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NetBSD/sys/uvm/uvm_fault.c
thorpej 1da427a80a Change the pmap_enter() API slightly; pmap_enter() now returns an error 
value (KERN_SUCCESS or KERN_RESOURCE_SHORTAGE) indicating if it succeeded
or failed.  Change the `wired' and `access_type' arguments to a single
`flags' argument, which includes the access type, and flags:

	PMAP_WIRED	the old `wired' boolean
	PMAP_CANFAIL	pmap_enter() is allowed to fail

If PMAP_CANFAIL is not specified, the pmap should behave as it always
has in the face of a drastic resource shortage: fall over dead.

Change the fault handler to deal with failure (which indicates resource
shortage) by unlocking everything, waiting for the pagedaemon to free
more memory, then retrying the fault.
1999-11-13 00:24:38 +00:00

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/* $NetBSD: uvm_fault.c,v 1.46 1999/11/13 00:24:38 thorpej Exp $ */
/*
*
* Copyright (c) 1997 Charles D. Cranor and Washington University.
* All rights reserved.
*
* 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 Charles D. Cranor and
* Washington University.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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: Id: uvm_fault.c,v 1.1.2.23 1998/02/06 05:29:05 chs Exp
*/
#include "opt_uvmhist.h"
/*
* uvm_fault.c: fault handler
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/user.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_kern.h>
#include <uvm/uvm.h>
/*
*
* a word on page faults:
*
* types of page faults we handle:
*
* CASE 1: upper layer faults CASE 2: lower layer faults
*
* CASE 1A CASE 1B CASE 2A CASE 2B
* read/write1 write>1 read/write +-cow_write/zero
* | | | |
* +--|--+ +--|--+ +-----+ + | + | +-----+
* amap | V | | ----------->new| | | | ^ |
* +-----+ +-----+ +-----+ + | + | +--|--+
* | | |
* +-----+ +-----+ +--|--+ | +--|--+
* uobj | d/c | | d/c | | V | +----| |
* +-----+ +-----+ +-----+ +-----+
*
* d/c = don't care
*
* case [0]: layerless fault
* no amap or uobj is present. this is an error.
*
* case [1]: upper layer fault [anon active]
* 1A: [read] or [write with anon->an_ref == 1]
* I/O takes place in top level anon and uobj is not touched.
* 1B: [write with anon->an_ref > 1]
* new anon is alloc'd and data is copied off ["COW"]
*
* case [2]: lower layer fault [uobj]
* 2A: [read on non-NULL uobj] or [write to non-copy_on_write area]
* I/O takes place directly in object.
* 2B: [write to copy_on_write] or [read on NULL uobj]
* data is "promoted" from uobj to a new anon.
* if uobj is null, then we zero fill.
*
* we follow the standard UVM locking protocol ordering:
*
* MAPS => AMAP => UOBJ => ANON => PAGE QUEUES (PQ)
* we hold a PG_BUSY page if we unlock for I/O
*
*
* the code is structured as follows:
*
* - init the "IN" params in the ufi structure
* ReFault:
* - do lookups [locks maps], check protection, handle needs_copy
* - check for case 0 fault (error)
* - establish "range" of fault
* - if we have an amap lock it and extract the anons
* - if sequential advice deactivate pages behind us
* - at the same time check pmap for unmapped areas and anon for pages
* that we could map in (and do map it if found)
* - check object for resident pages that we could map in
* - if (case 2) goto Case2
* - >>> handle case 1
* - ensure source anon is resident in RAM
* - if case 1B alloc new anon and copy from source
* - map the correct page in
* Case2:
* - >>> handle case 2
* - ensure source page is resident (if uobj)
* - if case 2B alloc new anon and copy from source (could be zero
* fill if uobj == NULL)
* - map the correct page in
* - done!
*
* note on paging:
* if we have to do I/O we place a PG_BUSY page in the correct object,
* unlock everything, and do the I/O. when I/O is done we must reverify
* the state of the world before assuming that our data structures are
* valid. [because mappings could change while the map is unlocked]
*
* alternative 1: unbusy the page in question and restart the page fault
* from the top (ReFault). this is easy but does not take advantage
* of the information that we already have from our previous lookup,
* although it is possible that the "hints" in the vm_map will help here.
*
* alternative 2: the system already keeps track of a "version" number of
* a map. [i.e. every time you write-lock a map (e.g. to change a
* mapping) you bump the version number up by one...] so, we can save
* the version number of the map before we release the lock and start I/O.
* then when I/O is done we can relock and check the version numbers
* to see if anything changed. this might save us some over 1 because
* we don't have to unbusy the page and may be less compares(?).
*
* alternative 3: put in backpointers or a way to "hold" part of a map
* in place while I/O is in progress. this could be complex to
* implement (especially with structures like amap that can be referenced
* by multiple map entries, and figuring out what should wait could be
* complex as well...).
*
* given that we are not currently multiprocessor or multithreaded we might
* as well choose alternative 2 now. maybe alternative 3 would be useful
* in the future. XXX keep in mind for future consideration//rechecking.
*/
/*
* local data structures
*/
struct uvm_advice {
int advice;
int nback;
int nforw;
};
/*
* page range array:
* note: index in array must match "advice" value
* XXX: borrowed numbers from freebsd. do they work well for us?
*/
static struct uvm_advice uvmadvice[] = {
{ MADV_NORMAL, 3, 4 },
{ MADV_RANDOM, 0, 0 },
{ MADV_SEQUENTIAL, 8, 7},
};
#define UVM_MAXRANGE 16 /* must be max() of nback+nforw+1 */
/*
* private prototypes
*/
static void uvmfault_amapcopy __P((struct uvm_faultinfo *));
static __inline void uvmfault_anonflush __P((struct vm_anon **, int));
/*
* inline functions
*/
/*
* uvmfault_anonflush: try and deactivate pages in specified anons
*
* => does not have to deactivate page if it is busy
*/
static __inline void
uvmfault_anonflush(anons, n)
struct vm_anon **anons;
int n;
{
int lcv;
struct vm_page *pg;
for (lcv = 0 ; lcv < n ; lcv++) {
if (anons[lcv] == NULL)
continue;
simple_lock(&anons[lcv]->an_lock);
pg = anons[lcv]->u.an_page;
if (pg && (pg->flags & PG_BUSY) == 0 && pg->loan_count == 0) {
uvm_lock_pageq();
if (pg->wire_count == 0) {
pmap_page_protect(pg, VM_PROT_NONE);
uvm_pagedeactivate(pg);
}
uvm_unlock_pageq();
}
simple_unlock(&anons[lcv]->an_lock);
}
}
/*
* normal functions
*/
/*
* uvmfault_amapcopy: clear "needs_copy" in a map.
*
* => called with VM data structures unlocked (usually, see below)
* => we get a write lock on the maps and clear needs_copy for a VA
* => if we are out of RAM we sleep (waiting for more)
*/
static void
uvmfault_amapcopy(ufi)
struct uvm_faultinfo *ufi;
{
/*
* while we haven't done the job
*/
while (1) {
/*
* no mapping? give up.
*/
if (uvmfault_lookup(ufi, TRUE) == FALSE)
return;
/*
* copy if needed.
*/
if (UVM_ET_ISNEEDSCOPY(ufi->entry))
amap_copy(ufi->map, ufi->entry, M_NOWAIT, TRUE,
ufi->orig_rvaddr, ufi->orig_rvaddr + 1);
/*
* didn't work? must be out of RAM. unlock and sleep.
*/
if (UVM_ET_ISNEEDSCOPY(ufi->entry)) {
uvmfault_unlockmaps(ufi, TRUE);
uvm_wait("fltamapcopy");
continue;
}
/*
* got it! unlock and return.
*/
uvmfault_unlockmaps(ufi, TRUE);
return;
}
/*NOTREACHED*/
}
/*
* uvmfault_anonget: get data in an anon into a non-busy, non-released
* page in that anon.
*
* => maps, amap, and anon locked by caller.
* => if we fail (result != VM_PAGER_OK) we unlock everything.
* => if we are successful, we return with everything still locked.
* => we don't move the page on the queues [gets moved later]
* => if we allocate a new page [we_own], it gets put on the queues.
* either way, the result is that the page is on the queues at return time
* => for pages which are on loan from a uvm_object (and thus are not
* owned by the anon): if successful, we return with the owning object
* locked. the caller must unlock this object when it unlocks everything
* else.
*/
int uvmfault_anonget(ufi, amap, anon)
struct uvm_faultinfo *ufi;
struct vm_amap *amap;
struct vm_anon *anon;
{
boolean_t we_own; /* we own anon's page? */
boolean_t locked; /* did we relock? */
struct vm_page *pg;
int result;
UVMHIST_FUNC("uvmfault_anonget"); UVMHIST_CALLED(maphist);
result = 0; /* XXX shut up gcc */
uvmexp.fltanget++;
/* bump rusage counters */
if (anon->u.an_page)
curproc->p_addr->u_stats.p_ru.ru_minflt++;
else
curproc->p_addr->u_stats.p_ru.ru_majflt++;
/*
* loop until we get it, or fail.
*/
while (1) {
we_own = FALSE; /* TRUE if we set PG_BUSY on a page */
pg = anon->u.an_page;
/*
* if there is a resident page and it is loaned, then anon
* may not own it. call out to uvm_anon_lockpage() to ensure
* the real owner of the page has been identified and locked.
*/
if (pg && pg->loan_count)
pg = uvm_anon_lockloanpg(anon);
/*
* page there? make sure it is not busy/released.
*/
if (pg) {
/*
* at this point, if the page has a uobject [meaning
* we have it on loan], then that uobject is locked
* by us! if the page is busy, we drop all the
* locks (including uobject) and try again.
*/
if ((pg->flags & (PG_BUSY|PG_RELEASED)) == 0) {
UVMHIST_LOG(maphist, "<- OK",0,0,0,0);
return (VM_PAGER_OK);
}
pg->flags |= PG_WANTED;
uvmexp.fltpgwait++;
/*
* the last unlock must be an atomic unlock+wait on
* the owner of page
*/
if (pg->uobject) { /* owner is uobject ? */
uvmfault_unlockall(ufi, amap, NULL, anon);
UVMHIST_LOG(maphist, " unlock+wait on uobj",0,
0,0,0);
UVM_UNLOCK_AND_WAIT(pg,
&pg->uobject->vmobjlock,
FALSE, "anonget1",0);
} else {
/* anon owns page */
uvmfault_unlockall(ufi, amap, NULL, NULL);
UVMHIST_LOG(maphist, " unlock+wait on anon",0,
0,0,0);
UVM_UNLOCK_AND_WAIT(pg,&anon->an_lock,0,
"anonget2",0);
}
/* ready to relock and try again */
} else {
/*
* no page, we must try and bring it in.
*/
pg = uvm_pagealloc(NULL, 0, anon, 0);
if (pg == NULL) { /* out of RAM. */
uvmfault_unlockall(ufi, amap, NULL, anon);
uvmexp.fltnoram++;
UVMHIST_LOG(maphist, " noram -- UVM_WAIT",0,
0,0,0);
uvm_wait("flt_noram1");
/* ready to relock and try again */
} else {
/* we set the PG_BUSY bit */
we_own = TRUE;
uvmfault_unlockall(ufi, amap, NULL, anon);
/*
* we are passing a PG_BUSY+PG_FAKE+PG_CLEAN
* page into the uvm_swap_get function with
* all data structures unlocked. note that
* it is ok to read an_swslot here because
* we hold PG_BUSY on the page.
*/
uvmexp.pageins++;
result = uvm_swap_get(pg, anon->an_swslot,
PGO_SYNCIO);
/*
* we clean up after the i/o below in the
* "we_own" case
*/
/* ready to relock and try again */
}
}
/*
* now relock and try again
*/
locked = uvmfault_relock(ufi);
if (locked) {
amap_lock(amap);
}
if (locked || we_own)
simple_lock(&anon->an_lock);
/*
* if we own the page (i.e. we set PG_BUSY), then we need
* to clean up after the I/O. there are three cases to
* consider:
* [1] page released during I/O: free anon and ReFault.
* [2] I/O not OK. free the page and cause the fault
* to fail.
* [3] I/O OK! activate the page and sync with the
* non-we_own case (i.e. drop anon lock if not locked).
*/
if (we_own) {
if (pg->flags & PG_WANTED) {
/* still holding object lock */
wakeup(pg);
}
/* un-busy! */
pg->flags &= ~(PG_WANTED|PG_BUSY|PG_FAKE);
UVM_PAGE_OWN(pg, NULL);
/*
* if we were RELEASED during I/O, then our anon is
* no longer part of an amap. we need to free the
* anon and try again.
*/
if (pg->flags & PG_RELEASED) {
pmap_page_protect(pg, VM_PROT_NONE);
simple_unlock(&anon->an_lock);
uvm_anfree(anon); /* frees page for us */
if (locked)
uvmfault_unlockall(ufi, amap, NULL, NULL);
uvmexp.fltpgrele++;
UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0);
return (VM_PAGER_REFAULT); /* refault! */
}
if (result != VM_PAGER_OK) {
#ifdef DIAGNOSTIC
if (result == VM_PAGER_PEND)
panic("uvmfault_anonget: got PENDING for non-async I/O");
#endif
/* remove page from anon */
anon->u.an_page = NULL;
/*
* note: page was never !PG_BUSY, so it
* can't be mapped and thus no need to
* pmap_page_protect it...
*/
uvm_lock_pageq();
uvm_pagefree(pg);
uvm_unlock_pageq();
if (locked)
uvmfault_unlockall(ufi, amap, NULL,
anon);
else
simple_unlock(&anon->an_lock);
UVMHIST_LOG(maphist, "<- ERROR", 0,0,0,0);
return (VM_PAGER_ERROR);
}
/*
* must be OK, clear modify (already PG_CLEAN)
* and activate
*/
pmap_clear_modify(pg);
uvm_lock_pageq();
uvm_pageactivate(pg);
uvm_unlock_pageq();
if (!locked)
simple_unlock(&anon->an_lock);
}
/*
* we were not able to relock. restart fault.
*/
if (!locked) {
UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0);
return (VM_PAGER_REFAULT);
}
/*
* verify no one has touched the amap and moved the anon on us.
*/
if (amap_lookup(&ufi->entry->aref,
ufi->orig_rvaddr - ufi->entry->start) != anon) {
uvmfault_unlockall(ufi, amap, NULL, anon);
UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0);
return (VM_PAGER_REFAULT);
}
/*
* try it again!
*/
uvmexp.fltanretry++;
continue;
} /* while (1) */
/*NOTREACHED*/
}
/*
* F A U L T - m a i n e n t r y p o i n t
*/
/*
* uvm_fault: page fault handler
*
* => called from MD code to resolve a page fault
* => VM data structures usually should be unlocked. however, it is
* possible to call here with the main map locked if the caller
* gets a write lock, sets it recusive, and then calls us (c.f.
* uvm_map_pageable). this should be avoided because it keeps
* the map locked off during I/O.
*/
#define MASK(entry) (UVM_ET_ISCOPYONWRITE(entry) ? \
~VM_PROT_WRITE : VM_PROT_ALL)
int
uvm_fault(orig_map, vaddr, fault_type, access_type)
vm_map_t orig_map;
vaddr_t vaddr;
vm_fault_t fault_type;
vm_prot_t access_type;
{
struct uvm_faultinfo ufi;
vm_prot_t enter_prot;
boolean_t wired, narrow, promote, locked, shadowed;
int npages, nback, nforw, centeridx, result, lcv, gotpages;
vaddr_t startva, objaddr, currva, offset;
paddr_t pa;
struct vm_amap *amap;
struct uvm_object *uobj;
struct vm_anon *anons_store[UVM_MAXRANGE], **anons, *anon, *oanon;
struct vm_page *pages[UVM_MAXRANGE], *pg, *uobjpage;
UVMHIST_FUNC("uvm_fault"); UVMHIST_CALLED(maphist);
UVMHIST_LOG(maphist, "(map=0x%x, vaddr=0x%x, ft=%d, at=%d)",
orig_map, vaddr, fault_type, access_type);
anon = NULL; /* XXX: shut up gcc */
uvmexp.faults++; /* XXX: locking? */
/*
* init the IN parameters in the ufi
*/
ufi.orig_map = orig_map;
ufi.orig_rvaddr = trunc_page(vaddr);
ufi.orig_size = PAGE_SIZE; /* can't get any smaller than this */
if (fault_type == VM_FAULT_WIRE)
narrow = TRUE; /* don't look for neighborhood
* pages on wire */
else
narrow = FALSE; /* normal fault */
/*
* before we do anything else, if this is a fault on a kernel
* address, check to see if the address is managed by an
* interrupt-safe map. If it is, we fail immediately. Intrsafe
* maps are never pageable, and this approach avoids an evil
* locking mess.
*/
if (orig_map == kernel_map && uvmfault_check_intrsafe(&ufi)) {
UVMHIST_LOG(maphist, "<- VA 0x%lx in intrsafe map %p",
ufi.orig_rvaddr, ufi.map, 0, 0);
return (KERN_FAILURE);
}
/*
* "goto ReFault" means restart the page fault from ground zero.
*/
ReFault:
/*
* lookup and lock the maps
*/
if (uvmfault_lookup(&ufi, FALSE) == FALSE) {
UVMHIST_LOG(maphist, "<- no mapping @ 0x%x", vaddr, 0,0,0);
return (KERN_INVALID_ADDRESS);
}
/* locked: maps(read) */
/*
* check protection
*/
if ((ufi.entry->protection & access_type) != access_type) {
UVMHIST_LOG(maphist,
"<- protection failure (prot=0x%x, access=0x%x)",
ufi.entry->protection, access_type, 0, 0);
uvmfault_unlockmaps(&ufi, FALSE);
return (KERN_PROTECTION_FAILURE);
}
/*
* if the map is not a pageable map, a page fault always fails.
*/
if ((ufi.map->flags & VM_MAP_PAGEABLE) == 0) {
UVMHIST_LOG(maphist,
"<- map %p not pageable", ufi.map, 0, 0, 0);
uvmfault_unlockmaps(&ufi, FALSE);
return (KERN_FAILURE);
}
/*
* "enter_prot" is the protection we want to enter the page in at.
* for certain pages (e.g. copy-on-write pages) this protection can
* be more strict than ufi.entry->protection. "wired" means either
* the entry is wired or we are fault-wiring the pg.
*/
enter_prot = ufi.entry->protection;
wired = VM_MAPENT_ISWIRED(ufi.entry) || (fault_type == VM_FAULT_WIRE);
if (wired)
access_type = enter_prot; /* full access for wired */
/*
* handle "needs_copy" case. if we need to copy the amap we will
* have to drop our readlock and relock it with a write lock. (we
* need a write lock to change anything in a map entry [e.g.
* needs_copy]).
*/
if (UVM_ET_ISNEEDSCOPY(ufi.entry)) {
if ((access_type & VM_PROT_WRITE) ||
(ufi.entry->object.uvm_obj == NULL)) {
/* need to clear */
UVMHIST_LOG(maphist,
" need to clear needs_copy and refault",0,0,0,0);
uvmfault_unlockmaps(&ufi, FALSE);
uvmfault_amapcopy(&ufi);
uvmexp.fltamcopy++;
goto ReFault;
} else {
/*
* ensure that we pmap_enter page R/O since
* needs_copy is still true
*/
enter_prot &= ~VM_PROT_WRITE;
}
}
/*
* identify the players
*/
amap = ufi.entry->aref.ar_amap; /* top layer */
uobj = ufi.entry->object.uvm_obj; /* bottom layer */
/*
* check for a case 0 fault. if nothing backing the entry then
* error now.
*/
if (amap == NULL && uobj == NULL) {
uvmfault_unlockmaps(&ufi, FALSE);
UVMHIST_LOG(maphist,"<- no backing store, no overlay",0,0,0,0);
return (KERN_INVALID_ADDRESS);
}
/*
* establish range of interest based on advice from mapper
* and then clip to fit map entry. note that we only want
* to do this the first time through the fault. if we
* ReFault we will disable this by setting "narrow" to true.
*/
if (narrow == FALSE) {
/* wide fault (!narrow) */
#ifdef DIAGNOSTIC
if (uvmadvice[ufi.entry->advice].advice != ufi.entry->advice)
panic("fault: advice mismatch!");
#endif
nback = min(uvmadvice[ufi.entry->advice].nback,
(ufi.orig_rvaddr - ufi.entry->start) >> PAGE_SHIFT);
startva = ufi.orig_rvaddr - (nback << PAGE_SHIFT);
nforw = min(uvmadvice[ufi.entry->advice].nforw,
((ufi.entry->end - ufi.orig_rvaddr) >>
PAGE_SHIFT) - 1);
/*
* note: "-1" because we don't want to count the
* faulting page as forw
*/
npages = nback + nforw + 1;
centeridx = nback;
narrow = TRUE; /* ensure only once per-fault */
} else {
/* narrow fault! */
nback = nforw = 0;
startva = ufi.orig_rvaddr;
npages = 1;
centeridx = 0;
}
/* locked: maps(read) */
UVMHIST_LOG(maphist, " narrow=%d, back=%d, forw=%d, startva=0x%x",
narrow, nback, nforw, startva);
UVMHIST_LOG(maphist, " entry=0x%x, amap=0x%x, obj=0x%x", ufi.entry,
amap, uobj, 0);
/*
* if we've got an amap, lock it and extract current anons.
*/
if (amap) {
amap_lock(amap);
anons = anons_store;
amap_lookups(&ufi.entry->aref, startva - ufi.entry->start,
anons, npages);
} else {
anons = NULL; /* to be safe */
}
/* locked: maps(read), amap(if there) */
/*
* for MADV_SEQUENTIAL mappings we want to deactivate the back pages
* now and then forget about them (for the rest of the fault).
*/
if (ufi.entry->advice == MADV_SEQUENTIAL) {
UVMHIST_LOG(maphist, " MADV_SEQUENTIAL: flushing backpages",
0,0,0,0);
/* flush back-page anons? */
if (amap)
uvmfault_anonflush(anons, nback);
/* flush object? */
if (uobj) {
objaddr =
(startva - ufi.entry->start) + ufi.entry->offset;
simple_lock(&uobj->vmobjlock);
(void) uobj->pgops->pgo_flush(uobj, objaddr, objaddr +
(nback << PAGE_SHIFT), PGO_DEACTIVATE);
simple_unlock(&uobj->vmobjlock);
}
/* now forget about the backpages */
if (amap)
anons += nback;
startva = startva + (nback << PAGE_SHIFT);
npages -= nback;
nback = centeridx = 0;
}
/* locked: maps(read), amap(if there) */
/*
* map in the backpages and frontpages we found in the amap in hopes
* of preventing future faults. we also init the pages[] array as
* we go.
*/
currva = startva;
shadowed = FALSE;
for (lcv = 0 ; lcv < npages ; lcv++, currva += PAGE_SIZE) {
/*
* dont play with VAs that are already mapped
* except for center)
*/
if (lcv != centeridx) {
if (pmap_extract(ufi.orig_map->pmap, currva, &pa) ==
TRUE) {
pages[lcv] = PGO_DONTCARE;
continue;
}
}
/*
* unmapped or center page. check if any anon at this level.
*/
if (amap == NULL || anons[lcv] == NULL) {
pages[lcv] = NULL;
continue;
}
/*
* check for present page and map if possible. re-activate it.
*/
pages[lcv] = PGO_DONTCARE;
if (lcv == centeridx) { /* save center for later! */
shadowed = TRUE;
continue;
}
anon = anons[lcv];
simple_lock(&anon->an_lock);
/* ignore loaned pages */
if (anon->u.an_page && anon->u.an_page->loan_count == 0 &&
(anon->u.an_page->flags & (PG_RELEASED|PG_BUSY)) == 0) {
uvm_lock_pageq();
uvm_pageactivate(anon->u.an_page); /* reactivate */
uvm_unlock_pageq();
UVMHIST_LOG(maphist,
" MAPPING: n anon: pm=0x%x, va=0x%x, pg=0x%x",
ufi.orig_map->pmap, currva, anon->u.an_page, 0);
uvmexp.fltnamap++;
/*
* Since this isn't the page that's actually faulting,
* ignore pmap_enter() failures; it's not critical
* that we enter these right now.
*/
(void) pmap_enter(ufi.orig_map->pmap, currva,
VM_PAGE_TO_PHYS(anon->u.an_page),
(anon->an_ref > 1) ? (enter_prot & ~VM_PROT_WRITE) :
enter_prot,
PMAP_CANFAIL |
(VM_MAPENT_ISWIRED(ufi.entry) ? PMAP_WIRED : 0));
}
simple_unlock(&anon->an_lock);
}
/* locked: maps(read), amap(if there) */
/* (shadowed == TRUE) if there is an anon at the faulting address */
UVMHIST_LOG(maphist, " shadowed=%d, will_get=%d", shadowed,
(uobj && shadowed == FALSE),0,0);
/*
* note that if we are really short of RAM we could sleep in the above
* call to pmap_enter with everything locked. bad?
*
* XXX Actually, that is bad; pmap_enter() should just fail in that
* XXX case. --thorpej
*/
/*
* if the desired page is not shadowed by the amap and we have a
* backing object, then we check to see if the backing object would
* prefer to handle the fault itself (rather than letting us do it
* with the usual pgo_get hook). the backing object signals this by
* providing a pgo_fault routine.
*/
if (uobj && shadowed == FALSE && uobj->pgops->pgo_fault != NULL) {
simple_lock(&uobj->vmobjlock);
/* locked: maps(read), amap (if there), uobj */
result = uobj->pgops->pgo_fault(&ufi, startva, pages, npages,
centeridx, fault_type, access_type,
PGO_LOCKED);
/* locked: nothing, pgo_fault has unlocked everything */
if (result == VM_PAGER_OK)
return (KERN_SUCCESS); /* pgo_fault did pmap enter */
else if (result == VM_PAGER_REFAULT)
goto ReFault; /* try again! */
else
return (KERN_PROTECTION_FAILURE);
}
/*
* now, if the desired page is not shadowed by the amap and we have
* a backing object that does not have a special fault routine, then
* we ask (with pgo_get) the object for resident pages that we care
* about and attempt to map them in. we do not let pgo_get block
* (PGO_LOCKED).
*
* ("get" has the option of doing a pmap_enter for us)
*/
if (uobj && shadowed == FALSE) {
simple_lock(&uobj->vmobjlock);
/* locked (!shadowed): maps(read), amap (if there), uobj */
/*
* the following call to pgo_get does _not_ change locking state
*/
uvmexp.fltlget++;
gotpages = npages;
result = uobj->pgops->pgo_get(uobj, ufi.entry->offset +
(startva - ufi.entry->start),
pages, &gotpages, centeridx,
access_type & MASK(ufi.entry),
ufi.entry->advice, PGO_LOCKED);
/*
* check for pages to map, if we got any
*/
uobjpage = NULL;
if (gotpages) {
currva = startva;
for (lcv = 0 ; lcv < npages ;
lcv++, currva += PAGE_SIZE) {
if (pages[lcv] == NULL ||
pages[lcv] == PGO_DONTCARE)
continue;
#ifdef DIAGNOSTIC
/*
* pager sanity check: pgo_get with
* PGO_LOCKED should never return a
* released page to us.
*/
if (pages[lcv]->flags & PG_RELEASED)
panic("uvm_fault: pgo_get PGO_LOCKED gave us a RELEASED page");
#endif
/*
* if center page is resident and not
* PG_BUSY|PG_RELEASED then pgo_get
* made it PG_BUSY for us and gave
* us a handle to it. remember this
* page as "uobjpage." (for later use).
*/
if (lcv == centeridx) {
uobjpage = pages[lcv];
UVMHIST_LOG(maphist, " got uobjpage (0x%x) with locked get",
uobjpage, 0,0,0);
continue;
}
/*
* note: calling pgo_get with locked data
* structures returns us pages which are
* neither busy nor released, so we don't
* need to check for this. we can just
* directly enter the page (after moving it
* to the head of the active queue [useful?]).
*/
uvm_lock_pageq();
uvm_pageactivate(pages[lcv]); /* reactivate */
uvm_unlock_pageq();
UVMHIST_LOG(maphist,
" MAPPING: n obj: pm=0x%x, va=0x%x, pg=0x%x",
ufi.orig_map->pmap, currva, pages[lcv], 0);
uvmexp.fltnomap++;
/*
* Since this page isn't the page that's
* actually fauling, ignore pmap_enter()
* failures; it's not critical that we
* enter these right now.
*/
(void) pmap_enter(ufi.orig_map->pmap, currva,
VM_PAGE_TO_PHYS(pages[lcv]),
enter_prot & MASK(ufi.entry),
PMAP_CANFAIL |
(wired ? PMAP_WIRED : 0));
/*
* NOTE: page can't be PG_WANTED or PG_RELEASED
* because we've held the lock the whole time
* we've had the handle.
*/
pages[lcv]->flags &= ~(PG_BUSY); /* un-busy! */
UVM_PAGE_OWN(pages[lcv], NULL);
/* done! */
} /* for "lcv" loop */
} /* "gotpages" != 0 */
/* note: object still _locked_ */
} else {
uobjpage = NULL;
}
/* locked (shadowed): maps(read), amap */
/* locked (!shadowed): maps(read), amap(if there),
uobj(if !null), uobjpage(if !null) */
/*
* note that at this point we are done with any front or back pages.
* we are now going to focus on the center page (i.e. the one we've
* faulted on). if we have faulted on the top (anon) layer
* [i.e. case 1], then the anon we want is anons[centeridx] (we have
* not touched it yet). if we have faulted on the bottom (uobj)
* layer [i.e. case 2] and the page was both present and available,
* then we've got a pointer to it as "uobjpage" and we've already
* made it BUSY.
*/
/*
* there are four possible cases we must address: 1A, 1B, 2A, and 2B
*/
/*
* redirect case 2: if we are not shadowed, go to case 2.
*/
if (shadowed == FALSE)
goto Case2;
/* locked: maps(read), amap */
/*
* handle case 1: fault on an anon in our amap
*/
anon = anons[centeridx];
UVMHIST_LOG(maphist, " case 1 fault: anon=0x%x", anon, 0,0,0);
simple_lock(&anon->an_lock);
/* locked: maps(read), amap, anon */
/*
* no matter if we have case 1A or case 1B we are going to need to
* have the anon's memory resident. ensure that now.
*/
/*
* let uvmfault_anonget do the dirty work. if it fails (!OK) it will
* unlock for us. if it is OK, locks are still valid and locked.
* also, if it is OK, then the anon's page is on the queues.
* if the page is on loan from a uvm_object, then anonget will
* lock that object for us if it does not fail.
*/
result = uvmfault_anonget(&ufi, amap, anon);
if (result == VM_PAGER_REFAULT)
goto ReFault;
if (result == VM_PAGER_AGAIN) {
tsleep((caddr_t)&lbolt, PVM, "fltagain1", 0);
goto ReFault;
}
if (result != VM_PAGER_OK)
return (KERN_PROTECTION_FAILURE); /* XXX??? */
/*
* uobj is non null if the page is on loan from an object (i.e. uobj)
*/
uobj = anon->u.an_page->uobject; /* locked by anonget if !NULL */
/* locked: maps(read), amap, anon, uobj(if one) */
/*
* special handling for loaned pages
*/
if (anon->u.an_page->loan_count) {
if ((access_type & VM_PROT_WRITE) == 0) {
/*
* for read faults on loaned pages we just cap the
* protection at read-only.
*/
enter_prot = enter_prot & ~VM_PROT_WRITE;
} else {
/*
* note that we can't allow writes into a loaned page!
*
* if we have a write fault on a loaned page in an
* anon then we need to look at the anon's ref count.
* if it is greater than one then we are going to do
* a normal copy-on-write fault into a new anon (this
* is not a problem). however, if the reference count
* is one (a case where we would normally allow a
* write directly to the page) then we need to kill
* the loan before we continue.
*/
/* >1 case is already ok */
if (anon->an_ref == 1) {
/* get new un-owned replacement page */
pg = uvm_pagealloc(NULL, 0, NULL, 0);
if (pg == NULL) {
uvmfault_unlockall(&ufi, amap, uobj,
anon);
uvm_wait("flt_noram2");
goto ReFault;
}
/*
* copy data, kill loan, and drop uobj lock
* (if any)
*/
/* copy old -> new */
uvm_pagecopy(anon->u.an_page, pg);
/* force reload */
pmap_page_protect(anon->u.an_page,
VM_PROT_NONE);
uvm_lock_pageq(); /* KILL loan */
if (uobj)
/* if we were loaning */
anon->u.an_page->loan_count--;
anon->u.an_page->uanon = NULL;
/* in case we owned */
anon->u.an_page->pqflags &= ~PQ_ANON;
uvm_unlock_pageq();
if (uobj) {
simple_unlock(&uobj->vmobjlock);
uobj = NULL;
}
/* install new page in anon */
anon->u.an_page = pg;
pg->uanon = anon;
pg->pqflags |= PQ_ANON;
pg->flags &= ~(PG_BUSY|PG_FAKE);
UVM_PAGE_OWN(pg, NULL);
/* done! */
} /* ref == 1 */
} /* write fault */
} /* loan count */
/*
* if we are case 1B then we will need to allocate a new blank
* anon to transfer the data into. note that we have a lock
* on anon, so no one can busy or release the page until we are done.
* also note that the ref count can't drop to zero here because
* it is > 1 and we are only dropping one ref.
*
* in the (hopefully very rare) case that we are out of RAM we
* will unlock, wait for more RAM, and refault.
*
* if we are out of anon VM we kill the process (XXX: could wait?).
*/
if ((access_type & VM_PROT_WRITE) != 0 && anon->an_ref > 1) {
UVMHIST_LOG(maphist, " case 1B: COW fault",0,0,0,0);
uvmexp.flt_acow++;
oanon = anon; /* oanon = old, locked anon */
anon = uvm_analloc();
if (anon)
pg = uvm_pagealloc(NULL, 0, anon, 0);
#ifdef __GNUC__
else
pg = NULL; /* XXX: gcc */
#endif
/* check for out of RAM */
if (anon == NULL || pg == NULL) {
if (anon)
uvm_anfree(anon);
uvmfault_unlockall(&ufi, amap, uobj, oanon);
#ifdef DIAGNOSTIC
if (uvmexp.swpgonly > uvmexp.swpages) {
panic("uvmexp.swpgonly botch");
}
#endif
if (anon == NULL || uvmexp.swpgonly == uvmexp.swpages) {
UVMHIST_LOG(maphist,
"<- failed. out of VM",0,0,0,0);
uvmexp.fltnoanon++;
return (KERN_RESOURCE_SHORTAGE);
}
uvmexp.fltnoram++;
uvm_wait("flt_noram3"); /* out of RAM, wait for more */
goto ReFault;
}
/* got all resources, replace anon with nanon */
uvm_pagecopy(oanon->u.an_page, pg); /* pg now !PG_CLEAN */
pg->flags &= ~(PG_BUSY|PG_FAKE); /* un-busy! new page */
UVM_PAGE_OWN(pg, NULL);
amap_add(&ufi.entry->aref, ufi.orig_rvaddr - ufi.entry->start,
anon, 1);
/* deref: can not drop to zero here by defn! */
oanon->an_ref--;
/*
* note: oanon still locked. anon is _not_ locked, but we
* have the sole references to in from amap which _is_ locked.
* thus, no one can get at it until we are done with it.
*/
} else {
uvmexp.flt_anon++;
oanon = anon; /* old, locked anon is same as anon */
pg = anon->u.an_page;
if (anon->an_ref > 1) /* disallow writes to ref > 1 anons */
enter_prot = enter_prot & ~VM_PROT_WRITE;
}
/* locked: maps(read), amap, anon */
/*
* now map the page in ...
* XXX: old fault unlocks object before pmap_enter. this seems
* suspect since some other thread could blast the page out from
* under us between the unlock and the pmap_enter.
*/
UVMHIST_LOG(maphist, " MAPPING: anon: pm=0x%x, va=0x%x, pg=0x%x",
ufi.orig_map->pmap, ufi.orig_rvaddr, pg, 0);
if (pmap_enter(ufi.orig_map->pmap, ufi.orig_rvaddr, VM_PAGE_TO_PHYS(pg),
enter_prot, access_type | PMAP_CANFAIL | (wired ? PMAP_WIRED : 0))
!= KERN_SUCCESS) {
/*
* No need to undo what we did; we can simply think of
* this as the pmap throwing away the mapping information.
*
* We do, however, have to go through the ReFault path,
* as the map may change while we're asleep.
*/
uvmfault_unlockall(&ufi, amap, uobj, oanon);
#ifdef DIAGNOSTIC
if (uvmexp.swpgonly > uvmexp.swpages)
panic("uvmexp.swpgonly botch");
#endif
if (uvmexp.swpgonly == uvmexp.swpages) {
UVMHIST_LOG(maphist,
"<- failed. out of VM",0,0,0,0);
/* XXX instrumentation */
return (KERN_RESOURCE_SHORTAGE);
}
/* XXX instrumentation */
uvm_wait("flt_pmfail1");
goto ReFault;
}
/*
* ... update the page queues.
*/
uvm_lock_pageq();
if (fault_type == VM_FAULT_WIRE) {
uvm_pagewire(pg);
/*
* since the now-wired page cannot be paged out,
* release its swap resources for others to use.
* since an anon with no swap cannot be PG_CLEAN,
* clear its clean flag now.
*/
pg->flags &= ~(PG_CLEAN);
uvm_anon_dropswap(anon);
} else {
/* activate it */
uvm_pageactivate(pg);
}
uvm_unlock_pageq();
/*
* done case 1! finish up by unlocking everything and returning success
*/
uvmfault_unlockall(&ufi, amap, uobj, oanon);
return (KERN_SUCCESS);
Case2:
/*
* handle case 2: faulting on backing object or zero fill
*/
/*
* locked:
* maps(read), amap(if there), uobj(if !null), uobjpage(if !null)
*/
/*
* note that uobjpage can not be PGO_DONTCARE at this point. we now
* set uobjpage to PGO_DONTCARE if we are doing a zero fill. if we
* have a backing object, check and see if we are going to promote
* the data up to an anon during the fault.
*/
if (uobj == NULL) {
uobjpage = PGO_DONTCARE;
promote = TRUE; /* always need anon here */
} else {
/* assert(uobjpage != PGO_DONTCARE) */
promote = (access_type & VM_PROT_WRITE) &&
UVM_ET_ISCOPYONWRITE(ufi.entry);
}
UVMHIST_LOG(maphist, " case 2 fault: promote=%d, zfill=%d",
promote, (uobj == NULL), 0,0);
/*
* if uobjpage is not null then we do not need to do I/O to get the
* uobjpage.
*
* if uobjpage is null, then we need to unlock and ask the pager to
* get the data for us. once we have the data, we need to reverify
* the state the world. we are currently not holding any resources.
*/
if (uobjpage) {
/* update rusage counters */
curproc->p_addr->u_stats.p_ru.ru_minflt++;
} else {
/* update rusage counters */
curproc->p_addr->u_stats.p_ru.ru_majflt++;
/* locked: maps(read), amap(if there), uobj */
uvmfault_unlockall(&ufi, amap, NULL, NULL);
/* locked: uobj */
uvmexp.fltget++;
gotpages = 1;
result = uobj->pgops->pgo_get(uobj,
(ufi.orig_rvaddr - ufi.entry->start) + ufi.entry->offset,
&uobjpage, &gotpages, 0,
access_type & MASK(ufi.entry),
ufi.entry->advice, 0);
/* locked: uobjpage(if result OK) */
/*
* recover from I/O
*/
if (result != VM_PAGER_OK) {
#ifdef DIAGNOSTIC
if (result == VM_PAGER_PEND)
panic("uvm_fault: pgo_get got PENDing "
"on non-async I/O");
#endif
if (result == VM_PAGER_AGAIN) {
UVMHIST_LOG(maphist,
" pgo_get says TRY AGAIN!",0,0,0,0);
tsleep((caddr_t)&lbolt, PVM, "fltagain2", 0);
goto ReFault;
}
UVMHIST_LOG(maphist, "<- pgo_get failed (code %d)",
result, 0,0,0);
return (KERN_PROTECTION_FAILURE); /* XXX i/o error */
}
/* locked: uobjpage */
/*
* re-verify the state of the world by first trying to relock
* the maps. always relock the object.
*/
locked = uvmfault_relock(&ufi);
if (locked && amap)
amap_lock(amap);
simple_lock(&uobj->vmobjlock);
/* locked(locked): maps(read), amap(if !null), uobj, uobjpage */
/* locked(!locked): uobj, uobjpage */
/*
* verify that the page has not be released and re-verify
* that amap slot is still free. if there is a problem,
* we unlock and clean up.
*/
if ((uobjpage->flags & PG_RELEASED) != 0 ||
(locked && amap &&
amap_lookup(&ufi.entry->aref,
ufi.orig_rvaddr - ufi.entry->start))) {
if (locked)
uvmfault_unlockall(&ufi, amap, NULL, NULL);
locked = FALSE;
}
/*
* didn't get the lock? release the page and retry.
*/
if (locked == FALSE) {
UVMHIST_LOG(maphist,
" wasn't able to relock after fault: retry",
0,0,0,0);
if (uobjpage->flags & PG_WANTED)
/* still holding object lock */
wakeup(uobjpage);
if (uobjpage->flags & PG_RELEASED) {
uvmexp.fltpgrele++;
#ifdef DIAGNOSTIC
if (uobj->pgops->pgo_releasepg == NULL)
panic("uvm_fault: object has no "
"releasepg function");
#endif
/* frees page */
if (uobj->pgops->pgo_releasepg(uobjpage,NULL))
/* unlock if still alive */
simple_unlock(&uobj->vmobjlock);
goto ReFault;
}
uvm_lock_pageq();
/* make sure it is in queues */
uvm_pageactivate(uobjpage);
uvm_unlock_pageq();
uobjpage->flags &= ~(PG_BUSY|PG_WANTED);
UVM_PAGE_OWN(uobjpage, NULL);
simple_unlock(&uobj->vmobjlock);
goto ReFault;
}
/*
* we have the data in uobjpage which is PG_BUSY and
* !PG_RELEASED. we are holding object lock (so the page
* can't be released on us).
*/
/* locked: maps(read), amap(if !null), uobj, uobjpage */
}
/*
* locked:
* maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj)
*/
/*
* notes:
* - at this point uobjpage can not be NULL
* - at this point uobjpage can not be PG_RELEASED (since we checked
* for it above)
* - at this point uobjpage could be PG_WANTED (handle later)
*/
if (promote == FALSE) {
/*
* we are not promoting. if the mapping is COW ensure that we
* don't give more access than we should (e.g. when doing a read
* fault on a COPYONWRITE mapping we want to map the COW page in
* R/O even though the entry protection could be R/W).
*
* set "pg" to the page we want to map in (uobjpage, usually)
*/
uvmexp.flt_obj++;
if (UVM_ET_ISCOPYONWRITE(ufi.entry))
enter_prot &= ~VM_PROT_WRITE;
pg = uobjpage; /* map in the actual object */
/* assert(uobjpage != PGO_DONTCARE) */
/*
* we are faulting directly on the page. be careful
* about writing to loaned pages...
*/
if (uobjpage->loan_count) {
if ((access_type & VM_PROT_WRITE) == 0) {
/* read fault: cap the protection at readonly */
/* cap! */
enter_prot = enter_prot & ~VM_PROT_WRITE;
} else {
/* write fault: must break the loan here */
/* alloc new un-owned page */
pg = uvm_pagealloc(NULL, 0, NULL, 0);
if (pg == NULL) {
/*
* drop ownership of page, it can't
* be released
*/
if (uobjpage->flags & PG_WANTED)
wakeup(uobjpage);
uobjpage->flags &= ~(PG_BUSY|PG_WANTED);
UVM_PAGE_OWN(uobjpage, NULL);
uvm_lock_pageq();
/* activate: we will need it later */
uvm_pageactivate(uobjpage);
uvm_unlock_pageq();
uvmfault_unlockall(&ufi, amap, uobj,
NULL);
UVMHIST_LOG(maphist,
" out of RAM breaking loan, waiting",
0,0,0,0);
uvmexp.fltnoram++;
uvm_wait("flt_noram4");
goto ReFault;
}
/*
* copy the data from the old page to the new
* one and clear the fake/clean flags on the
* new page (keep it busy). force a reload
* of the old page by clearing it from all
* pmaps. then lock the page queues to
* rename the pages.
*/
uvm_pagecopy(uobjpage, pg); /* old -> new */
pg->flags &= ~(PG_FAKE|PG_CLEAN);
pmap_page_protect(uobjpage, VM_PROT_NONE);
if (uobjpage->flags & PG_WANTED)
wakeup(uobjpage);
/* uobj still locked */
uobjpage->flags &= ~(PG_WANTED|PG_BUSY);
UVM_PAGE_OWN(uobjpage, NULL);
uvm_lock_pageq();
offset = uobjpage->offset;
/* remove old page */
uvm_pagerealloc(uobjpage, NULL, 0);
/*
* at this point we have absolutely no
* control over uobjpage
*/
/* install new page */
uvm_pagerealloc(pg, uobj, offset);
uvm_unlock_pageq();
/*
* done! loan is broken and "pg" is
* PG_BUSY. it can now replace uobjpage.
*/
uobjpage = pg;
} /* write fault case */
} /* if loan_count */
} else {
/*
* if we are going to promote the data to an anon we
* allocate a blank anon here and plug it into our amap.
*/
#if DIAGNOSTIC
if (amap == NULL)
panic("uvm_fault: want to promote data, but no anon");
#endif
anon = uvm_analloc();
if (anon)
pg = uvm_pagealloc(NULL, 0, anon, 0);
#ifdef __GNUC__
else
pg = NULL; /* XXX: gcc */
#endif
/*
* out of memory resources?
*/
if (anon == NULL || pg == NULL) {
/*
* arg! must unbusy our page and fail or sleep.
*/
if (uobjpage != PGO_DONTCARE) {
if (uobjpage->flags & PG_WANTED)
/* still holding object lock */
wakeup(uobjpage);
uvm_lock_pageq();
/* make sure it is in queues */
uvm_pageactivate(uobjpage);
uvm_unlock_pageq();
/* un-busy! (still locked) */
uobjpage->flags &= ~(PG_BUSY|PG_WANTED);
UVM_PAGE_OWN(uobjpage, NULL);
}
/* unlock and fail ... */
uvmfault_unlockall(&ufi, amap, uobj, NULL);
#ifdef DIAGNOSTIC
if (uvmexp.swpgonly > uvmexp.swpages) {
panic("uvmexp.swpgonly botch");
}
#endif
if (anon == NULL || uvmexp.swpgonly == uvmexp.swpages) {
UVMHIST_LOG(maphist, " promote: out of VM",
0,0,0,0);
uvmexp.fltnoanon++;
return (KERN_RESOURCE_SHORTAGE);
}
UVMHIST_LOG(maphist, " out of RAM, waiting for more",
0,0,0,0);
uvm_anfree(anon);
uvmexp.fltnoram++;
uvm_wait("flt_noram5");
goto ReFault;
}
/*
* fill in the data
*/
if (uobjpage != PGO_DONTCARE) {
uvmexp.flt_prcopy++;
/* copy page [pg now dirty] */
uvm_pagecopy(uobjpage, pg);
/*
* promote to shared amap? make sure all sharing
* procs see it
*/
if ((amap_flags(amap) & AMAP_SHARED) != 0) {
pmap_page_protect(uobjpage, VM_PROT_NONE);
}
/*
* dispose of uobjpage. it can't be PG_RELEASED
* since we still hold the object lock. drop
* handle to uobj as well.
*/
if (uobjpage->flags & PG_WANTED)
/* still have the obj lock */
wakeup(uobjpage);
uobjpage->flags &= ~(PG_BUSY|PG_WANTED);
UVM_PAGE_OWN(uobjpage, NULL);
uvm_lock_pageq();
uvm_pageactivate(uobjpage); /* put it back */
uvm_unlock_pageq();
simple_unlock(&uobj->vmobjlock);
uobj = NULL;
UVMHIST_LOG(maphist,
" promote uobjpage 0x%x to anon/page 0x%x/0x%x",
uobjpage, anon, pg, 0);
} else {
uvmexp.flt_przero++;
uvm_pagezero(pg); /* zero page [pg now dirty] */
UVMHIST_LOG(maphist," zero fill anon/page 0x%x/0%x",
anon, pg, 0, 0);
}
amap_add(&ufi.entry->aref, ufi.orig_rvaddr - ufi.entry->start,
anon, 0);
}
/*
* locked:
* maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj)
*
* note: pg is either the uobjpage or the new page in the new anon
*/
/*
* all resources are present. we can now map it in and free our
* resources.
*/
UVMHIST_LOG(maphist,
" MAPPING: case2: pm=0x%x, va=0x%x, pg=0x%x, promote=%d",
ufi.orig_map->pmap, ufi.orig_rvaddr, pg, promote);
if (pmap_enter(ufi.orig_map->pmap, ufi.orig_rvaddr, VM_PAGE_TO_PHYS(pg),
enter_prot, access_type | PMAP_CANFAIL | (wired ? PMAP_WIRED : 0))
!= KERN_SUCCESS) {
/*
* No need to undo what we did; we can simply think of
* this as the pmap throwing away the mapping information.
*
* We do, however, have to go through the ReFault path,
* as the map may change while we're asleep.
*/
if (pg->flags & PG_WANTED)
wakeup(pg); /* lock still held */
/*
* note that pg can't be PG_RELEASED since we did not drop
* the object lock since the last time we checked.
*/
pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED);
UVM_PAGE_OWN(pg, NULL);
uvmfault_unlockall(&ufi, amap, uobj, NULL);
#ifdef DIAGNOSTIC
if (uvmexp.swpgonly > uvmexp.swpages)
panic("uvmexp.swpgonly botch");
#endif
if (uvmexp.swpgonly == uvmexp.swpages) {
UVMHIST_LOG(maphist,
"<- failed. out of VM",0,0,0,0);
/* XXX instrumentation */
return (KERN_RESOURCE_SHORTAGE);
}
/* XXX instrumentation */
uvm_wait("flt_pmfail2");
goto ReFault;
}
uvm_lock_pageq();
if (fault_type == VM_FAULT_WIRE) {
uvm_pagewire(pg);
if (pg->pqflags & PQ_AOBJ) {
/*
* since the now-wired page cannot be paged out,
* release its swap resources for others to use.
* since an aobj page with no swap cannot be PG_CLEAN,
* clear its clean flag now.
*/
pg->flags &= ~(PG_CLEAN);
uao_dropswap(uobj, pg->offset >> PAGE_SHIFT);
}
} else {
/* activate it */
uvm_pageactivate(pg);
}
uvm_unlock_pageq();
if (pg->flags & PG_WANTED)
wakeup(pg); /* lock still held */
/*
* note that pg can't be PG_RELEASED since we did not drop the object
* lock since the last time we checked.
*/
pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED);
UVM_PAGE_OWN(pg, NULL);
uvmfault_unlockall(&ufi, amap, uobj, NULL);
UVMHIST_LOG(maphist, "<- done (SUCCESS!)",0,0,0,0);
return (KERN_SUCCESS);
}
/*
* uvm_fault_wire: wire down a range of virtual addresses in a map.
*
* => map may be read-locked by caller, but MUST NOT be write-locked.
* => if map is read-locked, any operations which may cause map to
* be write-locked in uvm_fault() must be taken care of by
* the caller. See uvm_map_pageable().
*/
int
uvm_fault_wire(map, start, end, access_type)
vm_map_t map;
vaddr_t start, end;
vm_prot_t access_type;
{
vaddr_t va;
pmap_t pmap;
int rv;
pmap = vm_map_pmap(map);
/*
* fault it in page at a time. if the fault fails then we have
* to undo what we have done.
*/
for (va = start ; va < end ; va += PAGE_SIZE) {
rv = uvm_fault(map, va, VM_FAULT_WIRE, access_type);
if (rv) {
if (va != start) {
uvm_fault_unwire(map, start, va);
}
return (rv);
}
}
return (KERN_SUCCESS);
}
/*
* uvm_fault_unwire(): unwire range of virtual space.
*/
void
uvm_fault_unwire(map, start, end)
vm_map_t map;
vaddr_t start, end;
{
vm_map_lock_read(map);
uvm_fault_unwire_locked(map, start, end);
vm_map_unlock_read(map);
}
/*
* uvm_fault_unwire_locked(): the guts of uvm_fault_unwire().
*
* => map must be at least read-locked.
*/
void
uvm_fault_unwire_locked(map, start, end)
vm_map_t map;
vaddr_t start, end;
{
vm_map_entry_t entry;
pmap_t pmap = vm_map_pmap(map);
vaddr_t va;
paddr_t pa;
struct vm_page *pg;
#ifdef DIAGNOSTIC
if (map->flags & VM_MAP_INTRSAFE)
panic("uvm_fault_unwire_locked: intrsafe map");
#endif
/*
* we assume that the area we are unwiring has actually been wired
* in the first place. this means that we should be able to extract
* the PAs from the pmap. we also lock out the page daemon so that
* we can call uvm_pageunwire.
*/
uvm_lock_pageq();
/*
* find the beginning map entry for the region.
*/
#ifdef DIAGNOSTIC
if (start < vm_map_min(map) || end > vm_map_max(map))
panic("uvm_fault_unwire_locked: address out of range");
#endif
if (uvm_map_lookup_entry(map, start, &entry) == FALSE)
panic("uvm_fault_unwire_locked: address not in map");
for (va = start; va < end ; va += PAGE_SIZE) {
if (pmap_extract(pmap, va, &pa) == FALSE)
panic("uvm_fault_unwire_locked: unwiring "
"non-wired memory");
/*
* make sure the current entry is for the address we're
* dealing with. if not, grab the next entry.
*/
#ifdef DIAGNOSTIC
if (va < entry->start)
panic("uvm_fault_unwire_locked: hole 1");
#endif
if (va >= entry->end) {
#ifdef DIAGNOSTIC
if (entry->next == &map->header ||
entry->next->start > entry->end)
panic("uvm_fault_unwire_locked: hole 2");
#endif
entry = entry->next;
}
/*
* if the entry is no longer wired, tell the pmap.
*/
if (VM_MAPENT_ISWIRED(entry) == 0)
pmap_unwire(pmap, va);
pg = PHYS_TO_VM_PAGE(pa);
if (pg)
uvm_pageunwire(pg);
}
uvm_unlock_pageq();
}
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