thp, s390: architecture backend for thp on s390

This implements the architecture backend for transparent hugepages
on s390.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index e86a523875eb..c8188a18af05 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -898,6 +898,28 @@ bool kernel_page_present(struct page *page)
 #endif /* CONFIG_HIBERNATION && CONFIG_DEBUG_PAGEALLOC */
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
+int pmdp_clear_flush_young(struct vm_area_struct *vma, unsigned long address,
+                           pmd_t *pmdp)
+{
+        VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+        /* No need to flush TLB
+         * On s390 reference bits are in storage key and never in TLB */
+        return pmdp_test_and_clear_young(vma, address, pmdp);
+}
+
+int pmdp_set_access_flags(struct vm_area_struct *vma,
+                          unsigned long address, pmd_t *pmdp,
+                          pmd_t entry, int dirty)
+{
+        VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+
+        if (pmd_same(*pmdp, entry))
+                return 0;
+        pmdp_invalidate(vma, address, pmdp);
+        set_pmd_at(vma->vm_mm, address, pmdp, entry);
+        return 1;
+}
+
 static void pmdp_splitting_flush_sync(void *arg)
 {
         /* Simply deliver the interrupt */