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Code Issues Releases Activity

Optimize the TLB invalidations performed by pmap_protect(). Use the new

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range-based invalidation function instead of performing per-page
invalidations.  Don't bother invalidating mappings that don't have PTE_D
set, since they don't allow write access.
This commit is contained in:
Alan Cox 2012-10-07 18:07:45 +00:00
parent aae8db90ec
commit 312188ac4a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=241313
1 changed files with 41 additions and 20 deletions
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61
sys/mips/mips/pmap.c
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@ -1913,9 +1913,11 @@ pmap_remove_all(vm_page_t m)
void
pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
{
pt_entry_t *pte;
pt_entry_t pbits, *pte;
pd_entry_t *pde, *pdpe;
vm_offset_t va_next;
vm_offset_t va, va_next;
vm_paddr_t pa;
vm_page_t m;
if ((prot & VM_PROT_READ) == VM_PROT_NONE) {
pmap_remove(pmap, sva, eva);
@ -1927,10 +1929,6 @@ pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
rw_wlock(&pvh_global_lock);
PMAP_LOCK(pmap);
for (; sva < eva; sva = va_next) {
pt_entry_t pbits;
vm_page_t m;
vm_paddr_t pa;
pdpe = pmap_segmap(pmap, sva);
#ifdef __mips_n64
if (*pdpe == 0) {
@ -1947,29 +1945,52 @@ pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
pde = pmap_pdpe_to_pde(pdpe, sva);
if (*pde == NULL)
continue;
/*
* Limit our scan to either the end of the va represented
* by the current page table page, or to the end of the
* range being write protected.
*/
if (va_next > eva)
va_next = eva;
va = va_next;
for (pte = pmap_pde_to_pte(pde, sva); sva != va_next; pte++,
sva += PAGE_SIZE) {
/* Skip invalid PTEs */
if (!pte_test(pte, PTE_V))
continue;
sva += PAGE_SIZE) {
pbits = *pte;
if (pte_test(&pbits, PTE_MANAGED | PTE_D)) {
pa = TLBLO_PTE_TO_PA(pbits);
m = PHYS_TO_VM_PAGE(pa);
vm_page_dirty(m);
if (!pte_test(&pbits, PTE_V) || pte_test(&pbits,
PTE_RO)) {
if (va != va_next) {
pmap_invalidate_range(pmap, va, sva);
va = va_next;
}
continue;
}
pte_clear(&pbits, PTE_D);
pte_set(&pbits, PTE_RO);
if (pbits != *pte) {
*pte = pbits;
pmap_update_page(pmap, sva, pbits);
if (pte_test(&pbits, PTE_D)) {
pte_clear(&pbits, PTE_D);
if (pte_test(&pbits, PTE_MANAGED)) {
pa = TLBLO_PTE_TO_PA(pbits);
m = PHYS_TO_VM_PAGE(pa);
vm_page_dirty(m);
}
if (va == va_next)
va = sva;
} else {
/*
* Unless PTE_D is set, any TLB entries
* mapping "sva" don't allow write access, so
* they needn't be invalidated.
*/
if (va != va_next) {
pmap_invalidate_range(pmap, va, sva);
va = va_next;
}
}
*pte = pbits;
}
if (va != va_next)
pmap_invalidate_range(pmap, va, sva);
}
rw_wunlock(&pvh_global_lock);
PMAP_UNLOCK(pmap);