File: [local] / src / sys / uvm / uvm_fault.c (download)
Revision 1.135, Tue Sep 5 05:08:26 2023 UTC (8 months, 4 weeks ago) by guenther
Branch: MAIN
CVS Tags: OPENBSD_7_5_BASE, OPENBSD_7_5, OPENBSD_7_4_BASE, OPENBSD_7_4, HEAD
Changes since 1.134: +15 -2 lines
Address the case 2b version of inconsistent view across threads of
a page undergoing copy-on-write faulting. We fixed the case 1b
version in rev 1.125 (2022-02-01), but missed this other path.
jsg@ noted that in NetBSD Chuck Silvers had a relevant commit, their
rev 1.234 (2023-08-13), which looks like it fixed both cases due
to their refactoring of common code into a uvmfault_promote()
function.
ok mpi@ jca@
|
/* $OpenBSD: uvm_fault.c,v 1.135 2023/09/05 05:08:26 guenther Exp $ */
/* $NetBSD: uvm_fault.c,v 1.51 2000/08/06 00:22:53 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.
*
* 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/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/percpu.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/tracepoint.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 upper 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: (ERESTART returned to the loop in uvm_fault)
* - 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...).
*
* we use alternative 2. given that we are multi-threaded now we may want
* to reconsider the choice.
*/
/*
* local data structures
*/
struct uvm_advice {
int nback;
int nforw;
};
/*
* page range array: set up in uvmfault_init().
*/
static struct uvm_advice uvmadvice[MADV_MASK + 1];
#define UVM_MAXRANGE 16 /* must be max() of nback+nforw+1 */
/*
* private prototypes
*/
static void uvmfault_amapcopy(struct uvm_faultinfo *);
static inline void uvmfault_anonflush(struct vm_anon **, int);
void uvmfault_unlockmaps(struct uvm_faultinfo *, boolean_t);
void uvmfault_update_stats(struct uvm_faultinfo *);
/*
* 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(struct vm_anon **anons, int n)
{
int lcv;
struct vm_page *pg;
for (lcv = 0; lcv < n; lcv++) {
if (anons[lcv] == NULL)
continue;
KASSERT(rw_lock_held(anons[lcv]->an_lock));
pg = anons[lcv]->an_page;
if (pg && (pg->pg_flags & PG_BUSY) == 0) {
uvm_lock_pageq();
if (pg->wire_count == 0) {
pmap_page_protect(pg, PROT_NONE);
uvm_pagedeactivate(pg);
}
uvm_unlock_pageq();
}
}
}
/*
* normal functions
*/
/*
* uvmfault_init: compute proper values for the uvmadvice[] array.
*/
void
uvmfault_init(void)
{
int npages;
npages = atop(16384);
if (npages > 0) {
KASSERT(npages <= UVM_MAXRANGE / 2);
uvmadvice[MADV_NORMAL].nforw = npages;
uvmadvice[MADV_NORMAL].nback = npages - 1;
}
npages = atop(32768);
if (npages > 0) {
KASSERT(npages <= UVM_MAXRANGE / 2);
uvmadvice[MADV_SEQUENTIAL].nforw = npages - 1;
uvmadvice[MADV_SEQUENTIAL].nback = npages;
}
}
/*
* 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(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,
UVM_ET_ISSTACK(ufi->entry) ? FALSE : 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.
*
* => Map, amap and thus anon should be locked by caller.
* => If we fail, we unlock everything and error is returned.
* => If we are successful, return with everything still locked.
* => We do not 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
*/
int
uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap,
struct vm_anon *anon)
{
struct vm_page *pg;
int error;
KASSERT(rw_lock_held(anon->an_lock));
KASSERT(anon->an_lock == amap->am_lock);
/* Increment the counters.*/
counters_inc(uvmexp_counters, flt_anget);
if (anon->an_page) {
curproc->p_ru.ru_minflt++;
} else {
curproc->p_ru.ru_majflt++;
}
error = 0;
/*
* Loop until we get the anon data, or fail.
*/
for (;;) {
boolean_t we_own, locked;
/*
* Note: 'we_own' will become true if we set PG_BUSY on a page.
*/
we_own = FALSE;
pg = anon->an_page;
/*
* Is page resident? Make sure it is not busy/released.
*/
if (pg) {
KASSERT(pg->pg_flags & PQ_ANON);
KASSERT(pg->uanon == anon);
/*
* if the page is busy, we drop all the locks and
* try again.
*/
if ((pg->pg_flags & (PG_BUSY|PG_RELEASED)) == 0)
return (VM_PAGER_OK);
atomic_setbits_int(&pg->pg_flags, PG_WANTED);
counters_inc(uvmexp_counters, flt_pgwait);
/*
* The last unlock must be an atomic unlock and wait
* on the owner of page.
*/
if (pg->uobject) {
/* Owner of page is UVM object. */
uvmfault_unlockall(ufi, amap, NULL);
rwsleep_nsec(pg, pg->uobject->vmobjlock,
PVM | PNORELOCK, "anonget1", INFSLP);
} else {
/* Owner of page is anon. */
uvmfault_unlockall(ufi, NULL, NULL);
rwsleep_nsec(pg, anon->an_lock, PVM | PNORELOCK,
"anonget2", INFSLP);
}
} else {
/*
* No page, therefore allocate one.
*/
pg = uvm_pagealloc(NULL, 0, anon, 0);
if (pg == NULL) {
/* Out of memory. Wait a little. */
uvmfault_unlockall(ufi, amap, NULL);
counters_inc(uvmexp_counters, flt_noram);
uvm_wait("flt_noram1");
} else {
/* PG_BUSY bit is set. */
we_own = TRUE;
uvmfault_unlockall(ufi, amap, NULL);
/*
* Pass 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.
*/
counters_inc(uvmexp_counters, pageins);
error = uvm_swap_get(pg, anon->an_swslot,
PGO_SYNCIO);
/*
* We clean up after the I/O below in the
* 'we_own' case.
*/
}
}
/*
* Re-lock the map and anon.
*/
locked = uvmfault_relock(ufi);
if (locked || we_own) {
rw_enter(anon->an_lock, RW_WRITE);
}
/*
* 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 was 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->pg_flags & PG_WANTED) {
wakeup(pg);
}
/*
* 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->pg_flags & PG_RELEASED) {
KASSERT(anon->an_ref == 0);
/*
* Released while we had unlocked amap.
*/
if (locked)
uvmfault_unlockall(ufi, NULL, NULL);
uvm_anon_release(anon); /* frees page for us */
counters_inc(uvmexp_counters, flt_pgrele);
return (VM_PAGER_REFAULT); /* refault! */
}
if (error != VM_PAGER_OK) {
KASSERT(error != VM_PAGER_PEND);
/* remove page from anon */
anon->an_page = NULL;
/*
* Remove the swap slot from the anon and
* mark the anon as having no real slot.
* Do not 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
* cannot 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, NULL, NULL);
}
rw_exit(anon->an_lock);
return (VM_PAGER_ERROR);
}
/*
* We have successfully read the page, activate it.
*/
pmap_clear_modify(pg);
uvm_lock_pageq();
uvm_pageactivate(pg);
uvm_unlock_pageq();
atomic_clearbits_int(&pg->pg_flags,
PG_WANTED|PG_BUSY|PG_FAKE);
UVM_PAGE_OWN(pg, NULL);
}
/*
* We were not able to re-lock the map - restart the fault.
*/
if (!locked) {
if (we_own) {
rw_exit(anon->an_lock);
}
return (VM_PAGER_REFAULT);
}
/*
* Verify that 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);
return (VM_PAGER_REFAULT);
}
/*
* Retry..
*/
counters_inc(uvmexp_counters, flt_anretry);
continue;
}
/*NOTREACHED*/
}
/*
* Update statistics after fault resolution.
* - maxrss
*/
void
uvmfault_update_stats(struct uvm_faultinfo *ufi)
{
struct vm_map *map;
struct proc *p;
vsize_t res;
map = ufi->orig_map;
/*
* If this is a nested pmap (eg, a virtual machine pmap managed
* by vmm(4) on amd64/i386), don't do any updating, just return.
*
* pmap_nested() on other archs is #defined to 0, so this is a
* no-op.
*/
if (pmap_nested(map->pmap))
return;
/* Update the maxrss for the process. */
if (map->flags & VM_MAP_ISVMSPACE) {
p = curproc;
KASSERT(p != NULL && &p->p_vmspace->vm_map == map);
res = pmap_resident_count(map->pmap);
/* Convert res from pages to kilobytes. */
res <<= (PAGE_SHIFT - 10);
if (p->p_ru.ru_maxrss < res)
p->p_ru.ru_maxrss = res;
}
}
/*
* 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 recursive, 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) ? \
~PROT_WRITE : PROT_MASK)
struct uvm_faultctx {
/*
* the following members are set up by uvm_fault_check() and
* read-only after that.
*/
vm_prot_t enter_prot;
vm_prot_t access_type;
vaddr_t startva;
int npages;
int centeridx;
boolean_t narrow;
boolean_t wired;
paddr_t pa_flags;
};
int uvm_fault_check(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct vm_anon ***);
int uvm_fault_upper(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct vm_anon **, vm_fault_t);
boolean_t uvm_fault_upper_lookup(
struct uvm_faultinfo *, const struct uvm_faultctx *,
struct vm_anon **, struct vm_page **);
int uvm_fault_lower(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct vm_page **, vm_fault_t);
int
uvm_fault(vm_map_t orig_map, vaddr_t vaddr, vm_fault_t fault_type,
vm_prot_t access_type)
{
struct uvm_faultinfo ufi;
struct uvm_faultctx flt;
boolean_t shadowed;
struct vm_anon *anons_store[UVM_MAXRANGE], **anons;
struct vm_page *pages[UVM_MAXRANGE];
int error;
counters_inc(uvmexp_counters, faults);
TRACEPOINT(uvm, fault, vaddr, fault_type, access_type, NULL);
/*
* 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)
flt.narrow = TRUE; /* don't look for neighborhood
* pages on wire */
else
flt.narrow = FALSE; /* normal fault */
flt.access_type = access_type;
error = ERESTART;
while (error == ERESTART) { /* ReFault: */
anons = anons_store;
error = uvm_fault_check(&ufi, &flt, &anons);
if (error != 0)
continue;
/* True if there is an anon at the faulting address */
shadowed = uvm_fault_upper_lookup(&ufi, &flt, anons, pages);
if (shadowed == TRUE) {
/* case 1: fault on an anon in our amap */
error = uvm_fault_upper(&ufi, &flt, anons, fault_type);
} else {
struct uvm_object *uobj = ufi.entry->object.uvm_obj;
/*
* 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 != NULL && uobj->pgops->pgo_fault != NULL) {
KERNEL_LOCK();
rw_enter(uobj->vmobjlock, RW_WRITE);
error = uobj->pgops->pgo_fault(&ufi,
flt.startva, pages, flt.npages,
flt.centeridx, fault_type, flt.access_type,
PGO_LOCKED);
KERNEL_UNLOCK();
if (error == VM_PAGER_OK)
error = 0;
else if (error == VM_PAGER_REFAULT)
error = ERESTART;
else
error = EACCES;
} else {
/* case 2: fault on backing obj or zero fill */
error = uvm_fault_lower(&ufi, &flt, pages,
fault_type);
}
}
}
return error;
}
/*
* uvm_fault_check: check prot, handle needs-copy, etc.
*
* 1. lookup entry.
* 2. check protection.
* 3. adjust fault condition (mainly for simulated fault).
* 4. handle needs-copy (lazy amap copy).
* 5. establish range of interest for neighbor fault (aka pre-fault).
* 6. look up anons (if amap exists).
* 7. flush pages (if MADV_SEQUENTIAL)
*
* => called with nothing locked.
* => if we fail (result != 0) we unlock everything.
* => initialize/adjust many members of flt.
*/
int
uvm_fault_check(struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
struct vm_anon ***ranons)
{
struct vm_amap *amap;
struct uvm_object *uobj;
int nback, nforw;
/*
* lookup and lock the maps
*/
if (uvmfault_lookup(ufi, FALSE) == FALSE) {
return EFAULT;
}
/* locked: maps(read) */
#ifdef DIAGNOSTIC
if ((ufi->map->flags & VM_MAP_PAGEABLE) == 0)
panic("uvm_fault: fault on non-pageable map (%p, 0x%lx)",
ufi->map, ufi->orig_rvaddr);
#endif
/*
* check protection
*/
if ((ufi->entry->protection & flt->access_type) != flt->access_type) {
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.
*/
flt->enter_prot = ufi->entry->protection;
flt->pa_flags = UVM_ET_ISWC(ufi->entry) ? PMAP_WC : 0;
flt->wired = VM_MAPENT_ISWIRED(ufi->entry) || (flt->narrow == TRUE);
if (flt->wired)
flt->access_type = flt->enter_prot; /* full access for wired */
/* handle "needs_copy" case. */
if (UVM_ET_ISNEEDSCOPY(ufi->entry)) {
if ((flt->access_type & PROT_WRITE) ||
(ufi->entry->object.uvm_obj == NULL)) {
/* need to clear */
uvmfault_unlockmaps(ufi, FALSE);
uvmfault_amapcopy(ufi);
counters_inc(uvmexp_counters, flt_amcopy);
return ERESTART;
} else {
/*
* ensure that we pmap_enter page R/O since
* needs_copy is still true
*/
flt->enter_prot &= ~PROT_WRITE;
}
}
/*
* identify the players
*/
amap = ufi->entry->aref.ar_amap; /* upper layer */
uobj = ufi->entry->object.uvm_obj; /* lower layer */
/*
* check for a case 0 fault. if nothing backing the entry then
* error now.
*/
if (amap == NULL && uobj == NULL) {
uvmfault_unlockmaps(ufi, FALSE);
return EFAULT;
}
/*
* for a case 2B fault waste no time on adjacent pages because
* they are likely already entered.
*/
if (uobj != NULL && amap != NULL &&
(flt->access_type & PROT_WRITE) != 0) {
/* wide fault (!narrow) */
flt->narrow = TRUE;
}
/*
* 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 (flt->narrow == FALSE) {
/* wide fault (!narrow) */
nback = min(uvmadvice[ufi->entry->advice].nback,
(ufi->orig_rvaddr - ufi->entry->start) >> PAGE_SHIFT);
flt->startva = ufi->orig_rvaddr - ((vsize_t)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
*/
flt->npages = nback + nforw + 1;
flt->centeridx = nback;
flt->narrow = TRUE; /* ensure only once per-fault */
} else {
/* narrow fault! */
nback = nforw = 0;
flt->startva = ufi->orig_rvaddr;
flt->npages = 1;
flt->centeridx = 0;
}
/*
* if we've got an amap then lock it and extract current anons.
*/
if (amap) {
amap_lock(amap);
amap_lookups(&ufi->entry->aref,
flt->startva - ufi->entry->start, *ranons, flt->npages);
} else {
*ranons = NULL; /* to be safe */
}
/*
* 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) {
/* flush back-page anons? */
if (amap)
uvmfault_anonflush(*ranons, nback);
/*
* flush object?
*/
if (uobj) {
voff_t uoff;
uoff = (flt->startva - ufi->entry->start) + ufi->entry->offset;
rw_enter(uobj->vmobjlock, RW_WRITE);
(void) uobj->pgops->pgo_flush(uobj, uoff, uoff +
((vsize_t)nback << PAGE_SHIFT), PGO_DEACTIVATE);
rw_exit(uobj->vmobjlock);
}
/* now forget about the backpages */
if (amap)
*ranons += nback;
flt->startva += ((vsize_t)nback << PAGE_SHIFT);
flt->npages -= nback;
flt->centeridx = 0;
}
return 0;
}
/*
* uvm_fault_upper_lookup: look up existing h/w mapping and amap.
*
* iterate range of interest:
* 1. check if h/w mapping exists. if yes, we don't care
* 2. check if anon exists. if not, page is lower.
* 3. if anon exists, enter h/w mapping for neighbors.
*
* => called with amap locked (if exists).
*/
boolean_t
uvm_fault_upper_lookup(struct uvm_faultinfo *ufi,
const struct uvm_faultctx *flt, struct vm_anon **anons,
struct vm_page **pages)
{
struct vm_amap *amap = ufi->entry->aref.ar_amap;
struct vm_anon *anon;
boolean_t shadowed;
vaddr_t currva;
paddr_t pa;
int lcv;
/* locked: maps(read), amap(if there) */
KASSERT(amap == NULL ||
rw_write_held(amap->am_lock));
/*
* 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 = flt->startva;
shadowed = FALSE;
for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) {
/*
* dont play with VAs that are already mapped
* except for center)
*/
if (lcv != flt->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.
*/
pages[lcv] = PGO_DONTCARE;
if (lcv == flt->centeridx) { /* save center for later! */
shadowed = TRUE;
continue;
}
anon = anons[lcv];
KASSERT(anon->an_lock == amap->am_lock);
if (anon->an_page &&
(anon->an_page->pg_flags & (PG_RELEASED|PG_BUSY)) == 0) {
uvm_lock_pageq();
uvm_pageactivate(anon->an_page); /* reactivate */
uvm_unlock_pageq();
counters_inc(uvmexp_counters, flt_namap);
/*
* 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->an_page) | flt->pa_flags,
(anon->an_ref > 1) ?
(flt->enter_prot & ~PROT_WRITE) : flt->enter_prot,
PMAP_CANFAIL |
(VM_MAPENT_ISWIRED(ufi->entry) ? PMAP_WIRED : 0));
}
}
if (flt->npages > 1)
pmap_update(ufi->orig_map->pmap);
return shadowed;
}
/*
* uvm_fault_upper: handle upper fault.
*
* 1. acquire anon lock.
* 2. get anon. let uvmfault_anonget do the dirty work.
* 3. if COW, promote data to new anon
* 4. enter h/w mapping
*/
int
uvm_fault_upper(struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
struct vm_anon **anons, vm_fault_t fault_type)
{
struct vm_amap *amap = ufi->entry->aref.ar_amap;
struct vm_anon *oanon, *anon = anons[flt->centeridx];
struct vm_page *pg = NULL;
int error, ret;
/* locked: maps(read), amap, anon */
KASSERT(rw_write_held(amap->am_lock));
KASSERT(anon->an_lock == amap->am_lock);
/*
* 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 everything for us.
* if it succeeds, 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.
*/
error = uvmfault_anonget(ufi, amap, anon);
switch (error) {
case VM_PAGER_OK:
break;
case VM_PAGER_REFAULT:
return ERESTART;
case VM_PAGER_ERROR:
/*
* An error occurred while trying to bring in the
* page -- this is the only error we return right
* now.
*/
return EACCES; /* XXX */
default:
#ifdef DIAGNOSTIC
panic("uvm_fault: uvmfault_anonget -> %d", error);
#else
return EACCES;
#endif
}
KASSERT(rw_write_held(amap->am_lock));
KASSERT(anon->an_lock == amap->am_lock);
/*
* 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 wait for RAM to become available.
*/
if ((flt->access_type & PROT_WRITE) != 0 && anon->an_ref > 1) {
counters_inc(uvmexp_counters, flt_acow);
oanon = anon; /* oanon = old */
anon = uvm_analloc();
if (anon) {
anon->an_lock = amap->am_lock;
pg = uvm_pagealloc(NULL, 0, anon, 0);
}
/* check for out of RAM */
if (anon == NULL || pg == NULL) {
uvmfault_unlockall(ufi, amap, NULL);
if (anon == NULL)
counters_inc(uvmexp_counters, flt_noanon);
else {
anon->an_lock = NULL;
anon->an_ref--;
uvm_anfree(anon);
counters_inc(uvmexp_counters, flt_noram);
}
if (uvm_swapisfull())
return ENOMEM;
/* out of RAM, wait for more */
if (anon == NULL)
uvm_anwait();
else
uvm_wait("flt_noram3");
return ERESTART;
}
/* got all resources, replace anon with nanon */
uvm_pagecopy(oanon->an_page, pg); /* pg now !PG_CLEAN */
/* un-busy! new page */
atomic_clearbits_int(&pg->pg_flags, PG_BUSY|PG_FAKE);
UVM_PAGE_OWN(pg, NULL);
ret = amap_add(&ufi->entry->aref,
ufi->orig_rvaddr - ufi->entry->start, anon, 1);
KASSERT(ret == 0);
/* deref: can not drop to zero here by defn! */
oanon->an_ref--;
#if defined(MULTIPROCESSOR) && !defined(__HAVE_PMAP_MPSAFE_ENTER_COW)
/*
* If there are multiple threads, either uvm or the
* pmap has to make sure no threads see the old RO
* mapping once any have seen the new RW mapping.
* uvm does it by inserting the new mapping RO and
* letting it fault again.
* This is only a problem on MP systems.
*/
if (P_HASSIBLING(curproc)) {
flt->enter_prot &= ~PROT_WRITE;
flt->access_type &= ~PROT_WRITE;
}
#endif
/*
* note: anon is _not_ locked, but we have the sole references
* to in from amap.
* thus, no one can get at it until we are done with it.
*/
} else {
counters_inc(uvmexp_counters, flt_anon);
oanon = anon;
pg = anon->an_page;
if (anon->an_ref > 1) /* disallow writes to ref > 1 anons */
flt->enter_prot = flt->enter_prot & ~PROT_WRITE;
}
/*
* now map the page in .
*/
if (pmap_enter(ufi->orig_map->pmap, ufi->orig_rvaddr,
VM_PAGE_TO_PHYS(pg) | flt->pa_flags, flt->enter_prot,
flt->access_type | PMAP_CANFAIL | (flt->wired ? PMAP_WIRED : 0)) != 0) {
/*
* 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, NULL);
if (uvm_swapisfull()) {
/* XXX instrumentation */
return ENOMEM;
}
/* XXX instrumentation */
uvm_wait("flt_pmfail1");
return ERESTART;
}
/*
* ... 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.
*/
atomic_clearbits_int(&pg->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, NULL);
pmap_update(ufi->orig_map->pmap);
return 0;
}
/*
* uvm_fault_lower_lookup: look up on-memory uobj pages.
*
* 1. get on-memory pages.
* 2. if failed, give up (get only center page later).
* 3. if succeeded, enter h/w mapping of neighbor pages.
*/
struct vm_page *
uvm_fault_lower_lookup(
struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt,
struct vm_page **pages)
{
struct uvm_object *uobj = ufi->entry->object.uvm_obj;
struct vm_page *uobjpage = NULL;
int lcv, gotpages;
vaddr_t currva;
rw_enter(uobj->vmobjlock, RW_WRITE);
counters_inc(uvmexp_counters, flt_lget);
gotpages = flt->npages;
(void) uobj->pgops->pgo_get(uobj,
ufi->entry->offset + (flt->startva - ufi->entry->start),
pages, &gotpages, flt->centeridx,
flt->access_type & MASK(ufi->entry), ufi->entry->advice,
PGO_LOCKED);
/*
* check for pages to map, if we got any
*/
if (gotpages == 0) {
return NULL;
}
currva = flt->startva;
for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) {
if (pages[lcv] == NULL ||
pages[lcv] == PGO_DONTCARE)
continue;
KASSERT((pages[lcv]->pg_flags & PG_RELEASED) == 0);
/*
* if center page is resident and not
* PG_BUSY, 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 == flt->centeridx) {
uobjpage = pages[lcv];
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();
counters_inc(uvmexp_counters, flt_nomap);
/*
* Since this page 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(pages[lcv]) | flt->pa_flags,
flt->enter_prot & MASK(ufi->entry),
PMAP_CANFAIL |
(flt->wired ? PMAP_WIRED : 0));
/*
* NOTE: page can't be PG_WANTED because
* we've held the lock the whole time
* we've had the handle.
*/
atomic_clearbits_int(&pages[lcv]->pg_flags, PG_BUSY);
UVM_PAGE_OWN(pages[lcv], NULL);
}
pmap_update(ufi->orig_map->pmap);
return uobjpage;
}
/*
* uvm_fault_lower: handle lower fault.
*
*/
int
uvm_fault_lower(struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
struct vm_page **pages, vm_fault_t fault_type)
{
struct vm_amap *amap = ufi->entry->aref.ar_amap;
struct uvm_object *uobj = ufi->entry->object.uvm_obj;
boolean_t promote, locked;
int result;
struct vm_page *uobjpage, *pg = NULL;
struct vm_anon *anon = NULL;
voff_t uoff;
/*
* 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 == NULL) {
/* zero fill; don't care neighbor pages */
uobjpage = NULL;
} else {
uobjpage = uvm_fault_lower_lookup(ufi, flt, pages);
}
/*
* 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 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.
*/
/*
* locked:
*/
KASSERT(amap == NULL ||
rw_write_held(amap->am_lock));
KASSERT(uobj == NULL ||
rw_write_held(uobj->vmobjlock));
/*
* 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 {
KASSERT(uobjpage != PGO_DONTCARE);
promote = (flt->access_type & PROT_WRITE) &&
UVM_ET_ISCOPYONWRITE(ufi->entry);
}
/*
* 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 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_ru.ru_minflt++;
} else {
int gotpages;
/* update rusage counters */
curproc->p_ru.ru_majflt++;
uvmfault_unlockall(ufi, amap, NULL);
counters_inc(uvmexp_counters, flt_get);
gotpages = 1;
uoff = (ufi->orig_rvaddr - ufi->entry->start) + ufi->entry->offset;
result = uobj->pgops->pgo_get(uobj, uoff, &uobjpage, &gotpages,
0, flt->access_type & MASK(ufi->entry), ufi->entry->advice,
PGO_SYNCIO);
/*
* recover from I/O
*/
if (result != VM_PAGER_OK) {
KASSERT(result != VM_PAGER_PEND);
if (result == VM_PAGER_AGAIN) {
tsleep_nsec(&nowake, PVM, "fltagain2",
MSEC_TO_NSEC(5));
return ERESTART;
}
if (!UVM_ET_ISNOFAULT(ufi->entry))
return (EIO);
uobjpage = PGO_DONTCARE;
uobj = NULL;
promote = TRUE;
}
/* re-verify the state of the world. */
locked = uvmfault_relock(ufi);
if (locked && amap != NULL)
amap_lock(amap);
/* might be changed */
if (uobjpage != PGO_DONTCARE) {
uobj = uobjpage->uobject;
rw_enter(uobj->vmobjlock, RW_WRITE);
}
/*
* Re-verify that amap slot is still free. if there is
* a problem, we clean up.
*/
if (locked && amap && amap_lookup(&ufi->entry->aref,
ufi->orig_rvaddr - ufi->entry->start)) {
if (locked)
uvmfault_unlockall(ufi, amap, NULL);
locked = FALSE;
}
/* didn't get the lock? release the page and retry. */
if (locked == FALSE && uobjpage != PGO_DONTCARE) {
uvm_lock_pageq();
/* make sure it is in queues */
uvm_pageactivate(uobjpage);
uvm_unlock_pageq();
if (uobjpage->pg_flags & PG_WANTED)
/* still holding object lock */
wakeup(uobjpage);
atomic_clearbits_int(&uobjpage->pg_flags,
PG_BUSY|PG_WANTED);
UVM_PAGE_OWN(uobjpage, NULL);
}
if (locked == FALSE) {
if (uobjpage != PGO_DONTCARE)
rw_exit(uobj->vmobjlock);
return ERESTART;
}
/*
* we have the data in uobjpage which is PG_BUSY
*/
}
/*
* notes:
* - at this point uobjpage can not be NULL
* - 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)
*/
counters_inc(uvmexp_counters, flt_obj);
if (UVM_ET_ISCOPYONWRITE(ufi->entry))
flt->enter_prot &= ~PROT_WRITE;
pg = uobjpage; /* map in the actual object */
/* assert(uobjpage != PGO_DONTCARE) */
/*
* we are faulting directly on the page.
*/
} else {
/*
* if we are going to promote the data to an anon we
* allocate a blank anon here and plug it into our amap.
*/
#ifdef DIAGNOSTIC
if (amap == NULL)
panic("uvm_fault: want to promote data, but no anon");
#endif
anon = uvm_analloc();
if (anon) {
/*
* In `Fill in data...' below, if
* uobjpage == PGO_DONTCARE, we want
* a zero'd, dirty page, so have
* uvm_pagealloc() do that for us.
*/
anon->an_lock = amap->am_lock;
pg = uvm_pagealloc(NULL, 0, anon,
(uobjpage == PGO_DONTCARE) ? UVM_PGA_ZERO : 0);
}
/*
* out of memory resources?
*/
if (anon == NULL || pg == NULL) {
/*
* arg! must unbusy our page and fail or sleep.
*/
if (uobjpage != PGO_DONTCARE) {
uvm_lock_pageq();
uvm_pageactivate(uobjpage);
uvm_unlock_pageq();
if (uobjpage->pg_flags & PG_WANTED)
wakeup(uobjpage);
atomic_clearbits_int(&uobjpage->pg_flags,
PG_BUSY|PG_WANTED);
UVM_PAGE_OWN(uobjpage, NULL);
}
/* unlock and fail ... */
uvmfault_unlockall(ufi, amap, uobj);
if (anon == NULL)
counters_inc(uvmexp_counters, flt_noanon);
else {
anon->an_lock = NULL;
anon->an_ref--;
uvm_anfree(anon);
counters_inc(uvmexp_counters, flt_noram);
}
if (uvm_swapisfull())
return (ENOMEM);
/* out of RAM, wait for more */
if (anon == NULL)
uvm_anwait();
else
uvm_wait("flt_noram5");
return ERESTART;
}
/*
* fill in the data
*/
if (uobjpage != PGO_DONTCARE) {
counters_inc(uvmexp_counters, 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, PROT_NONE);
}
#if defined(MULTIPROCESSOR) && !defined(__HAVE_PMAP_MPSAFE_ENTER_COW)
/*
* Otherwise:
* If there are multiple threads, either uvm or the
* pmap has to make sure no threads see the old RO
* mapping once any have seen the new RW mapping.
* uvm does it here by forcing it to PROT_NONE before
* inserting the new mapping.
*/
else if (P_HASSIBLING(curproc)) {
pmap_page_protect(uobjpage, PROT_NONE);
}
#endif
/* dispose of uobjpage. drop handle to uobj as well. */
if (uobjpage->pg_flags & PG_WANTED)
wakeup(uobjpage);
atomic_clearbits_int(&uobjpage->pg_flags,
PG_BUSY|PG_WANTED);
UVM_PAGE_OWN(uobjpage, NULL);
uvm_lock_pageq();
uvm_pageactivate(uobjpage);
uvm_unlock_pageq();
rw_exit(uobj->vmobjlock);
uobj = NULL;
} else {
counters_inc(uvmexp_counters, flt_przero);
/*
* Page is zero'd and marked dirty by uvm_pagealloc()
* above.
*/
}
if (amap_add(&ufi->entry->aref,
ufi->orig_rvaddr - ufi->entry->start, anon, 0)) {
uvmfault_unlockall(ufi, amap, uobj);
uvm_anfree(anon);
counters_inc(uvmexp_counters, flt_noamap);
if (uvm_swapisfull())
return (ENOMEM);
amap_populate(&ufi->entry->aref,
ufi->orig_rvaddr - ufi->entry->start);
return ERESTART;
}
}
/* 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.
*/
if (amap == NULL)
KASSERT(anon == NULL);
else {
KASSERT(rw_write_held(amap->am_lock));
KASSERT(anon == NULL || anon->an_lock == amap->am_lock);
}
if (pmap_enter(ufi->orig_map->pmap, ufi->orig_rvaddr,
VM_PAGE_TO_PHYS(pg) | flt->pa_flags, flt->enter_prot,
flt->access_type | PMAP_CANFAIL | (flt->wired ? PMAP_WIRED : 0)) != 0) {
/*
* 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->pg_flags & PG_WANTED)
wakeup(pg);
atomic_clearbits_int(&pg->pg_flags, PG_BUSY|PG_FAKE|PG_WANTED);
UVM_PAGE_OWN(pg, NULL);
uvmfault_unlockall(ufi, amap, uobj);
if (uvm_swapisfull()) {
/* XXX instrumentation */
return (ENOMEM);
}
/* XXX instrumentation */
uvm_wait("flt_pmfail2");
return ERESTART;
}
if (fault_type == VM_FAULT_WIRE) {
uvm_lock_pageq();
uvm_pagewire(pg);
uvm_unlock_pageq();
if (pg->pg_flags & 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 clean,
* mark it dirty now.
*
* use pg->uobject here. if the page is from a
* tmpfs vnode, the pages are backed by its UAO and
* not the vnode.
*/
KASSERT(uobj != NULL);
KASSERT(uobj->vmobjlock == pg->uobject->vmobjlock);
atomic_clearbits_int(&pg->pg_flags, PG_CLEAN);
uao_dropswap(uobj, pg->offset >> PAGE_SHIFT);
}
} else {
/* activate it */
uvm_lock_pageq();
uvm_pageactivate(pg);
uvm_unlock_pageq();
}
if (pg->pg_flags & PG_WANTED)
wakeup(pg);
atomic_clearbits_int(&pg->pg_flags, PG_BUSY|PG_FAKE|PG_WANTED);
UVM_PAGE_OWN(pg, NULL);
uvmfault_unlockall(ufi, amap, uobj);
pmap_update(ufi->orig_map->pmap);
return (0);
}
/*
* 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(vm_map_t map, vaddr_t start, vaddr_t end, vm_prot_t access_type)
{
vaddr_t va;
int rv;
/*
* now fault it in a page at a time. if the fault fails then we have
* to undo what we have done. note that in uvm_fault 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, access_type);
if (rv) {
if (va != start) {
uvm_fault_unwire(map, start, va);
}
return (rv);
}
}
return (0);
}
/*
* uvm_fault_unwire(): unwire range of virtual space.
*/
void
uvm_fault_unwire(vm_map_t map, vaddr_t start, vaddr_t 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(vm_map_t map, vaddr_t start, vaddr_t end)
{
vm_map_entry_t entry, oentry = NULL, next;
pmap_t pmap = vm_map_pmap(map);
vaddr_t va;
paddr_t pa;
struct vm_page *pg;
KASSERT((map->flags & VM_MAP_INTRSAFE) == 0);
vm_map_assert_anylock(map);
/*
* 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.
*/
/*
* find the beginning map entry for the region.
*/
KASSERT(start >= vm_map_min(map) && end <= vm_map_max(map));
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)
continue;
/*
* find the map entry for the current address.
*/
KASSERT(va >= entry->start);
while (entry && va >= entry->end) {
next = RBT_NEXT(uvm_map_addr, entry);
entry = next;
}
if (entry == NULL)
return;
if (va < entry->start)
continue;
/*
* lock it.
*/
if (entry != oentry) {
if (oentry != NULL) {
uvm_map_unlock_entry(oentry);
}
uvm_map_lock_entry(entry);
oentry = entry;
}
/*
* 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_lock_pageq();
uvm_pageunwire(pg);
uvm_unlock_pageq();
}
}
if (oentry != NULL) {
uvm_map_unlock_entry(oentry);
}
}
/*
* uvmfault_unlockmaps: unlock the maps
*/
void
uvmfault_unlockmaps(struct uvm_faultinfo *ufi, boolean_t write_locked)
{
/*
* ufi can be NULL when this isn't really a fault,
* but merely paging in anon data.
*/
if (ufi == NULL) {
return;
}
uvmfault_update_stats(ufi);
if (write_locked) {
vm_map_unlock(ufi->map);
} else {
vm_map_unlock_read(ufi->map);
}
}
/*
* uvmfault_unlockall: unlock everything passed in.
*
* => maps must be read-locked (not write-locked).
*/
void
uvmfault_unlockall(struct uvm_faultinfo *ufi, struct vm_amap *amap,
struct uvm_object *uobj)
{
if (uobj)
rw_exit(uobj->vmobjlock);
if (amap != NULL)
amap_unlock(amap);
uvmfault_unlockmaps(ufi, FALSE);
}
/*
* uvmfault_lookup: lookup a virtual address in a map
*
* => caller must provide a uvm_faultinfo structure with the IN
* params properly filled in
* => we will lookup the map entry (handling submaps) as we go
* => if the lookup is a success we will return with the maps locked
* => if "write_lock" is TRUE, we write_lock the map, otherwise we only
* get a read lock.
* => note that submaps can only appear in the kernel and they are
* required to use the same virtual addresses as the map they
* are referenced by (thus address translation between the main
* map and the submap is unnecessary).
*/
boolean_t
uvmfault_lookup(struct uvm_faultinfo *ufi, boolean_t write_lock)
{
vm_map_t tmpmap;
/*
* init ufi values for lookup.
*/
ufi->map = ufi->orig_map;
ufi->size = ufi->orig_size;
/*
* keep going down levels until we are done. note that there can
* only be two levels so we won't loop very long.
*/
while (1) {
if (ufi->orig_rvaddr < ufi->map->min_offset ||
ufi->orig_rvaddr >= ufi->map->max_offset)
return FALSE;
/* lock map */
if (write_lock) {
vm_map_lock(ufi->map);
} else {
vm_map_lock_read(ufi->map);
}
/* lookup */
if (!uvm_map_lookup_entry(ufi->map, ufi->orig_rvaddr,
&ufi->entry)) {
uvmfault_unlockmaps(ufi, write_lock);
return FALSE;
}
/* reduce size if necessary */
if (ufi->entry->end - ufi->orig_rvaddr < ufi->size)
ufi->size = ufi->entry->end - ufi->orig_rvaddr;
/*
* submap? replace map with the submap and lookup again.
* note: VAs in submaps must match VAs in main map.
*/
if (UVM_ET_ISSUBMAP(ufi->entry)) {
tmpmap = ufi->entry->object.sub_map;
uvmfault_unlockmaps(ufi, write_lock);
ufi->map = tmpmap;
continue;
}
/*
* got it!
*/
ufi->mapv = ufi->map->timestamp;
return TRUE;
} /* while loop */
/*NOTREACHED*/
}
/*
* uvmfault_relock: attempt to relock the same version of the map
*
* => fault data structures should be unlocked before calling.
* => if a success (TRUE) maps will be locked after call.
*/
boolean_t
uvmfault_relock(struct uvm_faultinfo *ufi)
{
/*
* ufi can be NULL when this isn't really a fault,
* but merely paging in anon data.
*/
if (ufi == NULL) {
return TRUE;
}
counters_inc(uvmexp_counters, flt_relck);
/*
* relock map. fail if version mismatch (in which case nothing
* gets locked).
*/
vm_map_lock_read(ufi->map);
if (ufi->mapv != ufi->map->timestamp) {
vm_map_unlock_read(ufi->map);
return FALSE;
}
counters_inc(uvmexp_counters, flt_relckok);
return TRUE; /* got it! */
}
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