1/* SPDX-License-Identifier: GPL-2.0 */
 2/* Copyright (c) 2020 Facebook */
 3#include <linux/bpf.h>
 4#include <bpf/bpf_helpers.h>
 5
 6struct inner_map {
 7	__uint(type, BPF_MAP_TYPE_ARRAY);
 8	__uint(max_entries, 1);
 9	__type(key, int);
10	__type(value, int);
11} inner_map1 SEC(".maps"),
12  inner_map2 SEC(".maps");
13
14struct outer_arr {
15	__uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
16	__uint(max_entries, 3);
17	__uint(key_size, sizeof(int));
18	__uint(value_size, sizeof(int));
19	/* it's possible to use anonymous struct as inner map definition here */
20	__array(values, struct {
21		__uint(type, BPF_MAP_TYPE_ARRAY);
22		/* changing max_entries to 2 will fail during load
23		 * due to incompatibility with inner_map definition */
24		__uint(max_entries, 1);
25		__type(key, int);
26		__type(value, int);
27	});
28} outer_arr SEC(".maps") = {
29	/* (void *) cast is necessary because we didn't use `struct inner_map`
30	 * in __inner(values, ...)
31	 * Actually, a conscious effort is required to screw up initialization
32	 * of inner map slots, which is a great thing!
33	 */
34	.values = { (void *)&inner_map1, 0, (void *)&inner_map2 },
35};
36
37struct outer_hash {
38	__uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
39	__uint(max_entries, 5);
40	__uint(key_size, sizeof(int));
41	/* Here everything works flawlessly due to reuse of struct inner_map
42	 * and compiler will complain at the attempt to use non-inner_map
43	 * references below. This is great experience.
44	 */
45	__array(values, struct inner_map);
46} outer_hash SEC(".maps") = {
47	.values = {
48		[0] = &inner_map2,
49		[4] = &inner_map1,
50	},
51};
52
53int input = 0;
54
55SEC("raw_tp/sys_enter")
56int handle__sys_enter(void *ctx)
57{
58	struct inner_map *inner_map;
59	int key = 0, val;
60
61	inner_map = bpf_map_lookup_elem(&outer_arr, &key);
62	if (!inner_map)
63		return 1;
64	val = input;
65	bpf_map_update_elem(inner_map, &key, &val, 0);
66
67	inner_map = bpf_map_lookup_elem(&outer_hash, &key);
68	if (!inner_map)
69		return 1;
70	val = input + 1;
71	bpf_map_update_elem(inner_map, &key, &val, 0);
72
73	return 0;
74}
75
76char _license[] SEC("license") = "GPL";