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Do not access pv_table array for fictitious pages, since the array

Browse source 
does not cover the dynamically registered ficititious ranges, and
fictitious pages mappings are not promoted.  Offer a dummy struct
md_page to fetch constant superpage pv list generation to satisfy
logic.  Also, by initializing the pv_dummy pv_list to empty, we can
remove several explicit PG_FICTITIOUS tests.

Reported and tested by:	Michael Butler <imb@protected-networks.net>
	(previous version)
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D6728
Approved by:	re (hrs)
This commit is contained in:
Konstantin Belousov 2016-06-13 03:45:08 +00:00
parent eb4d6a1b3b
commit b9c8a54dc3
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=301853
1 changed files with 10 additions and 15 deletions
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25
sys/amd64/amd64/pmap.c
View file

@ -386,6 +386,7 @@ static struct mtx pv_chunks_mutex;
static struct rwlock pv_list_locks[NPV_LIST_LOCKS];
static u_long pv_invl_gen[NPV_LIST_LOCKS];
static struct md_page *pv_table;
static struct md_page pv_dummy;
/*
* All those kernel PT submaps that BSD is so fond of
@ -1264,6 +1265,7 @@ pmap_init(void)
M_WAITOK | M_ZERO);
for (i = 0; i < pv_npg; i++)
TAILQ_INIT(&pv_table[i].pv_list);
TAILQ_INIT(&pv_dummy.pv_list);
pmap_initialized = 1;
for (i = 0; i < PMAP_PREINIT_MAPPING_COUNT; i++) {
@ -3920,11 +3922,10 @@ pmap_remove_all(vm_page_t m)
("pmap_remove_all: page %p is not managed", m));
SLIST_INIT(&free);
lock = VM_PAGE_TO_PV_LIST_LOCK(m);
pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
pvh = (m->flags & PG_FICTITIOUS) != 0 ? &pv_dummy :
pa_to_pvh(VM_PAGE_TO_PHYS(m));
retry:
rw_wlock(lock);
if ((m->flags & PG_FICTITIOUS) != 0)
goto small_mappings;
while ((pv = TAILQ_FIRST(&pvh->pv_list)) != NULL) {
pmap = PV_PMAP(pv);
if (!PMAP_TRYLOCK(pmap)) {
@ -3943,7 +3944,6 @@ pmap_remove_all(vm_page_t m)
(void)pmap_demote_pde_locked(pmap, pde, va, &lock);
PMAP_UNLOCK(pmap);
}
small_mappings:
while ((pv = TAILQ_FIRST(&m->md.pv_list)) != NULL) {
pmap = PV_PMAP(pv);
if (!PMAP_TRYLOCK(pmap)) {
@ -5743,11 +5743,10 @@ pmap_remove_write(vm_page_t m)
if (!vm_page_xbusied(m) && (m->aflags & PGA_WRITEABLE) == 0)
return;
lock = VM_PAGE_TO_PV_LIST_LOCK(m);
pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
pvh = (m->flags & PG_FICTITIOUS) != 0 ? &pv_dummy :
pa_to_pvh(VM_PAGE_TO_PHYS(m));
retry_pv_loop:
rw_wlock(lock);
if ((m->flags & PG_FICTITIOUS) != 0)
goto small_mappings;
TAILQ_FOREACH_SAFE(pv, &pvh->pv_list, pv_next, next_pv) {
pmap = PV_PMAP(pv);
if (!PMAP_TRYLOCK(pmap)) {
@ -5771,7 +5770,6 @@ pmap_remove_write(vm_page_t m)
lock, VM_PAGE_TO_PV_LIST_LOCK(m), m));
PMAP_UNLOCK(pmap);
}
small_mappings:
TAILQ_FOREACH(pv, &m->md.pv_list, pv_next) {
pmap = PV_PMAP(pv);
if (!PMAP_TRYLOCK(pmap)) {
@ -5877,12 +5875,11 @@ pmap_ts_referenced(vm_page_t m)
cleared = 0;
pa = VM_PAGE_TO_PHYS(m);
lock = PHYS_TO_PV_LIST_LOCK(pa);
pvh = pa_to_pvh(pa);
pvh = (m->flags & PG_FICTITIOUS) != 0 ? &pv_dummy : pa_to_pvh(pa);
rw_wlock(lock);
retry:
not_cleared = 0;
if ((m->flags & PG_FICTITIOUS) != 0 ||
(pvf = TAILQ_FIRST(&pvh->pv_list)) == NULL)
if ((pvf = TAILQ_FIRST(&pvh->pv_list)) == NULL)
goto small_mappings;
pv = pvf;
do {
@ -6194,12 +6191,11 @@ pmap_clear_modify(vm_page_t m)
*/
if ((m->aflags & PGA_WRITEABLE) == 0)
return;
pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
pvh = (m->flags & PG_FICTITIOUS) != 0 ? &pv_dummy :
pa_to_pvh(VM_PAGE_TO_PHYS(m));
lock = VM_PAGE_TO_PV_LIST_LOCK(m);
rw_wlock(lock);
restart:
if ((m->flags & PG_FICTITIOUS) != 0)
goto small_mappings;
TAILQ_FOREACH_SAFE(pv, &pvh->pv_list, pv_next, next_pv) {
pmap = PV_PMAP(pv);
if (!PMAP_TRYLOCK(pmap)) {
@ -6243,7 +6239,6 @@ pmap_clear_modify(vm_page_t m)
}
PMAP_UNLOCK(pmap);
}
small_mappings:
TAILQ_FOREACH(pv, &m->md.pv_list, pv_next) {
pmap = PV_PMAP(pv);
if (!PMAP_TRYLOCK(pmap)) {