tools/testing/selftests/bpf/progs/test_obj_id.c

// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2017 Facebook
 */
#include <stddef.h>
#include <linux/bpf.h>
#include <linux/pkt_cls.h>
#include "bpf_helpers.h"

/* It is a dumb bpf program such that it must have no
 * issue to be loaded since testing the verifier is
 * not the focus here.
 */

int _version SEC("version") = 1;

struct {
	__uint(type, BPF_MAP_TYPE_ARRAY);
	__uint(max_entries, 1);
	__type(key, __u32);
	__type(value, __u64);
} test_map_id SEC(".maps");

SEC("test_obj_id_dummy")
int test_obj_id(struct __sk_buff *skb)
{
	__u32 key = 0;
	__u64 *value;

	value = bpf_map_lookup_elem(&test_map_id, &key);

	return TC_ACT_OK;
}