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Only extract a physical address from a pte in pmap_extract() if the pte is

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valid.

Implement the protection check required by the pmap_extract_and_hold()
specification.  (This enables the elimination of Giant from that function.)
This commit is contained in:
Alan Cox 2004-07-18 05:09:28 +00:00
parent d8582da660
commit 4a28f15ccd
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=132338
1 changed files with 13 additions and 9 deletions
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22
sys/alpha/alpha/pmap.c
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@ -751,8 +751,8 @@ pmap_extract(pmap_t pmap, vm_offset_t va)
return (pa);
PMAP_LOCK(pmap);
pte = pmap_lev3pte(pmap, va);
if (pte != NULL)
pa = alpha_ptob(ALPHA_PTE_TO_PFN(*pte));
if (pte != NULL && pmap_pte_v(pte))
pa = pmap_pte_pa(pte);
PMAP_UNLOCK(pmap);
return (pa);
}
@ -767,18 +767,22 @@ pmap_extract(pmap_t pmap, vm_offset_t va)
vm_page_t
pmap_extract_and_hold(pmap_t pmap, vm_offset_t va, vm_prot_t prot)
{
vm_paddr_t pa;
pt_entry_t *pte;
vm_page_t m;
m = NULL;
mtx_lock(&Giant);
if ((pa = pmap_extract(pmap, va)) != 0) {
m = PHYS_TO_VM_PAGE(pa);
vm_page_lock_queues();
if (pmap == NULL)
return (m);
vm_page_lock_queues();
PMAP_LOCK(pmap);
pte = pmap_lev3pte(pmap, va);
if (pte != NULL && pmap_pte_v(pte) &&
(*pte & pte_prot(pmap, prot)) == pte_prot(pmap, prot)) {
m = PHYS_TO_VM_PAGE(pmap_pte_pa(pte));
vm_page_hold(m);
vm_page_unlock_queues();
}
mtx_unlock(&Giant);
vm_page_unlock_queues();
PMAP_UNLOCK(pmap);
return (m);
}