idx_hash
list = net->xfrm.policy_byidx + idx_hash(net, idx);
hlist_add_head(&policy->byidx, net->xfrm.policy_byidx+idx_hash(net, policy->index));
chain = net->xfrm.policy_byidx + idx_hash(net, id);
bpf_map__set_max_entries(skel->maps.idx_hash, MAX_IDX_HASH);
idx = bpf_map_lookup_elem(&idx_hash, &key);
} idx_hash SEC(".maps");