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x86: Introduce function to get pmd entry pointer

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Introduces lookup_pmd_address() to get the address of the pmd entry
related to a virtual address in the current address space. This
function is needed for support of a virtual mapped sparse p2m list
in xen pv domains, as we need the address of the pmd entry, not the
one of the pte in that case.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
This commit is contained in:
Juergen Gross
2014-11-28 11:53:56 +01:00
committed by David Vrabel
parent 5b8e7d8054
commit 792230c3a6
2 changed files with 21 additions and 0 deletions
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20
arch/x86/mm/pageattr.c
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@@ -383,6 +383,26 @@ static pte_t *_lookup_address_cpa(struct cpa_data *cpa, unsigned long address,
return lookup_address(address, level);
}
/*
* Lookup the PMD entry for a virtual address. Return a pointer to the entry
* or NULL if not present.
*/
pmd_t *lookup_pmd_address(unsigned long address)
{
pgd_t *pgd;
pud_t *pud;
pgd = pgd_offset_k(address);
if (pgd_none(*pgd))
return NULL;
pud = pud_offset(pgd, address);
if (pud_none(*pud) || pud_large(*pud) || !pud_present(*pud))
return NULL;
return pmd_offset(pud, address);
}
/*
* This is necessary because __pa() does not work on some
* kinds of memory, like vmalloc() or the alloc_remap()