x86: add gbpages support to lookup_address

[ [e-mail]: fix bootup crash on sparse mappings. ]

Signed-off-by: Andi Kleen <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>

arch/x86/mm/pageattr.c

···
 	pud = pud_offset(pgd, address);
 	if (pud_none(*pud))
 		return NULL;
+
+	*level = PG_LEVEL_1G;
+	if (pud_large(*pud) || !pud_present(*pud))
+		return (pte_t *)pud;
+
 	pmd = pmd_offset(pud, address);
 	if (pmd_none(*pmd))
 		return NULL;