ArmVirtualizationPkg: add a relocatable version of PrePi

This patch introduces a relocatable PrePi, which can execute
from arbitrary offsets in RAM. This is intendend to be run
from a boot loader which passes a description of the actual
platform in a device tree, for instance.

This module is based on the PrePi implementations residing under
ArmPlatformPkg.

Contributed-under: TianoCore Contribution Agreement 1.0
Reviewed-by: Olivier Martin <olivier.martin@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16961 6f19259b-4bc3-4df7-8a09-765794883524

ArmPlatformPkg/ArmVirtualizationPkg/PrePi/AArch64/ArchPrePi.c

@@ -0,0 +1,33 @@
+/** @file
+*
+*  Copyright (c) 2011-2013, ARM Limited. All rights reserved.
+*
+*  This program and the accompanying materials
+*  are licensed and made available under the terms and conditions of the BSD License
+*  which accompanies this distribution.  The full text of the license may be found at
+*  http://opensource.org/licenses/bsd-license.php
+*
+*  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+*  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+*
+**/
+
+#include "PrePi.h"
+
+#include <Chipset/AArch64.h>
+
+VOID
+ArchInitialize (
+  VOID
+  )
+{
+  // Enable Floating Point
+  if (FixedPcdGet32 (PcdVFPEnabled)) {
+    ArmEnableVFP ();
+  }
+
+  if (ArmReadCurrentEL () == AARCH64_EL2) {
+    // Trap General Exceptions. All exceptions that would be routed to EL1 are routed to EL2
+    ArmWriteHcr (ARM_HCR_TGE);
+  }
+}