1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2021 Facebook */
3 
4 #include "vmlinux.h"
5 #include <bpf/bpf_helpers.h>
6 #include <bpf/bpf_tracing.h>
7 
8 char _license[] SEC("license") = "GPL";
9 
10 struct {
11 	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
12 	__uint(map_flags, BPF_F_NO_PREALLOC);
13 	__type(key, int);
14 	__type(value, long);
15 } enter_id SEC(".maps");
16 
17 #define MAGIC_VALUE 0xabcd1234
18 
19 pid_t target_pid = 0;
20 int mismatch_cnt = 0;
21 int enter_cnt = 0;
22 int exit_cnt = 0;
23 
24 SEC("tp_btf/sys_enter")
25 int BPF_PROG(on_enter, struct pt_regs *regs, long id)
26 {
27 	struct task_struct *task;
28 	long *ptr;
29 
30 	task = bpf_get_current_task_btf();
31 	if (task->pid != target_pid)
32 		return 0;
33 
34 	ptr = bpf_task_storage_get(&enter_id, task, 0,
35 				   BPF_LOCAL_STORAGE_GET_F_CREATE);
36 	if (!ptr)
37 		return 0;
38 
39 	__sync_fetch_and_add(&enter_cnt, 1);
40 	*ptr = MAGIC_VALUE + enter_cnt;
41 
42 	return 0;
43 }
44 
45 SEC("tp_btf/sys_exit")
46 int BPF_PROG(on_exit, struct pt_regs *regs, long id)
47 {
48 	struct task_struct *task;
49 	long *ptr;
50 
51 	task = bpf_get_current_task_btf();
52 	if (task->pid != target_pid)
53 		return 0;
54 
55 	ptr = bpf_task_storage_get(&enter_id, task, 0,
56 				   BPF_LOCAL_STORAGE_GET_F_CREATE);
57 	if (!ptr)
58 		return 0;
59 
60 	__sync_fetch_and_add(&exit_cnt, 1);
61 	if (*ptr != MAGIC_VALUE + exit_cnt)
62 		__sync_fetch_and_add(&mismatch_cnt, 1);
63 	return 0;
64 }
65