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/bpf_helpers.h>
   7
   8 char _license[] SEC("license") = "GPL";
   9
  10 struct {
  11         __uint(type, BPF_MAP_TYPE_ARRAY);
  12         __uint(max_entries, 4096);
  13         __uint(map_flags, BPF_F_MMAPABLE | BPF_F_RDONLY_PROG);
  14         __type(key, __u32);
  15         __type(value, char);
  16 } rdonly_map SEC(".maps");
  17
  18 struct {
  19         __uint(type, BPF_MAP_TYPE_ARRAY);
  20         __uint(max_entries, 512 * 4); /* at least 4 pages of data */
  21         __uint(map_flags, BPF_F_MMAPABLE);
  22         __type(key, __u32);
  23         __type(value, __u64);
  24 } data_map SEC(".maps");
  25
  26 __u64 in_val = 0;
  27 __u64 out_val = 0;
  28
  29 SEC("raw_tracepoint/sys_enter")
  30 int test_mmap(void *ctx)
  31 {
  32         int zero = 0, one = 1, two = 2, far = 1500;
  33         __u64 val, *p;
  34
  35         out_val = in_val;
  36
  37         /* data_map[2] = in_val; */
  38         bpf_map_update_elem(&data_map, &two, (const void *)&in_val, 0);
  39
  40         /* data_map[1] = data_map[0] * 2; */
  41         p = bpf_map_lookup_elem(&data_map, &zero);
  42         if (p) {
  43                 val = (*p) * 2;
  44                 bpf_map_update_elem(&data_map, &one, &val, 0);
  45         }
  46
  47         /* data_map[far] = in_val * 3; */
  48         val = in_val * 3;
  49         bpf_map_update_elem(&data_map, &far, &val, 0);
  50
  51         return 0;
  52 }
  53