s390/mm: implement dirty bits for large segment table entries

The large segment table entry format has block of bits for the
ACC/F values for the large page. These bits are valid only if
another bit (AV bit 0x10000) of the segment table entry is set.
The ACC/F bits do not have a meaning if the AV bit is off.
This allows to put the THP splitting bit, the segment young bit
and the new segment dirty bit into the ACC/F bits as long as
the AV bit stays off. The dirty and young information is only
available if the pmd is large.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index f90ad8592b36..19daa53a3da4 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -1433,6 +1433,9 @@ int pmdp_set_access_flags(struct vm_area_struct *vma,
 {
         VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 
+        entry = pmd_mkyoung(entry);
+        if (dirty)
+                entry = pmd_mkdirty(entry);
         if (pmd_same(*pmdp, entry))
                 return 0;
         pmdp_invalidate(vma, address, pmdp);