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 BPF_ARRAY4(map_sh, 0, PIN_OBJECT_NS, 1); /* or PIN_GLOBAL_NS, or PIN_NONE */
22
23 __section("egress")
emain(struct __sk_buff * skb)24 int emain(struct __sk_buff *skb)
25 {
26 int key = 0, *val;
27
28 val = map_lookup_elem(&map_sh, &key);
29 if (val)
30 lock_xadd(val, 1);
31
32 return BPF_H_DEFAULT;
33 }
34
35 __section("ingress")
imain(struct __sk_buff * skb)36 int imain(struct __sk_buff *skb)
37 {
38 char fmt[] = "map val: %d\n";
39 int key = 0, *val;
40
41 val = map_lookup_elem(&map_sh, &key);
42 if (val)
43 trace_printk(fmt, sizeof(fmt), *val);
44
45 return BPF_H_DEFAULT;
46 }
47
48 BPF_LICENSE("GPL");
49