1// SPDX-License-Identifier: GPL-2.0
2
3/*
4 * Copyright 2020 Google LLC.
5 */
6
7#include <linux/bpf.h>
8#include <bpf/bpf_helpers.h>
9#include <bpf/bpf_tracing.h>
10
11char _license[] SEC("license") = "GPL";
12
13static int sequence = 0;
14__s32 input_retval = 0;
15
16__u64 fentry_result = 0;
17SEC("fentry/bpf_modify_return_test")
18int BPF_PROG(fentry_test, int a, __u64 b)
19{
20 sequence++;
21 fentry_result = (sequence == 1);
22 return 0;
23}
24
25__u64 fmod_ret_result = 0;
26SEC("fmod_ret/bpf_modify_return_test")
27int BPF_PROG(fmod_ret_test, int a, int *b, int ret)
28{
29 sequence++;
30 /* This is the first fmod_ret program, the ret passed should be 0 */
31 fmod_ret_result = (sequence == 2 && ret == 0);
32 return input_retval;
33}
34
35__u64 fexit_result = 0;
36SEC("fexit/bpf_modify_return_test")
37int BPF_PROG(fexit_test, int a, __u64 b, int ret)
38{
39 sequence++;
40 /* If the input_reval is non-zero a successful modification should have
41 * occurred.
42 */
43 if (input_retval)
44 fexit_result = (sequence == 3 && ret == input_retval);
45 else
46 fexit_result = (sequence == 3 && ret == 4);
47
48 return 0;
49}
50
51static int sequence2;
52
53__u64 fentry_result2 = 0;
54SEC("fentry/bpf_modify_return_test2")
55int BPF_PROG(fentry_test2, int a, int *b, short c, int d, void *e, char f,
56 int g)
57{
58 sequence2++;
59 fentry_result2 = (sequence2 == 1);
60 return 0;
61}
62
63__u64 fmod_ret_result2 = 0;
64SEC("fmod_ret/bpf_modify_return_test2")
65int BPF_PROG(fmod_ret_test2, int a, int *b, short c, int d, void *e, char f,
66 int g, int ret)
67{
68 sequence2++;
69 /* This is the first fmod_ret program, the ret passed should be 0 */
70 fmod_ret_result2 = (sequence2 == 2 && ret == 0);
71 return input_retval;
72}
73
74__u64 fexit_result2 = 0;
75SEC("fexit/bpf_modify_return_test2")
76int BPF_PROG(fexit_test2, int a, int *b, short c, int d, void *e, char f,
77 int g, int ret)
78{
79 sequence2++;
80 /* If the input_reval is non-zero a successful modification should have
81 * occurred.
82 */
83 if (input_retval)
84 fexit_result2 = (sequence2 == 3 && ret == input_retval);
85 else
86 fexit_result2 = (sequence2 == 3 && ret == 29);
87
88 return 0;
89}
90

source code of linux/tools/testing/selftests/bpf/progs/modify_return.c