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")
handler(void * ctx)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 still 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