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uvm_fault.c
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uvm_fault.c
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/* $NetBSD: uvm_fault.c,v 1.76.4.3 2002/12/10 07:14:41 jmc 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
*/
/*
* uvm_fault.c: fault handler
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_fault.c,v 1.76.4.3 2002/12/10 07:14:41 jmc Exp $");
#include "opt_uvmhist.h"
#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 <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_clear_reference(pg);
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;
{
for (;;) {
/*
* 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 != 0) 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 error;
UVMHIST_FUNC("uvmfault_anonget"); UVMHIST_CALLED(maphist);
LOCK_ASSERT(simple_lock_held(&anon->an_lock));
error = 0;
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.
*/
for (;;) {
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) == 0) {
UVMHIST_LOG(maphist, "<- OK",0,0,0,0);
return (0);
}
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);
}
} 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");
} 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++;
error = uvm_swap_get(pg, anon->an_swslot,
PGO_SYNCIO);
/*
* we clean up after the i/o below in the
* "we_own" case
*/
}
}
/*
* now relock and try again
*/
locked = uvmfault_relock(ufi);
if (locked && amap != NULL) {
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) {
wakeup(pg);
}
if (error) {
/* remove page from anon */
anon->u.an_page = NULL;
/*
* remove the swap slot from the anon
* and mark the anon as having no real slot.
* don't free the swap slot, thus preventing
* it from being used again.
*/
uvm_swap_markbad(anon->an_swslot, 1);
anon->an_swslot = SWSLOT_BAD;
/*
* 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 error;
}
/*
* we've successfully read the page, activate it.
*/
uvm_lock_pageq();
uvm_pageactivate(pg);
uvm_unlock_pageq();
pg->flags &= ~(PG_WANTED|PG_BUSY|PG_FAKE);
UVM_PAGE_OWN(pg, NULL);
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 (ERESTART);
}
/*
* verify no one has touched the amap and moved the anon on us.
*/
if (ufi != NULL &&
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 (ERESTART);
}
/*
* try it again!
*/
uvmexp.fltanretry++;
continue;
}
/*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.
* => MUST NEVER BE CALLED IN INTERRUPT CONTEXT
*/
#define MASK(entry) (UVM_ET_ISCOPYONWRITE(entry) ? \
~VM_PROT_WRITE : VM_PROT_ALL)
int
uvm_fault(orig_map, vaddr, fault_type, access_type)
struct vm_map *orig_map;
vaddr_t vaddr;
vm_fault_t fault_type;
vm_prot_t access_type;
{
struct uvm_faultinfo ufi;
vm_prot_t enter_prot, check_prot;
boolean_t wired, narrow, promote, locked, shadowed, wire_fault, cow_now;
int npages, nback, nforw, centeridx, error, lcv, gotpages;
vaddr_t startva, objaddr, currva, offset;
voff_t uoff;
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;
pg = NULL;
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 */
wire_fault = fault_type == VM_FAULT_WIRE ||
fault_type == VM_FAULT_WIREMAX;
if (wire_fault)
narrow = TRUE; /* don't look for neighborhood
* pages on wire */
else
narrow = FALSE; /* normal fault */
/*
* "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 (EFAULT);
}
/* locked: maps(read) */
#ifdef DIAGNOSTIC
if ((ufi.map->flags & VM_MAP_PAGEABLE) == 0) {
printf("Page fault on non-pageable map:\n");
printf("ufi.map = %p\n", ufi.map);
printf("ufi.orig_map = %p\n", ufi.orig_map);
printf("ufi.orig_rvaddr = 0x%lx\n", (u_long) ufi.orig_rvaddr);
panic("uvm_fault: (ufi.map->flags & VM_MAP_PAGEABLE) == 0");
}
#endif
/*
* check protection
*/
check_prot = fault_type == VM_FAULT_WIREMAX ?
ufi.entry->max_protection : ufi.entry->protection;
if ((check_prot & 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 EACCES;
}
/*
* "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) || wire_fault;
if (wired) {
access_type = enter_prot; /* full access for wired */
cow_now = (check_prot & VM_PROT_WRITE) != 0;
} else {
cow_now = (access_type & VM_PROT_WRITE) != 0;
}
/*
* 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)) {
KASSERT(fault_type != VM_FAULT_WIREMAX);
if (cow_now || (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 (EFAULT);
}
/*
* 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) */
KASSERT(uvmadvice[ufi.entry->advice].advice ==
ufi.entry->advice);
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 && nback != 0) {
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_put)(uobj, objaddr, objaddr +
(nback << PAGE_SHIFT), PGO_DEACTIVATE);
}
/* now forget about the backpages */
if (amap)
anons += nback;
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 &&
pmap_extract(ufi.orig_map->pmap, currva, &pa)) {
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_BUSY) == 0) {
uvm_lock_pageq();
uvm_pageactivate(anon->u.an_page);
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);
pmap_update(ufi.orig_map->pmap);
}
/* 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 */
error = uobj->pgops->pgo_fault(&ufi, startva, pages, npages,
centeridx, fault_type, access_type, PGO_LOCKED|PGO_SYNCIO);
/* locked: nothing, pgo_fault has unlocked everything */
if (error == ERESTART)
goto ReFault; /* try again! */
/*
* object fault routine responsible for pmap_update().
*/
return error;
}
/*
* 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).
*/
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;
(void) 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;
}
/*
* 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;
}
/*
* calling pgo_get with PGO_LOCKED returns us
* pages which are neither busy nor released,
* so we don't need to check for this.
* we can just directly enter the pages.
*/
uvm_lock_pageq();
uvm_pageactivate(pages[lcv]);
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]),
pages[lcv]->flags & PG_RDONLY ?
enter_prot & ~VM_PROT_WRITE :
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);
UVM_PAGE_OWN(pages[lcv], NULL);
}
pmap_update(ufi.orig_map->pmap);
}
} 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);