Author: neel
Date: Wed Jul 3 23:21:25 2013
New Revision: 252646
URL: http://svnweb.freebsd.org/changeset/base/252646
Log:
If a superpage mapping is being removed then we need to ignore the PG_PDE_PAT
bit when looking up the vm_page associated with the superpage's physical
address.
If the caching attribute for the mapping is write combining or write protected
then the PG_PDE_PAT bit will be set and thus cause an 'off-by-one' error
when looking up the vm_page.
Fix this by using the PG_PS_FRAME mask to compute the physical address for
a superpage mapping instead of PG_FRAME.
This is a theoretical issue at this point since non-writeback attributes are
currently used only for fictitious mappings and fictitious mappings are not
subject to promotion.
Discussed with: alc, kib
MFC after: 2 weeks
Modified:
head/sys/amd64/amd64/pmap.c
Modified: head/sys/amd64/amd64/pmap.c
==============================================================================
--- head/sys/amd64/amd64/pmap.c Wed Jul 3 23:19:57 2013 (r252645)
+++ head/sys/amd64/amd64/pmap.c Wed Jul 3 23:21:25 2013 (r252646)
@@ -4400,6 +4400,7 @@ pmap_remove_pages(pmap_t pmap)
int64_t bit;
uint64_t inuse, bitmask;
int allfree, field, freed, idx;
+ vm_paddr_t pa;
if (pmap != PCPU_GET(curpmap)) {
printf("warning: pmap_remove_pages called with non-current
pmap\n");
@@ -4429,7 +4430,7 @@ pmap_remove_pages(pmap_t pmap)
pte = (pt_entry_t *)PHYS_TO_DMAP(tpte &
PG_FRAME);
pte = &pte[pmap_pte_index(pv->pv_va)];
- tpte = *pte & ~PG_PTE_PAT;
+ tpte = *pte;
}
if ((tpte & PG_V) == 0) {
panic("bad pte va %lx pte %lx",
@@ -4444,8 +4445,13 @@ pmap_remove_pages(pmap_t pmap)
continue;
}
- m = PHYS_TO_VM_PAGE(tpte & PG_FRAME);
- KASSERT(m->phys_addr == (tpte & PG_FRAME),
+ if (tpte & PG_PS)
+ pa = tpte & PG_PS_FRAME;
+ else
+ pa = tpte & PG_FRAME;
+
+ m = PHYS_TO_VM_PAGE(pa);
+ KASSERT(m->phys_addr == pa,
("vm_page_t %p phys_addr mismatch %016jx
%016jx",
m, (uintmax_t)m->phys_addr,
(uintmax_t)tpte));
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