s390/mm: use _SEGMENT_ENTRY_EMPTY in the code

_SEGMENT_ENTRY_INVALID denotes the invalid bit in a segment table
entry whereas _SEGMENT_ENTRY_EMPTY means that the value of the whole
entry is only the invalid bit, as the entry is completely empty.

Therefore we use _SEGMENT_ENTRY_INVALID only to check and set the
invalid bit with bitwise operations. _SEGMENT_ENTRY_EMPTY is only used
to check for (un)equality.
Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/pgtable.h

@@ -640,12 +640,12 @@ static inline int pud_bad(pud_t pud)
 
 static inline int pmd_present(pmd_t pmd)
 {
-	return pmd_val(pmd) != _SEGMENT_ENTRY_INVALID;
+	return pmd_val(pmd) != _SEGMENT_ENTRY_EMPTY;
 }
 
 static inline int pmd_none(pmd_t pmd)
 {
-	return pmd_val(pmd) == _SEGMENT_ENTRY_INVALID;
+	return pmd_val(pmd) == _SEGMENT_ENTRY_EMPTY;
 }
 
 static inline unsigned long pmd_pfn(pmd_t pmd)
@@ -803,7 +803,7 @@ static inline void pud_clear(pud_t *pud)
 
 static inline void pmd_clear(pmd_t *pmdp)
 {
-	pmd_val(*pmdp) = _SEGMENT_ENTRY_INVALID;
+	pmd_val(*pmdp) = _SEGMENT_ENTRY_EMPTY;
 }
 
 static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
@@ -1357,7 +1357,7 @@ static inline pmd_t pmd_mkhuge(pmd_t pmd)
 static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
 					    unsigned long addr, pmd_t *pmdp)
 {
-	return pmdp_xchg_direct(mm, addr, pmdp, __pmd(_SEGMENT_ENTRY_INVALID));
+	return pmdp_xchg_direct(mm, addr, pmdp, __pmd(_SEGMENT_ENTRY_EMPTY));
 }
 
 #define __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR_FULL
@@ -1367,10 +1367,10 @@ static inline pmd_t pmdp_huge_get_and_clear_full(struct mm_struct *mm,
 {
 	if (full) {
 		pmd_t pmd = *pmdp;
-		*pmdp = __pmd(_SEGMENT_ENTRY_INVALID);
+		*pmdp = __pmd(_SEGMENT_ENTRY_EMPTY);
 		return pmd;
 	}
-	return pmdp_xchg_lazy(mm, addr, pmdp, __pmd(_SEGMENT_ENTRY_INVALID));
+	return pmdp_xchg_lazy(mm, addr, pmdp, __pmd(_SEGMENT_ENTRY_EMPTY));
 }
 
 #define __HAVE_ARCH_PMDP_HUGE_CLEAR_FLUSH
@@ -1384,7 +1384,7 @@ static inline pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma,
 static inline void pmdp_invalidate(struct vm_area_struct *vma,
 				   unsigned long addr, pmd_t *pmdp)
 {
-	pmdp_xchg_direct(vma->vm_mm, addr, pmdp, __pmd(_SEGMENT_ENTRY_INVALID));
+	pmdp_xchg_direct(vma->vm_mm, addr, pmdp, __pmd(_SEGMENT_ENTRY_EMPTY));
 }
 
 #define __HAVE_ARCH_PMDP_SET_WRPROTECT

arch/s390/mm/gmap.c

@@ -359,8 +359,8 @@ static int __gmap_unlink_by_vmaddr(struct gmap *gmap, unsigned long vmaddr)
 	spin_lock(&gmap->guest_table_lock);
 	entry = radix_tree_delete(&gmap->host_to_guest, vmaddr >> PMD_SHIFT);
 	if (entry) {
-		flush = (*entry != _SEGMENT_ENTRY_INVALID);
-		*entry = _SEGMENT_ENTRY_INVALID;
+		flush = (*entry != _SEGMENT_ENTRY_EMPTY);
+		*entry = _SEGMENT_ENTRY_EMPTY;
 	}
 	spin_unlock(&gmap->guest_table_lock);
 	return flush;
@@ -589,7 +589,7 @@ int __gmap_link(struct gmap *gmap, unsigned long gaddr, unsigned long vmaddr)
 		return rc;
 	ptl = pmd_lock(mm, pmd);
 	spin_lock(&gmap->guest_table_lock);
-	if (*table == _SEGMENT_ENTRY_INVALID) {
+	if (*table == _SEGMENT_ENTRY_EMPTY) {
 		rc = radix_tree_insert(&gmap->host_to_guest,
 				       vmaddr >> PMD_SHIFT, table);
 		if (!rc)

arch/s390/mm/hugetlbpage.c

@@ -62,7 +62,7 @@ static inline unsigned long __pte_to_rste(pte_t pte)
 		rste |= move_set_bit(pte_val(pte), _PAGE_NOEXEC,
 				     _SEGMENT_ENTRY_NOEXEC);
 	} else
-		rste = _SEGMENT_ENTRY_INVALID;
+		rste = _SEGMENT_ENTRY_EMPTY;
 	return rste;
 }