s390/mm,gmap: don't use pte_val()/pXd_val() as lvalue

Convert pgtable code so pte_val()/pXd_val() aren't used as lvalue
anymore. This allows in later step to convert pte_val()/pXd_val() to
functions, which in turn makes it impossible to use these macros to
modify page table entries like they have been used before.

Therefore a construct like this:

        pte_val(*pte) = __pa(addr) | prot;

which would directly write into a page table, isn't possible anymore
with the last step of this series.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/mm/gmap.c

@@ -974,13 +974,13 @@ static int gmap_protect_pmd(struct gmap *gmap, unsigned long gaddr,
 		return -EAGAIN;
 
 	if (prot == PROT_NONE && !pmd_i) {
-		pmd_val(new) |= _SEGMENT_ENTRY_INVALID;
+		new = set_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_INVALID));
 		gmap_pmdp_xchg(gmap, pmdp, new, gaddr);
 	}
 
 	if (prot == PROT_READ && !pmd_p) {
-		pmd_val(new) &= ~_SEGMENT_ENTRY_INVALID;
-		pmd_val(new) |= _SEGMENT_ENTRY_PROTECT;
+		new = clear_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_INVALID));
+		new = set_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_PROTECT));
 		gmap_pmdp_xchg(gmap, pmdp, new, gaddr);
 	}
 
@@ -2294,7 +2294,7 @@ static void gmap_pmdp_xchg(struct gmap *gmap, pmd_t *pmdp, pmd_t new,
 {
 	gaddr &= HPAGE_MASK;
 	pmdp_notify_gmap(gmap, pmdp, gaddr);
-	pmd_val(new) &= ~_SEGMENT_ENTRY_GMAP_IN;
+	new = clear_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_GMAP_IN));
 	if (MACHINE_HAS_TLB_GUEST)
 		__pmdp_idte(gaddr, (pmd_t *)pmdp, IDTE_GUEST_ASCE, gmap->asce,
 			    IDTE_GLOBAL);