bpf_calls_callback
bool bpf_calls_callback(struct bpf_verifier_env *env, int insn_idx);
alive = bpf_calls_callback(env, callsite)
if (!bpf_calls_callback(env, callee->callsite)) {
if (bpf_calls_callback(env, insn_idx)) {
if (bpf_calls_callback(env, w)) /* implicit loop? */
if (subseq_idx >= 0 && bpf_calls_callback(env, subseq_idx))