BL2: Enable pointer authentication support

The size increase after enabling options related to ARMv8.3-PAuth is:

+----------------------------+-------+-------+-------+--------+
|                            |  text |  bss  |  data | rodata |
+----------------------------+-------+-------+-------+--------+
| CTX_INCLUDE_PAUTH_REGS = 1 |   +40 |   +0  |   +0  |   +0   |
|                            |  0.2% |       |       |        |
+----------------------------+-------+-------+-------+--------+
| ENABLE_PAUTH = 1           |  +664 |   +0  |  +16  |   +0   |
|                            |  3.1% |       |  0.9% |        |
+----------------------------+-------+-------+-------+--------+

Results calculated with the following build configuration:

    make PLAT=fvp SPD=tspd DEBUG=1 \
    SDEI_SUPPORT=1                 \
    EL3_EXCEPTION_HANDLING=1       \
    TSP_NS_INTR_ASYNC_PREEMPT=1    \
    CTX_INCLUDE_PAUTH_REGS=1       \
    ENABLE_PAUTH=1

The changes for BL2_AT_EL3 aren't done in this commit.

Change-Id: I8c803b40c7160525a06173bc6cdca21c4505837d
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/bl2/bl2.mk b/bl2/bl2.mk
index f905bc2..9523918 100644
--- a/bl2/bl2.mk
+++ b/bl2/bl2.mk
@@ -1,10 +1,11 @@
 #
-# Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2013-2019, ARM Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
 
-BL2_SOURCES		+=	bl2/bl2_main.c				\
+BL2_SOURCES		+=	bl2/bl2_image_load_v2.c			\
+				bl2/bl2_main.c				\
 				bl2/${ARCH}/bl2_arch_setup.c		\
 				lib/locks/exclusive/${ARCH}/spinlock.S	\
 				plat/common/${ARCH}/platform_up_stack.S	\
@@ -14,7 +15,9 @@
 BL2_SOURCES		+=	common/aarch64/early_exceptions.S
 endif
 
-BL2_SOURCES		+=	bl2/bl2_image_load_v2.c
+ifeq (${ENABLE_PAUTH},1)
+BL2_CFLAGS		+=	-msign-return-address=non-leaf
+endif
 
 ifeq (${BL2_AT_EL3},0)
 BL2_SOURCES		+=	bl2/${ARCH}/bl2_entrypoint.S