tools/testing/selftests/bpf/progs/test_mmap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (c) 2019 Facebook
   3
   4 #include <linux/bpf.h>
   5 #include <stdint.h>
   6 #include "bpf_helpers.h"
   7
   8 char _license[] SEC("license") = "GPL";
   9
  10 struct {
  11         __uint(type, BPF_MAP_TYPE_ARRAY);
  12         __uint(max_entries, 512 * 4); /* at least 4 pages of data */
  13         __uint(map_flags, BPF_F_MMAPABLE);
  14         __type(key, __u32);
  15         __type(value, __u64);
  16 } data_map SEC(".maps");
  17
  18 static volatile __u64 in_val;
  19 static volatile __u64 out_val;
  20
  21 SEC("raw_tracepoint/sys_enter")
  22 int test_mmap(void *ctx)
  23 {
  24         int zero = 0, one = 1, two = 2, far = 1500;
  25         __u64 val, *p;
  26
  27         out_val = in_val;
  28
  29         /* data_map[2] = in_val; */
  30         bpf_map_update_elem(&data_map, &two, (const void *)&in_val, 0);
  31
  32         /* data_map[1] = data_map[0] * 2; */
  33         p = bpf_map_lookup_elem(&data_map, &zero);
  34         if (p) {
  35                 val = (*p) * 2;
  36                 bpf_map_update_elem(&data_map, &one, &val, 0);
  37         }
  38
  39         /* data_map[far] = in_val * 3; */
  40         val = in_val * 3;
  41         bpf_map_update_elem(&data_map, &far, &val, 0);
  42
  43         return 0;
  44 }
  45