[S390] implement is_compat_task

Implement is_compat_task and use it all over the place.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
index 7b76ee4..45e1708 100644
--- a/arch/s390/kernel/vdso.c
+++ b/arch/s390/kernel/vdso.c
@@ -22,7 +22,7 @@
 #include <linux/elf.h>
 #include <linux/security.h>
 #include <linux/bootmem.h>
-
+#include <linux/compat.h>
 #include <asm/pgtable.h>
 #include <asm/system.h>
 #include <asm/processor.h>
@@ -214,7 +214,7 @@
 	vdso_pagelist = vdso64_pagelist;
 	vdso_pages = vdso64_pages;
 #ifdef CONFIG_COMPAT
-	if (test_thread_flag(TIF_31BIT)) {
+	if (is_compat_task()) {
 		vdso_pagelist = vdso32_pagelist;
 		vdso_pages = vdso32_pages;
 	}