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. 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