ArmPlatformPkg/ArmPlatformLib: Introduce ArmPlatformSecBootAction function

This function is called at the initial stage of the Secure boot process to allow
platform vendors to add early actions.



git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12413 6f19259b-4bc3-4df7-8a09-765794883524

ArmPlatformPkg/Sec/SecEntryPoint.asm

@@ -20,6 +20,7 @@
   INCLUDE AsmMacroIoLib.inc
   
   IMPORT  CEntryPoint
+  IMPORT  ArmPlatformSecBootAction
   IMPORT  ArmPlatformIsMemoryInitialized
   IMPORT  ArmPlatformInitializeBootMemory
   IMPORT  ArmDisableInterrupts
@@ -39,16 +40,19 @@
 StartupAddr        DCD      CEntryPoint
 
 _ModuleEntryPoint
-  //Set VBAR to the start of the exception vectors in Secure Mode
-  ldr   r0, =SecVectorTable
-  blx   ArmWriteVBar
-
   // First ensure all interrupts are disabled
   blx   ArmDisableInterrupts
 
   // Ensure that the MMU and caches are off
   blx   ArmDisableCachesAndMmu
 
+  // Jump to Platform Specific Boot Action function
+  blx   ArmPlatformSecBootAction
+
+  // Set VBAR to the start of the exception vectors in Secure Mode
+  ldr   r0, =SecVectorTable
+  blx   ArmWriteVBar
+
 _IdentifyCpu 
   // Identify CPU ID
   bl    ArmReadMpidr