ebpf: constify various function pointer structs

We can move bpf_map_ops and bpf_verifier_ops and other structs into ro
section, bpf_map_type_list and bpf_prog_type_list into read mostly.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 9e3414d..a3c7701 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -41,7 +41,7 @@
 	return (unsigned long) value;
 }
 
-struct bpf_func_proto bpf_map_lookup_elem_proto = {
+const struct bpf_func_proto bpf_map_lookup_elem_proto = {
 	.func = bpf_map_lookup_elem,
 	.gpl_only = false,
 	.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
@@ -60,7 +60,7 @@
 	return map->ops->map_update_elem(map, key, value, r4);
 }
 
-struct bpf_func_proto bpf_map_update_elem_proto = {
+const struct bpf_func_proto bpf_map_update_elem_proto = {
 	.func = bpf_map_update_elem,
 	.gpl_only = false,
 	.ret_type = RET_INTEGER,
@@ -80,7 +80,7 @@
 	return map->ops->map_delete_elem(map, key);
 }
 
-struct bpf_func_proto bpf_map_delete_elem_proto = {
+const struct bpf_func_proto bpf_map_delete_elem_proto = {
 	.func = bpf_map_delete_elem,
 	.gpl_only = false,
 	.ret_type = RET_INTEGER,