1 // SPDX-License-Identifier: (Apache-2.0 OR MIT)
2 // Copyright 2017 6WIND S.A. <quentin.monnet@6wind.com>
3
4 #[macro_use]
5 extern crate json;
6
7 extern crate elf;
8 use std::path::PathBuf;
9
10 extern crate rbpf;
11 use rbpf::disassembler;
12
13 // Turn a program into a JSON string.
14 //
15 // Relies on `json` crate.
16 //
17 // You may copy this function and adapt it according to your needs. For instance, you may want to:
18 //
19 // * Remove the "desc" (description) attributes from the output.
20 // * Print integers as integers, and not as strings containing their hexadecimal representation
21 // (just replace the relevant `format!()` calls by the commented values.
to_json(prog: &[u8]) -> String22 fn to_json(prog: &[u8]) -> String {
23 // This call returns a high-level representation of the instructions, with the two parts of
24 // `LD_DW_IMM` instructions merged, and name and descriptions of the instructions.
25 // If you prefer to use a lower-level representation, use `ebpf::to_insn_vec()` function
26 // instead.
27 let insns = disassembler::to_insn_vec(prog);
28 let mut json_insns = vec![];
29 for insn in insns {
30 json_insns.push(object!(
31 "opc" => format!("{:#x}", insn.opc), // => insn.opc,
32 "dst" => format!("{:#x}", insn.dst), // => insn.dst,
33 "src" => format!("{:#x}", insn.src), // => insn.src,
34 "off" => format!("{:#x}", insn.off), // => insn.off,
35 // Warning: for imm we use a i64 instead of a i32 (to have correct values for
36 // `lddw` operation. If we print a number in the JSON this is not a problem, the
37 // internal i64 has the same value with extended sign on 32 most significant bytes.
38 // If we print the hexadecimal value as a string however, we want to cast as a i32
39 // to prevent all other instructions to print spurious `ffffffff` prefix if the
40 // number is negative. When values takes more than 32 bits with `lddw`, the cast
41 // has no effect and the complete value is printed anyway.
42 "imm" => format!("{:#x}", insn.imm as i32), // => insn.imm,
43 "desc" => insn.desc
44 ));
45 }
46 json::stringify_pretty(
47 object!(
48 "size" => json_insns.len(),
49 "insns" => json_insns
50 ),
51 4,
52 )
53 }
54
55 // Load a program from an object file, and prints it to standard output as a JSON string.
main()56 fn main() {
57 // Let's reuse this file from `load_elf/example`.
58 let filename = "examples/load_elf__block_a_port.elf";
59
60 let path = PathBuf::from(filename);
61 let file = match elf::File::open_path(path) {
62 Ok(f) => f,
63 Err(e) => panic!("Error: {:?}", e),
64 };
65
66 let text_scn = match file.get_section(".classifier") {
67 Some(s) => s,
68 None => panic!("Failed to look up .classifier section"),
69 };
70
71 let prog = &text_scn.data;
72
73 println!("{}", to_json(prog));
74 }
75