root/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy1.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "bpf_legacy.h"
#include "bpf_test_utils.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;

static __noinline
int subprog_tail(struct __sk_buff *skb)
{
        bpf_tail_call_static(skb, &jmp_table, 0);
        return 0;
}

SEC("tc")
int entry(struct __sk_buff *skb)
{
        int ret = 1;

        clobber_regs_stack();

        count++;
        subprog_tail(skb);
        subprog_tail(skb);

        return ret;
}

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