bpf_lookup_system_key
struct bpf_key *bpf_lookup_system_key(u64 id);
BTF_ID_FLAGS(func, bpf_lookup_system_key, KF_ACQUIRE | KF_RET_NULL)
key = bpf_lookup_system_key(attr->keyring_id);
extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym;
trusted_keyring = bpf_lookup_system_key(0);
extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym;
bkey = bpf_lookup_system_key(key_id);
trusted_keyring = bpf_lookup_system_key(system_keyring_id);
__imm(bpf_lookup_system_key)
extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym;
__imm(bpf_lookup_system_key)
: __imm(bpf_lookup_system_key)
bpf_lookup_system_key(0);