tailcall_bpf2bpf_hierarchy_fentry.c

 1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright Leon Hwang */
 3
 4#include "vmlinux.h"
 5#include <bpf/bpf_helpers.h>
 6#include <bpf/bpf_tracing.h>
 7#include "bpf_test_utils.h"
 8
 9struct {
10	__uint(type, BPF_MAP_TYPE_PROG_ARRAY);
11	__uint(max_entries, 1);
12	__uint(key_size, sizeof(__u32));
13	__uint(value_size, sizeof(__u32));
14} jmp_table SEC(".maps");
15
16int count = 0;
17
18static __noinline
19int subprog_tail(void *ctx)
20{
21	bpf_tail_call_static(ctx, &jmp_table, 0);
22	return 0;
23}
24
25SEC("fentry/dummy")
26int BPF_PROG(fentry, struct sk_buff *skb)
27{
28	clobber_regs_stack();
29
30	count++;
31	subprog_tail(ctx);
32	subprog_tail(ctx);
33
34	return 0;
35}
36
37
38char _license[] SEC("license") = "GPL";