[S390] check addressing mode in s390_enable_sie
The sie instruction requires address spaces to be switched
to run proper. This patch verifies that this is the case
in s390_enable_sie, otherwise the kernel would crash badly
as soon as the process runs into sie.
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 6b6ddc4..9bf8612 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -258,6 +258,10 @@
struct task_struct *tsk = current;
struct mm_struct *mm, *old_mm;
+ /* Do we have switched amode? If no, we cannot do sie */
+ if (!switch_amode)
+ return -EINVAL;
+
/* Do we have pgstes? if yes, we are done */
if (tsk->mm->context.has_pgste)
return 0;