LXR linux/samples/bpf/tracex4

   1/* Copyright (c) 2015 PLUMgrid, http://plumgrid.com
   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/ptrace.h>
   8#include <linux/version.h>
   9#include <uapi/linux/bpf.h>
  10#include "bpf_helpers.h"
  11
  12struct pair {
  13        u64 val;
  14        u64 ip;
  15};
  16
  17struct bpf_map_def SEC("maps") my_map = {
  18        .type = BPF_MAP_TYPE_HASH,
  19        .key_size = sizeof(long),
  20        .value_size = sizeof(struct pair),
  21        .max_entries = 1000000,
  22};
  23
  24/* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
  25 * example will no longer be meaningful
  26 */
  27SEC("kprobe/kmem_cache_free")
  28int bpf_prog1(struct pt_regs *ctx)
  29{
  30        long ptr = PT_REGS_PARM2(ctx);
  31
  32        bpf_map_delete_elem(&my_map, &ptr);
  33        return 0;
  34}
  35
  36SEC("kretprobe/kmem_cache_alloc_node")
  37int bpf_prog2(struct pt_regs *ctx)
  38{
  39        long ptr = PT_REGS_RC(ctx);
  40        long ip = 0;
  41
  42        /* get ip address of kmem_cache_alloc_node() caller */
  43        bpf_probe_read(&ip, sizeof(ip), (void *)(PT_REGS_FP(ctx) + sizeof(ip)));
  44
  45        struct pair v = {
  46                .val = bpf_ktime_get_ns(),
  47                .ip = ip,
  48        };
  49
  50        bpf_map_update_elem(&my_map, &ptr, &v, BPF_ANY);
  51        return 0;
  52}
  53char _license[] SEC("license") = "GPL";
  54u32 _version SEC("version") = LINUX_VERSION_CODE;
  55