Definition globalfunction_ptr_inject (j:meminj):=
  forall b f, Genv.find_funct_ptr ge b = Some f ->
              j b = Some(b,0) /\ isGlobalBlock ge b = true.

Lemma restrict_preserves_globalfun_ptr: forall j X (PG : globalfunction_ptr_inject j) (Glob : forall b, isGlobalBlock ge b = true -> X b = true), globalfunction_ptr_inject (restrict j X).