symbol "PT_REGS_PARM2": unsatisfied program reference

[actor168]

When I write code like this, it show errors, need Community help...

ebpf code:

#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_core_read.h>

char __license[] SEC("license") = "Dual MIT/GPL";

SEC("kprobe/__tcp_transmit_skb")
int kprobe_tcp_transmit_skb(struct pt_regs *ctx) 
{
    struct sk_buff *skb = (struct sk_buff *)PT_REGS_PARM2(ctx);
    u16 len = BPF_CORE_READ(skb, len);
    bpf_trace_printk("sk_buff len: %p\n", len);
    return 0;
}

cilium ebpf load program and run with errors like:

can't load bpf: program kprobe_tcp_transmit_skb: Call at insn 0: symbol "PT_REGS_PARM2": unsatisfied program reference

[actor168]

closed, it is because bpf_trace_printk, should be bpf_printk