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Refine the changes made in SVN rev 180430. Specifically, instantiate a new

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page table page only if the 2MB page mapping has been used.  Also, refactor
some assertions.
This commit is contained in:
Alan Cox 2008-07-12 21:24:42 +00:00
parent 1aad294b4e
commit 8bfadfd616
1 changed files with 26 additions and 16 deletions
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42
sys/amd64/amd64/pmap.c
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@ -2213,7 +2213,8 @@ pmap_fill_ptp(pt_entry_t *firstpte, pt_entry_t newpte)
}
/*
* Tries to demote a 2MB page mapping.
* Tries to demote a 2MB page mapping. If demotion fails, the 2MB page
* mapping is invalidated.
*/
static boolean_t
pmap_demote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va)
@ -2224,32 +2225,41 @@ pmap_demote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va)
vm_page_t free, mpte;
PMAP_LOCK_ASSERT(pmap, MA_OWNED);
oldpde = *pde;
KASSERT((oldpde & (PG_PS | PG_V)) == (PG_PS | PG_V),
("pmap_demote_pde: oldpde is missing PG_PS and/or PG_V"));
mpte = pmap_lookup_pt_page(pmap, va);
if (mpte != NULL)
pmap_remove_pt_page(pmap, mpte);
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,
else {
KASSERT((oldpde & PG_W) == 0,
("pmap_demote_pde: page table page for a wired mapping"
" is missing"));
free = NULL;
pmap_remove_pde(pmap, pde, trunc_2mpage(va), &free);
pmap_invalidate_page(pmap, trunc_2mpage(va));
pmap_free_zero_pages(free);
CTR2(KTR_PMAP, "pmap_demote_pde: failure for va %#lx"
" in pmap %p", va, pmap);
return (FALSE);
/*
* Invalidate the 2MB page mapping and return "failure" if the
* mapping was never accessed or the allocation of the new
* page table page fails.
*/
if ((oldpde & PG_A) == 0 || (mpte = vm_page_alloc(NULL,
pmap_pde_pindex(va), VM_ALLOC_NOOBJ | VM_ALLOC_NORMAL |
VM_ALLOC_WIRED)) == NULL) {
free = NULL;
pmap_remove_pde(pmap, pde, trunc_2mpage(va), &free);
pmap_invalidate_page(pmap, trunc_2mpage(va));
pmap_free_zero_pages(free);
CTR2(KTR_PMAP, "pmap_demote_pde: failure for va %#lx"
" in pmap %p", va, pmap);
return (FALSE);
}
}
mptepa = VM_PAGE_TO_PHYS(mpte);
firstpte = (pt_entry_t *)PHYS_TO_DMAP(mptepa);
oldpde = *pde;
newpde = mptepa | PG_M | PG_A | (oldpde & PG_U) | PG_RW | PG_V;
KASSERT((oldpde & (PG_A | PG_V)) == (PG_A | PG_V),
("pmap_demote_pde: oldpde is missing PG_A and/or PG_V"));
KASSERT((oldpde & PG_A) != 0,
("pmap_demote_pde: oldpde is missing PG_A"));
KASSERT((oldpde & (PG_M | PG_RW)) != PG_RW,
("pmap_demote_pde: oldpde is missing PG_M"));
KASSERT((oldpde & PG_PS) != 0,
("pmap_demote_pde: oldpde is missing PG_PS"));
newpte = oldpde & ~PG_PS;
if ((newpte & PG_PDE_PAT) != 0)
newpte ^= PG_PDE_PAT | PG_PTE_PAT;