ArmPkg/Library/ArmExceptionLib/ArmExceptionLib.c - third_party/edk2 - Git at Google

 /* @file
 *  Main file supporting the SEC Phase for Versatile Express
 *
 *  Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
 *  Copyright (c) 2011-2021, Arm Limited. All rights reserved.<BR>
 *  Copyright (c) 2016 HP Development Company, L.P.
 *
 *  SPDX-License-Identifier: BSD-2-Clause-Patent
 *
 **/

 #include <Uefi.h>
 #include <Library/CpuExceptionHandlerLib.h>

 #include <Library/ArmLib.h>
 #include <Library/PcdLib.h>
 #include <Library/CacheMaintenanceLib.h>
 #include <Library/BaseLib.h>
 #include <Library/BaseMemoryLib.h>
 #include <Library/DebugLib.h>
 #include <Library/DefaultExceptionHandlerLib.h>

 STATIC
 RETURN_STATUS
 CopyExceptionHandlers (
   IN  PHYSICAL_ADDRESS  BaseAddress
   );

 EFI_STATUS
 EFIAPI
 RegisterExceptionHandler (
   IN EFI_EXCEPTION_TYPE         ExceptionType,
   IN EFI_CPU_INTERRUPT_HANDLER  InterruptHandler
   );

 VOID
 ExceptionHandlersStart (
   VOID
   );

 VOID
 ExceptionHandlersEnd (
   VOID
   );

 RETURN_STATUS
 ArchVectorConfig (
   IN  UINTN  VectorBaseAddress
   );

 // these globals are provided by the architecture specific source (Arm or AArch64)
 extern UINTN                   gMaxExceptionNumber;
 extern EFI_EXCEPTION_CALLBACK  gExceptionHandlers[];
 extern EFI_EXCEPTION_CALLBACK  gDebuggerExceptionHandlers[];
 extern PHYSICAL_ADDRESS        gExceptionVectorAlignmentMask;
 extern UINTN                   gDebuggerNoHandlerValue;

 // A compiler flag adjusts the compilation of this library to a variant where
 // the vectors are relocated (copied) to another location versus using the
 // vectors in-place.  Since this effects an assembly .align directive we must
 // address this at library build time.  Since this affects the build of the
 // library we cannot represent this in a PCD since PCDs are evaluated on
 // a per-module basis.
 #if defined (ARM_RELOCATE_VECTORS)
 STATIC CONST BOOLEAN  gArmRelocateVectorTable = TRUE;
 #else
 STATIC CONST BOOLEAN  gArmRelocateVectorTable = FALSE;
 #endif

 /**
 Initializes all CPU exceptions entries and provides the default exception handlers.

 Caller should try to get an array of interrupt and/or exception vectors that are in use and need to
 persist by EFI_VECTOR_HANDOFF_INFO defined in PI 1.3 specification.
 If caller cannot get reserved vector list or it does not exists, set VectorInfo to NULL.
 If VectorInfo is not NULL, the exception vectors will be initialized per vector attribute accordingly.

 @param[in]  VectorInfo    Pointer to reserved vector list.

 @retval EFI_SUCCESS           CPU Exception Entries have been successfully initialized
 with default exception handlers.
 @retval EFI_INVALID_PARAMETER VectorInfo includes the invalid content if VectorInfo is not NULL.
 @retval EFI_UNSUPPORTED       This function is not supported.

 **/
 EFI_STATUS
 EFIAPI
 InitializeCpuExceptionHandlers (
   IN EFI_VECTOR_HANDOFF_INFO  *VectorInfo OPTIONAL
   )
 {
   RETURN_STATUS  Status;
   UINTN          VectorBase;

   Status = EFI_SUCCESS;

   // if we are requested to copy exception handlers to another location
   if (gArmRelocateVectorTable) {
     VectorBase = PcdGet64 (PcdCpuVectorBaseAddress);
     Status     = CopyExceptionHandlers (VectorBase);
   } else {
     // use VBAR to point to where our exception handlers are

     // The vector table must be aligned for the architecture.  If this
     // assertion fails ensure the appropriate FFS alignment is in effect,
     // which can be accomplished by ensuring the proper Align=X statement
     // in the platform packaging rules.  For ARM Align=32 is required and
     // for AArch64 Align=4K is required.  Align=Auto can be used but this
     // is known to cause an issue with populating the reset vector area
     // for encapsulated FVs.
     ASSERT (((UINTN)ExceptionHandlersStart & gExceptionVectorAlignmentMask) == 0);

     // We do not copy the Exception Table at PcdGet64(PcdCpuVectorBaseAddress). We just set Vector
     // Base Address to point into CpuDxe code.
     VectorBase = (UINTN)ExceptionHandlersStart;

     Status = RETURN_SUCCESS;
   }

   if (!RETURN_ERROR (Status)) {
     // call the architecture-specific routine to prepare for the new vector
     // configuration to take effect
     ArchVectorConfig (VectorBase);

     ArmWriteVBar (VectorBase);
   }

   return RETURN_SUCCESS;
 }

 /**
 Copies exception handlers to the specified address.

 Caller should try to get an array of interrupt and/or exception vectors that are in use and need to
 persist by EFI_VECTOR_HANDOFF_INFO defined in PI 1.3 specification.
 If caller cannot get reserved vector list or it does not exists, set VectorInfo to NULL.
 If VectorInfo is not NULL, the exception vectors will be initialized per vector attribute accordingly.

 @param[in]  VectorInfo    Pointer to reserved vector list.

 @retval EFI_SUCCESS           CPU Exception Entries have been successfully initialized
 with default exception handlers.
 @retval EFI_INVALID_PARAMETER VectorInfo includes the invalid content if VectorInfo is not NULL.
 @retval EFI_UNSUPPORTED       This function is not supported.

 **/
 STATIC
 RETURN_STATUS
 CopyExceptionHandlers (
   IN  PHYSICAL_ADDRESS  BaseAddress
   )
 {
   RETURN_STATUS  Status;
   UINTN          Length;
   UINTN          Index;
   UINT32         *VectorBase;

   // ensure that the destination value specifies an address meeting the vector alignment requirements
   ASSERT ((BaseAddress & gExceptionVectorAlignmentMask) == 0);

   //
   // Copy an implementation of the exception vectors to PcdCpuVectorBaseAddress.
   //
   Length = (UINTN)ExceptionHandlersEnd - (UINTN)ExceptionHandlersStart;

   VectorBase = (UINT32 *)(UINTN)BaseAddress;

   if (FeaturePcdGet (PcdDebuggerExceptionSupport) == TRUE) {
     // Save existing vector table, in case debugger is already hooked in
     CopyMem ((VOID *)gDebuggerExceptionHandlers, (VOID *)VectorBase, sizeof (EFI_EXCEPTION_CALLBACK)* (gMaxExceptionNumber+1));
   }

   // Copy our assembly code into the page that contains the exception vectors.
   CopyMem ((VOID *)VectorBase, (VOID *)ExceptionHandlersStart, Length);

   //
   // Initialize the C entry points for interrupts
   //
   for (Index = 0; Index <= gMaxExceptionNumber; Index++) {
     if (!FeaturePcdGet (PcdDebuggerExceptionSupport) ||
         (gDebuggerExceptionHandlers[Index] == 0) || (gDebuggerExceptionHandlers[Index] == (VOID *)gDebuggerNoHandlerValue))
     {
       Status = RegisterExceptionHandler (Index, NULL);
       ASSERT_EFI_ERROR (Status);
     } else {
       // If the debugger has already hooked put its vector back
       VectorBase[Index] = (UINT32)(UINTN)gDebuggerExceptionHandlers[Index];
     }
   }

   // Flush Caches since we updated executable stuff
   InvalidateInstructionCacheRange ((VOID *)(UINTN)BaseAddress, Length);

   return RETURN_SUCCESS;
 }

 /**
 Initializes all CPU interrupt/exceptions entries and provides the default interrupt/exception handlers.

 Caller should try to get an array of interrupt and/or exception vectors that are in use and need to
 persist by EFI_VECTOR_HANDOFF_INFO defined in PI 1.3 specification.
 If caller cannot get reserved vector list or it does not exists, set VectorInfo to NULL.
 If VectorInfo is not NULL, the exception vectors will be initialized per vector attribute accordingly.

 @param[in]  VectorInfo    Pointer to reserved vector list.

 @retval EFI_SUCCESS           All CPU interrupt/exception entries have been successfully initialized
 with default interrupt/exception handlers.
 @retval EFI_INVALID_PARAMETER VectorInfo includes the invalid content if VectorInfo is not NULL.
 @retval EFI_UNSUPPORTED       This function is not supported.

 **/
 EFI_STATUS
 EFIAPI
 InitializeCpuInterruptHandlers (
   IN EFI_VECTOR_HANDOFF_INFO  *VectorInfo OPTIONAL
   )
 {
   // not needed, this is what the CPU driver is for
   return EFI_UNSUPPORTED;
 }

 /**
 Registers a function to be called from the processor exception handler. (On ARM/AArch64 this only
 provides exception handlers, not interrupt handling which is provided through the Hardware Interrupt
 Protocol.)

 This function registers and enables the handler specified by ExceptionHandler for a processor
 interrupt or exception type specified by ExceptionType. If ExceptionHandler is NULL, then the
 handler for the processor interrupt or exception type specified by ExceptionType is uninstalled.
 The installed handler is called once for each processor interrupt or exception.
 NOTE: This function should be invoked after InitializeCpuExceptionHandlers() or
 InitializeCpuInterruptHandlers() invoked, otherwise EFI_UNSUPPORTED returned.

 @param[in]  ExceptionType     Defines which interrupt or exception to hook.
 @param[in]  ExceptionHandler  A pointer to a function of type EFI_CPU_INTERRUPT_HANDLER that is called
 when a processor interrupt occurs. If this parameter is NULL, then the handler
 will be uninstalled.

 @retval EFI_SUCCESS           The handler for the processor interrupt was successfully installed or uninstalled.
 @retval EFI_ALREADY_STARTED   ExceptionHandler is not NULL, and a handler for ExceptionType was
 previously installed.
 @retval EFI_INVALID_PARAMETER ExceptionHandler is NULL, and a handler for ExceptionType was not
 previously installed.
 @retval EFI_UNSUPPORTED       The interrupt specified by ExceptionType is not supported,
 or this function is not supported.
 **/
 RETURN_STATUS
 RegisterCpuInterruptHandler (
   IN EFI_EXCEPTION_TYPE         ExceptionType,
   IN EFI_CPU_INTERRUPT_HANDLER  ExceptionHandler
   )
 {
   if (ExceptionType > gMaxExceptionNumber) {
     return RETURN_UNSUPPORTED;
   }

   if ((ExceptionHandler != NULL) && (gExceptionHandlers[ExceptionType] != NULL)) {
     return RETURN_ALREADY_STARTED;
   }

   gExceptionHandlers[ExceptionType] = ExceptionHandler;

   return RETURN_SUCCESS;
 }

 /**
 Register exception handler.

 @param  This                  A pointer to the SMM_CPU_SERVICE_PROTOCOL instance.
 @param  ExceptionType         Defines which interrupt or exception to hook. Type EFI_EXCEPTION_TYPE and
 the valid values for this parameter are defined in EFI_DEBUG_SUPPORT_PROTOCOL
 of the UEFI 2.0 specification.
 @param  InterruptHandler      A pointer to a function of type EFI_CPU_INTERRUPT_HANDLER
 that is called when a processor interrupt occurs.
 If this parameter is NULL, then the handler will be uninstalled.

 @retval EFI_SUCCESS           The handler for the processor interrupt was successfully installed or uninstalled.
 @retval EFI_ALREADY_STARTED   InterruptHandler is not NULL, and a handler for InterruptType was previously installed.
 @retval EFI_INVALID_PARAMETER InterruptHandler is NULL, and a handler for InterruptType was not previously installed.
 @retval EFI_UNSUPPORTED       The interrupt specified by InterruptType is not supported.

 **/
 EFI_STATUS
 EFIAPI
 RegisterExceptionHandler (
   IN EFI_EXCEPTION_TYPE         ExceptionType,
   IN EFI_CPU_INTERRUPT_HANDLER  InterruptHandler
   )
 {
   return RegisterCpuInterruptHandler (ExceptionType, InterruptHandler);
 }

 VOID
 EFIAPI
 CommonCExceptionHandler (
   IN     EFI_EXCEPTION_TYPE  ExceptionType,
   IN OUT EFI_SYSTEM_CONTEXT  SystemContext
   )
 {
   if (ExceptionType <= gMaxExceptionNumber) {
     if (gExceptionHandlers[ExceptionType]) {
       gExceptionHandlers[ExceptionType](ExceptionType, SystemContext);
       return;
     }
   } else {
     DEBUG ((DEBUG_ERROR, "Unknown exception type %d\n", ExceptionType));
     ASSERT (FALSE);
   }

   DefaultExceptionHandler (ExceptionType, SystemContext);
 }

 /**
   Initializes all CPU exceptions entries with optional extra initializations.

   By default, this method should include all functionalities implemented by
   InitializeCpuExceptionHandlers(), plus extra initialization works, if any.
   This could be done by calling InitializeCpuExceptionHandlers() directly
   in this method besides the extra works.

   InitData is optional and its use and content are processor arch dependent.
   The typical usage of it is to convey resources which have to be reserved
   elsewhere and are necessary for the extra initializations of exception.

   @param[in]  VectorInfo    Pointer to reserved vector list.
   @param[in]  InitData      Pointer to data optional for extra initializations
                             of exception.

   @retval EFI_SUCCESS             The exceptions have been successfully
                                   initialized.
   @retval EFI_INVALID_PARAMETER   VectorInfo or InitData contains invalid
                                   content.

 **/
 EFI_STATUS
 EFIAPI
 InitializeCpuExceptionHandlersEx (
   IN EFI_VECTOR_HANDOFF_INFO  *VectorInfo OPTIONAL,
   IN CPU_EXCEPTION_INIT_DATA  *InitData OPTIONAL
   )
 {
   return InitializeCpuExceptionHandlers (VectorInfo);
 }
	/* @file
	* Main file supporting the SEC Phase for Versatile Express
	*
	* Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
	* Copyright (c) 2011-2021, Arm Limited. All rights reserved.<BR>
	* Copyright (c) 2016 HP Development Company, L.P.
	*
	* SPDX-License-Identifier: BSD-2-Clause-Patent
	*
	**/

	#include <Uefi.h>
	#include <Library/CpuExceptionHandlerLib.h>

	#include <Library/ArmLib.h>
	#include <Library/PcdLib.h>
	#include <Library/CacheMaintenanceLib.h>
	#include <Library/BaseLib.h>
	#include <Library/BaseMemoryLib.h>
	#include <Library/DebugLib.h>
	#include <Library/DefaultExceptionHandlerLib.h>

	STATIC
	RETURN_STATUS
	CopyExceptionHandlers (
	IN PHYSICAL_ADDRESS BaseAddress
	);

	EFI_STATUS
	EFIAPI
	RegisterExceptionHandler (
	IN EFI_EXCEPTION_TYPE ExceptionType,
	IN EFI_CPU_INTERRUPT_HANDLER InterruptHandler
	);

	VOID
	ExceptionHandlersStart (
	VOID
	);

	VOID
	ExceptionHandlersEnd (
	VOID
	);

	RETURN_STATUS
	ArchVectorConfig (
	IN UINTN VectorBaseAddress
	);

	// these globals are provided by the architecture specific source (Arm or AArch64)
	extern UINTN gMaxExceptionNumber;
	extern EFI_EXCEPTION_CALLBACK gExceptionHandlers[];
	extern EFI_EXCEPTION_CALLBACK gDebuggerExceptionHandlers[];
	extern PHYSICAL_ADDRESS gExceptionVectorAlignmentMask;
	extern UINTN gDebuggerNoHandlerValue;

	// A compiler flag adjusts the compilation of this library to a variant where
	// the vectors are relocated (copied) to another location versus using the
	// vectors in-place. Since this effects an assembly .align directive we must
	// address this at library build time. Since this affects the build of the
	// library we cannot represent this in a PCD since PCDs are evaluated on
	// a per-module basis.
	#if defined (ARM_RELOCATE_VECTORS)
	STATIC CONST BOOLEAN gArmRelocateVectorTable = TRUE;
	#else
	STATIC CONST BOOLEAN gArmRelocateVectorTable = FALSE;
	#endif

	/**
	Initializes all CPU exceptions entries and provides the default exception handlers.

	Caller should try to get an array of interrupt and/or exception vectors that are in use and need to
	persist by EFI_VECTOR_HANDOFF_INFO defined in PI 1.3 specification.
	If caller cannot get reserved vector list or it does not exists, set VectorInfo to NULL.
	If VectorInfo is not NULL, the exception vectors will be initialized per vector attribute accordingly.

	@param[in] VectorInfo Pointer to reserved vector list.

	@retval EFI_SUCCESS CPU Exception Entries have been successfully initialized
	with default exception handlers.
	@retval EFI_INVALID_PARAMETER VectorInfo includes the invalid content if VectorInfo is not NULL.
	@retval EFI_UNSUPPORTED This function is not supported.

	**/
	EFI_STATUS
	EFIAPI
	InitializeCpuExceptionHandlers (
	IN EFI_VECTOR_HANDOFF_INFO *VectorInfo OPTIONAL
	)
	{
	RETURN_STATUS Status;
	UINTN VectorBase;

	Status = EFI_SUCCESS;

	// if we are requested to copy exception handlers to another location
	if (gArmRelocateVectorTable) {
	VectorBase = PcdGet64 (PcdCpuVectorBaseAddress);
	Status = CopyExceptionHandlers (VectorBase);
	} else {
	// use VBAR to point to where our exception handlers are

	// The vector table must be aligned for the architecture. If this
	// assertion fails ensure the appropriate FFS alignment is in effect,
	// which can be accomplished by ensuring the proper Align=X statement
	// in the platform packaging rules. For ARM Align=32 is required and
	// for AArch64 Align=4K is required. Align=Auto can be used but this
	// is known to cause an issue with populating the reset vector area
	// for encapsulated FVs.
	ASSERT (((UINTN)ExceptionHandlersStart & gExceptionVectorAlignmentMask) == 0);

	// We do not copy the Exception Table at PcdGet64(PcdCpuVectorBaseAddress). We just set Vector
	// Base Address to point into CpuDxe code.
	VectorBase = (UINTN)ExceptionHandlersStart;

	Status = RETURN_SUCCESS;
	}

	if (!RETURN_ERROR (Status)) {
	// call the architecture-specific routine to prepare for the new vector
	// configuration to take effect
	ArchVectorConfig (VectorBase);

	ArmWriteVBar (VectorBase);
	}

	return RETURN_SUCCESS;
	}

	/**
	Copies exception handlers to the specified address.

	Caller should try to get an array of interrupt and/or exception vectors that are in use and need to
	persist by EFI_VECTOR_HANDOFF_INFO defined in PI 1.3 specification.
	If caller cannot get reserved vector list or it does not exists, set VectorInfo to NULL.
	If VectorInfo is not NULL, the exception vectors will be initialized per vector attribute accordingly.

	@param[in] VectorInfo Pointer to reserved vector list.

	@retval EFI_SUCCESS CPU Exception Entries have been successfully initialized
	with default exception handlers.
	@retval EFI_INVALID_PARAMETER VectorInfo includes the invalid content if VectorInfo is not NULL.
	@retval EFI_UNSUPPORTED This function is not supported.

	**/
	STATIC
	RETURN_STATUS
	CopyExceptionHandlers (
	IN PHYSICAL_ADDRESS BaseAddress
	)
	{
	RETURN_STATUS Status;
	UINTN Length;
	UINTN Index;
	UINT32 *VectorBase;

	// ensure that the destination value specifies an address meeting the vector alignment requirements
	ASSERT ((BaseAddress & gExceptionVectorAlignmentMask) == 0);

	//
	// Copy an implementation of the exception vectors to PcdCpuVectorBaseAddress.
	//
	Length = (UINTN)ExceptionHandlersEnd - (UINTN)ExceptionHandlersStart;

	VectorBase = (UINT32 *)(UINTN)BaseAddress;

	if (FeaturePcdGet (PcdDebuggerExceptionSupport) == TRUE) {
	// Save existing vector table, in case debugger is already hooked in
	CopyMem ((VOID )gDebuggerExceptionHandlers, (VOID )VectorBase, sizeof (EFI_EXCEPTION_CALLBACK)* (gMaxExceptionNumber+1));
	}

	// Copy our assembly code into the page that contains the exception vectors.
	CopyMem ((VOID )VectorBase, (VOID )ExceptionHandlersStart, Length);

	//
	// Initialize the C entry points for interrupts
	//
	for (Index = 0; Index <= gMaxExceptionNumber; Index++) {
	if (!FeaturePcdGet (PcdDebuggerExceptionSupport) \|\|
	(gDebuggerExceptionHandlers[Index] == 0) \|\| (gDebuggerExceptionHandlers[Index] == (VOID *)gDebuggerNoHandlerValue))
	{
	Status = RegisterExceptionHandler (Index, NULL);
	ASSERT_EFI_ERROR (Status);
	} else {
	// If the debugger has already hooked put its vector back
	VectorBase[Index] = (UINT32)(UINTN)gDebuggerExceptionHandlers[Index];
	}
	}

	// Flush Caches since we updated executable stuff
	InvalidateInstructionCacheRange ((VOID *)(UINTN)BaseAddress, Length);

	return RETURN_SUCCESS;
	}

	/**
	Initializes all CPU interrupt/exceptions entries and provides the default interrupt/exception handlers.

	Caller should try to get an array of interrupt and/or exception vectors that are in use and need to
	persist by EFI_VECTOR_HANDOFF_INFO defined in PI 1.3 specification.
	If caller cannot get reserved vector list or it does not exists, set VectorInfo to NULL.
	If VectorInfo is not NULL, the exception vectors will be initialized per vector attribute accordingly.

	@param[in] VectorInfo Pointer to reserved vector list.

	@retval EFI_SUCCESS All CPU interrupt/exception entries have been successfully initialized
	with default interrupt/exception handlers.
	@retval EFI_INVALID_PARAMETER VectorInfo includes the invalid content if VectorInfo is not NULL.
	@retval EFI_UNSUPPORTED This function is not supported.

	**/
	EFI_STATUS
	EFIAPI
	InitializeCpuInterruptHandlers (
	IN EFI_VECTOR_HANDOFF_INFO *VectorInfo OPTIONAL
	)
	{
	// not needed, this is what the CPU driver is for
	return EFI_UNSUPPORTED;
	}

	/**
	Registers a function to be called from the processor exception handler. (On ARM/AArch64 this only
	provides exception handlers, not interrupt handling which is provided through the Hardware Interrupt
	Protocol.)

	This function registers and enables the handler specified by ExceptionHandler for a processor
	interrupt or exception type specified by ExceptionType. If ExceptionHandler is NULL, then the
	handler for the processor interrupt or exception type specified by ExceptionType is uninstalled.
	The installed handler is called once for each processor interrupt or exception.
	NOTE: This function should be invoked after InitializeCpuExceptionHandlers() or
	InitializeCpuInterruptHandlers() invoked, otherwise EFI_UNSUPPORTED returned.

	@param[in] ExceptionType Defines which interrupt or exception to hook.
	@param[in] ExceptionHandler A pointer to a function of type EFI_CPU_INTERRUPT_HANDLER that is called
	when a processor interrupt occurs. If this parameter is NULL, then the handler
	will be uninstalled.

	@retval EFI_SUCCESS The handler for the processor interrupt was successfully installed or uninstalled.
	@retval EFI_ALREADY_STARTED ExceptionHandler is not NULL, and a handler for ExceptionType was
	previously installed.
	@retval EFI_INVALID_PARAMETER ExceptionHandler is NULL, and a handler for ExceptionType was not
	previously installed.
	@retval EFI_UNSUPPORTED The interrupt specified by ExceptionType is not supported,
	or this function is not supported.
	**/
	RETURN_STATUS
	RegisterCpuInterruptHandler (
	IN EFI_EXCEPTION_TYPE ExceptionType,
	IN EFI_CPU_INTERRUPT_HANDLER ExceptionHandler
	)
	{
	if (ExceptionType > gMaxExceptionNumber) {
	return RETURN_UNSUPPORTED;
	}

	if ((ExceptionHandler != NULL) && (gExceptionHandlers[ExceptionType] != NULL)) {
	return RETURN_ALREADY_STARTED;
	}

	gExceptionHandlers[ExceptionType] = ExceptionHandler;

	return RETURN_SUCCESS;
	}

	/**
	Register exception handler.

	@param This A pointer to the SMM_CPU_SERVICE_PROTOCOL instance.
	@param ExceptionType Defines which interrupt or exception to hook. Type EFI_EXCEPTION_TYPE and
	the valid values for this parameter are defined in EFI_DEBUG_SUPPORT_PROTOCOL
	of the UEFI 2.0 specification.
	@param InterruptHandler A pointer to a function of type EFI_CPU_INTERRUPT_HANDLER
	that is called when a processor interrupt occurs.
	If this parameter is NULL, then the handler will be uninstalled.

	@retval EFI_SUCCESS The handler for the processor interrupt was successfully installed or uninstalled.
	@retval EFI_ALREADY_STARTED InterruptHandler is not NULL, and a handler for InterruptType was previously installed.
	@retval EFI_INVALID_PARAMETER InterruptHandler is NULL, and a handler for InterruptType was not previously installed.
	@retval EFI_UNSUPPORTED The interrupt specified by InterruptType is not supported.

	**/
	EFI_STATUS
	EFIAPI
	RegisterExceptionHandler (
	IN EFI_EXCEPTION_TYPE ExceptionType,
	IN EFI_CPU_INTERRUPT_HANDLER InterruptHandler
	)
	{
	return RegisterCpuInterruptHandler (ExceptionType, InterruptHandler);
	}

	VOID
	EFIAPI
	CommonCExceptionHandler (
	IN EFI_EXCEPTION_TYPE ExceptionType,
	IN OUT EFI_SYSTEM_CONTEXT SystemContext
	)
	{
	if (ExceptionType <= gMaxExceptionNumber) {
	if (gExceptionHandlers[ExceptionType]) {
	gExceptionHandlers[ExceptionType](ExceptionType, SystemContext);
	return;
	}
	} else {
	DEBUG ((DEBUG_ERROR, "Unknown exception type %d\n", ExceptionType));
	ASSERT (FALSE);
	}

	DefaultExceptionHandler (ExceptionType, SystemContext);
	}

	/**
	Initializes all CPU exceptions entries with optional extra initializations.

	By default, this method should include all functionalities implemented by
	InitializeCpuExceptionHandlers(), plus extra initialization works, if any.
	This could be done by calling InitializeCpuExceptionHandlers() directly
	in this method besides the extra works.

	InitData is optional and its use and content are processor arch dependent.
	The typical usage of it is to convey resources which have to be reserved
	elsewhere and are necessary for the extra initializations of exception.

	@param[in] VectorInfo Pointer to reserved vector list.
	@param[in] InitData Pointer to data optional for extra initializations
	of exception.

	@retval EFI_SUCCESS The exceptions have been successfully
	initialized.
	@retval EFI_INVALID_PARAMETER VectorInfo or InitData contains invalid
	content.

	**/
	EFI_STATUS
	EFIAPI
	InitializeCpuExceptionHandlersEx (
	IN EFI_VECTOR_HANDOFF_INFO *VectorInfo OPTIONAL,
	IN CPU_EXCEPTION_INIT_DATA *InitData OPTIONAL
	)
	{
	return InitializeCpuExceptionHandlers (VectorInfo);
	}