samples/bpf/syscall_tp_kern.c

   1 /* Copyright (c) 2017 Facebook
   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 <uapi/linux/bpf.h>
   8 #include "bpf_helpers.h"
   9
  10 struct syscalls_enter_open_args {
  11         unsigned long long unused;
  12         long syscall_nr;
  13         long filename_ptr;
  14         long flags;
  15         long mode;
  16 };
  17
  18 struct syscalls_exit_open_args {
  19         unsigned long long unused;
  20         long syscall_nr;
  21         long ret;
  22 };
  23
  24 struct bpf_map_def SEC("maps") enter_open_map = {
  25         .type = BPF_MAP_TYPE_ARRAY,
  26         .key_size = sizeof(u32),
  27         .value_size = sizeof(u32),
  28         .max_entries = 1,
  29 };
  30
  31 struct bpf_map_def SEC("maps") exit_open_map = {
  32         .type = BPF_MAP_TYPE_ARRAY,
  33         .key_size = sizeof(u32),
  34         .value_size = sizeof(u32),
  35         .max_entries = 1,
  36 };
  37
  38 static __always_inline void count(void *map)
  39 {
  40         u32 key = 0;
  41         u32 *value, init_val = 1;
  42
  43         value = bpf_map_lookup_elem(map, &key);
  44         if (value)
  45                 *value += 1;
  46         else
  47                 bpf_map_update_elem(map, &key, &init_val, BPF_NOEXIST);
  48 }
  49
  50 SEC("tracepoint/syscalls/sys_enter_open")
  51 int trace_enter_open(struct syscalls_enter_open_args *ctx)
  52 {
  53         count((void *)&enter_open_map);
  54         return 0;
  55 }
  56
  57 SEC("tracepoint/syscalls/sys_exit_open")
  58 int trace_enter_exit(struct syscalls_exit_open_args *ctx)
  59 {
  60         count((void *)&exit_open_map);
  61         return 0;
  62 }