Inductive valid_genv {F V:Type} (ge:Genv.t F V) (m:mem) : Type :=
mk_valid_genv :
(forall b, isGlobalBlock ge b=true -> val_valid (Vptr b Ptrofs.zero) m) ->
(forall b f, Genv.find_funct_ptr ge b = Some f -> val_valid (Vptr b Ptrofs.zero) m) ->
valid_genv ge m.

Lemma valid_genv_drop: forall {F V:Type} (ge:Genv.t F V) (m m1:mem) b lo hi p
(DROP: Mem.drop_perm m b lo hi p = Some m1) (G: valid_genv ge m),
valid_genv ge m1.