1 // SPDX-License-Identifier: (Apache-2.0 OR MIT)
2 // Copyright 2017 6WIND S.A. <quentin.monnet@6wind.com>
3
4 extern crate rbpf;
5 use rbpf::helpers;
6
7 // The main objectives of this example is to show:
8 //
9 // * the use of EbpfVmNoData function,
10 // * and the use of a helper.
11 //
12 // The two eBPF programs are independent and are not related to one another.
main()13 fn main() {
14 let prog1 = &[
15 0xb4, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // mov32 r0, 0
16 0xb4, 0x01, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, // mov32 r1, 2
17 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, // add32 r0, 1
18 0x0c, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // add32 r0, r1
19 0x95, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // exit and return r0
20 ];
21
22 // We use helper `bpf_time_getns()`, which is similar to helper `bpf_ktime_getns()` from Linux
23 // kernel. Hence rbpf::helpers module provides the index of this in-kernel helper as a
24 // constant, so that we can remain compatible with programs for the kernel. Here we also cast
25 // it to a u8 so as to use it directly in program instructions.
26 let hkey = helpers::BPF_KTIME_GETNS_IDX as u8;
27 let prog2 = &[
28 0xb7, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // mov64 r1, 0
29 0xb7, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // mov64 r1, 0
30 0xb7, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // mov64 r1, 0
31 0xb7, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // mov64 r1, 0
32 0xb7, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // mov64 r1, 0
33 0x85, 0x00, 0x00, 0x00, hkey, 0x00, 0x00, 0x00, // call helper <hkey>
34 0x95, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // exit and return r0
35 ];
36
37 // Create a VM: this one takes no data. Load prog1 in it.
38 let mut vm = rbpf::EbpfVmNoData::new(Some(prog1)).unwrap();
39 // Execute prog1.
40 assert_eq!(vm.execute_program().unwrap(), 0x3);
41
42 // As struct EbpfVmNoData does not takes any memory area, its return value is mostly
43 // deterministic. So we know prog1 will always return 3. There is an exception: when it uses
44 // helpers, the latter may have non-deterministic values, and all calls may not return the same
45 // value.
46 //
47 // In the following example we use a helper to get the elapsed time since boot time: we
48 // reimplement uptime in eBPF, in Rust. Because why not.
49
50 vm.set_program(prog2).unwrap();
51 vm.register_helper(helpers::BPF_KTIME_GETNS_IDX, helpers::bpf_time_getns)
52 .unwrap();
53
54 let time;
55
56 #[cfg(all(not(windows), feature = "std"))]
57 {
58 vm.jit_compile().unwrap();
59
60 time = unsafe { vm.execute_program_jit().unwrap() };
61 }
62
63 #[cfg(any(windows, not(feature = "std")))]
64 {
65 time = vm.execute_program().unwrap();
66 }
67
68 let days = time / 10u64.pow(9) / 60 / 60 / 24;
69 let hours = (time / 10u64.pow(9) / 60 / 60) % 24;
70 let minutes = (time / 10u64.pow(9) / 60) % 60;
71 let seconds = (time / 10u64.pow(9)) % 60;
72 let nanosec = time % 10u64.pow(9);
73
74 println!(
75 "Uptime: {:#x} ns == {} days {:02}:{:02}:{:02}, {} ns",
76 time, days, hours, minutes, seconds, nanosec
77 );
78 }
79