Using Go BCC for instrumenting tail calls

main.go

package main

import (
	"io/ioutil"
	"log"
	"time"

	"github.com/iovisor/gobpf/bcc"
)

func main() {
	content, err := ioutil.ReadFile("./program.c")
	if err != nil {
		log.Fatal(err)
	}

	mod := bcc.NewModule(string(content), nil)

	sfd, err := mod.LoadKprobe("tail_call")
	if err != nil {
		log.Fatal(err)
	}

	progTable := bcc.NewTable(mod.TableId("prog_array"), mod)
	progTable.Set([]byte{2}, []byte{byte(sfd)})

	dfd, err := mod.LoadKprobe("do_tail_call")
	if err != nil {
		log.Fatal(err)
	}

	err = mod.AttachKprobe("__x64_sys_getcwd", dfd, 2)
	if err != nil {
		log.Fatal(err)
	}

	time.Sleep(time.Minute)
}

program.c

#include <uapi/linux/ptrace.h>
#include <net/sock.h>
#include <bcc/proto.h>
#include <linux/bpf.h>
#include <linux/kernel.h>
#include <uapi/linux/bpf.h>

BPF_PROG_ARRAY(prog_array, 10);

int tail_call(void *ctx) {
    bpf_trace_printk("tail-call\n");
    return 0;
}

int do_tail_call(void *ctx) {
    bpf_trace_printk("Original program\n");
    prog_array.call(ctx, 1);
    return 0;
}