s390/pgtable: Fix check for pgste/storage key handling

pte_present might return true on PAGE_TYPE_NONE, even if
the invalid bit is on. Modify the existing check of the
pgste functions to avoid crashes.

[ Martin Schwidefsky: added ptep_modify_prot_[start|commit] bits ]

Reported-by: Martin Schwidefky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
CC: stable@vger.kernel.org
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 11 insertions, 4 deletions

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 0f0de30e3e3f..ac01463038f1 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -646,7 +646,7 @@ static inline pgste_t pgste_update_all(pte_t *ptep, pgste_t pgste)
         unsigned long address, bits;
         unsigned char skey;
 
-        if (!pte_present(*ptep))
+        if (pte_val(*ptep) & _PAGE_INVALID)
                 return pgste;
         address = pte_val(*ptep) & PAGE_MASK;
         skey = page_get_storage_key(address);
@@ -680,7 +680,7 @@ static inline pgste_t pgste_update_young(pte_t *ptep, pgste_t pgste)
 #ifdef CONFIG_PGSTE
         int young;
 
-        if (!pte_present(*ptep))
+        if (pte_val(*ptep) & _PAGE_INVALID)
                 return pgste;
         /* Get referenced bit from storage key */
         young = page_reset_referenced(pte_val(*ptep) & PAGE_MASK);
@@ -706,7 +706,7 @@ static inline void pgste_set_key(pte_t *ptep, pgste_t pgste, pte_t entry)
         unsigned long address;
         unsigned long okey, nkey;
 
-        if (!pte_present(entry))
+        if (pte_val(entry) & _PAGE_INVALID)
                 return;
         address = pte_val(entry) & PAGE_MASK;
         okey = nkey = page_get_storage_key(address);
@@ -1098,6 +1098,9 @@ static inline pte_t ptep_modify_prot_start(struct mm_struct *mm,
         pte = *ptep;
         if (!mm_exclusive(mm))
                 __ptep_ipte(address, ptep);
+
+        if (mm_has_pgste(mm))
+                pgste = pgste_update_all(&pte, pgste);
         return pte;
 }
 
@@ -1105,9 +1108,13 @@ static inline void ptep_modify_prot_commit(struct mm_struct *mm,
                                            unsigned long address,
                                            pte_t *ptep, pte_t pte)
 {
+        pgste_t pgste;
+
         if (mm_has_pgste(mm)) {
+                pgste = *(pgste_t *)(ptep + PTRS_PER_PTE);
+                pgste_set_key(ptep, pgste, pte);
                 pgste_set_pte(ptep, pte);
-                pgste_set_unlock(ptep, *(pgste_t *)(ptep + PTRS_PER_PTE));
+                pgste_set_unlock(ptep, pgste);
         } else
                 *ptep = pte;
 }