2 files changed, 93 insertions, 6 deletions

diff --git a/include/asm-s390/pgtable.h b/include/asm-s390/pgtable.h
index 8e9a629dc199..7fe5c4b6d82d 100644
--- a/include/asm-s390/pgtable.h
+++ b/include/asm-s390/pgtable.h
@@ -30,6 +30,7 @@
  */
 #ifndef __ASSEMBLY__
 #include <linux/mm_types.h>
+#include <asm/bitops.h>
 #include <asm/bug.h>
 #include <asm/processor.h>
 
@@ -258,6 +259,13 @@ extern char empty_zero_page[PAGE_SIZE];
  * swap pte is 1011 and 0001, 0011, 0101, 0111 are invalid.
  */
 
+/* Page status table bits for virtualization */
+#define RCP_PCL_BIT     55
+#define RCP_HR_BIT      54
+#define RCP_HC_BIT      53
+#define RCP_GR_BIT      50
+#define RCP_GC_BIT      49
+
 #ifndef __s390x__
 
 /* Bits in the segment table address-space-control-element */
@@ -513,6 +521,48 @@ static inline int pte_file(pte_t pte)
 #define __HAVE_ARCH_PTE_SAME
 #define pte_same(a,b)  (pte_val(a) == pte_val(b))
 
+static inline void rcp_lock(pte_t *ptep)
+{
+#ifdef CONFIG_PGSTE
+        unsigned long *pgste = (unsigned long *) (ptep + PTRS_PER_PTE);
+        preempt_disable();
+        while (test_and_set_bit(RCP_PCL_BIT, pgste))
+                ;
+#endif
+}
+
+static inline void rcp_unlock(pte_t *ptep)
+{
+#ifdef CONFIG_PGSTE
+        unsigned long *pgste = (unsigned long *) (ptep + PTRS_PER_PTE);
+        clear_bit(RCP_PCL_BIT, pgste);
+        preempt_enable();
+#endif
+}
+
+/* forward declaration for SetPageUptodate in page-flags.h*/
+static inline void page_clear_dirty(struct page *page);
+#include <linux/page-flags.h>
+
+static inline void ptep_rcp_copy(pte_t *ptep)
+{
+#ifdef CONFIG_PGSTE
+        struct page *page = virt_to_page(pte_val(*ptep));
+        unsigned int skey;
+        unsigned long *pgste = (unsigned long *) (ptep + PTRS_PER_PTE);
+
+        skey = page_get_storage_key(page_to_phys(page));
+        if (skey & _PAGE_CHANGED)
+                set_bit(RCP_GC_BIT, pgste);
+        if (skey & _PAGE_REFERENCED)
+                set_bit(RCP_GR_BIT, pgste);
+        if (test_and_clear_bit(RCP_HC_BIT, pgste))
+                SetPageDirty(page);
+        if (test_and_clear_bit(RCP_HR_BIT, pgste))
+                SetPageReferenced(page);
+#endif
+}
+
 /*
  * query functions pte_write/pte_dirty/pte_young only work if
  * pte_present() is true. Undefined behaviour if not..
@@ -599,6 +649,8 @@ static inline void pmd_clear(pmd_t *pmd)
 
 static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
 {
+        if (mm->context.pgstes)
+                ptep_rcp_copy(ptep);
         pte_val(*ptep) = _PAGE_TYPE_EMPTY;
         if (mm->context.noexec)
                 pte_val(ptep[PTRS_PER_PTE]) = _PAGE_TYPE_EMPTY;
@@ -667,6 +719,24 @@ static inline pte_t pte_mkyoung(pte_t pte)
 static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
                                             unsigned long addr, pte_t *ptep)
 {
+#ifdef CONFIG_PGSTE
+        unsigned long physpage;
+        int young;
+        unsigned long *pgste;
+
+        if (!vma->vm_mm->context.pgstes)
+                return 0;
+        physpage = pte_val(*ptep) & PAGE_MASK;
+        pgste = (unsigned long *) (ptep + PTRS_PER_PTE);
+
+        young = ((page_get_storage_key(physpage) & _PAGE_REFERENCED) != 0);
+        rcp_lock(ptep);
+        if (young)
+                set_bit(RCP_GR_BIT, pgste);
+        young |= test_and_clear_bit(RCP_HR_BIT, pgste);
+        rcp_unlock(ptep);
+        return young;
+#endif
         return 0;
 }
 
@@ -674,7 +744,13 @@ static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
 static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
                                          unsigned long address, pte_t *ptep)
 {
-        /* No need to flush TLB; bits are in storage key */
+        /* No need to flush TLB
+         * On s390 reference bits are in storage key and never in TLB
+         * With virtualization we handle the reference bit, without we
+         * we can simply return */
+#ifdef CONFIG_PGSTE
+        return ptep_test_and_clear_young(vma, address, ptep);
+#endif
         return 0;
 }
 
@@ -693,15 +769,25 @@ static inline void __ptep_ipte(unsigned long address, pte_t *ptep)
                         : "=m" (*ptep) : "m" (*ptep),
                           "a" (pto), "a" (address));
         }
-        pte_val(*ptep) = _PAGE_TYPE_EMPTY;
 }
 
 static inline void ptep_invalidate(struct mm_struct *mm,
                                    unsigned long address, pte_t *ptep)
 {
+        if (mm->context.pgstes) {
+                rcp_lock(ptep);
+                __ptep_ipte(address, ptep);
+                ptep_rcp_copy(ptep);
+                pte_val(*ptep) = _PAGE_TYPE_EMPTY;
+                rcp_unlock(ptep);
+                return;
+        }
         __ptep_ipte(address, ptep);
-        if (mm->context.noexec)
+        pte_val(*ptep) = _PAGE_TYPE_EMPTY;
+        if (mm->context.noexec) {
                 __ptep_ipte(address, ptep + PTRS_PER_PTE);
+                pte_val(*(ptep + PTRS_PER_PTE)) = _PAGE_TYPE_EMPTY;
+        }
 }
 
 /*
diff --git a/mm/rmap.c b/mm/rmap.c
index 997f06907b6d..e9bb6b1093f6 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -413,9 +413,6 @@ int page_referenced(struct page *page, int is_locked,
 {
         int referenced = 0;
 
-        if (page_test_and_clear_young(page))
-                referenced++;
-
         if (TestClearPageReferenced(page))
                 referenced++;
 
@@ -433,6 +430,10 @@ int page_referenced(struct page *page, int is_locked,
                         unlock_page(page);
                 }
         }
+
+        if (page_test_and_clear_young(page))
+                referenced++;
+
         return referenced;
 }