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freebsd-nq/sys/vm/vm_fault.c
David Greenman 5663e6de1c Various changes to allow operation without any swapspace configured. Note 
that this is intended for use only in floppy situations and is done at
the sacrifice of performance in that case (in ther words, this is not the
best solution, but works okay for this exceptional situation).

Submitted by:	John Dyson
1994-10-22 02:18:03 +00:00

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/*
* 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 1.9 1994/10/15 13:33:07 davidg Exp $
*/
/*
* Page fault handling module.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/resource.h>
#include <sys/signalvar.h>
#include <sys/resourcevar.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
int vm_fault_additional_pages __P((vm_object_t, vm_offset_t, vm_page_t, int, int, vm_page_t *, int *));
#define VM_FAULT_READ_AHEAD 4
#define VM_FAULT_READ_AHEAD_MIN 1
#define VM_FAULT_READ_BEHIND 3
#define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1)
extern int swap_pager_full;
extern int vm_pageout_proc_limit;
/*
* 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(map, vaddr, fault_type, change_wiring)
vm_map_t map;
vm_offset_t vaddr;
vm_prot_t fault_type;
boolean_t change_wiring;
{
vm_object_t first_object;
vm_offset_t first_offset;
vm_map_entry_t entry;
register vm_object_t object;
register vm_offset_t offset;
vm_page_t m;
vm_page_t first_m;
vm_prot_t prot;
int result;
boolean_t wired;
boolean_t su;
boolean_t lookup_still_valid;
boolean_t page_exists;
vm_page_t old_m;
vm_object_t next_object;
vm_page_t marray[VM_FAULT_READ];
int spl;
int hardfault=0;
cnt.v_vm_faults++; /* needs lock XXX */
/*
* Recovery actions
*/
#define FREE_PAGE(m) { \
PAGE_WAKEUP(m); \
vm_page_lock_queues(); \
vm_page_free(m); \
vm_page_unlock_queues(); \
}
#define RELEASE_PAGE(m) { \
PAGE_WAKEUP(m); \
vm_page_lock_queues(); \
vm_page_activate(m); \
vm_page_unlock_queues(); \
}
#define UNLOCK_MAP { \
if (lookup_still_valid) { \
vm_map_lookup_done(map, entry); \
lookup_still_valid = FALSE; \
} \
}
#define UNLOCK_THINGS { \
object->paging_in_progress--; \
if (object->paging_in_progress == 0) \
wakeup((caddr_t)object); \
vm_object_unlock(object); \
if (object != first_object) { \
vm_object_lock(first_object); \
FREE_PAGE(first_m); \
first_object->paging_in_progress--; \
if (first_object->paging_in_progress == 0) \
wakeup((caddr_t)first_object); \
vm_object_unlock(first_object); \
} \
UNLOCK_MAP; \
}
#define UNLOCK_AND_DEALLOCATE { \
UNLOCK_THINGS; \
vm_object_deallocate(first_object); \
}
RetryFault: ;
/*
* 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_offset,
&prot, &wired, &su)) != KERN_SUCCESS) {
return(result);
}
lookup_still_valid = TRUE;
if (wired)
fault_type = prot;
first_m = NULL;
/*
* 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_lock(first_object);
first_object->ref_count++;
first_object->paging_in_progress++;
/*
* 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 thread 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 thread 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;
offset = first_offset;
/*
* See whether this page is resident
*/
while (TRUE) {
m = vm_page_lookup(object, offset);
if (m != NULL) {
/*
* If the page is being brought in,
* wait for it and then retry.
*/
if (m->flags & (PG_BUSY|PG_VMIO)) {
int s;
UNLOCK_THINGS;
s = splhigh();
if (m->flags & (PG_BUSY|PG_VMIO)) {
m->flags |= PG_WANTED;
cnt.v_intrans++;
tsleep((caddr_t)m,PSWP,"vmpfw",0);
}
splx(s);
vm_object_deallocate(first_object);
goto RetryFault;
}
/*
* Remove the page from the pageout daemon's
* reach while we play with it.
*/
vm_page_lock_queues();
spl = splhigh();
if (m->flags & PG_INACTIVE) {
TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq);
m->flags &= ~PG_INACTIVE;
cnt.v_inactive_count--;
cnt.v_reactivated++;
}
if (m->flags & PG_ACTIVE) {
TAILQ_REMOVE(&vm_page_queue_active, m, pageq);
m->flags &= ~PG_ACTIVE;
cnt.v_active_count--;
}
splx(spl);
vm_page_unlock_queues();
/*
* Mark page busy for other threads.
*/
m->flags |= PG_BUSY;
break;
}
if (((object->pager != NULL) &&
(!change_wiring || wired))
|| (object == first_object)) {
#if 0
if (curproc && (vaddr < VM_MAXUSER_ADDRESS) &&
(curproc->p_rlimit[RLIMIT_RSS].rlim_max <
curproc->p_vmspace->vm_pmap.pm_stats.resident_count * NBPG)) {
UNLOCK_AND_DEALLOCATE;
vm_fault_free_pages(curproc);
goto RetryFault;
}
#endif
if ((cnt.v_free_count < cnt.v_free_min) &&
swap_pager_full && !object->shadow && (!object->pager ||
(object->pager && object->pager->pg_type == PG_SWAP &&
!vm_pager_has_page(object->pager, offset+object->paging_offset)))) {
if (vaddr < VM_MAXUSER_ADDRESS &&
curproc && curproc->p_pid >= 48) /* XXX */ {
printf("Process %lu killed by vm_fault -- out of swap\n", (u_long)curproc->p_pid);
psignal(curproc, SIGKILL);
curproc->p_estcpu = 0;
curproc->p_nice = PRIO_MIN;
resetpriority(curproc);
}
}
/*
* Allocate a new page for this object/offset
* pair.
*/
m = vm_page_alloc(object, offset);
if (m == NULL) {
UNLOCK_AND_DEALLOCATE;
VM_WAIT;
goto RetryFault;
}
}
if (object->pager != NULL && (!change_wiring || wired)) {
int rv;
int faultcount;
int reqpage;
/*
* Now that we have a busy page, we can
* release the object lock.
*/
vm_object_unlock(object);
/*
* 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(
first_object, first_offset,
m, VM_FAULT_READ_BEHIND, VM_FAULT_READ_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->pager,
marray, faultcount, reqpage, TRUE): VM_PAGER_FAIL;
if (rv == VM_PAGER_OK) {
/*
* Found the page.
* Leave it busy while we play with it.
*/
vm_object_lock(object);
/*
* Relookup in case pager changed page.
* Pager is responsible for disposition
* of old page if moved.
*/
m = vm_page_lookup(object, offset);
m->flags &= ~PG_FAKE;
pmap_clear_modify(VM_PAGE_TO_PHYS(m));
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 thread that may want
* to bring in this page.
*
* If this is the top-level object, we must
* leave the busy page to prevent another
* thread from rushing past us, and inserting
* the page in that object at the same time
* that we are.
*/
vm_object_lock(object);
/*
* Data outside the range of the pager; an error
*/
if ((rv == VM_PAGER_ERROR) || (rv == VM_PAGER_BAD)) {
FREE_PAGE(m);
UNLOCK_AND_DEALLOCATE;
return(KERN_PROTECTION_FAILURE); /* XXX */
}
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 no 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.
*/
offset += object->shadow_offset;
next_object = object->shadow;
if (next_object == NULL) {
/*
* If there's no object left, fill the page
* in the top object with zeros.
*/
if (object != first_object) {
object->paging_in_progress--;
if (object->paging_in_progress == 0)
wakeup((caddr_t) object);
vm_object_unlock(object);
object = first_object;
offset = first_offset;
m = first_m;
vm_object_lock(object);
}
first_m = NULL;
vm_page_zero_fill(m);
cnt.v_zfod++;
m->flags &= ~PG_FAKE;
break;
}
else {
vm_object_lock(next_object);
if (object != first_object) {
object->paging_in_progress--;
if (object->paging_in_progress == 0)
wakeup((caddr_t) object);
}
vm_object_unlock(object);
object = next_object;
object->paging_in_progress++;
}
}
if ((m->flags & (PG_ACTIVE|PG_INACTIVE) != 0) ||
(m->flags & PG_BUSY) == 0)
panic("vm_fault: absent or active or inactive or not busy after main loop");
/*
* PAGE HAS BEEN FOUND.
* [Loop invariant still holds -- the object lock
* is held.]
*/
old_m = m; /* save page that would be copied */
/*
* If the page is being written, but isn't
* already owned by the top-level object,
* we have to copy it into a new page owned
* by the top-level object.
*/
if (object != first_object) {
/*
* We only really need to copy if we
* want to write it.
*/
if (fault_type & VM_PROT_WRITE) {
/*
* If we try to collapse first_object at this
* point, we may deadlock when we try to get
* the lock on an intermediate object (since we
* have the bottom object locked). We can't
* unlock the bottom object, because the page
* we found may move (by collapse) if we do.
*
* Instead, we first copy the page. Then, when
* we have no more use for the bottom object,
* we unlock it and try to collapse.
*
* Note that we copy the page even if we didn't
* need to... that's the breaks.
*/
/*
* We already have an empty page in
* first_object - use it.
*/
vm_page_copy(m, first_m);
first_m->flags &= ~PG_FAKE;
/*
* If another map is truly sharing this
* page with us, we have to flush all
* uses of the original page, since we
* can't distinguish those which want the
* original from those which need the
* new copy.
*
* XXX If we know that only one map has
* access to this page, then we could
* avoid the pmap_page_protect() call.
*/
vm_page_lock_queues();
vm_page_activate(m);
pmap_page_protect(VM_PAGE_TO_PHYS(m), VM_PROT_NONE);
if ((m->flags & PG_CLEAN) == 0)
m->flags |= PG_LAUNDRY;
vm_page_unlock_queues();
/*
* We no longer need the old page or object.
*/
PAGE_WAKEUP(m);
object->paging_in_progress--;
if (object->paging_in_progress == 0)
wakeup((caddr_t) object);
vm_object_unlock(object);
/*
* Only use the new page below...
*/
cnt.v_cow_faults++;
m = first_m;
object = first_object;
offset = first_offset;
/*
* Now that we've gotten the copy out of the
* way, let's try to collapse the top object.
*/
vm_object_lock(object);
/*
* But we have to play ugly games with
* paging_in_progress to do that...
*/
object->paging_in_progress--;
if (object->paging_in_progress == 0)
wakeup((caddr_t) object);
vm_object_collapse(object);
object->paging_in_progress++;
}
else {
prot &= ~VM_PROT_WRITE;
m->flags |= PG_COPYONWRITE;
}
}
if (m->flags & (PG_ACTIVE|PG_INACTIVE))
panic("vm_fault: active or inactive before copy object handling");
/*
* If the page is being written, but hasn't been
* copied to the copy-object, we have to copy it there.
*/
RetryCopy:
if (first_object->copy != NULL) {
vm_object_t copy_object = first_object->copy;
vm_offset_t copy_offset;
vm_page_t copy_m;
/*
* We only need to copy if we want to write it.
*/
if ((fault_type & VM_PROT_WRITE) == 0) {
prot &= ~VM_PROT_WRITE;
m->flags |= PG_COPYONWRITE;
}
else {
/*
* Try to get the lock on the copy_object.
*/
if (!vm_object_lock_try(copy_object)) {
vm_object_unlock(object);
/* should spin a bit here... */
vm_object_lock(object);
goto RetryCopy;
}
/*
* Make another reference to the copy-object,
* to keep it from disappearing during the
* copy.
*/
copy_object->ref_count++;
/*
* Does the page exist in the copy?
*/
copy_offset = first_offset
- copy_object->shadow_offset;
copy_m = vm_page_lookup(copy_object, copy_offset);
page_exists = (copy_m != NULL);
if (page_exists) {
if (copy_m->flags & (PG_BUSY|PG_VMIO)) {
/*
* If the page is being brought
* in, wait for it and then retry.
*/
PAGE_ASSERT_WAIT(copy_m, !change_wiring);
RELEASE_PAGE(m);
copy_object->ref_count--;
vm_object_unlock(copy_object);
UNLOCK_THINGS;
thread_block("fltcpy");
vm_object_deallocate(first_object);
goto RetryFault;
}
}
/*
* If the page is not in memory (in the object)
* and the object has a pager, we have to check
* if the pager has the data in secondary
* storage.
*/
if (!page_exists) {
/*
* If we don't allocate a (blank) page
* here... another thread could try
* to page it in, allocate a page, and
* then block on the busy page in its
* shadow (first_object). Then we'd
* trip over the busy page after we
* found that the copy_object's pager
* doesn't have the page...
*/
copy_m = vm_page_alloc(copy_object, copy_offset);
if (copy_m == NULL) {
/*
* Wait for a page, then retry.
*/
RELEASE_PAGE(m);
copy_object->ref_count--;
vm_object_unlock(copy_object);
UNLOCK_AND_DEALLOCATE;
VM_WAIT;
goto RetryFault;
}
if (copy_object->pager != NULL) {
vm_object_unlock(object);
vm_object_unlock(copy_object);
UNLOCK_MAP;
page_exists = vm_pager_has_page(
copy_object->pager,
(copy_offset + copy_object->paging_offset));
vm_object_lock(copy_object);
/*
* Since the map is unlocked, someone
* else could have copied this object
* and put a different copy_object
* between the two. Or, the last
* reference to the copy-object (other
* than the one we have) may have
* disappeared - if that has happened,
* we don't need to make the copy.
*/
if (copy_object->shadow != object ||
copy_object->ref_count == 1) {
/*
* Gaah... start over!
*/
FREE_PAGE(copy_m);
vm_object_unlock(copy_object);
vm_object_deallocate(copy_object);
/* may block */
vm_object_lock(object);
goto RetryCopy;
}
vm_object_lock(object);
if (page_exists) {
/*
* We didn't need the page
*/
FREE_PAGE(copy_m);
}
}
}
if (!page_exists) {
/*
* Must copy page into copy-object.
*/
vm_page_copy(m, copy_m);
copy_m->flags &= ~PG_FAKE;
/*
* Things to remember:
* 1. The copied page must be marked 'dirty'
* so it will be paged out to the copy
* object.
* 2. If the old page was in use by any users
* of the copy-object, it must be removed
* from all pmaps. (We can't know which
* pmaps use it.)
*/
vm_page_lock_queues();
vm_page_activate(old_m);
pmap_page_protect(VM_PAGE_TO_PHYS(old_m),
VM_PROT_NONE);
if ((old_m->flags & PG_CLEAN) == 0)
old_m->flags |= PG_LAUNDRY;
copy_m->flags &= ~PG_CLEAN;
vm_page_activate(copy_m);
vm_page_unlock_queues();
PAGE_WAKEUP(copy_m);
}
/*
* The reference count on copy_object must be
* at least 2: one for our extra reference,
* and at least one from the outside world
* (we checked that when we last locked
* copy_object).
*/
copy_object->ref_count--;
vm_object_unlock(copy_object);
m->flags &= ~PG_COPYONWRITE;
}
}
if (m->flags & (PG_ACTIVE | PG_INACTIVE))
panic("vm_fault: active or inactive before retrying lookup");
/*
* We must verify that the maps have not changed
* since our last lookup.
*/
if (!lookup_still_valid) {
vm_object_t retry_object;
vm_offset_t retry_offset;
vm_prot_t retry_prot;
/*
* Since map entries may be pageable, make sure we can
* take a page fault on them.
*/
vm_object_unlock(object);
/*
* To avoid trying to write_lock the map while another
* thread has it read_locked (in vm_map_pageable), we
* do not try for write permission. If the page is
* still writable, we will get write permission. If it
* is not, or has been marked needs_copy, we enter the
* mapping without write permission, and will merely
* take another fault.
*/
result = vm_map_lookup(&map, vaddr,
fault_type & ~VM_PROT_WRITE, &entry,
&retry_object, &retry_offset, &retry_prot,
&wired, &su);
vm_object_lock(object);
/*
* If we don't need the page any longer, put it on the
* active list (the easiest thing to do here). If no
* one needs it, pageout will grab it eventually.
*/
if (result != KERN_SUCCESS) {
RELEASE_PAGE(m);
UNLOCK_AND_DEALLOCATE;
return(result);
}
lookup_still_valid = TRUE;
if ((retry_object != first_object) ||
(retry_offset != first_offset)) {
RELEASE_PAGE(m);
UNLOCK_AND_DEALLOCATE;
goto RetryFault;
}
/*
* Check whether the protection has changed or the object
* has been copied while we left the map unlocked.
* Changing from read to write permission is OK - we leave
* the page write-protected, and catch the write fault.
* Changing from write to read permission means that we
* can't mark the page write-enabled after all.
*/
prot &= retry_prot;
if (m->flags & PG_COPYONWRITE)
prot &= ~VM_PROT_WRITE;
}
/*
* (the various bits we're fiddling with here are locked by
* the object's lock)
*/
/* XXX This distorts the meaning of the copy_on_write bit */
if (prot & VM_PROT_WRITE)
m->flags &= ~PG_COPYONWRITE;
/*
* It's critically important that a wired-down page be faulted
* only once in each map for which it is wired.
*/
if (m->flags & (PG_ACTIVE | PG_INACTIVE))
panic("vm_fault: active or inactive before pmap_enter");
vm_object_unlock(object);
/*
* Put this page into the physical map.
* We had to do the unlock above because pmap_enter
* may cause other faults. We don't put the
* page back on the active queue until later so
* that the page-out daemon won't find us (yet).
*/
pmap_enter(map->pmap, vaddr, VM_PAGE_TO_PHYS(m), prot, wired);
/*
* If the page is not wired down, then put it where the
* pageout daemon can find it.
*/
vm_object_lock(object);
vm_page_lock_queues();
if (change_wiring) {
if (wired)
vm_page_wire(m);
else
vm_page_unwire(m);
}
else {
vm_page_activate(m);
}
if( curproc && curproc->p_stats) {
if (hardfault) {
curproc->p_stats->p_ru.ru_majflt++;
} else {
curproc->p_stats->p_ru.ru_minflt++;
}
}
vm_page_unlock_queues();
/*
* Unlock everything, and return
*/
PAGE_WAKEUP(m);
UNLOCK_AND_DEALLOCATE;
return(KERN_SUCCESS);
}
/*
* vm_fault_wire:
*
* Wire down a range of virtual addresses in a map.
*/
int
vm_fault_wire(map, start, end)
vm_map_t map;
vm_offset_t start, end;
{
register vm_offset_t va;
register pmap_t pmap;
int rv;
pmap = vm_map_pmap(map);
/*
* Inform the physical mapping system that the
* range of addresses may not fault, so that
* page tables and such can be locked down as well.
*/
pmap_pageable(pmap, start, end, FALSE);
/*
* We simulate a fault to get the page and enter it
* in the physical map.
*/
for (va = start; va < end; va += PAGE_SIZE) {
rv = vm_fault(map, va, VM_PROT_NONE, TRUE);
if (rv) {
if (va != start)
vm_fault_unwire(map, start, va);
return(rv);
}
}
return(KERN_SUCCESS);
}
/*
* vm_fault_unwire:
*
* Unwire a range of virtual addresses in a map.
*/
void
vm_fault_unwire(map, start, end)
vm_map_t map;
vm_offset_t start, end;
{
register vm_offset_t va, pa;
register pmap_t pmap;
pmap = vm_map_pmap(map);
/*
* Since the pages are wired down, we must be able to
* get their mappings from the physical map system.
*/
vm_page_lock_queues();
for (va = start; va < end; va += PAGE_SIZE) {
pa = pmap_extract(pmap, va);
if (pa == (vm_offset_t) 0) {
panic("unwire: page not in pmap");
}
pmap_change_wiring(pmap, va, FALSE);
vm_page_unwire(PHYS_TO_VM_PAGE(pa));
}
vm_page_unlock_queues();
/*
* Inform the physical mapping system that the range
* of addresses may fault, so that page tables and
* such may be unwired themselves.
*/
pmap_pageable(pmap, start, end, TRUE);
}
/*
* Routine:
* vm_fault_copy_entry
* Function:
* Copy all of the pages from a wired-down map entry to another.
*
* In/out conditions:
* The source and destination maps must be locked for write.
* The source map entry must be wired down (or be a sharing map
* entry corresponding to a main map entry that is wired down).
*/
void
vm_fault_copy_entry(dst_map, src_map, dst_entry, src_entry)
vm_map_t dst_map;
vm_map_t src_map;
vm_map_entry_t dst_entry;
vm_map_entry_t src_entry;
{
vm_object_t dst_object;
vm_object_t src_object;
vm_offset_t dst_offset;
vm_offset_t src_offset;
vm_prot_t prot;
vm_offset_t vaddr;
vm_page_t dst_m;
vm_page_t src_m;
#ifdef lint
src_map++;
#endif lint
src_object = src_entry->object.vm_object;
src_offset = src_entry->offset;
/*
* Create the top-level object for the destination entry.
* (Doesn't actually shadow anything - we copy the pages
* directly.)
*/
dst_object = vm_object_allocate(
(vm_size_t) (dst_entry->end - dst_entry->start));
dst_entry->object.vm_object = dst_object;
dst_entry->offset = 0;
prot = dst_entry->max_protection;
/*
* Loop through all of the pages in the entry's range, copying
* each one from the source object (it should be there) to the
* destination object.
*/
for (vaddr = dst_entry->start, dst_offset = 0;
vaddr < dst_entry->end;
vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) {
/*
* Allocate a page in the destination object
*/
vm_object_lock(dst_object);
do {
dst_m = vm_page_alloc(dst_object, dst_offset);
if (dst_m == NULL) {
vm_object_unlock(dst_object);
VM_WAIT;
vm_object_lock(dst_object);
}
} while (dst_m == NULL);
/*
* Find the page in the source object, and copy it in.
* (Because the source is wired down, the page will be
* in memory.)
*/
vm_object_lock(src_object);
src_m = vm_page_lookup(src_object, dst_offset + src_offset);
if (src_m == NULL)
panic("vm_fault_copy_wired: page missing");
vm_page_copy(src_m, dst_m);
/*
* Enter it in the pmap...
*/
vm_object_unlock(src_object);
vm_object_unlock(dst_object);
pmap_enter(dst_map->pmap, vaddr, VM_PAGE_TO_PHYS(dst_m),
prot, FALSE);
/*
* Mark it no longer busy, and put it on the active list.
*/
vm_object_lock(dst_object);
vm_page_lock_queues();
vm_page_activate(dst_m);
vm_page_unlock_queues();
PAGE_WAKEUP(dst_m);
vm_object_unlock(dst_object);
}
}
/*
* looks page up in shadow chain
*/
int
vm_fault_page_lookup(object, offset, rtobject, rtoffset, rtm)
vm_object_t object;
vm_offset_t offset;
vm_object_t *rtobject;
vm_offset_t *rtoffset;
vm_page_t *rtm;
{
vm_page_t m;
*rtm = 0;
*rtobject = 0;
*rtoffset = 0;
while (!(m=vm_page_lookup(object, offset))) {
if (object->pager) {
if (vm_pager_has_page(object->pager, object->paging_offset+offset)) {
*rtobject = object;
*rtoffset = offset;
return 1;
}
}
if (!object->shadow)
return 0;
else {
offset += object->shadow_offset;
object = object->shadow;
}
}
*rtobject = object;
*rtoffset = offset;
*rtm = m;
return 1;
}
/*
* This routine checks around the requested page for other pages that
* might be able to be faulted in.
*
* Inputs:
* first_object, first_offset, m, rbehind, rahead
*
* Outputs:
* marray (array of vm_page_t), reqpage (index of requested page)
*
* Return value:
* number of pages in marray
*/
int
vm_fault_additional_pages(first_object, first_offset, m, rbehind, raheada, marray, reqpage)
vm_object_t first_object;
vm_offset_t first_offset;
vm_page_t m;
int rbehind;
int raheada;
vm_page_t *marray;
int *reqpage;
{
int i;
vm_object_t object;
vm_offset_t offset, startoffset, endoffset, toffset, size;
vm_object_t rtobject;
vm_page_t rtm;
vm_offset_t rtoffset;
vm_offset_t offsetdiff;
int rahead;
int treqpage;
object = m->object;
offset = m->offset;
offsetdiff = offset - first_offset;
/*
* if the requested page is not available, then give up now
*/
if (!vm_pager_has_page(object->pager, object->paging_offset+offset))
return 0;
/*
* if there is no getmulti routine for this pager, then just allow
* one page to be read.
*/
/*
if (!object->pager->pg_ops->pgo_getpages) {
*reqpage = 0;
marray[0] = m;
return 1;
}
*/
/*
* try to do any readahead that we might have free pages for.
*/
rahead = raheada;
if (rahead > (cnt.v_free_count - cnt.v_free_reserved)) {
rahead = cnt.v_free_count - cnt.v_free_reserved;
rbehind = 0;
}
if (cnt.v_free_count < cnt.v_free_min) {
if (rahead > VM_FAULT_READ_AHEAD_MIN)
rahead = VM_FAULT_READ_AHEAD_MIN;
rbehind = 0;
}
/*
* if we don't have any free pages, then just read one page.
*/
if (rahead <= 0) {
*reqpage = 0;
marray[0] = m;
return 1;
}
/*
* scan backward for the read behind pages --
* in memory or on disk not in same object
*/
toffset = offset - NBPG;
if( rbehind*NBPG > offset)
rbehind = offset / NBPG;
startoffset = offset - rbehind*NBPG;
while (toffset >= startoffset) {
if (!vm_fault_page_lookup(first_object, toffset - offsetdiff, &rtobject, &rtoffset, &rtm) ||
rtm != 0 || rtobject != object) {
startoffset = toffset + NBPG;
break;
}
if( toffset == 0)
break;
toffset -= NBPG;
}
/*
* scan forward for the read ahead pages --
* in memory or on disk not in same object
*/
toffset = offset + NBPG;
endoffset = offset + (rahead+1)*NBPG;
while (toffset < object->size && toffset < endoffset) {
if (!vm_fault_page_lookup(first_object, toffset - offsetdiff, &rtobject, &rtoffset, &rtm) ||
rtm != 0 || rtobject != object) {
break;
}
toffset += NBPG;
}
endoffset = toffset;
/* calculate number of bytes of pages */
size = (endoffset - startoffset) / NBPG;
/* calculate the page offset of the required page */
treqpage = (offset - startoffset) / NBPG;
/* see if we have space (again) */
if (cnt.v_free_count >= cnt.v_free_reserved + size) {
bzero(marray, (rahead + rbehind + 1) * sizeof(vm_page_t));
/*
* get our pages and don't block for them
*/
for (i = 0; i < size; i++) {
if (i != treqpage)
rtm = vm_page_alloc(object, startoffset + i * NBPG);
else
rtm = m;
marray[i] = rtm;
}
for (i = 0; i < size; i++) {
if (marray[i] == 0)
break;
}
/*
* if we could not get our block of pages, then
* free the readahead/readbehind pages.
*/
if (i < size) {
for (i = 0; i < size; i++) {
if (i != treqpage && marray[i])
FREE_PAGE(marray[i]);
}
*reqpage = 0;
marray[0] = m;
return 1;
}
*reqpage = treqpage;
return size;
}
*reqpage = 0;
marray[0] = m;
return 1;
}
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