linux/tools/testing/selftests/bpf/progs/tailcall_freplace.c

// SPDX-License-Identifier: GPL-2.0

#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>

struct {
	__uint(type, BPF_MAP_TYPE_PROG_ARRAY);
	__uint(max_entries, 1);
	__uint(key_size, sizeof(__u32));
	__uint(value_size, sizeof(__u32));
} jmp_table SEC(".maps");

int count = 0;

SEC("freplace")
int entry_freplace(struct __sk_buff *skb)
{
	count++;
	bpf_tail_call_static(skb, &jmp_table, 0);
	return count;
}

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