1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2019 Facebook
3
4 #include <linux/bpf.h>
5 #include <stdint.h>
6 #include <bpf/bpf_helpers.h>
7
8 char _license[] SEC("license") = "GPL";
9
10 struct {
11 __uint(type, BPF_MAP_TYPE_ARRAY);
12 __uint(map_flags, BPF_F_MMAPABLE | BPF_F_RDONLY_PROG);
13 __type(key, __u32);
14 __type(value, char);
15 } rdonly_map SEC(".maps");
16
17 struct {
18 __uint(type, BPF_MAP_TYPE_ARRAY);
19 __uint(map_flags, BPF_F_MMAPABLE);
20 __type(key, __u32);
21 __type(value, __u64);
22 } data_map SEC(".maps");
23
24 __u64 in_val = 0;
25 __u64 out_val = 0;
26
27 SEC("raw_tracepoint/sys_enter")
test_mmap(void * ctx)28 int test_mmap(void *ctx)
29 {
30 int zero = 0, one = 1, two = 2, far = 1500;
31 __u64 val, *p;
32
33 out_val = in_val;
34
35 /* data_map[2] = in_val; */
36 bpf_map_update_elem(&data_map, &two, (const void *)&in_val, 0);
37
38 /* data_map[1] = data_map[0] * 2; */
39 p = bpf_map_lookup_elem(&data_map, &zero);
40 if (p) {
41 val = (*p) * 2;
42 bpf_map_update_elem(&data_map, &one, &val, 0);
43 }
44
45 /* data_map[far] = in_val * 3; */
46 val = in_val * 3;
47 bpf_map_update_elem(&data_map, &far, &val, 0);
48
49 return 0;
50 }
51
52