diff --git a/ArmPkg/Include/Library/DefaultExceptionHandlerLib.h b/ArmPkg/Include/Library/DefaultExceptionHandlerLib.h
index f5ddc256bd..1381cb4f6d 100644
--- a/ArmPkg/Include/Library/DefaultExceptionHandlerLib.h
+++ b/ArmPkg/Include/Library/DefaultExceptionHandlerLib.h
@@ -23,4 +23,10 @@ DefaultExceptionHandler (
   IN OUT EFI_SYSTEM_CONTEXT  SystemContext
   );
 
+VOID
+EFIAPI
+InitializeSysCallHandler (
+  IN VOID  *Handler
+  );
+
 #endif // DEFAULT_EXCEPTION_HANDLER_LIB_H_
diff --git a/ArmPkg/Library/DefaultExceptionHandlerLib/AArch64/DefaultExceptionHandler.c b/ArmPkg/Library/DefaultExceptionHandlerLib/AArch64/DefaultExceptionHandler.c
index ccde4412f4..877f66a55e 100644
--- a/ArmPkg/Library/DefaultExceptionHandlerLib/AArch64/DefaultExceptionHandler.c
+++ b/ArmPkg/Library/DefaultExceptionHandlerLib/AArch64/DefaultExceptionHandler.c
@@ -29,6 +29,14 @@
 //
 #define MAX_PRINT_CHARS  100
 
+typedef
+EFI_STATUS
+(EFIAPI *EFI_SYS_CALL_BOOT_SERVICE)(
+  IN  UINT8             Type,
+  IN  VOID              *CoreRbp,
+  IN  VOID              *UserRsp
+  );
+
 STATIC CHAR8  *gExceptionTypeString[] = {
   "Synchronous",
   "IRQ",
@@ -36,7 +44,8 @@ STATIC CHAR8  *gExceptionTypeString[] = {
   "SError"
 };
 
-STATIC BOOLEAN  mRecursiveException;
+STATIC BOOLEAN                    mRecursiveException;
+STATIC EFI_SYS_CALL_BOOT_SERVICE  mSysCallHandler;
 
 CONST CHAR8 *
 GetImageName (
@@ -177,6 +186,15 @@ BaseName (
   return Str;
 }
 
+VOID
+EFIAPI
+InitializeSysCallHandler (
+  IN VOID  *Handler
+  )
+{
+  mSysCallHandler = (EFI_SYS_CALL_BOOT_SERVICE)Handler;
+}
+
 /**
   This is the default action to take on an unexpected exception
 
@@ -199,11 +217,11 @@ DefaultExceptionHandler (
   INT32   Offset;
 
   if (AARCH64_ESR_EC (SystemContext.SystemContextAArch64->ESR) == AARCH64_ESR_EC_SVC64) {
-    return gBS->SysCallBootService (
-                  SystemContext.SystemContextAArch64->X0,
-                  &(SystemContext.SystemContextAArch64->X1),
-                  &(SystemContext.SystemContextAArch64->X0)
-                  );
+    return mSysCallHandler (
+             SystemContext.SystemContextAArch64->X0,
+             &(SystemContext.SystemContextAArch64->X1),
+             &(SystemContext.SystemContextAArch64->X0)
+             );
   }
 
   if (mRecursiveException) {
diff --git a/MdeModulePkg/Core/Dxe/DxeMain.h b/MdeModulePkg/Core/Dxe/DxeMain.h
index 9ce1b30e5c..33653cb325 100644
--- a/MdeModulePkg/Core/Dxe/DxeMain.h
+++ b/MdeModulePkg/Core/Dxe/DxeMain.h
@@ -232,6 +232,17 @@ typedef struct {
   BOOLEAN                                 IsRing3EntryPoint;
 } LOADED_IMAGE_PRIVATE_DATA;
 
+typedef struct {
+  UINTN  Argument1;
+  UINTN  Argument2;
+  UINTN  Argument3;
+} CORE_STACK;
+
+typedef struct {
+  UINTN  Rip;
+  UINTN  Arguments[];
+} RING3_STACK;
+
 #define LOADED_IMAGE_PRIVATE_DATA_FROM_THIS(a) \
           CR(a, LOADED_IMAGE_PRIVATE_DATA, Info, LOADED_IMAGE_PRIVATE_DATA_SIGNATURE)
 
@@ -2718,11 +2729,11 @@ CoreBootServices (
 
 EFI_STATUS
 EFIAPI
-SysCallBootService (
-  IN  UINT8  Type,
-  IN  VOID   *CoreRbp,
-  IN  VOID   *UserRsp
-  );
+CallBootService (
+  IN UINT8       Type,
+  IN CORE_STACK  *CoreRbp,
+  IN RING3_STACK *UserRsp
+  );
 
 EFI_STATUS
 EFIAPI
diff --git a/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c b/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
index ae99b63285..7a5d96775a 100644
--- a/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
+++ b/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
@@ -89,8 +89,7 @@ EFI_BOOT_SERVICES  mBootServices = {
   (EFI_CALCULATE_CRC32)CoreEfiNotAvailableYetArg3,                                        // CalculateCrc32
   (EFI_COPY_MEM)CopyMem,                                                                  // CopyMem
   (EFI_SET_MEM)SetMem,                                                                    // SetMem
-  (EFI_CREATE_EVENT_EX)CoreCreateEventEx,                                                 // CreateEventEx
-  (EFI_SYS_CALL_BOOT_SERVICE)SysCallBootService
+  (EFI_CREATE_EVENT_EX)CoreCreateEventEx                                                  // CreateEventEx
 };
 
 EFI_DXE_SERVICES  mDxeServices = {
diff --git a/MdeModulePkg/Core/Dxe/SysCall/AARCH64/InitializeMsr.c b/MdeModulePkg/Core/Dxe/SysCall/AARCH64/InitializeMsr.c
index 6db895d8de..9bed7c8d7d 100644
--- a/MdeModulePkg/Core/Dxe/SysCall/AARCH64/InitializeMsr.c
+++ b/MdeModulePkg/Core/Dxe/SysCall/AARCH64/InitializeMsr.c
@@ -7,10 +7,11 @@
 
 #include <Chipset/AArch64.h>
 #include <Library/ArmLib.h>
+#include <Library/DefaultExceptionHandlerLib.h>
 
 #include "DxeMain.h"
 
-extern UINTN  CoreSp;
+UINTN  CoreSp;
 
 EFI_STATUS
 EFIAPI
@@ -22,6 +23,53 @@ ArmCallRing3 (
   IN VOID            *CoreStack
   );
 
+VOID
+EFIAPI
+ReturnToCore (
+  IN EFI_STATUS Status,
+  IN UINTN      CoreSp
+  );
+
+EFI_STATUS
+EFIAPI
+SysCallBootService (
+  IN  UINT8  Type,
+  IN  VOID   *CoreRbp,
+  IN  VOID   *UserRsp
+  )
+{
+  EFI_STATUS              Status;
+  EFI_PHYSICAL_ADDRESS    Physical;
+
+  if (Type == SysCallReturnToCore) {
+    ReturnToCore (*(EFI_STATUS *)CoreRbp, CoreSp);
+  }
+
+  Status = CoreAllocatePages (
+             AllocateAnyPages,
+             EfiRing3MemoryType,
+             EFI_SIZE_TO_PAGES (8 * sizeof (UINTN)),
+             &Physical
+             );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  DisableSMAP ();
+  CopyMem ((VOID *)(UINTN)Physical, (VOID *)UserRsp, 8 * sizeof (UINTN));
+  EnableSMAP ();
+
+  Status = CallBootService (
+             Type,
+             (CORE_STACK *)CoreRbp,
+             (RING3_STACK *)(UINTN)Physical
+             );
+
+  CoreFreePages (Physical, EFI_SIZE_TO_PAGES (8 * sizeof (UINTN)));
+
+  return Status;
+}
+
 VOID
 EFIAPI
 InitializeMsr (
@@ -52,6 +100,8 @@ InitializeMsr (
     DEBUG ((DEBUG_ERROR, "Core: Failed to initialize MSRs for Ring3.\n"));
     ASSERT (FALSE);
   }
+
+  InitializeSysCallHandler ((VOID *)SysCallBootService);
 }
 
 VOID
diff --git a/MdeModulePkg/Core/Dxe/SysCall/BootServices.c b/MdeModulePkg/Core/Dxe/SysCall/BootServices.c
index 061ac97855..7a00ec8dea 100644
--- a/MdeModulePkg/Core/Dxe/SysCall/BootServices.c
+++ b/MdeModulePkg/Core/Dxe/SysCall/BootServices.c
@@ -8,8 +8,6 @@
 #include "DxeMain.h"
 #include "SupportedProtocols.h"
 
-UINTN  CoreSp;
-
 LIST_ENTRY mProtocolsHead = INITIALIZE_LIST_HEAD_VARIABLE (mProtocolsHead);
 
 typedef struct {
@@ -67,13 +65,6 @@ CallInstallMultipleProtocolInterfaces (
   IN VOID        *Function
   );
 
-VOID
-EFIAPI
-ReturnToCore (
-  IN EFI_STATUS Status,
-  IN UINTN      CoreSp
-  );
-
 VOID
 EFIAPI
 FreeProtocolsList (
@@ -270,16 +261,6 @@ PrepareRing3Interface (
   return Ring3Interface;
 }
 
-typedef struct {
-  UINTN  Argument1;
-  UINTN  Argument2;
-  UINTN  Argument3;
-} CORE_STACK;
-
-typedef struct {
-  UINTN  Rip;
-  UINTN  Arguments[];
-} RING3_STACK;
 //
 // Stack:
 //  rsp - User Rsp
@@ -1400,43 +1381,3 @@ CallBootService (
 
   return EFI_UNSUPPORTED;
 }
-
-EFI_STATUS
-EFIAPI
-SysCallBootService (
-  IN  UINT8  Type,
-  IN  VOID   *CoreRbp,
-  IN  VOID   *UserRsp
-  )
-{
-  EFI_STATUS              Status;
-  EFI_PHYSICAL_ADDRESS    Physical;
-
-  if (Type == SysCallReturnToCore) {
-    ReturnToCore (*(EFI_STATUS *)CoreRbp, CoreSp);
-  }
-
-  Status = CoreAllocatePages (
-             AllocateAnyPages,
-             EfiRing3MemoryType,
-             EFI_SIZE_TO_PAGES (8 * sizeof (UINTN)),
-             &Physical
-             );
-  if (EFI_ERROR (Status)) {
-    return Status;
-  }
-
-  DisableSMAP ();
-  CopyMem ((VOID *)(UINTN)Physical, (VOID *)UserRsp, 8 * sizeof (UINTN));
-  EnableSMAP ();
-
-  Status = CallBootService (
-             Type,
-             (CORE_STACK *)CoreRbp,
-             (RING3_STACK *)(UINTN)Physical
-             );
-
-  CoreFreePages (Physical, EFI_SIZE_TO_PAGES (8 * sizeof (UINTN)));
-
-  return Status;
-}
diff --git a/MdePkg/Include/Uefi/UefiSpec.h b/MdePkg/Include/Uefi/UefiSpec.h
index 160c3ba402..7129b29b9f 100644
--- a/MdePkg/Include/Uefi/UefiSpec.h
+++ b/MdePkg/Include/Uefi/UefiSpec.h
@@ -1780,14 +1780,6 @@ EFI_STATUS
   OUT UINT64            *MaximumVariableSize
   );
 
-typedef
-EFI_STATUS
-(EFIAPI *EFI_SYS_CALL_BOOT_SERVICE)(
-  IN  UINT8             Type,
-  IN  VOID              *CoreRbp,
-  IN  VOID              *UserRsp
-  );
-
 //
 // Firmware should stop at a firmware user interface on next boot
 //
@@ -1968,7 +1960,6 @@ typedef struct {
   EFI_COPY_MEM                                  CopyMem;
   EFI_SET_MEM                                   SetMem;
   EFI_CREATE_EVENT_EX                           CreateEventEx;
-  EFI_SYS_CALL_BOOT_SERVICE                     SysCallBootService;
 } EFI_BOOT_SERVICES;
 
 typedef enum {