eaf13dd73a
MUST be PG_BUSY. It is bogus to free a page that isn't busy, because it is in a state of being "unavailable" when being freed. The additional advantage is that the page_remove code has a better cross-check that the page should be busy and unavailable for other use. There were some minor problems with the collapse code, and this plugs those subtile "holes." Also, the vfs_bio code wasn't checking correctly for PG_BUSY pages. I am going to develop a more consistant scheme for grabbing pages, busy or otherwise. For now, we are stuck with the current morass.
1136 lines
28 KiB
C
1136 lines
28 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.
|
|
*
|
|
* $Id: vm_fault.c,v 1.76 1998/01/22 17:30:33 dyson Exp $
|
|
*/
|
|
|
|
/*
|
|
* Page fault handling module.
|
|
*/
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/proc.h>
|
|
#include <sys/vnode.h>
|
|
#include <sys/resourcevar.h>
|
|
#include <sys/vmmeter.h>
|
|
|
|
#include <vm/vm.h>
|
|
#include <vm/vm_param.h>
|
|
#include <vm/vm_prot.h>
|
|
#include <sys/lock.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/vnode_pager.h>
|
|
#include <vm/vm_extern.h>
|
|
|
|
int vm_fault_additional_pages __P((vm_page_t, int, int, vm_page_t *, int *));
|
|
|
|
#define VM_FAULT_READ_AHEAD 8
|
|
#define VM_FAULT_READ_BEHIND 7
|
|
#define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1)
|
|
|
|
/*
|
|
* vm_fault:
|
|
*
|
|
* Handle a page fault occuring 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)
|
|
{
|
|
vm_object_t first_object;
|
|
vm_pindex_t first_pindex;
|
|
vm_map_entry_t entry;
|
|
register vm_object_t object;
|
|
register vm_pindex_t pindex;
|
|
vm_page_t m;
|
|
vm_page_t first_m;
|
|
vm_prot_t prot;
|
|
int result;
|
|
boolean_t wired;
|
|
boolean_t lookup_still_valid;
|
|
int map_generation;
|
|
vm_page_t old_m;
|
|
vm_object_t next_object;
|
|
vm_page_t marray[VM_FAULT_READ];
|
|
int hardfault = 0;
|
|
int faultcount;
|
|
struct vnode *vp = NULL;
|
|
struct proc *p = curproc; /* XXX */
|
|
|
|
cnt.v_vm_faults++; /* needs lock XXX */
|
|
/*
|
|
* Recovery actions
|
|
*/
|
|
#define FREE_PAGE(m) { \
|
|
vm_page_free(m); \
|
|
}
|
|
|
|
#define RELEASE_PAGE(m) { \
|
|
PAGE_WAKEUP(m); \
|
|
vm_page_activate(m); \
|
|
}
|
|
|
|
#define UNLOCK_MAP { \
|
|
if (lookup_still_valid) { \
|
|
vm_map_lookup_done(map, entry); \
|
|
lookup_still_valid = FALSE; \
|
|
} \
|
|
}
|
|
|
|
#define UNLOCK_THINGS { \
|
|
vm_object_pip_wakeup(object); \
|
|
if (object != first_object) { \
|
|
FREE_PAGE(first_m); \
|
|
vm_object_pip_wakeup(first_object); \
|
|
} \
|
|
UNLOCK_MAP; \
|
|
if (vp != NULL) { \
|
|
vput(vp); \
|
|
vp = NULL; \
|
|
} \
|
|
}
|
|
|
|
#define UNLOCK_AND_DEALLOCATE { \
|
|
UNLOCK_THINGS; \
|
|
vm_object_deallocate(first_object); \
|
|
}
|
|
|
|
|
|
RetryFault:;
|
|
faultcount = 0;
|
|
|
|
/*
|
|
* Find the backing store object and offset into it to begin the
|
|
* search.
|
|
*/
|
|
if ((result = vm_map_lookup(&map, vaddr,
|
|
fault_type, &entry, &first_object,
|
|
&first_pindex, &prot, &wired)) != KERN_SUCCESS) {
|
|
if ((result != KERN_PROTECTION_FAILURE) ||
|
|
((fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE)) {
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* If we are user-wiring a r/w segment, and it is COW, then
|
|
* we need to do the COW operation. Note that we don't COW
|
|
* currently RO sections now, because it is NOT desirable
|
|
* to COW .text. We simply keep .text from ever being COW'ed
|
|
* and take the heat that one cannot debug wired .text sections.
|
|
*/
|
|
result = vm_map_lookup(&map, vaddr,
|
|
VM_PROT_READ|VM_PROT_WRITE|VM_PROT_OVERRIDE_WRITE,
|
|
&entry, &first_object, &first_pindex, &prot, &wired);
|
|
if (result != KERN_SUCCESS) {
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* If we don't COW now, on a user wire, the user will never
|
|
* be able to write to the mapping. If we don't make this
|
|
* restriction, the bookkeeping would be nearly impossible.
|
|
*/
|
|
if ((entry->protection & VM_PROT_WRITE) == 0)
|
|
entry->max_protection &= ~VM_PROT_WRITE;
|
|
}
|
|
|
|
map_generation = map->timestamp;
|
|
|
|
if (entry->eflags & MAP_ENTRY_NOFAULT) {
|
|
panic("vm_fault: fault on nofault entry, addr: %lx",
|
|
vaddr);
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
vm_object_reference(first_object);
|
|
first_object->paging_in_progress++;
|
|
|
|
vp = vnode_pager_lock(first_object);
|
|
if ((fault_type & VM_PROT_WRITE) &&
|
|
(first_object->type == OBJT_VNODE)) {
|
|
vm_freeze_copyopts(first_object, first_pindex, first_pindex + 1);
|
|
}
|
|
|
|
lookup_still_valid = TRUE;
|
|
|
|
if (wired)
|
|
fault_type = prot;
|
|
|
|
first_m = NULL;
|
|
|
|
/*
|
|
* INVARIANTS (through entire routine):
|
|
*
|
|
* 1) At all times, we must either have the object lock or a busy
|
|
* page in some object to prevent some other process from trying to
|
|
* bring in the same page.
|
|
*
|
|
* Note that we cannot hold any locks during the pager access or when
|
|
* waiting for memory, so we use a busy page then.
|
|
*
|
|
* Note also that we aren't as concerned about more than one thead
|
|
* attempting to pager_data_unlock the same page at once, so we don't
|
|
* hold the page as busy then, but do record the highest unlock value
|
|
* so far. [Unlock requests may also be delivered out of order.]
|
|
*
|
|
* 2) Once we have a busy page, we must remove it from the pageout
|
|
* queues, so that the pageout daemon will not grab it away.
|
|
*
|
|
* 3) To prevent another process from racing us down the shadow chain
|
|
* and entering a new page in the top object before we do, we must
|
|
* keep a busy page in the top object while following the shadow
|
|
* chain.
|
|
*
|
|
* 4) We must increment paging_in_progress on any object for which
|
|
* we have a busy page, to prevent vm_object_collapse from removing
|
|
* the busy page without our noticing.
|
|
*/
|
|
|
|
/*
|
|
* Search for the page at object/offset.
|
|
*/
|
|
|
|
object = first_object;
|
|
pindex = first_pindex;
|
|
|
|
/*
|
|
* See whether this page is resident
|
|
*/
|
|
|
|
while (TRUE) {
|
|
|
|
if (object->flags & OBJ_DEAD) {
|
|
UNLOCK_AND_DEALLOCATE;
|
|
return (KERN_PROTECTION_FAILURE);
|
|
}
|
|
|
|
m = vm_page_lookup(object, pindex);
|
|
if (m != NULL) {
|
|
int queue;
|
|
/*
|
|
* If the page is being brought in, wait for it and
|
|
* then retry.
|
|
*/
|
|
if ((m->flags & PG_BUSY) || m->busy) {
|
|
int s;
|
|
|
|
UNLOCK_THINGS;
|
|
s = splvm();
|
|
if (((m->flags & PG_BUSY) || m->busy)) {
|
|
m->flags |= PG_WANTED | PG_REFERENCED;
|
|
cnt.v_intrans++;
|
|
tsleep(m, PSWP, "vmpfw", 0);
|
|
}
|
|
splx(s);
|
|
vm_object_deallocate(first_object);
|
|
goto RetryFault;
|
|
}
|
|
|
|
queue = m->queue;
|
|
vm_page_unqueue_nowakeup(m);
|
|
|
|
/*
|
|
* Mark page busy for other processes, and the pagedaemon.
|
|
*/
|
|
if (((queue - m->pc) == PQ_CACHE) &&
|
|
(cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min) {
|
|
vm_page_activate(m);
|
|
UNLOCK_AND_DEALLOCATE;
|
|
VM_WAIT;
|
|
goto RetryFault;
|
|
}
|
|
|
|
m->flags |= PG_BUSY;
|
|
|
|
if (((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) &&
|
|
m->object != kernel_object && m->object != kmem_object) {
|
|
goto readrest;
|
|
}
|
|
break;
|
|
}
|
|
if (((object->type != OBJT_DEFAULT) &&
|
|
(((fault_flags & VM_FAULT_WIRE_MASK) == 0) || wired))
|
|
|| (object == first_object)) {
|
|
|
|
if (pindex >= object->size) {
|
|
UNLOCK_AND_DEALLOCATE;
|
|
return (KERN_PROTECTION_FAILURE);
|
|
}
|
|
|
|
/*
|
|
* Allocate a new page for this object/offset pair.
|
|
*/
|
|
m = vm_page_alloc(object, pindex,
|
|
(vp || object->backing_object)? VM_ALLOC_NORMAL: VM_ALLOC_ZERO);
|
|
|
|
if (m == NULL) {
|
|
UNLOCK_AND_DEALLOCATE;
|
|
VM_WAIT;
|
|
goto RetryFault;
|
|
}
|
|
}
|
|
|
|
readrest:
|
|
if (object->type != OBJT_DEFAULT &&
|
|
(((fault_flags & VM_FAULT_WIRE_MASK) == 0) || wired)) {
|
|
int rv;
|
|
int reqpage;
|
|
int ahead, behind;
|
|
|
|
if (first_object->behavior == OBJ_RANDOM) {
|
|
ahead = 0;
|
|
behind = 0;
|
|
} else {
|
|
behind = (vaddr - entry->start) >> PAGE_SHIFT;
|
|
if (behind > VM_FAULT_READ_BEHIND)
|
|
behind = VM_FAULT_READ_BEHIND;
|
|
|
|
ahead = ((entry->end - vaddr) >> PAGE_SHIFT) - 1;
|
|
if (ahead > VM_FAULT_READ_AHEAD)
|
|
ahead = VM_FAULT_READ_AHEAD;
|
|
}
|
|
|
|
if ((first_object->type != OBJT_DEVICE) &&
|
|
(first_object->behavior == OBJ_SEQUENTIAL)) {
|
|
vm_pindex_t firstpindex, tmppindex;
|
|
if (first_pindex <
|
|
2*(VM_FAULT_READ_BEHIND + VM_FAULT_READ_AHEAD + 1))
|
|
firstpindex = 0;
|
|
else
|
|
firstpindex = first_pindex -
|
|
2*(VM_FAULT_READ_BEHIND + VM_FAULT_READ_AHEAD + 1);
|
|
|
|
for(tmppindex = first_pindex - 1;
|
|
tmppindex >= firstpindex;
|
|
--tmppindex) {
|
|
vm_page_t mt;
|
|
mt = vm_page_lookup( first_object, tmppindex);
|
|
if (mt == NULL || (mt->valid != VM_PAGE_BITS_ALL))
|
|
break;
|
|
if (mt->busy ||
|
|
(mt->flags & (PG_BUSY|PG_FICTITIOUS)) ||
|
|
mt->hold_count ||
|
|
mt->wire_count)
|
|
continue;
|
|
if (mt->dirty == 0)
|
|
vm_page_test_dirty(mt);
|
|
if (mt->dirty) {
|
|
vm_page_protect(mt, VM_PROT_NONE);
|
|
vm_page_deactivate(mt);
|
|
} else {
|
|
vm_page_cache(mt);
|
|
}
|
|
}
|
|
|
|
ahead += behind;
|
|
behind = 0;
|
|
}
|
|
|
|
/*
|
|
* now we find out if any other pages should be paged
|
|
* in at this time this routine checks to see if the
|
|
* pages surrounding this fault reside in the same
|
|
* object as the page for this fault. If they do,
|
|
* then they are faulted in also into the object. The
|
|
* array "marray" returned contains an array of
|
|
* vm_page_t structs where one of them is the
|
|
* vm_page_t passed to the routine. The reqpage
|
|
* return value is the index into the marray for the
|
|
* vm_page_t passed to the routine.
|
|
*/
|
|
faultcount = vm_fault_additional_pages(
|
|
m, behind, ahead, marray, &reqpage);
|
|
|
|
/*
|
|
* Call the pager to retrieve the data, if any, after
|
|
* releasing the lock on the map.
|
|
*/
|
|
UNLOCK_MAP;
|
|
|
|
rv = faultcount ?
|
|
vm_pager_get_pages(object, marray, faultcount,
|
|
reqpage) : VM_PAGER_FAIL;
|
|
|
|
if (rv == VM_PAGER_OK) {
|
|
/*
|
|
* Found the page. Leave it busy while we play
|
|
* with it.
|
|
*/
|
|
|
|
/*
|
|
* Relookup in case pager changed page. Pager
|
|
* is responsible for disposition of old page
|
|
* if moved.
|
|
*/
|
|
m = vm_page_lookup(object, pindex);
|
|
if( !m) {
|
|
UNLOCK_AND_DEALLOCATE;
|
|
goto RetryFault;
|
|
}
|
|
|
|
hardfault++;
|
|
break;
|
|
}
|
|
/*
|
|
* Remove the bogus page (which does not exist at this
|
|
* object/offset); before doing so, we must get back
|
|
* our object lock to preserve our invariant.
|
|
*
|
|
* Also wake up any other process that may want to bring
|
|
* in this page.
|
|
*
|
|
* If this is the top-level object, we must leave the
|
|
* busy page to prevent another process from rushing
|
|
* past us, and inserting the page in that object at
|
|
* the same time that we are.
|
|
*/
|
|
|
|
if (rv == VM_PAGER_ERROR)
|
|
printf("vm_fault: pager input (probably hardware) error, PID %d failure\n",
|
|
curproc->p_pid);
|
|
/*
|
|
* Data outside the range of the pager or an I/O error
|
|
*/
|
|
/*
|
|
* XXX - the check for kernel_map is a kludge to work
|
|
* around having the machine panic on a kernel space
|
|
* fault w/ I/O error.
|
|
*/
|
|
if (((map != kernel_map) && (rv == VM_PAGER_ERROR)) ||
|
|
(rv == VM_PAGER_BAD)) {
|
|
FREE_PAGE(m);
|
|
UNLOCK_AND_DEALLOCATE;
|
|
return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE);
|
|
}
|
|
if (object != first_object) {
|
|
FREE_PAGE(m);
|
|
/*
|
|
* XXX - we cannot just fall out at this
|
|
* point, m has been freed and is invalid!
|
|
*/
|
|
}
|
|
}
|
|
/*
|
|
* We get here if the object has default pager (or unwiring) or the
|
|
* pager doesn't have the page.
|
|
*/
|
|
if (object == first_object)
|
|
first_m = m;
|
|
|
|
/*
|
|
* Move on to the next object. Lock the next object before
|
|
* unlocking the current one.
|
|
*/
|
|
|
|
pindex += OFF_TO_IDX(object->backing_object_offset);
|
|
next_object = object->backing_object;
|
|
if (next_object == NULL) {
|
|
/*
|
|
* If there's no object left, fill the page in the top
|
|
* object with zeros.
|
|
*/
|
|
if (object != first_object) {
|
|
vm_object_pip_wakeup(object);
|
|
|
|
object = first_object;
|
|
pindex = first_pindex;
|
|
m = first_m;
|
|
}
|
|
first_m = NULL;
|
|
|
|
if ((m->flags & PG_ZERO) == 0)
|
|
vm_page_zero_fill(m);
|
|
cnt.v_zfod++;
|
|
break;
|
|
} else {
|
|
if (object != first_object) {
|
|
vm_object_pip_wakeup(object);
|
|
}
|
|
object = next_object;
|
|
object->paging_in_progress++;
|
|
}
|
|
}
|
|
|
|
#if defined(DIAGNOSTIC)
|
|
if ((m->flags & PG_BUSY) == 0)
|
|
panic("vm_fault: not busy after main loop");
|
|
#endif
|
|
|
|
/*
|
|
* PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
|
|
* is held.]
|
|
*/
|
|
|
|
old_m = m; /* save page that would be copied */
|
|
|
|
/*
|
|
* If the page is being written, but isn't already owned by the
|
|
* top-level object, we have to copy it into a new page owned by the
|
|
* top-level object.
|
|
*/
|
|
|
|
if (object != first_object) {
|
|
/*
|
|
* We only really need to copy if we want to write it.
|
|
*/
|
|
|
|
if (fault_type & VM_PROT_WRITE) {
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (map_generation == map->timestamp &&
|
|
/*
|
|
* Only one shadow object
|
|
*/
|
|
(object->shadow_count == 1) &&
|
|
/*
|
|
* No COW refs, except us
|
|
*/
|
|
(object->ref_count == 1) &&
|
|
/*
|
|
* Noone else can look this object up
|
|
*/
|
|
(object->handle == NULL) &&
|
|
/*
|
|
* No other ways to look the object up
|
|
*/
|
|
((object->type == OBJT_DEFAULT) ||
|
|
(object->type == OBJT_SWAP)) &&
|
|
/*
|
|
* We don't chase down the shadow chain
|
|
*/
|
|
(object == first_object->backing_object) &&
|
|
|
|
/*
|
|
* grab the lock if we need to
|
|
*/
|
|
(lookup_still_valid ||
|
|
(((entry->eflags & MAP_ENTRY_IS_A_MAP) == 0) &&
|
|
lockmgr(&map->lock,
|
|
LK_EXCLUSIVE|LK_NOWAIT, (void *)0, curproc) == 0))) {
|
|
|
|
lookup_still_valid = 1;
|
|
/*
|
|
* get rid of the unnecessary page
|
|
*/
|
|
vm_page_protect(first_m, VM_PROT_NONE);
|
|
FREE_PAGE(first_m);
|
|
/*
|
|
* grab the page and put it into the process'es object
|
|
*/
|
|
vm_page_rename(m, first_object, first_pindex);
|
|
first_m = m;
|
|
m->dirty = VM_PAGE_BITS_ALL;
|
|
m = NULL;
|
|
} else {
|
|
/*
|
|
* Oh, well, lets copy it.
|
|
*/
|
|
vm_page_copy(m, first_m);
|
|
}
|
|
|
|
if (m) {
|
|
vm_page_activate(m);
|
|
|
|
/*
|
|
* We no longer need the old page or object.
|
|
*/
|
|
PAGE_WAKEUP(m);
|
|
}
|
|
|
|
vm_object_pip_wakeup(object);
|
|
/*
|
|
* Only use the new page below...
|
|
*/
|
|
|
|
cnt.v_cow_faults++;
|
|
m = first_m;
|
|
object = first_object;
|
|
pindex = first_pindex;
|
|
|
|
} else {
|
|
prot &= ~VM_PROT_WRITE;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We must verify that the maps have not changed since our last
|
|
* lookup.
|
|
*/
|
|
|
|
if (!lookup_still_valid &&
|
|
(map->timestamp != map_generation)) {
|
|
vm_object_t retry_object;
|
|
vm_pindex_t retry_pindex;
|
|
vm_prot_t retry_prot;
|
|
|
|
/*
|
|
* Since map entries may be pageable, make sure we can take a
|
|
* page fault on them.
|
|
*/
|
|
|
|
/*
|
|
* To avoid trying to write_lock the map while another process
|
|
* has it read_locked (in vm_map_pageable), we do not try for
|
|
* write permission. If the page is still writable, we will
|
|
* get write permission. If it is not, or has been marked
|
|
* needs_copy, we enter the mapping without write permission,
|
|
* and will merely take another fault.
|
|
*/
|
|
result = vm_map_lookup(&map, vaddr, fault_type & ~VM_PROT_WRITE,
|
|
&entry, &retry_object, &retry_pindex, &retry_prot, &wired);
|
|
map_generation = map->timestamp;
|
|
|
|
/*
|
|
* If we don't need the page any longer, put it on the active
|
|
* list (the easiest thing to do here). If no one needs it,
|
|
* pageout will grab it eventually.
|
|
*/
|
|
|
|
if (result != KERN_SUCCESS) {
|
|
RELEASE_PAGE(m);
|
|
UNLOCK_AND_DEALLOCATE;
|
|
return (result);
|
|
}
|
|
lookup_still_valid = TRUE;
|
|
|
|
if ((retry_object != first_object) ||
|
|
(retry_pindex != first_pindex)) {
|
|
RELEASE_PAGE(m);
|
|
UNLOCK_AND_DEALLOCATE;
|
|
goto RetryFault;
|
|
}
|
|
/*
|
|
* Check whether the protection has changed or the object has
|
|
* been copied while we left the map unlocked. Changing from
|
|
* read to write permission is OK - we leave the page
|
|
* write-protected, and catch the write fault. Changing from
|
|
* write to read permission means that we can't mark the page
|
|
* write-enabled after all.
|
|
*/
|
|
prot &= retry_prot;
|
|
}
|
|
|
|
/*
|
|
* Put this page into the physical map. We had to do the unlock above
|
|
* because pmap_enter may cause other faults. We don't put the page
|
|
* back on the active queue until later so that the page-out daemon
|
|
* won't find us (yet).
|
|
*/
|
|
|
|
if (prot & VM_PROT_WRITE) {
|
|
m->flags |= PG_WRITEABLE;
|
|
m->object->flags |= OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY;
|
|
/*
|
|
* If the fault is a write, we know that this page is being
|
|
* written NOW. This will save on the pmap_is_modified() calls
|
|
* later.
|
|
*/
|
|
if (fault_flags & VM_FAULT_DIRTY) {
|
|
m->dirty = VM_PAGE_BITS_ALL;
|
|
}
|
|
}
|
|
|
|
UNLOCK_THINGS;
|
|
m->valid = VM_PAGE_BITS_ALL;
|
|
m->flags &= ~PG_ZERO;
|
|
|
|
pmap_enter(map->pmap, vaddr, VM_PAGE_TO_PHYS(m), prot, wired);
|
|
if (((fault_flags & VM_FAULT_WIRE_MASK) == 0) && (wired == 0)) {
|
|
pmap_prefault(map->pmap, vaddr, entry);
|
|
}
|
|
|
|
m->flags |= PG_MAPPED|PG_REFERENCED;
|
|
if (fault_flags & VM_FAULT_HOLD)
|
|
vm_page_hold(m);
|
|
|
|
/*
|
|
* If the page is not wired down, then put it where the pageout daemon
|
|
* can find it.
|
|
*/
|
|
if (fault_flags & VM_FAULT_WIRE_MASK) {
|
|
if (wired)
|
|
vm_page_wire(m);
|
|
else
|
|
vm_page_unwire(m);
|
|
} else {
|
|
vm_page_activate(m);
|
|
}
|
|
|
|
if (curproc && (curproc->p_flag & P_INMEM) && curproc->p_stats) {
|
|
if (hardfault) {
|
|
curproc->p_stats->p_ru.ru_majflt++;
|
|
} else {
|
|
curproc->p_stats->p_ru.ru_minflt++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Unlock everything, and return
|
|
*/
|
|
|
|
PAGE_WAKEUP(m);
|
|
vm_object_deallocate(first_object);
|
|
|
|
return (KERN_SUCCESS);
|
|
|
|
}
|
|
|
|
/*
|
|
* vm_fault_wire:
|
|
*
|
|
* Wire down a range of virtual addresses in a map.
|
|
*/
|
|
int
|
|
vm_fault_wire(map, start, end)
|
|
vm_map_t map;
|
|
vm_offset_t start, end;
|
|
{
|
|
|
|
register vm_offset_t va;
|
|
register pmap_t pmap;
|
|
int rv;
|
|
|
|
pmap = vm_map_pmap(map);
|
|
|
|
/*
|
|
* Inform the physical mapping system that the range of addresses may
|
|
* not fault, so that page tables and such can be locked down as well.
|
|
*/
|
|
|
|
pmap_pageable(pmap, start, end, FALSE);
|
|
|
|
/*
|
|
* We simulate a fault to get the page and enter it in the physical
|
|
* map.
|
|
*/
|
|
|
|
for (va = start; va < end; va += PAGE_SIZE) {
|
|
rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE,
|
|
VM_FAULT_CHANGE_WIRING);
|
|
if (rv) {
|
|
if (va != start)
|
|
vm_fault_unwire(map, start, va);
|
|
return (rv);
|
|
}
|
|
}
|
|
return (KERN_SUCCESS);
|
|
}
|
|
|
|
/*
|
|
* vm_fault_user_wire:
|
|
*
|
|
* Wire down a range of virtual addresses in a map. This
|
|
* is for user mode though, so we only ask for read access
|
|
* on currently read only sections.
|
|
*/
|
|
int
|
|
vm_fault_user_wire(map, start, end)
|
|
vm_map_t map;
|
|
vm_offset_t start, end;
|
|
{
|
|
|
|
register vm_offset_t va;
|
|
register pmap_t pmap;
|
|
int rv;
|
|
|
|
pmap = vm_map_pmap(map);
|
|
|
|
/*
|
|
* Inform the physical mapping system that the range of addresses may
|
|
* not fault, so that page tables and such can be locked down as well.
|
|
*/
|
|
|
|
pmap_pageable(pmap, start, end, FALSE);
|
|
|
|
/*
|
|
* We simulate a fault to get the page and enter it in the physical
|
|
* map.
|
|
*/
|
|
for (va = start; va < end; va += PAGE_SIZE) {
|
|
rv = vm_fault(map, va, VM_PROT_READ, VM_FAULT_USER_WIRE);
|
|
if (rv) {
|
|
if (va != start)
|
|
vm_fault_unwire(map, start, va);
|
|
return (rv);
|
|
}
|
|
}
|
|
return (KERN_SUCCESS);
|
|
}
|
|
|
|
|
|
/*
|
|
* vm_fault_unwire:
|
|
*
|
|
* Unwire a range of virtual addresses in a map.
|
|
*/
|
|
void
|
|
vm_fault_unwire(map, start, end)
|
|
vm_map_t map;
|
|
vm_offset_t start, end;
|
|
{
|
|
|
|
register vm_offset_t va, pa;
|
|
register pmap_t pmap;
|
|
|
|
pmap = vm_map_pmap(map);
|
|
|
|
/*
|
|
* Since the pages are wired down, we must be able to get their
|
|
* mappings from the physical map system.
|
|
*/
|
|
|
|
for (va = start; va < end; va += PAGE_SIZE) {
|
|
pa = pmap_extract(pmap, va);
|
|
if (pa != (vm_offset_t) 0) {
|
|
pmap_change_wiring(pmap, va, FALSE);
|
|
vm_page_unwire(PHYS_TO_VM_PAGE(pa));
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Inform the physical mapping system that the range of addresses may
|
|
* fault, so that page tables and such may be unwired themselves.
|
|
*/
|
|
|
|
pmap_pageable(pmap, start, end, TRUE);
|
|
|
|
}
|
|
|
|
/*
|
|
* Routine:
|
|
* vm_fault_copy_entry
|
|
* Function:
|
|
* Copy all of the pages from a wired-down map entry to another.
|
|
*
|
|
* In/out conditions:
|
|
* The source and destination maps must be locked for write.
|
|
* The source map entry must be wired down (or be a sharing map
|
|
* entry corresponding to a main map entry that is wired down).
|
|
*/
|
|
|
|
void
|
|
vm_fault_copy_entry(dst_map, src_map, dst_entry, src_entry)
|
|
vm_map_t dst_map;
|
|
vm_map_t src_map;
|
|
vm_map_entry_t dst_entry;
|
|
vm_map_entry_t src_entry;
|
|
{
|
|
vm_object_t dst_object;
|
|
vm_object_t src_object;
|
|
vm_ooffset_t dst_offset;
|
|
vm_ooffset_t src_offset;
|
|
vm_prot_t prot;
|
|
vm_offset_t vaddr;
|
|
vm_page_t dst_m;
|
|
vm_page_t src_m;
|
|
|
|
#ifdef lint
|
|
src_map++;
|
|
#endif /* lint */
|
|
|
|
src_object = src_entry->object.vm_object;
|
|
src_offset = src_entry->offset;
|
|
|
|
/*
|
|
* Create the top-level object for the destination entry. (Doesn't
|
|
* actually shadow anything - we copy the pages directly.)
|
|
*/
|
|
dst_object = vm_object_allocate(OBJT_DEFAULT,
|
|
(vm_size_t) OFF_TO_IDX(dst_entry->end - dst_entry->start));
|
|
|
|
dst_entry->object.vm_object = dst_object;
|
|
dst_entry->offset = 0;
|
|
|
|
prot = dst_entry->max_protection;
|
|
|
|
/*
|
|
* Loop through all of the pages in the entry's range, copying each
|
|
* one from the source object (it should be there) to the destination
|
|
* object.
|
|
*/
|
|
for (vaddr = dst_entry->start, dst_offset = 0;
|
|
vaddr < dst_entry->end;
|
|
vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) {
|
|
|
|
/*
|
|
* Allocate a page in the destination object
|
|
*/
|
|
do {
|
|
dst_m = vm_page_alloc(dst_object,
|
|
OFF_TO_IDX(dst_offset), VM_ALLOC_NORMAL);
|
|
if (dst_m == NULL) {
|
|
VM_WAIT;
|
|
}
|
|
} while (dst_m == NULL);
|
|
|
|
/*
|
|
* Find the page in the source object, and copy it in.
|
|
* (Because the source is wired down, the page will be in
|
|
* memory.)
|
|
*/
|
|
src_m = vm_page_lookup(src_object,
|
|
OFF_TO_IDX(dst_offset + src_offset));
|
|
if (src_m == NULL)
|
|
panic("vm_fault_copy_wired: page missing");
|
|
|
|
vm_page_copy(src_m, dst_m);
|
|
|
|
/*
|
|
* Enter it in the pmap...
|
|
*/
|
|
|
|
dst_m->flags &= ~PG_ZERO;
|
|
pmap_enter(dst_map->pmap, vaddr, VM_PAGE_TO_PHYS(dst_m),
|
|
prot, FALSE);
|
|
dst_m->flags |= PG_WRITEABLE|PG_MAPPED;
|
|
|
|
/*
|
|
* Mark it no longer busy, and put it on the active list.
|
|
*/
|
|
vm_page_activate(dst_m);
|
|
PAGE_WAKEUP(dst_m);
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
* This routine checks around the requested page for other pages that
|
|
* might be able to be faulted in. This routine brackets the viable
|
|
* pages for the pages to be paged in.
|
|
*
|
|
* Inputs:
|
|
* m, rbehind, rahead
|
|
*
|
|
* Outputs:
|
|
* marray (array of vm_page_t), reqpage (index of requested page)
|
|
*
|
|
* Return value:
|
|
* number of pages in marray
|
|
*/
|
|
int
|
|
vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage)
|
|
vm_page_t m;
|
|
int rbehind;
|
|
int rahead;
|
|
vm_page_t *marray;
|
|
int *reqpage;
|
|
{
|
|
int i,j;
|
|
vm_object_t object;
|
|
vm_pindex_t pindex, startpindex, endpindex, tpindex;
|
|
vm_page_t rtm;
|
|
int cbehind, cahead;
|
|
|
|
object = m->object;
|
|
pindex = m->pindex;
|
|
|
|
/*
|
|
* we don't fault-ahead for device pager
|
|
*/
|
|
if (object->type == OBJT_DEVICE) {
|
|
*reqpage = 0;
|
|
marray[0] = m;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* if the requested page is not available, then give up now
|
|
*/
|
|
|
|
if (!vm_pager_has_page(object,
|
|
OFF_TO_IDX(object->paging_offset) + pindex, &cbehind, &cahead)) {
|
|
return 0;
|
|
}
|
|
|
|
if ((cbehind == 0) && (cahead == 0)) {
|
|
*reqpage = 0;
|
|
marray[0] = m;
|
|
return 1;
|
|
}
|
|
|
|
if (rahead > cahead) {
|
|
rahead = cahead;
|
|
}
|
|
|
|
if (rbehind > cbehind) {
|
|
rbehind = cbehind;
|
|
}
|
|
|
|
/*
|
|
* try to do any readahead that we might have free pages for.
|
|
*/
|
|
if ((rahead + rbehind) >
|
|
((cnt.v_free_count + cnt.v_cache_count) - cnt.v_free_reserved)) {
|
|
pagedaemon_wakeup();
|
|
marray[0] = m;
|
|
*reqpage = 0;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* scan backward for the read behind pages -- in memory
|
|
*/
|
|
if (pindex > 0) {
|
|
if (rbehind > pindex) {
|
|
rbehind = pindex;
|
|
startpindex = 0;
|
|
} else {
|
|
startpindex = pindex - rbehind;
|
|
}
|
|
|
|
for ( tpindex = pindex - 1; tpindex >= startpindex; tpindex -= 1) {
|
|
if (vm_page_lookup( object, tpindex)) {
|
|
startpindex = tpindex + 1;
|
|
break;
|
|
}
|
|
if (tpindex == 0)
|
|
break;
|
|
}
|
|
|
|
for(i = 0, tpindex = startpindex; tpindex < pindex; i++, tpindex++) {
|
|
|
|
rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
|
|
if (rtm == NULL) {
|
|
for (j = 0; j < i; j++) {
|
|
FREE_PAGE(marray[j]);
|
|
}
|
|
marray[0] = m;
|
|
*reqpage = 0;
|
|
return 1;
|
|
}
|
|
|
|
marray[i] = rtm;
|
|
}
|
|
} else {
|
|
startpindex = 0;
|
|
i = 0;
|
|
}
|
|
|
|
marray[i] = m;
|
|
/* page offset of the required page */
|
|
*reqpage = i;
|
|
|
|
tpindex = pindex + 1;
|
|
i++;
|
|
|
|
/*
|
|
* scan forward for the read ahead pages
|
|
*/
|
|
endpindex = tpindex + rahead;
|
|
if (endpindex > object->size)
|
|
endpindex = object->size;
|
|
|
|
for( ; tpindex < endpindex; i++, tpindex++) {
|
|
|
|
if (vm_page_lookup(object, tpindex)) {
|
|
break;
|
|
}
|
|
|
|
rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
|
|
if (rtm == NULL) {
|
|
break;
|
|
}
|
|
|
|
marray[i] = rtm;
|
|
}
|
|
|
|
/* return number of bytes of pages */
|
|
return i;
|
|
}
|