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freebsd-skq/sys/vm/vm_fault.c
John Dyson a04c970a7a Fix the gdb executable modify problem. Thanks to the detective work 
by Alan Cox <alc@cs.rice.edu>, and his description of the problem.

The bug was primarily in procfs_mem, but the mistake likely happened
due to the lack of vm system support for the operation.  I added
better support for selective marking of page dirty flags so that
vm_map_pageable(wiring) will not cause this problem again.

The code in procfs_mem is now less bogus (but maybe still a little
so.)
1997-04-06 02:29:45 +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 1.66 1997/02/22 09:48:15 peter Exp $
*/
/*
* Page fault handling module.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/resource.h>
#include <sys/signalvar.h>
#include <sys/resourcevar.h>
#include <sys/vmmeter.h>
#include <sys/buf.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/swap_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 4
#define VM_FAULT_READ_BEHIND 3
#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(map, vaddr, fault_type, fault_flags)
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 su;
boolean_t lookup_still_valid;
vm_page_t old_m;
vm_object_t next_object;
vm_page_t marray[VM_FAULT_READ];
int hardfault = 0;
struct vnode *vp = NULL;
struct proc *p = curproc; /* XXX */
cnt.v_vm_faults++; /* needs lock XXX */
/*
* Recovery actions
*/
#define FREE_PAGE(m) { \
PAGE_WAKEUP(m); \
vm_page_free(m); \
}
#define RELEASE_PAGE(m) { \
PAGE_WAKEUP(m); \
if (m->queue != PQ_ACTIVE) 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) VOP_UNLOCK(vp, 0, p); \
}
#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_pindex, &prot, &wired, &su)) != KERN_SUCCESS) {
return (result);
}
if (entry->eflags & MAP_ENTRY_NOFAULT) {
panic("vm_fault: fault on nofault entry, addr: %lx",
vaddr);
}
/*
* 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.
*/
if (((fault_flags & VM_FAULT_WIRE_MASK) == VM_FAULT_USER_WIRE) && (entry->eflags & MAP_ENTRY_NEEDS_COPY)) {
if(entry->protection & VM_PROT_WRITE) {
int tresult;
vm_map_lookup_done(map, entry);
tresult = vm_map_lookup(&map, vaddr, VM_PROT_READ|VM_PROT_WRITE,
&entry, &first_object, &first_pindex, &prot, &wired, &su);
if (tresult != KERN_SUCCESS)
return tresult;
} else {
/*
* 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.
*/
entry->max_protection &= ~VM_PROT_WRITE;
}
}
vp = vnode_pager_lock(first_object);
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.
*/
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 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) {
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 &&
((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 faultcount;
int reqpage;
int ahead, behind;
ahead = VM_FAULT_READ_AHEAD;
behind = VM_FAULT_READ_BEHIND;
if (first_object->behavior == OBJ_RANDOM) {
ahead = 0;
behind = 0;
}
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 >= first_pindex;
--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 ((m->flags & PG_BUSY) == 0)
panic("vm_fault: 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) {
/*
* 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 (lookup_still_valid &&
/*
* 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)) {
/*
* get rid of the unnecessary page
*/
vm_page_protect(first_m, VM_PROT_NONE);
PAGE_WAKEUP(first_m);
vm_page_free(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);
}
/*
* This code handles the case where there are two references to the
* backing object, and one reference is getting a copy of the
* page. If the other reference is the only other object that
* points to the backing object, then perform a virtual copy
* from the backing object to the other object after the
* page is copied to the current first_object. If the other
* object already has the page, we destroy it in the backing object
* performing an optimized collapse-type operation. We don't
* bother removing the page from the backing object's swap space.
*/
if (lookup_still_valid &&
/*
* make sure that we have two shadow objs
*/
(object->shadow_count == 2) &&
/*
* And no COW refs -- note that there are sometimes
* temp refs to objs, but ignore that case -- we just
* punt.
*/
(object->ref_count == 2) &&
/*
* Noone else can look us up
*/
(object->handle == NULL) &&
/*
* Not something that can be referenced elsewhere
*/
((object->type == OBJT_DEFAULT) ||
(object->type == OBJT_SWAP)) &&
/*
* We don't bother chasing down object chain
*/
(object == first_object->backing_object)) {
vm_object_t other_object;
vm_pindex_t other_pindex, other_pindex_offset;
vm_page_t tm;
other_object = TAILQ_FIRST(&object->shadow_head);
if (other_object == first_object)
other_object = TAILQ_NEXT(other_object, shadow_list);
if (!other_object)
panic("vm_fault: other object missing");
if (other_object &&
(other_object->type == OBJT_DEFAULT) &&
(other_object->paging_in_progress == 0)) {
other_pindex_offset =
OFF_TO_IDX(other_object->backing_object_offset);
if (pindex >= other_pindex_offset) {
other_pindex = pindex - other_pindex_offset;
/*
* If the other object has the page, just free it.
*/
if ((tm = vm_page_lookup(other_object, other_pindex))) {
if ((tm->flags & PG_BUSY) == 0 &&
tm->busy == 0 &&
tm->valid == VM_PAGE_BITS_ALL) {
/*
* get rid of the unnecessary page
*/
vm_page_protect(m, VM_PROT_NONE);
PAGE_WAKEUP(m);
vm_page_free(m);
m = NULL;
tm->dirty = VM_PAGE_BITS_ALL;
first_m->dirty = VM_PAGE_BITS_ALL;
}
} else {
/*
* If the other object doesn't have the page,
* then we move it there.
*/
vm_page_rename(m, other_object, other_pindex);
m->dirty = VM_PAGE_BITS_ALL;
m->valid = VM_PAGE_BITS_ALL;
}
}
}
}
if (m) {
if (m->queue != PQ_ACTIVE)
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;
/*
* Now that we've gotten the copy out of the way,
* let's try to collapse the top object.
*
* But we have to play ugly games with
* paging_in_progress to do that...
*/
vm_object_pip_wakeup(object);
vm_object_collapse(object);
object->paging_in_progress++;
} else {
prot &= ~VM_PROT_WRITE;
}
}
/*
* We must verify that the maps have not changed since our last
* lookup.
*/
if (!lookup_still_valid) {
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, &su);
/*
* If we don't need the page any longer, put it on the active
* list (the easiest thing to do here). If no one needs it,
* pageout will grab it eventually.
*/
if (result != KERN_SUCCESS) {
RELEASE_PAGE(m);
UNLOCK_AND_DEALLOCATE;
return (result);
}
lookup_still_valid = TRUE;
if ((retry_object != first_object) ||
(retry_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, first_object);
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 {
if (m->queue != PQ_ACTIVE)
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;
vm_object_t object;
vm_pindex_t pindex, startpindex, endpindex, tpindex;
vm_offset_t size;
vm_page_t rtm;
int treqpage;
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();
*reqpage = 0;
marray[0] = m;
return 1;
}
/*
* scan backward for the read behind pages -- in memory or on disk not
* in same object
*/
tpindex = pindex - 1;
if (tpindex < pindex) {
if (rbehind > pindex)
rbehind = pindex;
startpindex = pindex - rbehind;
while (tpindex >= startpindex) {
if (vm_page_lookup( object, tpindex)) {
startpindex = tpindex + 1;
break;
}
if (tpindex == 0)
break;
tpindex -= 1;
}
} else {
startpindex = pindex;
}
/*
* scan forward for the read ahead pages -- in memory or on disk not
* in same object
*/
tpindex = pindex + 1;
endpindex = pindex + (rahead + 1);
if (endpindex > object->size)
endpindex = object->size;
while (tpindex < endpindex) {
if ( vm_page_lookup(object, tpindex)) {
break;
}
tpindex += 1;
}
endpindex = tpindex;
/* calculate number of bytes of pages */
size = endpindex - startpindex;
/* calculate the page offset of the required page */
treqpage = pindex - startpindex;
/* see if we have space (again) */
if ((cnt.v_free_count + cnt.v_cache_count) >
(cnt.v_free_reserved + size)) {
/*
* get our pages and don't block for them
*/
for (i = 0; i < size; i++) {
if (i != treqpage) {
rtm = vm_page_alloc(object,
startpindex + i,
VM_ALLOC_NORMAL);
if (rtm == NULL) {
if (i < treqpage) {
int j;
for (j = 0; j < i; j++) {
FREE_PAGE(marray[j]);
}
*reqpage = 0;
marray[0] = m;
return 1;
} else {
size = i;
*reqpage = treqpage;
return size;
}
}
marray[i] = rtm;
} else {
marray[i] = m;
}
}
*reqpage = treqpage;
return size;
}
*reqpage = 0;
marray[0] = m;
return 1;
}
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