1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
 3
 4#include "vmlinux.h"
 5#include <bpf/bpf_helpers.h>
 6
 7#include "bpf_misc.h"
 8
 9char _license[] SEC("license") = "GPL";
10
11struct inner_array_type {
12	__uint(type, BPF_MAP_TYPE_ARRAY);
13	__uint(map_flags, BPF_F_MMAPABLE);
14	__type(key, __u32);
15	__type(value, __u64);
16	__uint(max_entries, 1);
17} inner_array SEC(".maps");
18
19struct {
20	__uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
21	__uint(key_size, 4);
22	__uint(value_size, 4);
23	__uint(max_entries, 1);
24	__array(values, struct inner_array_type);
25} outer_map SEC(".maps");
26
27int pid = 0;
28__u64 match_value = 0x13572468;
29bool done = false;
30bool pid_match = false;
31bool outer_map_match = false;
32
33SEC("fentry/" SYS_PREFIX "sys_nanosleep")
34int add_to_list_in_inner_array(void *ctx)
35{
36	__u32 curr_pid, zero = 0;
37	struct bpf_map *map;
38	__u64 *value;
39
40	curr_pid = (u32)bpf_get_current_pid_tgid();
41	if (done || curr_pid != pid)
42		return 0;
43
44	pid_match = true;
45	map = bpf_map_lookup_elem(&outer_map, &curr_pid);
46	if (!map)
47		return 0;
48
49	outer_map_match = true;
50	value = bpf_map_lookup_elem(map, &zero);
51	if (!value)
52		return 0;
53
54	*value = match_value;
55	done = true;
56	return 0;
57}