SecurityPkg Variable: Reuse scratch data area(at the end of volatile variable store)

as serialization runtime buffer to reduce SMRAM consumption for SMM variable driver.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Guo Dong <guo.dong@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17059 6f19259b-4bc3-4df7-8a09-765794883524

SecurityPkg/VariableAuthenticated/RuntimeDxe/Variable.h

@@ -194,6 +194,23 @@ FindVariable (
   IN  BOOLEAN                 IgnoreRtCheck
   );
 
+/**
+
+  Gets the pointer to the end of the variable storage area.
+
+  This function gets pointer to the end of the variable storage
+  area, according to the input variable store header.
+
+  @param VarStoreHeader  Pointer to the Variable Store Header.
+
+  @return Pointer to the end of the variable storage area.
+
+**/
+VARIABLE_HEADER *
+GetEndPointer (
+  IN VARIABLE_STORE_HEADER       *VarStoreHeader
+  );
+
 /**
 
   This code gets the pointer to the variable data.