ArmPkg: Introduce ArmSetLowVectors/ArmSetHighVectors functions

These functions set/clear the SCTLR.V bit that controls the location
of the Vector Table.
This commit also forces the SCTLR.V to be clear when the VBAR register
is set.

Note: The original fix has been proposed by Eugene Cohen (HP).




git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11739 6f19259b-4bc3-4df7-8a09-765794883524

ArmPkg/Drivers/CpuDxe/Exception.c

@@ -149,6 +149,14 @@ InitializeExceptions (
     //
     Length = (UINTN)ExceptionHandlersEnd - (UINTN)ExceptionHandlersStart;
 
+    // Check if the exception vector is in the low address
+    if (PcdGet32 (PcdCpuVectorBaseAddress) == 0x0) {
+      // Set SCTLR.V to 0 to enable VBAR to be used
+      ArmSetLowVectors ();
+    } else {
+      ArmSetHighVectors ();
+    }
+
     //
     // Reserve space for the exception handlers
     //