[BUG]map 'index_map_rx' has to have BTF in order to use bpf_spin_lock

[babyyouyou]

Hello, After I manually compiled polycubed on the Ubuntu18.04 system and successfully installed it, I used the systemctl start polycubed command to start the daemon, and when I used the systemctl status polycubed command to view the status, the following error was reported:

================================================================
polycubed.service - polycube service
Loaded: loaded (/lib/systemd/system/polycubed.service; disabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Thu 2022-08-04 14:51:28 CST; 52min ago
Main PID: 1962 (code=exited, status=255)

Aug 04 14:51:28 ubuntu polycubed[1962]: 37: (bf) r8 = r7
Aug 04 14:51:28 ubuntu polycubed[1962]: 38: (07) r8 += 4
Aug 04 14:51:28 ubuntu polycubed[1962]: 39: (bf) r1 = r8
Aug 04 14:51:28 ubuntu polycubed[1962]: 40: (85) call bpf_spin_lock#93
Aug 04 14:51:28 ubuntu polycubed[1962]: map 'index_map_rx' has to have BTF in order to use bpf_spin_lock
Aug 04 14:51:28 ubuntu polycubed[1962]: processed 38 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 1
Aug 04 14:51:28 ubuntu polycubed[1962]: [2022-08-03 23:51:28.810] [polycubed] [error] cannot load ctrl_rx: Failed to load controller_module_rx: -1
Aug 04 14:51:28 ubuntu polycubed[1962]: [2022-08-03 23:51:28.842] [polycubed] [critical] Error starting polycube: cannot load controller_module_rx
Aug 04 14:51:28 ubuntu systemd[1]: polycubed.service: Main process exited, code=exited, status=255/n/a
Aug 04 14:51:28 ubuntu systemd[1]: polycubed.service: Failed with result 'exit-code'.

The above is the error message, it seems to be related to bpf_spin_lock, but I have correctly installed all components related to BPF under the Ubuntu system, and the kernel version also meets the requirements, my current kernel version = 5.4.0-122-generic, I am at a loss at present , hope to get help, thanks

system message:
Release version: Ubuntu18.04
Kernel version: 5.4.0-122-generic
clang version: clang10
llvm version: llvm10