fipa-sra func tcp_ack_update_rtt operation not permitted error

[kevin-intri-form3]

We are trying to test a function using BPF trampoline with fexit but it's failing because the kernel func is optimized and it seems the BTF entry doesn't exist for that function.
Do you know if there is a way to work with this without compile the kernel?

OS : Ubuntu 20.04
Kernel: 5.15

error attaching bpf program: loading objects: field TcpAckUpdateRtt: program tcp_ack_update_rtt: attach Tracing/TraceFExit: find target for fexit tcp_ack_update_rtt: find target in modules: iterate modules: get next BTF ID: operation not permitted

> strings /sys/kernel/btf/vmlinux | grep -i tcp_ack
__tcp_ack_snd_check
tcp_ack
tcp_ack_tstamp
cubictcp_acked
> cat /proc/kallsyms | grep "tcp_ack"
0000000000000000 t tcp_ack_tstamp
0000000000000000 t __tcp_ack_snd_check
0000000000000000 t tcp_ack_update_rtt.isra.0
0000000000000000 t tcp_ack
0000000000000000 t cubictcp_acked
0000000000000000 t tcp_ack_update_rtt.isra.0.cold
0000000000000000 t tcp_ack.cold
0000000000000000 r __BTF_ID__func__cubictcp_acked__639

Similar but with kprobe: iovisor/bcc#1963