bpf/progs/test_mmap.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 // Copyright (c) 2019 Facebook
0003
0004 #include <linux/bpf.h>
0005 #include <stdint.h>
0006 #include <bpf/bpf_helpers.h>
0007
0008 char _license[] SEC("license") = "GPL";
0009
0010 struct {
0011     __uint(type, BPF_MAP_TYPE_ARRAY);
0012     __uint(map_flags, BPF_F_MMAPABLE | BPF_F_RDONLY_PROG);
0013     __type(key, __u32);
0014     __type(value, char);
0015 } rdonly_map SEC(".maps");
0016
0017 struct {
0018     __uint(type, BPF_MAP_TYPE_ARRAY);
0019     __uint(map_flags, BPF_F_MMAPABLE);
0020     __type(key, __u32);
0021     __type(value, __u64);
0022 } data_map SEC(".maps");
0023
0024 __u64 in_val = 0;
0025 __u64 out_val = 0;
0026
0027 SEC("raw_tracepoint/sys_enter")
0028 int test_mmap(void *ctx)
0029 {
0030     int zero = 0, one = 1, two = 2, far = 1500;
0031     __u64 val, *p;
0032
0033     out_val = in_val;
0034
0035     /* data_map[2] = in_val; */
0036     bpf_map_update_elem(&data_map, &two, (const void *)&in_val, 0);
0037
0038     /* data_map[1] = data_map[0] * 2; */
0039     p = bpf_map_lookup_elem(&data_map, &zero);
0040     if (p) {
0041         val = (*p) * 2;
0042         bpf_map_update_elem(&data_map, &one, &val, 0);
0043     }
0044
0045     /* data_map[far] = in_val * 3; */
0046     val = in_val * 3;
0047     bpf_map_update_elem(&data_map, &far, &val, 0);
0048
0049     return 0;
0050 }
0051