Aren
/
NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
NetBSD/sys/uvm/uvm_fault.c

1753 lines
46 KiB
C
Raw Blame History

/* $NetBSD: uvm_fault.c,v 1.9 1998/03/26 21:50:14 chuck Exp $ */
/*
* XXXCDC: "ROUGH DRAFT" QUALITY UVM PRE-RELEASE FILE!
* >>>USE AT YOUR OWN RISK, WORK IS NOT FINISHED<<<
*/
/*
*
* 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/mount.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 <sys/syscallargs.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(PMAP_PGARG(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->rvaddr,
ufi->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);
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.
*/
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) {
simple_lock(&amap->am_l);
}
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 */
thread_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(PMAP_PGARG(pg),
VM_PROT_NONE); /* to be safe */
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(PMAP_PGARG(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->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.
*/
int
uvm_fault(orig_map, vaddr, fault_type, access_type)
vm_map_t orig_map;
vm_offset_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;
vm_offset_t orig_startva, startva, objaddr, currva, pa, offset;
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 */
/*
* "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);
}
/*
* "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 = (ufi.entry->wired_count != 0) || (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 = 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.rvaddr - ufi.entry->start) / PAGE_SIZE);
startva = ufi.rvaddr - (nback * PAGE_SIZE);
orig_startva = ufi.orig_rvaddr - (nback * PAGE_SIZE);
nforw = min(uvmadvice[ufi.entry->advice].nforw,
((ufi.entry->end - ufi.rvaddr) / PAGE_SIZE) - 1);
/*
* note: "-1" because we don't want to count the
* faulting page as forw
*/
npages = nback + nforw + 1;
centeridx = nback;
narrow = FALSE; /* ensure only once per-fault */
} else {
/* narrow fault! */
nback = nforw = 0;
startva = ufi.rvaddr;
orig_startva = ufi.orig_rvaddr;
npages = 1;
centeridx = 0;
}
/* locked: maps(read) */
UVMHIST_LOG(maphist, " narrow=%d, back=%d, forw=%d, orig_startva=0x%x",
narrow, nback, nforw, orig_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) {
simple_lock(&amap->am_l);
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_SIZE), PGO_DEACTIVATE);
simple_unlock(&uobj->vmobjlock);
}
/* now forget about the backpages */
if (amap)
anons += nback;
startva = startva + (nback * PAGE_SIZE);
orig_startva = orig_startva + (nback * PAGE_SIZE);
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 = orig_startva;
shadowed = FALSE;
for (lcv = 0 ; lcv < npages ; lcv++, currva += PAGE_SIZE) {
/*
* dont play with VAs that are already mapped
* *except for center)
* XXX: return value of pmap_extract disallows PA 0
*/
if (lcv != centeridx) {
pa = pmap_extract(ufi.orig_map->pmap, currva);
if (pa != NULL) {
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++;
pmap_enter(ufi.orig_map->pmap, currva,
VM_PAGE_TO_PHYS(anon->u.an_page),
(anon->an_ref > 1) ? VM_PROT_READ : enter_prot,
(ufi.entry->wired_count != 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?
* XXXCDC: this is fixed in PMAP_NEW (no sleep alloc's in pmap)
*/
/*
* 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.
*
* note: pgo_fault can obtain the correct VA for pmap_enter by using:
* real_va = [ ufi->orig_rvaddr + (startva - ufi->rvaddr)]
*/
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,
UVM_ET_ISCOPYONWRITE(ufi.entry) ?
VM_PROT_READ : access_type,
ufi.entry->advice, PGO_LOCKED);
/*
* check for pages to map, if we got any
*/
uobjpage = NULL;
if (gotpages) {
currva = orig_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++;
pmap_enter(ufi.orig_map->pmap, currva,
VM_PAGE_TO_PHYS(pages[lcv]),
UVM_ET_ISCOPYONWRITE(ufi.entry) ?
VM_PROT_READ : enter_prot, wired);
/*
* 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);
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(PMAP_PGARG(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);
#if defined(sparc)
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);
if (anon == NULL) {
UVMHIST_LOG(maphist,
"<- failed. out of VM",0,0,0,0);
uvmexp.fltnoanon++;
/* XXX: OUT OF VM, ??? */
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.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);
pmap_enter(ufi.orig_map->pmap, ufi.orig_rvaddr, VM_PAGE_TO_PHYS(pg),
enter_prot, wired);
/*
* ... and update the page queues.
*/
uvm_lock_pageq();
if (fault_type == VM_FAULT_WIRE) {
uvm_pagewire(pg);
} 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.rvaddr - ufi.entry->start) + ufi.entry->offset,
&uobjpage, &gotpages, 0,
UVM_ET_ISCOPYONWRITE(ufi.entry) ?
VM_PROT_READ : access_type,
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)
simple_lock(&amap->am_l);
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.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 */
thread_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 = 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);
if (pg == NULL) {
/*
* drop ownership of page, it can't
* be released
* */
if (uobjpage->flags & PG_WANTED)
thread_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(PMAP_PGARG(uobjpage),
VM_PROT_NONE);
if (uobjpage->flags & PG_WANTED)
thread_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); /* BUSY+CLEAN+FAKE */
#if defined(sparc)
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 */
thread_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);
if (anon == NULL) {
UVMHIST_LOG(maphist, " promote: out of VM",
0,0,0,0);
uvmexp.fltnoanon++;
/* XXX: out of VM */
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->am_flags & AMAP_SHARED) != 0) {
pmap_page_protect(PMAP_PGARG(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 */
thread_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.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);
pmap_enter(ufi.orig_map->pmap, ufi.orig_rvaddr, VM_PAGE_TO_PHYS(pg),
enter_prot, wired);
uvm_lock_pageq();
if (fault_type == VM_FAULT_WIRE) {
uvm_pagewire(pg);
} else {
/* activate it */
uvm_pageactivate(pg);
}
uvm_unlock_pageq();
if (pg->flags & PG_WANTED)
thread_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 should be locked by caller? If so how can we call
* uvm_fault? WRONG.
* => XXXCDC: locking here is all screwed up!!! start with
* uvm_map_pageable and fix it.
*/
int
uvm_fault_wire(map, start, end)
vm_map_t map;
vm_offset_t start, end;
{
vm_offset_t va;
pmap_t pmap;
int rv;
pmap = vm_map_pmap(map);
/*
* call pmap pageable: this tells the pmap layer to lock down these
* page tables.
*/
pmap_pageable(pmap, start, end, FALSE);
/*
* now fault it in page at a time. if the fault fails then we have
* to undo what we have done. note that in uvm_fault VM_PROT_NONE
* is replaced with the max protection if fault_type is VM_FAULT_WIRE.
*/
for (va = start ; va < end ; va += PAGE_SIZE) {
rv = uvm_fault(map, va, VM_FAULT_WIRE, VM_PROT_NONE);
if (rv) {
if (va != start) {
uvm_fault_unwire(map->pmap, start, va);
}
return(rv);
}
}
return(KERN_SUCCESS);
}
/*
* uvm_fault_unwire(): unwire range of virtual space.
*
* => caller holds reference to pmap (via its map)
*/
void
uvm_fault_unwire(pmap, start, end)
struct pmap *pmap;
vm_offset_t start, end;
{
vm_offset_t va, pa;
struct vm_page *pg;
/*
* 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();
for (va = start; va < end ; va += PAGE_SIZE) {
pa = pmap_extract(pmap, va);
/* XXX: assumes PA 0 cannot be in map */
if (pa == (vm_offset_t) 0) {
panic("uvm_fault_unwire: unwiring non-wired memory");
}
pmap_change_wiring(pmap, va, FALSE); /* tell the pmap */
pg = PHYS_TO_VM_PAGE(pa);
if (pg)
uvm_pageunwire(pg);
}
uvm_unlock_pageq();
/*
* now we call pmap_pageable to let the pmap know that the page tables
* in this space no longer need to be wired.
*/
pmap_pageable(pmap, start, end, TRUE);
}
Reference in New Issue View Git Blame Copy Permalink