test(el3-runtime): check DIT is retained on exception

Add a test to check that the PSTATE bits not set in the
Aarch64.TakeException but set to a default when taking an exception to
EL3 are maintained after an exception and that changes in TSP do not
effect the PSTATE in TFTF and vice versa.

Signed-off-by: Daniel Boulby <daniel.boulby@arm.com>
Change-Id: Id4d625c7e9cbb565ac236f844274319cc02c2335
diff --git a/include/lib/aarch32/arch_helpers.h b/include/lib/aarch32/arch_helpers.h
index 6e1097d..aca3952 100644
--- a/include/lib/aarch32/arch_helpers.h
+++ b/include/lib/aarch32/arch_helpers.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2021, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2022, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -422,6 +422,9 @@
 #define read_daif()		read_cpsr()
 #define write_daif(flags)	write_cpsr(flags)
 
+#define read_dit()		read_cpsr()
+#define write_dit(flags)	write_cpsr(flags)
+
 #define read_cnthp_cval_el2()	read64_cnthp_cval_el2()
 #define write_cnthp_cval_el2(v)	write64_cnthp_cval_el2(v)