ARM: pgtable: add pud-level code

Add pud_offset() et.al. between the pgd and pmd code in preparation of
using pgtable-nopud.h rather than 4level-fixup.h.

This incorporates a fix from Jamie Iles <jamie@jamieiles.com> for
uaccess_with_memcpy.c.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
index 01210db..7cab791 100644
--- a/arch/arm/mm/fault-armv.c
+++ b/arch/arm/mm/fault-armv.c
@@ -95,6 +95,7 @@
 {
 	spinlock_t *ptl;
 	pgd_t *pgd;
+	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
 	int ret;
@@ -103,7 +104,11 @@
 	if (pgd_none_or_clear_bad(pgd))
 		return 0;
 
-	pmd = pmd_offset(pgd, address);
+	pud = pud_offset(pgd, address);
+	if (pud_none_or_clear_bad(pud))
+		return 0;
+
+	pmd = pmd_offset(pud, address);
 	if (pmd_none_or_clear_bad(pmd))
 		return 0;