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
8struct my_key { long x; };
9struct my_value { long x; };
10
11struct {
12 __uint(type, BPF_MAP_TYPE_HASH);
13 __type(key, struct my_key);
14 __type(value, struct my_value);
15 __uint(max_entries, 16);
16} map1 SEC(".maps");
17
18 /* Matches map2 definition in linked_maps2.c. Order of the attributes doesn't
19 * matter.
20 */
21typedef struct {
22 __uint(max_entries, 8);
23 __type(key, int);
24 __type(value, int);
25 __uint(type, BPF_MAP_TYPE_ARRAY);
26} map2_t;
27
28extern map2_t map2 SEC(".maps");
29
30/* This should be the winning map definition, but we have no way of verifying,
31 * so we just make sure that it links and works without errors
32 */
33struct {
34 __uint(type, BPF_MAP_TYPE_ARRAY);
35 __type(key, int);
36 __type(value, int);
37 __uint(max_entries, 16);
38} map_weak __weak SEC(".maps");
39
40int output_first1;
41int output_second1;
42int output_weak1;
43
44SEC("raw_tp/sys_enter")
45int BPF_PROG(handler_enter1)
46{
47 /* update values with key = 1 */
48 int key = 1, val = 1;
49 struct my_key key_struct = { .x = 1 };
50 struct my_value val_struct = { .x = 1000 };
51
52 bpf_map_update_elem(&map1, &key_struct, &val_struct, 0);
53 bpf_map_update_elem(&map2, &key, &val, 0);
54 bpf_map_update_elem(&map_weak, &key, &val, 0);
55
56 return 0;
57}
58
59SEC("raw_tp/sys_exit")
60int BPF_PROG(handler_exit1)
61{
62 /* lookup values with key = 2, set in another file */
63 int key = 2, *val;
64 struct my_key key_struct = { .x = 2 };
65 struct my_value *value_struct;
66
67 value_struct = bpf_map_lookup_elem(&map1, &key_struct);
68 if (value_struct)
69 output_first1 = value_struct->x;
70
71 val = bpf_map_lookup_elem(&map2, &key);
72 if (val)
73 output_second1 = *val;
74
75 val = bpf_map_lookup_elem(&map_weak, &key);
76 if (val)
77 output_weak1 = *val;
78
79 return 0;
80}
81
82char LICENSE[] SEC("license") = "GPL";
83

source code of linux/tools/testing/selftests/bpf/progs/linked_maps1.c