Page MenuHomeFreeBSD
Files F147396859

D16133.id45021.diff
No OneTemporary
Actions

D16133.id45021.diff
View Options

Index: head/sys/i386/i386/pmap.c
===================================================================
--- head/sys/i386/i386/pmap.c
+++ head/sys/i386/i386/pmap.c
@@ -3636,7 +3636,6 @@
}
pa = VM_PAGE_TO_PHYS(m);
- om = NULL;
origpte = *pte;
opa = origpte & PG_FRAME;
@@ -3661,10 +3660,8 @@
if (mpte)
mpte->wire_count--;
- if (origpte & PG_MANAGED) {
- om = m;
+ if (origpte & PG_MANAGED)
pa |= PG_MANAGED;
- }
goto validate;
}
@@ -3672,15 +3669,42 @@
/*
* Mapping has changed, invalidate old range and fall through to
- * handle validating new mapping.
+ * handle validating new mapping. This ensures that all threads
+ * sharing the pmap keep a consistent view of the mapping, which is
+ * necessary for the correct handling of COW faults. It
+ * also permits reuse of the old mapping's PV entry,
+ * avoiding an allocation.
+ *
+ * For consistency, handle unmanaged mappings the same way.
*/
if (opa) {
+ origpte = pte_load_clear(pte);
+ KASSERT((origpte & PG_FRAME) == opa,
+ ("pmap_enter: unexpected pa update for %#x", va));
if (origpte & PG_W)
pmap->pm_stats.wired_count--;
if (origpte & PG_MANAGED) {
om = PHYS_TO_VM_PAGE(opa);
+
+ /*
+ * The pmap lock is sufficient to synchronize with
+ * concurrent calls to pmap_page_test_mappings() and
+ * pmap_ts_referenced().
+ */
+ if ((origpte & (PG_M | PG_RW)) == (PG_M | PG_RW))
+ vm_page_dirty(om);
+ if ((origpte & PG_A) != 0)
+ vm_page_aflag_set(om, PGA_REFERENCED);
pv = pmap_pvh_remove(&om->md, pmap, va);
+ if ((om->aflags & PGA_WRITEABLE) != 0 &&
+ TAILQ_EMPTY(&om->md.pv_list) &&
+ ((om->flags & PG_FICTITIOUS) != 0 ||
+ TAILQ_EMPTY(&pa_to_pvh(opa)->pv_list)))
+ vm_page_aflag_clear(om, PGA_WRITEABLE);
}
+ if ((origpte & PG_A) != 0)
+ pmap_invalidate_page(pmap, va);
+ origpte = 0;
if (mpte != NULL) {
mpte->wire_count--;
KASSERT(mpte->wire_count > 0,
@@ -3697,9 +3721,10 @@
KASSERT(pmap != kernel_pmap || va < kmi.clean_sva ||
va >= kmi.clean_eva,
("pmap_enter: managed mapping within the clean submap"));
- if (pv == NULL)
+ if (pv == NULL) {
pv = get_pv_entry(pmap, FALSE);
- pv->pv_va = va;
+ pv->pv_va = va;
+ }
TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_next);
pa |= PG_MANAGED;
} else if (pv != NULL)
@@ -3741,28 +3766,19 @@
if (origpte & PG_V) {
invlva = FALSE;
origpte = pte_load_store(pte, newpte);
- if (origpte & PG_A) {
- if (origpte & PG_MANAGED)
- vm_page_aflag_set(om, PGA_REFERENCED);
- if (opa != VM_PAGE_TO_PHYS(m))
- invlva = TRUE;
-#if defined(PAE) || defined(PAE_TABLES)
- if ((origpte & PG_NX) == 0 &&
- (newpte & PG_NX) != 0)
- invlva = TRUE;
-#endif
- }
- if ((origpte & (PG_M | PG_RW)) == (PG_M | PG_RW)) {
+ KASSERT((origpte & PG_FRAME) == VM_PAGE_TO_PHYS(m),
+ ("pmap_enter: unexpected pa update for %#x", va));
+ if ((origpte & (PG_M | PG_RW)) == (PG_M | PG_RW) &&
+ (newpte & PG_M) == 0) {
if ((origpte & PG_MANAGED) != 0)
- vm_page_dirty(om);
- if ((prot & VM_PROT_WRITE) == 0)
- invlva = TRUE;
+ vm_page_dirty(m);
+ invlva = TRUE;
}
- if ((origpte & PG_MANAGED) != 0 &&
- TAILQ_EMPTY(&om->md.pv_list) &&
- ((om->flags & PG_FICTITIOUS) != 0 ||
- TAILQ_EMPTY(&pa_to_pvh(opa)->pv_list)))
- vm_page_aflag_clear(om, PGA_WRITEABLE);
+#if defined(PAE) || defined(PAE_TABLES)
+ else if ((origpte & (PG_A | PG_NX)) == PG_A &&
+ (newpte & PG_NX) != 0)
+ invlva = TRUE;
+#endif
if (invlva)
pmap_invalidate_page(pmap, va);
} else

File Metadata

Mime Type
text/plain
Expires
Wed, Mar 11, 3:39 PM (8 h, 23 m)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
29512310
Default Alt Text
D16133.id45021.diff (3 KB)

Event Timeline