--filter-trace-tc option doesn't work with Cilium

[hwchiu]

Hi, I’m running the pwru in the k8s server which running the cilium 1.11 version.
everything works well but failed to start when I enabled the filter-trace-tc options, it showed the following error.

Failed to load objects: Verifier error: load program: invalid argument
func#0 @0
func#1 @37
func#2 @859
func#3 @1044
Subprog __send_drop_notify doesn't exist
Program fentry_tc: load program: invalid argument: Subprog __send_drop_notify doesn't exist (5 line(s) omitted

As I know, the _send_drop_notify is the function defined in the cilium code base and I don’t know how to fix it to ensure I can run the filter-trace-tc option with pwru in my server, any clue or options I can check?

Environment:
OS: Ubuntu 20.04
Kernel: 5.15.0.69
pwru: master branch(2024/02/01).

[brb]

@hwchiu Thanks for the issue! Have you tried running with more recent Cilium version?

[hwchiu]

@brb
Thanks for the reply and unfortunately, I'm not able to upgrade the cilium version in that environment, but
I will try to reproduce the issue in my home lab and then try the latest cilium to see if the issue still exists.

[garyhuang123]

Encountered the same issue on cilium 1.11.5, kernel 5.6

[wdullaer]

I just ran into this as well with an ebpf program I wrote.
I compiled it with clang and embedded the btf information.
Clearly the subprog in question exists.

What kind of extra info would be needed to investigate this? I can try to reduce my program to the minimal repro case.