1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2021 Facebook */
3
4#include <linux/bpf.h>
5#define BPF_NO_GLOBAL_DATA
6#include <bpf/bpf_helpers.h>
7
8char LICENSE[] SEC("license") = "GPL";
9
10struct {
11	__uint(type, BPF_MAP_TYPE_ARRAY);
12	__type(key, int);
13	__type(value, int);
14	__uint(max_entries, 1);
15} my_pid_map SEC(".maps");
16
17struct {
18	__uint(type, BPF_MAP_TYPE_ARRAY);
19	__type(key, int);
20	__type(value, int);
21	__uint(max_entries, 1);
22} res_map SEC(".maps");
23
24volatile int my_pid_var = 0;
25volatile int res_var = 0;
26
27SEC("tp/raw_syscalls/sys_enter")
28int handle_legacy(void *ctx)
29{
30	int zero = 0, *my_pid, cur_pid, *my_res;
31
32	my_pid = bpf_map_lookup_elem(&my_pid_map, &zero);
33	if (!my_pid)
34		return 1;
35
36	cur_pid = bpf_get_current_pid_tgid() >> 32;
37	if (cur_pid != *my_pid)
38		return 1;
39
40	my_res = bpf_map_lookup_elem(&res_map, &zero);
41	if (!my_res)
42		return 1;
43
44	if (*my_res == 0)
45		/* use bpf_printk() in combination with BPF_NO_GLOBAL_DATA to
46		 * force .rodata.str1.1 section that previously caused
47		 * problems on old kernels due to libbpf always tried to
48		 * create a global data map for it
49		 */
50		bpf_printk("Legacy-case bpf_printk test, pid %d\n", cur_pid);
51	*my_res = 1;
52
53	return *my_res;
54}
55
56SEC("tp/raw_syscalls/sys_enter")
57int handle_modern(void *ctx)
58{
59	int cur_pid;
60
61	cur_pid = bpf_get_current_pid_tgid() >> 32;
62	if (cur_pid != my_pid_var)
63		return 1;
64
65	if (res_var == 0)
66		/* we need bpf_printk() to validate libbpf logic around unused
67		 * global maps and legacy kernels; see comment in handle_legacy()
68		 */
69		bpf_printk("Modern-case bpf_printk test, pid %d\n", cur_pid);
70	res_var = 1;
71
72	return res_var;
73}
74