1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2020 Facebook
3 
4 #include "vmlinux.h"
5 #include <bpf/bpf_helpers.h>
6 #include <bpf/bpf_core_read.h>
7 
8 char _license[] SEC("license") = "GPL";
9 
10 /* shuffled layout for relocatable (CO-RE) reads */
11 struct callback_head___shuffled {
12 	void (*func)(struct callback_head___shuffled *head);
13 	struct callback_head___shuffled *next;
14 };
15 
16 struct callback_head k_probe_in = {};
17 struct callback_head___shuffled k_core_in = {};
18 
19 struct callback_head *u_probe_in = 0;
20 struct callback_head___shuffled *u_core_in = 0;
21 
22 long k_probe_out = 0;
23 long u_probe_out = 0;
24 
25 long k_core_out = 0;
26 long u_core_out = 0;
27 
28 int my_pid = 0;
29 
30 SEC("raw_tracepoint/sys_enter")
31 int handler(void *ctx)
32 {
33 	int pid = bpf_get_current_pid_tgid() >> 32;
34 
35 	if (my_pid != pid)
36 		return 0;
37 
38 	/* next pointers for kernel address space have to be initialized from
39 	 * BPF side, user-space mmaped addresses are stil user-space addresses
40 	 */
41 	k_probe_in.next = &k_probe_in;
42 	__builtin_preserve_access_index(({k_core_in.next = &k_core_in;}));
43 
44 	k_probe_out = (long)BPF_PROBE_READ(&k_probe_in, next, next, func);
45 	k_core_out = (long)BPF_CORE_READ(&k_core_in, next, next, func);
46 	u_probe_out = (long)BPF_PROBE_READ_USER(u_probe_in, next, next, func);
47 	u_core_out = (long)BPF_CORE_READ_USER(u_core_in, next, next, func);
48 
49 	return 0;
50 }
51