xlat: Add support for EL0 and EL1 mappings

This patch introduces the ability of the xlat tables library to manage
EL0 and EL1 mappings from a higher exception level.

Attributes MT_USER and MT_PRIVILEGED have been added to allow the user
specify the target EL in the translation regime EL1&0.

REGISTER_XLAT_CONTEXT2 macro is introduced to allow creating a
xlat_ctx_t that targets a given translation regime (EL1&0 or EL3).

A new member is added to xlat_ctx_t to represent the translation regime
the xlat_ctx_t manages. The execute_never mask member is removed as it
is computed from existing information.

Change-Id: I95e14abc3371d7a6d6a358cc54c688aa9975c110
Co-authored-by: Douglas Raillard <douglas.raillard@arm.com>
Co-authored-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Co-authored-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/lib/xlat_tables_v2/aarch32/xlat_tables_arch_private.h b/lib/xlat_tables_v2/aarch32/xlat_tables_arch_private.h
new file mode 100644
index 0000000..509395d
--- /dev/null
+++ b/lib/xlat_tables_v2/aarch32/xlat_tables_arch_private.h
@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __XLAT_TABLES_ARCH_PRIVATE_H__
+#define __XLAT_TABLES_ARCH_PRIVATE_H__
+
+#include <xlat_tables_defs.h>
+#include <xlat_tables_v2.h>
+
+/*
+ * Return the execute-never mask that will prevent instruction fetch at the
+ * given translation regime.
+ */
+static inline uint64_t xlat_arch_regime_get_xn_desc(xlat_regime_t regime __unused)
+{
+	return UPPER_ATTRS(XN);
+}
+
+#endif /* __XLAT_TABLES_ARCH_PRIVATE_H__ */