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Commit 9a14aefc authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
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x86: cpa, fix lookup_address 



lookup_address() returns a wrong level and a wrong pointer to a non
existing pte, when pmd or pud entries are marked !present. This
happens for example due to boot time mapping of GART into the low
memory space.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 34508f66

arch/x86/mm/pageattr.c

+9 −1
Original line number Diff line number Diff line
@@ -188,6 +188,14 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address) 
	return prot;

}



/*

 * Lookup the page table entry for a virtual address. Return a pointer

 * to the entry and the level of the mapping.

 *

 * Note: We return pud and pmd either when the entry is marked large

 * or when the present bit is not set. Otherwise we would return a

 * pointer to a nonexisting mapping.

 */

pte_t *lookup_address(unsigned long address, int *level)

{

	pgd_t *pgd = pgd_offset_k(address);
@@ -206,7 +214,7 @@ pte_t *lookup_address(unsigned long address, int *level) 
		return NULL;



	*level = PG_LEVEL_2M;

	if (pmd_large(*pmd))

	if (pmd_large(*pmd) || !pmd_present(*pmd))

		return (pte_t *)pmd;



	*level = PG_LEVEL_4K;