
#include <sys/resourcevar.h>
|
|
#include <sys/rwlock.h>
|
|
#include <sys/sysctl.h>
|
|
#include <sys/vmmeter.h>
|
|
#include <sys/vnode.h>
|
|
#ifdef KTRACE
|
|
#include <sys/ktrace.h>
|
|
#endif
|
|
|
|
#include <vm/vm.h>
|
|
#include <vm/vm_param.h>
|
|
#include <vm/pmap.h>
|
|
#include <vm/vm_map.h>
|
|
#include <vm/vm_object.h>
|
|
#include <vm/vm_page.h>
|
|
#include <vm/vm_pageout.h>
|
|
#include <vm/vm_kern.h>
|
|
#include <vm/vm_pager.h>
|
|
#include <vm/vm_extern.h>
|
|
#include <vm/vm_reserv.h>
|
|
|
|
#define PFBAK 4
|
|
#define PFFOR 4
|
|
|
|
#define VM_FAULT_READ_DEFAULT (1 + VM_FAULT_READ_AHEAD_INIT)
|
|
#define VM_FAULT_READ_MAX (1 + VM_FAULT_READ_AHEAD_MAX)
|
|
|
|
#define VM_FAULT_DONTNEED_MIN 1048576
|
|
|
|
struct faultstate {
|
|
vm_page_t m;
|
|
vm_object_t object;
|
|
vm_pindex_t pindex;
|
|
vm_page_t first_m;
|
|
vm_object_t first_object;
|
|
vm_pindex_t first_pindex;
|
|
vm_map_t map;
|
|
vm_map_entry_t entry;
|
|
int lookup_still_valid;
|
|
struct vnode *vp;
|
|
};
|
|
|
|
static void vm_fault_dontneed(const struct faultstate *fs, vm_offset_t vaddr,
|
|
int ahead);
|
|
static void vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra,
|
|
int backward, int forward);
|
|
|
|
static inline void
|
|
release_page(struct faultstate *fs)
|
|
{
|
|
|
|
vm_page_xunbusy(fs->m);
|
|
vm_page_lock(fs->m);
|
|
vm_page_deactivate(fs->m);
|
|
vm_page_unlock(fs->m);
|
|
fs->m = NULL;
|
|
}
|
|
|
|
static inline void
|
|
unlock_map(struct faultstate *fs)
|
|
{
|
|
|
|
if (fs->lookup_still_valid) {
|
|
vm_map_lookup_done(fs->map, fs->entry);
|
|
fs->lookup_still_valid = FALSE;
|
|
}
|
|
}
|
|
|
|
static void
|
|
unlock_and_deallocate(struct faultstate *fs)
|
|
{
|
|
|
|
vm_object_pip_wakeup(fs->object);
|
|
VM_OBJECT_WUNLOCK(fs->object);
|
|
if (fs->object != fs->first_object) {
|
|
VM_OBJECT_WLOCK(fs->first_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;
|
|
}
|
|
vm_object_deallocate(fs->first_object);
|
|
unlock_map(fs);
|
|
if (fs->vp != NULL) {
|
|
vput(fs->vp);
|
|
fs->vp = NULL;
|
|
}
|
|
}
|
|
|
|
static void
|
|
vm_fault_dirty(vm_map_entry_t entry, vm_page_t m, vm_prot_t prot,
|
|
vm_prot_t fault_type, int fault_flags, boolean_t set_wd)
|
|
{
|
|
boolean_t need_dirty;
|
|
|
|
if (((prot & VM_PROT_WRITE) == 0 &&
|
|
(fault_flags & VM_FAULT_DIRTY) == 0) ||
|
|
(m->oflags & VPO_UNMANAGED) != 0)
|
|
return;
|
|
|
|
VM_OBJECT_ASSERT_LOCKED(m->object);
|
|
|
|
need_dirty = ((fault_type & VM_PROT_WRITE) != 0 &&
|
|
(fault_flags & VM_FAULT_WIRE) == 0) ||
|
|
(fault_flags & VM_FAULT_DIRTY) != 0;
|
|
|
|
if (set_wd)
|
|
vm_object_set_writeable_dirty(m->object);
|
|
else
|
|
/*
|
|
* If two callers of vm_fault_dirty() with set_wd ==
|
|
* FALSE, one for the map entry with MAP_ENTRY_NOSYNC
|
|
* flag set, other with flag clear, race, it is
|
|
* possible for the no-NOSYNC thread to see m->dirty
|
|
* != 0 and not clear VPO_NOSYNC. Take vm_page lock
|
|
* around manipulation of VPO_NOSYNC and
|
|
* vm_page_dirty() call, to avoid the race and keep
|
|
* m->oflags consistent.
|
|
*/
|
|
vm_page_lock(m);
|
|
|
|
/*
|
|
* If this is a NOSYNC mmap we do not want to set VPO_NOSYNC
|
|
* if the page is already dirty to prevent data written with
|
|
* the expectation of being synced from not being synced.
|
|
* Likewise if this entry does not request NOSYNC then make
|
|
* sure the page isn't marked NOSYNC. Applications sharing
|
|
* data should use the same flags to avoid ping ponging.
|
|
*/
|
|
if ((entry->eflags & MAP_ENTRY_NOSYNC) != 0) {
|
|
if (m->dirty == 0) {
|
|
m->oflags |= VPO_NOSYNC;
|
|
}
|
|
} else {
|
|
m->oflags &= ~VPO_NOSYNC;
|
|
}
|
|
|
|
/*
|
|
* If the fault is a write, we know that this page is being
|
|
* written NOW so dirty it explicitly to save on
|
|
* pmap_is_modified() calls later.
|
|
*
|
|
* Also tell the backing pager, if any, that it should remove
|
|
* any swap backing since the page is now dirty.
|
|
*/
|
|
if (need_dirty)
|
|
vm_page_dirty(m);
|
|
if (!set_wd)
|
|
vm_page_unlock(m);
|
|
if (need_dirty)
|
|
vm_pager_page_unswapped(m);
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
vm_prot_t prot;
|
|
int alloc_req, era, faultcount, nera, result;
|
|
boolean_t growstack, is_first_object_locked, wired;
|
|
int map_generation;
|
|
vm_object_t next_object;
|
|
int hardfault;
|
|
struct faultstate fs;
|
|
struct vnode *vp;
|
|
vm_page_t m;
|
|
int ahead, behind, cluster_offset, dead, error, locked;
|
|
|
|
hardfault = 0;
|
|
growstack = TRUE;
|
|
PCPU_INC(cnt.v_vm_faults);
|
|
fs.vp = NULL;
|
|
faultcount = 0;
|
|
|
|
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, &fs.entry,
|
|
&fs.first_object, &fs.first_pindex, &prot, &wired);
|
|
if (result != KERN_SUCCESS) {
|
|
if (growstack && result == KERN_INVALID_ADDRESS &&
|
|
map != kernel_map) {
|
|
result = vm_map_growstack(curproc, vaddr);
|
|
if (result != KERN_SUCCESS)
|
|
return (KERN_FAILURE);
|
|
growstack = FALSE;
|
|
goto RetryFault;
|
|
}
|
|
return (result);
|
|
}
|
|
|
|
map_generation = fs.map->timestamp;
|
|
|
|
if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
|
|
panic("vm_fault: fault on nofault entry, addr: %lx",
|
|
(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)) {
|
|
if (fs.vp != NULL) {
|
|
vput(fs.vp);
|
|
fs.vp = NULL;
|
|
}
|
|
fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP;
|
|
vm_map_unlock_and_wait(fs.map, 0);
|
|
} else
|
|
vm_map_unlock(fs.map);
|
|
goto RetryFault;
|
|
}
|
|
|
|
if (wired)
|
|
fault_type = prot | (fault_type & VM_PROT_COPY);
|
|
else
|
|
KASSERT((fault_flags & VM_FAULT_WIRE) == 0,
|
|
("!wired && VM_FAULT_WIRE"));
|
|
|
|
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)
|
|
goto fast_failed;
|
|
m = vm_page_lookup(fs.first_object, fs.first_pindex);
|
|
/* A busy page can be mapped for read|execute access. */
|
|
if (m == NULL || ((prot & VM_PROT_WRITE) != 0 &&
|
|
vm_page_busied(m)) || m->valid != VM_PAGE_BITS_ALL)
|
|
goto fast_failed;
|
|
result = pmap_enter(fs.map->pmap, vaddr, m, prot,
|
|
fault_type | PMAP_ENTER_NOSLEEP | (wired ? PMAP_ENTER_WIRED :
|
|
0), 0);
|
|
if (result != KERN_SUCCESS)
|
|
goto fast_failed;
|
|
if (m_hold != NULL) {
|
|
*m_hold = m;
|
|
vm_page_lock(m);
|
|
vm_page_hold(m);
|
|
vm_page_unlock(m);
|
|
}
|
|
vm_fault_dirty(fs.entry, m, prot, fault_type, fault_flags,
|
|
FALSE);
|
|
VM_OBJECT_RUNLOCK(fs.first_object);
|
|
if (!wired)
|
|
vm_fault_prefault(&fs, vaddr, PFBAK, PFFOR);
|
|
vm_map_lookup_done(fs.map, fs.entry);
|
|
curthread->td_ru.ru_minflt++;
|
|
return (KERN_SUCCESS);
|
|
fast_failed:
|
|
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. This must be done after
|
|
* obtaining the vnode lock in order to avoid possible deadlocks.
|
|
*/
|
|
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);
|
|
PCPU_INC(cnt.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);
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
} else if (fs.m->valid == VM_PAGE_BITS_ALL)
|
|
break;
|
|
}
|
|
|
|
readrest:
|
|
/*
|
|
* We have either allocated a new page or found an existing
|
|
* page that is only partially valid.
|
|
*
|
|
* Attempt to fault-in the page if there is a chance that the
|
|
* pager has it, and potentially fault in additional pages
|
|
* at the same time.
|
|
*/
|
|
if (fs.object->type != OBJT_DEFAULT) {
|
|
int rv;
|
|
u_char behavior = vm_map_entry_behavior(fs.entry);
|
|
|
|
era = fs.entry->read_ahead;
|
|
if (behavior == MAP_ENTRY_BEHAV_RANDOM ||
|
|
P_KILLED(curproc)) {
|
|
behind = 0;
|
|
nera = 0;
|
|
ahead = 0;
|
|
} else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) {
|
|
behind = 0;
|
|
nera = VM_FAULT_READ_AHEAD_MAX;
|
|
ahead = nera;
|
|
if (fs.pindex == fs.entry->next_read)
|
|
vm_fault_dontneed(&fs, vaddr, ahead);
|
|
} else if (fs.pindex == 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"
|
|
*/
|
|
behind = 0;
|
|
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;
|
|
}
|
|
ahead = nera;
|
|
if (era == VM_FAULT_READ_AHEAD_MAX)
|
|
vm_fault_dontneed(&fs, vaddr, ahead);
|
|
} else {
|
|
/*
|
|
* This is a non-sequential fault. 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 - fs.entry->start));
|
|
nera = 0;
|
|
ahead = VM_FAULT_READ_DEFAULT - 1 -
|
|
cluster_offset;
|
|
}
|
|
ahead = ulmin(ahead, atop(fs.entry->end - vaddr) - 1);
|
|
if (era != nera)
|
|
fs.entry->read_ahead = nera;
|
|
|
|
/*
|
|
* Call the pager to retrieve the data, if any, after
|
|
* releasing the lock on the map. We hold a ref on
|
|
* fs.object and the pages are exclusive busied.
|
|
*/
|
|
unlock_map(&fs);
|
|
|
|
if (fs.object->type == OBJT_VNODE) {
|
|
vp = fs.object->handle;
|
|
if (vp == fs.vp)
|
|
goto vnode_locked;
|
|
else if (fs.vp != NULL) {
|
|
vput(fs.vp);
|
|
fs.vp = NULL;
|
|
}
|
|
locked = VOP_ISLOCKED(vp);
|
|
|
|
if (locked != LK_EXCLUSIVE)
|
|
locked = LK_SHARED;
|
|
/* Do not sleep for vnode lock while fs.m is busy */
|
|
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;
|
|
}
|
|
vnode_locked:
|
|
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.
|
|
*/
|
|
rv = vm_pager_get_pages(fs.object, &fs.m, 1,
|
|
&behind, &ahead);
|
|
if (rv == VM_PAGER_OK) {
|
|
faultcount = behind + 1 + ahead;
|
|
hardfault++;
|
|
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);
|
|
vm_page_free(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);
|
|
vm_page_free(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 {
|
|
PCPU_INC(cnt.v_ozfod);
|
|
}
|
|
PCPU_INC(cnt.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;
|
|
PCPU_INC(cnt.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);
|
|
PCPU_INC(cnt.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) {
|
|
vm_object_t retry_object;
|
|
vm_pindex_t retry_pindex;
|
|
vm_prot_t retry_prot;
|
|
|
|
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 != 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, update the map entry's
|
|
* last read offset.
|
|
*
|
|
* XXX The following assignment modifies the map
|
|
* without holding a write lock on it.
|
|
*/
|
|
if (hardfault)
|
|
fs.entry->next_read = fs.pindex + ahead + 1;
|
|
|
|
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) {
|
|
PCPU_INC(cnt.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;
|
|
|
|
starta = addra - backward * PAGE_SIZE;
|
|
if (starta < entry->start) {
|
|
starta = entry->start;
|
|
} else if (starta > addra) {
|
|
starta = 0;
|
|
}
|
|
|
|
/*
|
|
* 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,
|
|
OFF_TO_IDX(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);
|
|
}
|