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/aarch64/bl2_entrypoint.S b/bl2/aarch64/bl2_entrypoint.S
index d938947..611b807 100644
--- a/bl2/aarch64/bl2_entrypoint.S
+++ b/bl2/aarch64/bl2_entrypoint.S
@@ -1,5 +1,5 @@
 /*
- * 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
  */
@@ -106,17 +106,25 @@
 #endif
 
 	/* ---------------------------------------------
-	 * Perform early platform setup & platform
-	 * specific early arch. setup e.g. mmu setup
+	 * Perform BL2 setup
 	 * ---------------------------------------------
 	 */
 	mov	x0, x20
 	mov	x1, x21
 	mov	x2, x22
 	mov	x3, x23
-	bl	bl2_early_platform_setup2
+	bl	bl2_setup
 
-	bl	bl2_plat_arch_setup
+	/* ---------------------------------------------
+	 * Enable pointer authentication
+	 * ---------------------------------------------
+	 */
+#if ENABLE_PAUTH
+	mrs	x0, sctlr_el1
+	orr	x0, x0, #SCTLR_EnIA_BIT
+	msr	sctlr_el1, x0
+	isb
+#endif /* ENABLE_PAUTH */
 
 	/* ---------------------------------------------
 	 * Jump to main function.