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Clear the accessed bit when copying a managed superpage mapping

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pmap_copy() is used to speculatively create mappings, so those mappings
should not have their access bit preset.

Reviewed by:	kib, markj
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D31162
This commit is contained in:
Alan Cox 2021-07-13 02:30:43 -05:00
parent d379886a41
commit 325ff93274
2 changed files with 32 additions and 3 deletions
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17
sys/amd64/amd64/pmap.c
View File

@ -7775,6 +7775,9 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr, vm_size_t len,
continue;
if (srcptepaddr & PG_PS) {
/*
* We can only virtual copy whole superpages.
*/
if ((addr & PDRMASK) != 0 || addr + NBPDR > end_addr)
continue;
pde = pmap_alloc_pde(dst_pmap, addr, &dst_pdpg, NULL);
@ -7783,7 +7786,19 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr, vm_size_t len,
if (*pde == 0 && ((srcptepaddr & PG_MANAGED) == 0 ||
pmap_pv_insert_pde(dst_pmap, addr, srcptepaddr,
PMAP_ENTER_NORECLAIM, &lock))) {
*pde = srcptepaddr & ~PG_W;
/*
* We leave the dirty bit unchanged because
* managed read/write superpage mappings are
* required to be dirty. However, managed
* superpage mappings are not required to
* have their accessed bit set, so we clear
* it because we don't know if this mapping
* will be used.
*/
srcptepaddr &= ~PG_W;
if ((srcptepaddr & PG_MANAGED) != 0)
srcptepaddr &= ~PG_A;
*pde = srcptepaddr;
pmap_resident_count_adj(dst_pmap, NBPDR /
PAGE_SIZE);
counter_u64_add(pmap_pde_mappings, 1);

18
sys/arm64/arm64/pmap.c
View File

@ -4557,6 +4557,9 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr, vm_size_t len,
if (srcptepaddr == 0)
continue;
if ((srcptepaddr & ATTR_DESCR_MASK) == L2_BLOCK) {
/*
* We can only virtual copy whole superpages.
*/
if ((addr & L2_OFFSET) != 0 ||
addr + L2_SIZE > end_addr)
continue;
@ -4567,8 +4570,19 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr, vm_size_t len,
((srcptepaddr & ATTR_SW_MANAGED) == 0 ||
pmap_pv_insert_l2(dst_pmap, addr, srcptepaddr,
PMAP_ENTER_NORECLAIM, &lock))) {
mask = ATTR_SW_WIRED;
pmap_store(l2, srcptepaddr & ~mask);
/*
* We leave the dirty bit unchanged because
* managed read/write superpage mappings are
* required to be dirty. However, managed
* superpage mappings are not required to
* have their accessed bit set, so we clear
* it because we don't know if this mapping
* will be used.
*/
srcptepaddr &= ~ATTR_SW_WIRED;
if ((srcptepaddr & ATTR_SW_MANAGED) != 0)
srcptepaddr &= ~ATTR_AF;
pmap_store(l2, srcptepaddr);
pmap_resident_count_inc(dst_pmap, L2_SIZE /
PAGE_SIZE);
atomic_add_long(&pmap_l2_mappings, 1);