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Extend pmap_demote_pde() to include the ability to instantiate a new page

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table page where none existed before.
This commit is contained in:
alc 2008-07-10 16:22:24 +00:00
parent ede873c50b
commit bb93e65e81
1 changed files with 29 additions and 8 deletions
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37
sys/amd64/amd64/pmap.c
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@ -226,6 +226,7 @@ static boolean_t pmap_enter_pde(pmap_t pmap, vm_offset_t va, vm_page_t m,
vm_prot_t prot);
static vm_page_t pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va,
vm_page_t m, vm_prot_t prot, vm_page_t mpte);
static void pmap_fill_ptp(pt_entry_t *firstpte, pt_entry_t newpte);
static void pmap_insert_pt_page(pmap_t pmap, vm_page_t mpte);
static boolean_t pmap_is_modified_pvh(struct md_page *pvh);
static vm_page_t pmap_lookup_pt_page(pmap_t pmap, vm_offset_t va);
@ -2196,6 +2197,20 @@ pmap_pv_insert_pde(pmap_t pmap, vm_offset_t va, vm_paddr_t pa)
return (FALSE);
}
/*
* Fills a page table page with mappings to consecutive physical pages.
*/
static void
pmap_fill_ptp(pt_entry_t *firstpte, pt_entry_t newpte)
{
pt_entry_t *pte;
for (pte = firstpte; pte < firstpte + NPTEPG; pte++) {
*pte = newpte;
newpte += PAGE_SIZE;
}
}
/*
* Tries to demote a 2MB page mapping.
*/
@ -2203,7 +2218,7 @@ static boolean_t
pmap_demote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va)
{
pd_entry_t newpde, oldpde;
pt_entry_t *firstpte, newpte, *pte;
pt_entry_t *firstpte, newpte;
vm_paddr_t mptepa;
vm_page_t free, mpte;
@ -2211,7 +2226,8 @@ pmap_demote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va)
mpte = pmap_lookup_pt_page(pmap, va);
if (mpte != NULL)
pmap_remove_pt_page(pmap, mpte);
else {
else if ((mpte = vm_page_alloc(NULL, pmap_pde_pindex(va),
VM_ALLOC_NOOBJ | VM_ALLOC_NORMAL | VM_ALLOC_WIRED)) == NULL) {
KASSERT((*pde & PG_W) == 0,
("pmap_demote_pde: page table page for a wired mapping"
" is missing"));
@ -2238,17 +2254,22 @@ pmap_demote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va)
newpte ^= PG_PDE_PAT | PG_PTE_PAT;
/*
* If the mapping has changed attributes, update the page table
* entries.
* If the page table page is new, initialize it.
*/
if (mpte->wire_count == 1) {
mpte->wire_count = NPTEPG;
pmap_fill_ptp(firstpte, newpte);
}
KASSERT((*firstpte & PG_FRAME) == (newpte & PG_FRAME),
("pmap_demote_pde: firstpte and newpte map different physical"
" addresses"));
/*
* If the mapping has changed attributes, update the page table
* entries.
*/
if ((*firstpte & PG_PTE_PROMOTE) != (newpte & PG_PTE_PROMOTE))
for (pte = firstpte; pte < firstpte + NPTEPG; pte++) {
*pte = newpte;
newpte += PAGE_SIZE;
}
pmap_fill_ptp(firstpte, newpte);
/*
* Demote the mapping. This pmap is locked. The old PDE has