/
uvm_fault.c
2493 lines (2121 loc) · 64.2 KB
/
uvm_fault.c
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/* $NetBSD: uvm_fault.c,v 1.208 2019/11/10 20:38:33 chs 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_fault.c,v 1.208 2019/11/10 20:38:33 chs Exp $");
#include "opt_uvmhist.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/mman.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_internal)
* - 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 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 const struct uvm_advice uvmadvice[] = {
{ UVM_ADV_NORMAL, 3, 4 },
{ UVM_ADV_RANDOM, 0, 0 },
{ UVM_ADV_SEQUENTIAL, 8, 7},
};
#define UVM_MAXRANGE 16 /* must be MAX() of nback+nforw+1 */
/*
* private prototypes
*/
/*
* externs from other modules
*/
extern int start_init_exec; /* Is init_main() done / init running? */
/*
* 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(mutex_owned(anons[lcv]->an_lock));
pg = anons[lcv]->an_page;
if (pg && (pg->flags & PG_BUSY) == 0) {
mutex_enter(&uvm_pageqlock);
if (pg->wire_count == 0) {
uvm_pagedeactivate(pg);
}
mutex_exit(&uvm_pageqlock);
}
}
}
/*
* 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(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, AMAP_COPY_NOWAIT,
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
* => For pages which are on loan from a uvm_object (and thus are not owned
* by the anon): if successful, return with the owning object locked.
* The caller must unlock this object when it unlocks everything else.
*/
int
uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap,
struct vm_anon *anon)
{
struct vm_page *pg;
int error;
UVMHIST_FUNC("uvmfault_anonget"); UVMHIST_CALLED(maphist);
KASSERT(mutex_owned(anon->an_lock));
KASSERT(anon->an_lock == amap->am_lock);
/* Increment the counters.*/
uvmexp.fltanget++;
if (anon->an_page) {
curlwp->l_ru.ru_minflt++;
} else {
curlwp->l_ru.ru_majflt++;
}
error = 0;
/*
* Loop until we get the anon data, or fail.
*/
for (;;) {
bool we_own, locked;
/*
* Note: 'we_own' will become true if we set PG_BUSY on a page.
*/
we_own = false;
pg = anon->an_page;
/*
* If there is a resident page and it is loaned, then anon
* may not own it. Call out to uvm_anon_lockloanpg() to
* identify and lock the real owner of the page.
*/
if (pg && pg->loan_count)
pg = uvm_anon_lockloanpg(anon);
/*
* Is page resident? 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 and wait
* on the owner of page.
*/
if (pg->uobject) {
/* Owner of page is UVM object. */
uvmfault_unlockall(ufi, amap, NULL);
UVMHIST_LOG(maphist, " unlock+wait on uobj",0,
0,0,0);
UVM_UNLOCK_AND_WAIT(pg,
pg->uobject->vmobjlock,
false, "anonget1", 0);
} else {
/* Owner of page is anon. */
uvmfault_unlockall(ufi, NULL, NULL);
UVMHIST_LOG(maphist, " unlock+wait on anon",0,
0,0,0);
UVM_UNLOCK_AND_WAIT(pg, anon->an_lock,
false, "anonget2", 0);
}
} else {
#if defined(VMSWAP)
/*
* No page, therefore allocate one.
*/
pg = uvm_pagealloc(NULL,
ufi != NULL ? ufi->orig_rvaddr : 0,
anon, ufi != NULL ? UVM_FLAG_COLORMATCH : 0);
if (pg == NULL) {
/* Out of memory. Wait a little. */
uvmfault_unlockall(ufi, amap, NULL);
uvmexp.fltnoram++;
UVMHIST_LOG(maphist, " noram -- UVM_WAIT",0,
0,0,0);
if (!uvm_reclaimable()) {
return ENOMEM;
}
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.
*/
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.
*/
}
#else
panic("%s: no page", __func__);
#endif /* defined(VMSWAP) */
}
/*
* Re-lock the map and anon.
*/
locked = uvmfault_relock(ufi);
if (locked || we_own) {
mutex_enter(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 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 defined(VMSWAP)
if (pg->flags & PG_WANTED) {
wakeup(pg);
}
if (error) {
/*
* 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.
*/
if (anon->an_swslot > 0) {
uvm_swap_markbad(anon->an_swslot, 1);
}
anon->an_swslot = SWSLOT_BAD;
if ((pg->flags & PG_RELEASED) != 0) {
goto released;
}
/*
* Note: page was never !PG_BUSY, so it
* cannot be mapped and thus no need to
* pmap_page_protect() it.
*/
mutex_enter(&uvm_pageqlock);
uvm_pagefree(pg);
mutex_exit(&uvm_pageqlock);
if (locked) {
uvmfault_unlockall(ufi, NULL, NULL);
}
mutex_exit(anon->an_lock);
UVMHIST_LOG(maphist, "<- ERROR", 0,0,0,0);
return error;
}
if ((pg->flags & PG_RELEASED) != 0) {
released:
KASSERT(anon->an_ref == 0);
/*
* Released while we had unlocked amap.
*/
if (locked) {
uvmfault_unlockall(ufi, NULL, NULL);
}
uvm_anon_release(anon);
if (error) {
UVMHIST_LOG(maphist,
"<- ERROR/RELEASED", 0,0,0,0);
return error;
}
UVMHIST_LOG(maphist, "<- RELEASED", 0,0,0,0);
return ERESTART;
}
/*
* We have successfully read the page, activate it.
*/
mutex_enter(&uvm_pageqlock);
uvm_pageactivate(pg);
mutex_exit(&uvm_pageqlock);
pg->flags &= ~(PG_WANTED|PG_BUSY|PG_FAKE);
UVM_PAGE_OWN(pg, NULL);
#else
panic("%s: we_own", __func__);
#endif /* defined(VMSWAP) */
}
/*
* We were not able to re-lock the map - restart the fault.
*/
if (!locked) {
if (we_own) {
mutex_exit(anon->an_lock);
}
UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0);
return ERESTART;
}
/*
* 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);
UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0);
return ERESTART;
}
/*
* Retry..
*/
uvmexp.fltanretry++;
continue;
}
/*NOTREACHED*/
}
/*
* uvmfault_promote: promote data to a new anon. used for 1B and 2B.
*
* 1. allocate an anon and a page.
* 2. fill its contents.
* 3. put it into amap.
*
* => if we fail (result != 0) we unlock everything.
* => on success, return a new locked anon via 'nanon'.
* (*nanon)->an_page will be a resident, locked, dirty page.
* => it's caller's responsibility to put the promoted nanon->an_page to the
* page queue.
*/
static int
uvmfault_promote(struct uvm_faultinfo *ufi,
struct vm_anon *oanon,
struct vm_page *uobjpage,
struct vm_anon **nanon, /* OUT: allocated anon */
struct vm_anon **spare)
{
struct vm_amap *amap = ufi->entry->aref.ar_amap;
struct uvm_object *uobj;
struct vm_anon *anon;
struct vm_page *pg;
struct vm_page *opg;
int error;
UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist);
if (oanon) {
/* anon COW */
opg = oanon->an_page;
KASSERT(opg != NULL);
KASSERT(opg->uobject == NULL || opg->loan_count > 0);
} else if (uobjpage != PGO_DONTCARE) {
/* object-backed COW */
opg = uobjpage;
} else {
/* ZFOD */
opg = NULL;
}
if (opg != NULL) {
uobj = opg->uobject;
} else {
uobj = NULL;
}
KASSERT(amap != NULL);
KASSERT(uobjpage != NULL);
KASSERT(uobjpage == PGO_DONTCARE || (uobjpage->flags & PG_BUSY) != 0);
KASSERT(mutex_owned(amap->am_lock));
KASSERT(oanon == NULL || amap->am_lock == oanon->an_lock);
KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock));
if (*spare != NULL) {
anon = *spare;
*spare = NULL;
} else {
anon = uvm_analloc();
}
if (anon) {
/*
* The new anon is locked.
*
* if opg == NULL, we want a zero'd, dirty page,
* so have uvm_pagealloc() do that for us.
*/
KASSERT(anon->an_lock == NULL);
anon->an_lock = amap->am_lock;
pg = uvm_pagealloc(NULL, ufi->orig_rvaddr, anon,
UVM_FLAG_COLORMATCH | (opg == NULL ? UVM_PGA_ZERO : 0));
if (pg == NULL) {
anon->an_lock = NULL;
}
} else {
pg = NULL;
}
/*
* out of memory resources?
*/
if (pg == NULL) {
/* save anon for the next try. */
if (anon != NULL) {
*spare = anon;
}
/* unlock and fail ... */
uvm_page_unbusy(&uobjpage, 1);
uvmfault_unlockall(ufi, amap, uobj);
if (!uvm_reclaimable()) {
UVMHIST_LOG(maphist, "out of VM", 0,0,0,0);
uvmexp.fltnoanon++;
error = ENOMEM;
goto done;
}
UVMHIST_LOG(maphist, "out of RAM, waiting for more", 0,0,0,0);
uvmexp.fltnoram++;
uvm_wait("flt_noram5");
error = ERESTART;
goto done;
}
/* copy page [pg now dirty] */
if (opg) {
uvm_pagecopy(opg, pg);
}
amap_add(&ufi->entry->aref, ufi->orig_rvaddr - ufi->entry->start, anon,
oanon != NULL);
*nanon = anon;
error = 0;
done:
return error;
}
/*
* Update statistics after fault resolution.
* - maxrss
*/
void
uvmfault_update_stats(struct uvm_faultinfo *ufi)
{
struct vm_map *map;
struct vmspace *vm;
struct proc *p;
vsize_t res;
map = ufi->orig_map;
p = curproc;
KASSERT(p != NULL);
vm = p->p_vmspace;
if (&vm->vm_map != map)
return;
res = pmap_resident_count(map->pmap);
if (vm->vm_rssmax < res)
vm->vm_rssmax = 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 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)
/* fault_flag values passed from uvm_fault_wire to uvm_fault_internal */
#define UVM_FAULT_WIRE (1 << 0)
#define UVM_FAULT_MAXPROT (1 << 1)
struct uvm_faultctx {
/*
* the following members are set up by uvm_fault_check() and
* read-only after that.
*
* note that narrow is used by uvm_fault_check() to change
* the behaviour after ERESTART.
*
* most of them might change after RESTART if the underlying
* map entry has been changed behind us. an exception is
* wire_paging, which does never change.
*/
vm_prot_t access_type;
vaddr_t startva;
int npages;
int centeridx;
bool narrow; /* work on a single requested page only */
bool wire_mapping; /* request a PMAP_WIRED mapping
(UVM_FAULT_WIRE or VM_MAPENT_ISWIRED) */
bool wire_paging; /* request uvm_pagewire
(true for UVM_FAULT_WIRE) */
bool cow_now; /* VM_PROT_WRITE is actually requested
(ie. should break COW and page loaning) */
/*
* enter_prot is set up by uvm_fault_check() and clamped
* (ie. drop the VM_PROT_WRITE bit) in various places in case
* of !cow_now.
*/
vm_prot_t enter_prot; /* prot at which we want to enter pages in */
/*
* the following member is for uvmfault_promote() and ERESTART.
*/
struct vm_anon *anon_spare;
/*
* the folloing is actually a uvm_fault_lower() internal.
* it's here merely for debugging.
* (or due to the mechanical separation of the function?)
*/
bool promote;
};
static inline int uvm_fault_check(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct vm_anon ***, bool);
static int uvm_fault_upper(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct vm_anon **);
static inline int uvm_fault_upper_lookup(
struct uvm_faultinfo *, const struct uvm_faultctx *,
struct vm_anon **, struct vm_page **);
static inline void uvm_fault_upper_neighbor(
struct uvm_faultinfo *, const struct uvm_faultctx *,
vaddr_t, struct vm_page *, bool);
static inline int uvm_fault_upper_loan(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct vm_anon *, struct uvm_object **);
static inline int uvm_fault_upper_promote(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct uvm_object *, struct vm_anon *);
static inline int uvm_fault_upper_direct(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct uvm_object *, struct vm_anon *);
static int uvm_fault_upper_enter(
struct uvm_faultinfo *, const struct uvm_faultctx *,
struct uvm_object *, struct vm_anon *,
struct vm_page *, struct vm_anon *);
static inline void uvm_fault_upper_done(
struct uvm_faultinfo *, const struct uvm_faultctx *,
struct vm_anon *, struct vm_page *);
static int uvm_fault_lower(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct vm_page **);
static inline void uvm_fault_lower_lookup(
struct uvm_faultinfo *, const struct uvm_faultctx *,
struct vm_page **);
static inline void uvm_fault_lower_neighbor(
struct uvm_faultinfo *, const struct uvm_faultctx *,
vaddr_t, struct vm_page *, bool);
static inline int uvm_fault_lower_io(
struct uvm_faultinfo *, const struct uvm_faultctx *,
struct uvm_object **, struct vm_page **);
static inline int uvm_fault_lower_direct(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct uvm_object *, struct vm_page *);
static inline int uvm_fault_lower_direct_loan(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct uvm_object *, struct vm_page **,
struct vm_page **);
static inline int uvm_fault_lower_promote(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct uvm_object *, struct vm_page *);
static int uvm_fault_lower_enter(
struct uvm_faultinfo *, const struct uvm_faultctx *,
struct uvm_object *,
struct vm_anon *, struct vm_page *);
static inline void uvm_fault_lower_done(
struct uvm_faultinfo *, const struct uvm_faultctx *,
struct uvm_object *, struct vm_page *);
int
uvm_fault_internal(struct vm_map *orig_map, vaddr_t vaddr,
vm_prot_t access_type, int fault_flag)
{
struct cpu_data *cd;
struct uvm_cpu *ucpu;
struct uvm_faultinfo ufi;
struct uvm_faultctx flt = {
.access_type = access_type,
/* don't look for neighborhood * pages on "wire" fault */
.narrow = (fault_flag & UVM_FAULT_WIRE) != 0,
/* "wire" fault causes wiring of both mapping and paging */
.wire_mapping = (fault_flag & UVM_FAULT_WIRE) != 0,
.wire_paging = (fault_flag & UVM_FAULT_WIRE) != 0,
};
const bool maxprot = (fault_flag & UVM_FAULT_MAXPROT) != 0;
struct vm_anon *anons_store[UVM_MAXRANGE], **anons;
struct vm_page *pages_store[UVM_MAXRANGE], **pages;
int error;
UVMHIST_FUNC("uvm_fault"); UVMHIST_CALLED(maphist);
UVMHIST_LOG(maphist, "(map=%#jx, vaddr=%#jx, at=%jd, ff=%jd)",
(uintptr_t)orig_map, vaddr, access_type, fault_flag);
cd = &(curcpu()->ci_data);
cd->cpu_nfault++;
ucpu = cd->cpu_uvm;
/* Don't flood RNG subsystem with samples. */
if (cd->cpu_nfault % 503)
goto norng;
/* Don't count anything until user interaction is possible */
if (__predict_true(start_init_exec)) {
kpreempt_disable();
rnd_add_uint32(&ucpu->rs,
sizeof(vaddr_t) == sizeof(uint32_t) ?
(uint32_t)vaddr : sizeof(vaddr_t) ==
sizeof(uint64_t) ?
(uint32_t)(vaddr & 0x00000000ffffffff) :
(uint32_t)(cd->cpu_nfault & 0x00000000ffffffff));
kpreempt_enable();
}
norng:
/*
* 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 */
error = ERESTART;
while (error == ERESTART) { /* ReFault: */
anons = anons_store;
pages = pages_store;
error = uvm_fault_check(&ufi, &flt, &anons, maxprot);
if (error != 0)
continue;
error = uvm_fault_upper_lookup(&ufi, &flt, anons, pages);
if (error != 0)
continue;
if (pages[flt.centeridx] == PGO_DONTCARE)
error = uvm_fault_upper(&ufi, &flt, anons);
else {
struct uvm_object * const uobj =
ufi.entry->object.uvm_obj;
if (uobj && uobj->pgops->pgo_fault != NULL) {
/*
* invoke "special" fault routine.
*/
mutex_enter(uobj->vmobjlock);
/* locked: maps(read), amap(if there), uobj */
error = uobj->pgops->pgo_fault(&ufi,
flt.startva, pages, flt.npages,
flt.centeridx, flt.access_type,
PGO_LOCKED|PGO_SYNCIO);
/*
* locked: nothing, pgo_fault has unlocked
* everything
*/
/*
* object fault routine responsible for
* pmap_update().
*/
/*
* Wake up the pagedaemon if the fault method
* failed for lack of memory but some can be
* reclaimed.
*/
if (error == ENOMEM && uvm_reclaimable()) {
uvm_wait("pgo_fault");
error = ERESTART;
}
} else {
error = uvm_fault_lower(&ufi, &flt, pages);
}
}
}
if (flt.anon_spare != NULL) {
flt.anon_spare->an_ref--;
KASSERT(flt.anon_spare->an_ref == 0);
KASSERT(flt.anon_spare->an_lock == NULL);
uvm_anon_free(flt.anon_spare);
}
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.
*/
static int
uvm_fault_check(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
struct vm_anon ***ranons, bool maxprot)
{
struct vm_amap *amap;
struct uvm_object *uobj;
vm_prot_t check_prot;
int nback, nforw;
UVMHIST_FUNC("uvm_fault_check"); UVMHIST_CALLED(maphist);
/*
* lookup and lock the maps
*/
if (uvmfault_lookup(ufi, false) == false) {
UVMHIST_LOG(maphist, "<- no mapping @ 0x%#jx", ufi->orig_rvaddr,
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 = maxprot ?
ufi->entry->max_protection : ufi->entry->protection;
if ((check_prot & flt->access_type) != flt->access_type) {
UVMHIST_LOG(maphist,
"<- protection failure (prot=%#jx, access=%#jx)",
ufi->entry->protection, flt->access_type, 0, 0);
uvmfault_unlockmaps(ufi, false);
return EFAULT;
}
/*
* "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;
if (VM_MAPENT_ISWIRED(ufi->entry)) {
flt->wire_mapping = true;