samples/bpf/sampleip_kern.c

   1 /* Copyright 2016 Netflix, Inc.
   2  *
   3  * This program is free software; you can redistribute it and/or
   4  * modify it under the terms of version 2 of the GNU General Public
   5  * License as published by the Free Software Foundation.
   6  */
   7 #include <linux/version.h>
   8 #include <linux/ptrace.h>
   9 #include <uapi/linux/bpf.h>
  10 #include <uapi/linux/bpf_perf_event.h>
  11 #include <bpf/bpf_helpers.h>
  12 #include <bpf/bpf_tracing.h>
  13
  14 #define MAX_IPS         8192
  15
  16 struct bpf_map_def SEC("maps") ip_map = {
  17         .type = BPF_MAP_TYPE_HASH,
  18         .key_size = sizeof(u64),
  19         .value_size = sizeof(u32),
  20         .max_entries = MAX_IPS,
  21 };
  22
  23 SEC("perf_event")
  24 int do_sample(struct bpf_perf_event_data *ctx)
  25 {
  26         u64 ip;
  27         u32 *value, init_val = 1;
  28
  29         ip = PT_REGS_IP(&ctx->regs);
  30         value = bpf_map_lookup_elem(&ip_map, &ip);
  31         if (value)
  32                 *value += 1;
  33         else
  34                 /* E2BIG not tested for this example only */
  35                 bpf_map_update_elem(&ip_map, &ip, &init_val, BPF_NOEXIST);
  36
  37         return 0;
  38 }
  39 char _license[] SEC("license") = "GPL";