LXR iproute2/examples/bpf/bpf

   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
  21struct {
  22        __uint(type, BPF_MAP_TYPE_ARRAY);
  23        __uint(key_size, sizeof(uint32_t));
  24        __uint(value_size, sizeof(uint32_t));
  25        __uint(max_entries, 1);
  26        __uint(pinning, LIBBPF_PIN_BY_NAME);    /* or LIBBPF_PIN_NONE */
  27} map_sh __section(".maps");
  28
  29__section("egress")
  30int 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")
  42int 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
  53BPF_LICENSE("GPL");
  54