1 #include "../../include/bpf_api.h"
2
3 /* Minimal, stand-alone toy map pinning example:
4 *
5 * clang -target bpf -O2 [...] -o bpf_shared.o -c bpf_shared.c
6 * tc filter add dev foo parent 1: bpf obj bpf_shared.o sec egress
7 * tc filter add dev foo parent ffff: bpf obj bpf_shared.o sec ingress
8 *
9 * Both classifier will share the very same map instance in this example,
10 * so map content can be accessed from ingress *and* egress side!
11 *
12 * This example has a pinning of PIN_OBJECT_NS, so it's private and
13 * thus shared among various program sections within the object.
14 *
15 * A setting of PIN_GLOBAL_NS would place it into a global namespace,
16 * so that it can be shared among different object files. A setting
17 * of PIN_NONE (= 0) means no sharing, so each tc invocation a new map
18 * instance is being created.
19 */
20
21 struct bpf_elf_map __section_maps map_sh = {
22 .type = BPF_MAP_TYPE_ARRAY,
23 .size_key = sizeof(uint32_t),
24 .size_value = sizeof(uint32_t),
25 .pinning = PIN_OBJECT_NS, /* or PIN_GLOBAL_NS, or PIN_NONE */
26 .max_elem = 1,
27 };
28
29 __section("egress")
emain(struct __sk_buff * skb)30 int emain(struct __sk_buff *skb)
31 {
32 int key = 0, *val;
33
34 val = map_lookup_elem(&map_sh, &key);
35 if (val)
36 lock_xadd(val, 1);
37
38 return BPF_H_DEFAULT;
39 }
40
41 __section("ingress")
imain(struct __sk_buff * skb)42 int imain(struct __sk_buff *skb)
43 {
44 int key = 0, *val;
45
46 val = map_lookup_elem(&map_sh, &key);
47 if (val)
48 printt("map val: %d\n", *val);
49
50 return BPF_H_DEFAULT;
51 }
52
53 BPF_LICENSE("GPL");
54