text: /** @file
  *  Exception Handling support specific for AArch64
  *
  *  Copyright (c) 2016 HP Development Company, L.P.
  *
  *  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 <Uefi.h>
  
  #include <Chipset/AArch64.h>
  #include <Library/MemoryAllocationLib.h>
  #include <Protocol/DebugSupport.h> // for MAX_AARCH64_EXCEPTION
  
  UINTN                   gMaxExceptionNumber = MAX_AARCH64_EXCEPTION;
  EFI_EXCEPTION_CALLBACK  gExceptionHandlers[MAX_AARCH64_EXCEPTION + 1] = { 0 };
  EFI_EXCEPTION_CALLBACK  gDebuggerExceptionHandlers[MAX_AARCH64_EXCEPTION + 1] = { 0 };
  PHYSICAL_ADDRESS        gExceptionVectorAlignmentMask = ARM_VECTOR_TABLE_ALIGNMENT;
  UINTN                   gDebuggerNoHandlerValue = 0; // todo: define for AArch64
  
  #define EL0_STACK_PAGES   2
  
  VOID
  RegisterEl0Stack (
    IN  VOID    *Stack
    );
  
  RETURN_STATUS ArchVectorConfig(
    IN  UINTN       VectorBaseAddress
    )
  {
    UINTN             HcrReg;
    UINT8             *Stack;
  
    Stack = AllocatePages (EL0_STACK_PAGES);
    if (Stack == NULL) {
      return RETURN_OUT_OF_RESOURCES;
    }
  
    RegisterEl0Stack ((UINT8 *)Stack + EFI_PAGES_TO_SIZE (EL0_STACK_PAGES));
  
    if (ArmReadCurrentEL() == AARCH64_EL2) {
      HcrReg = ArmReadHcr();
  
      // Trap General Exceptions. All exceptions that would be routed to EL1 are routed to EL2
      HcrReg |= ARM_HCR_TGE;
  
      ArmWriteHcr(HcrReg);
    }
  
    return RETURN_SUCCESS;
  }
  