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Three changes to arm64's pmap_unwire():

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Implement wiring changes on superpage mappings.  Previously, a superpage
mapping was unconditionally demoted by pmap_unwire(), even if the wiring
change applied to the entire superpage mapping.

Rewrite a comment to use the arm64 names for bits in a page table entry.
Previously, the bits were referred to by their x86 names.

Use atomic_"op"_64() instead of atomic_"op"_long() to update a page table
entry in order to match the prevailing style in this file.

MFC after:	10 days
This commit is contained in:
Alan Cox 2019-06-16 22:13:27 +00:00
parent 4d210a60c3
commit c8f59059d8
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=349122
1 changed files with 18 additions and 6 deletions
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24
sys/arm64/arm64/pmap.c
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@ -3767,9 +3767,21 @@ pmap_unwire(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
continue;
if ((pmap_load(l2) & ATTR_DESCR_MASK) == L2_BLOCK) {
l3 = pmap_demote_l2(pmap, l2, sva);
if (l3 == NULL)
if ((pmap_load(l2) & ATTR_SW_WIRED) == 0)
panic("pmap_unwire: l2 %#jx is missing "
"ATTR_SW_WIRED", (uintmax_t)pmap_load(l2));
/*
* Are we unwiring the entire large page? If not,
* demote the mapping and fall through.
*/
if (sva + L2_SIZE == va_next && eva >= va_next) {
atomic_clear_64(l2, ATTR_SW_WIRED);
pmap_resident_count_dec(pmap, L2_SIZE /
PAGE_SIZE);
continue;
} else if (pmap_demote_l2(pmap, l2, sva) == NULL)
panic("pmap_unwire: demotion failed");
}
KASSERT((pmap_load(l2) & ATTR_DESCR_MASK) == L2_TABLE,
("pmap_unwire: Invalid l2 entry after demotion"));
@ -3785,11 +3797,11 @@ pmap_unwire(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
"ATTR_SW_WIRED", (uintmax_t)pmap_load(l3));
/*
* PG_W must be cleared atomically. Although the pmap
* lock synchronizes access to PG_W, another processor
* could be setting PG_M and/or PG_A concurrently.
* ATTR_SW_WIRED must be cleared atomically. Although
* the pmap lock synchronizes access to ATTR_SW_WIRED,
* the System MMU may write to the entry concurrently.
*/
atomic_clear_long(l3, ATTR_SW_WIRED);
atomic_clear_64(l3, ATTR_SW_WIRED);
pmap->pm_stats.wired_count--;
}
}