AArch64: Introduce External Abort handling

At present, any External Abort routed to EL3 is reported as an unhandled
exception and cause a panic. This patch enables ARM Trusted Firmware to
handle External Aborts routed to EL3.

With this patch, when an External Abort is received at EL3, its handling
is delegated to plat_ea_handler() function. Platforms can provide their
own implementation of this function. This patch adds a weak definition
of the said function that prints out a message and just panics.

In order to support handling External Aborts at EL3, the build option
HANDLE_EA_EL3_FIRST must be set to 1.

Before this patch, HANDLE_EA_EL3_FIRST wasn't passed down to
compilation; this patch fixes that too.

Change-Id: I4d07b7e65eb191ff72d63b909ae9512478cd01a1
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/include/lib/aarch64/arch.h b/include/lib/aarch64/arch.h
index ff3881e..a446941 100644
--- a/include/lib/aarch64/arch.h
+++ b/include/lib/aarch64/arch.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -528,6 +528,12 @@
 #define EC_AARCH64_FP			U(0x2c)
 #define EC_SERROR			U(0x2f)
 
+/*
+ * External Abort bit in Instruction and Data Aborts synchronous exception
+ * syndromes.
+ */
+#define ESR_ISS_EABORT_EA_BIT		U(9)
+
 #define EC_BITS(x)			(((x) >> ESR_EC_SHIFT) & ESR_EC_MASK)
 
 /* Reset bit inside the Reset management register for EL3 (RMR_EL3) */