[PATCH] ArmPkg/Library: Add ArmReadSctlr for aarch64

[Supreeth Venkatesh <supreeth.venkatesh@arm.com>]

One of the UEFI Self Certification tests (UEFI-SCT) need to read the
current exception level SCTLR Register.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: John Powell <john.powell@arm.com>
Signed-off-by: Supreeth Venkatesh <supreeth.venkatesh@arm.com>
---
 ArmPkg/Library/ArmLib/Common/AArch64/ArmLibSupport.S | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/ArmPkg/Library/ArmLib/Common/AArch64/ArmLibSupport.S b/ArmPkg/Library/ArmLib/Common/AArch64/ArmLibSupport.S
index a6fd5e3..c9f3bd1 100644
--- a/ArmPkg/Library/ArmLib/Common/AArch64/ArmLibSupport.S
+++ b/ArmPkg/Library/ArmLib/Common/AArch64/ArmLibSupport.S
@@ -1,7 +1,7 @@
 #------------------------------------------------------------------------------
 #
 # Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
-# Copyright (c) 2011 - 2014, ARM Limited. All rights reserved.
+# Copyright (c) 2011 - 2016, 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
@@ -39,6 +39,7 @@ GCC_ASM_EXPORT (ArmCallWFE)
 GCC_ASM_EXPORT (ArmCallSEV)
 GCC_ASM_EXPORT (ArmReadCpuActlr)
 GCC_ASM_EXPORT (ArmWriteCpuActlr)
+GCC_ASM_EXPORT (ArmReadSctlr)
 
 #------------------------------------------------------------------------------
 
@@ -205,4 +206,13 @@ ASM_PFX(ArmWriteCpuActlr):
   isb
   ret
 
+ASM_PFX(ArmReadSctlr):
+  EL1_OR_EL2_OR_EL3(x1)
+1:mrs   x0, sctlr_el1
+  ret
+2:mrs   x0, sctlr_el2
+  ret
+3:mrs   x0, sctlr_el3
+4:ret
+
 ASM_FUNCTION_REMOVE_IF_UNREFERENCED
-- 
2.8.0