tests/python/test_disassembler.py

#!/usr/bin/env python3
# Copyright (c) Clevernet
# Licensed under the Apache License, Version 2.0 (the "License")

# test program for the 'disassemble_func' and 'decode_table' methods

from bcc import BPF
from bcc import disassembler
import ctypes as ct
import random
from unittest import main, TestCase

class BPFInstr(ct.Structure):
    _pack_ = 1
    _fields_ = [('opcode', ct.c_uint8),
                ('dst', ct.c_uint8, 4),
                ('src', ct.c_uint8, 4),
                ('offset', ct.c_int16),
                ('imm', ct.c_int32)]

class TestDisassembler(TestCase):
    opcodes = [(0x04, "%dst += %imm"),
               (0x05, "goto %off <%jmp>"),
               (0x07, "%dst += %imm"),
               (0x0c, "%dst += %src"),
               (0x0f, "%dst += %src"),
               (0x14, "%dst -= %imm"),
               (0x15, "if %dst == %imm goto pc%off <%jmp>"),
               (0x17, "%dst -= %imm"),
               #(0x18, "lddw"),
               (0x1c, "%dst -= %src"),
               (0x1d, "if %dst == %src goto pc%off <%jmp>"),
               (0x1f, "%dst -= %src"),
               (0x20, "r0 = *(u32*)skb[%imm]"),
               (0x24, "%dst *= %imm"),
               (0x25, "if %dst > %imm goto pc%off <%jmp>"),
               (0x27, "%dst *= %imm"),
               (0x28, "r0 = *(u16*)skb[%imm]"),
               (0x2c, "%dst *= %src"),
               (0x2d, "if %dst > %src goto pc%off <%jmp>"),
               (0x2f, "%dst *= %src"),
               (0x30, "r0 = *(u8*)skb[%imm]"),
               (0x34, "%dst /= %imm"),
               (0x35, "if %dst >= %imm goto pc%off <%jmp>"),
               (0x37, "%dst /= %imm"),
               (0x38, "r0 = *(u64*)skb[%imm]"),
               (0x3c, "%dst /= %src"),
               (0x3d, "if %dst >= %src goto pc%off <%jmp>"),
               (0x3f, "%dst /= %src"),
               (0x40, "r0 = *(u32*)skb[%src %sim]"),
               (0x44, "%dst |= %ibw"),
               (0x45, "if %dst & %imm goto pc%off <%jmp>"),
               (0x47, "%dst |= %ibw"),
               (0x48, "r0 = *(u16*)skb[%src %sim]"),
               (0x4c, "%dst |= %src"),
               (0x4d, "if %dst & %src goto pc%off <%jmp>"),
               (0x4f, "%dst |= %src"),
               (0x50, "r0 = *(u8*)skb[%src %sim]"),
               (0x54, "%dst &= %ibw"),
               (0x55, "if %dst != %imm goto pc%off <%jmp>"),
               (0x57, "%dst &= %ibw"),
               (0x58, "r0 = *(u64*)skb[%src %sim]"),
               (0x5c, "%dst &= %src"),
               (0x5d, "if %dst != %src goto pc%off <%jmp>"),
               (0x5f, "%dst &= %src"),
               (0x61, "%dst = *(u32*)(%src %off)"),
               (0x62, "*(u32*)(%dst %off) = %imm"),
               (0x63, "*(u32*)(%dst %off) = %src"),
               (0x64, "%dst <<= %imm"),
               (0x65, "if %dst s> %imm goto pc%off <%jmp>"),
               (0x67, "%dst <<= %imm"),
               (0x69, "%dst = *(u16*)(%src %off)"),
               (0x6a, "*(u16*)(%dst %off) = %imm"),
               (0x6b, "*(u16*)(%dst %off) = %src"),
               (0x6c, "%dst <<= %src"),
               (0x6d, "if %dst s> %src goto pc%off <%jmp>"),
               (0x6f, "%dst <<= %src"),
               (0x71, "%dst = *(u8*)(%src %off)"),
               (0x72, "*(u8*)(%dst %off) = %imm"),
               (0x73, "*(u8*)(%dst %off) = %src"),
               (0x74, "%dst >>= %imm"),
               (0x75, "if %dst s>= %imm goto pc%off <%jmp>"),
               (0x77, "%dst >>= %imm"),
               (0x79, "%dst = *(u64*)(%src %off)"),
               (0x7a, "*(u64*)(%dst %off) = %imm"),
               (0x7b, "*(u64*)(%dst %off) = %src"),
               (0x7c, "%dst >>= %src"),
               (0x7d, "if %dst s>= %src goto pc%off <%jmp>"),
               (0x7f, "%dst >>= %src"),
               (0x84, "%dst = ~ (u32)%dst"),
               #(0x85, "call"),
               (0x87, "%dst = ~ (u64)%dst"),
               (0x94, "%dst %= %imm"),
               (0x95, "exit"),
               (0x97, "%dst %= %imm"),
               (0x9c, "%dst %= %src"),
               (0x9f, "%dst %= %src"),
               (0xa4, "%dst ^= %ibw"),
               (0xa5, "if %dst < %imm goto pc%off <%jmp>"),
               (0xa7, "%dst ^= %ibw"),
               (0xac, "%dst ^= %src"),
               (0xad, "if %dst < %src goto pc%off <%jmp>"),
               (0xaf, "%dst ^= %src"),
               (0xb4, "%dst = %imm"),
               (0xb5, "if %dst <= %imm goto pc%off <%jmp>"),
               (0xb7, "%dst = %imm"),
               (0xbc, "%dst = %src"),
               (0xbd, "if %dst <= %src goto pc%off <%jmp>"),
               (0xbf, "%dst = %src"),
               (0xc4, "%dst s>>= %imm"),
               (0xc5, "if %dst s< %imm goto pc%off <%jmp>"),
               (0xc7, "%dst s>>= %imm"),
               (0xcc, "%dst s>>= %src"),
               (0xcd, "if %dst s< %src goto pc%off <%jmp>"),
               (0xcf, "%dst s>>= %src"),
               (0xd5, "if %dst s<= %imm goto pc%off <%jmp>"),
               (0xdc, "%dst endian %src"),
               (0xdd, "if %dst s<= %imm goto pc%off <%jmp>"),]
    
    @classmethod
    def build_instr(cls, op):
        dst = random.randint(0, 0xf)
        src = random.randint(0, 0xf)
        offset = random.randint(0, 0xffff)
        imm = random.randint(0, 0xffffffff)
        return BPFInstr(op, dst, src, offset, imm)
    
    @classmethod
    def format_instr(cls, instr, fmt):
        uimm = ct.c_uint32(instr.imm).value
        return (fmt.replace("%dst", "r%d" % (instr.dst))
                   .replace("%src", "r%d" % (instr.src))
                   .replace("%imm", "%d" % (instr.imm))
                   .replace("%ibw", "0x%x" % (uimm))
                   .replace("%sim", "%+d" % (instr.imm))
                   .replace("%off", "%+d" % (instr.offset))
                   .replace("%jmp", "%d" % (instr.offset + 1)))
    
    def test_func(self):
        b = BPF(text=b"""
            struct key_t {int a; short b; struct {int c:4; int d:8;} e;} __attribute__((__packed__));
            BPF_HASH(test_map, struct key_t);
            int test_func(void)
            {
                return 1;
            }""")

        self.assertEqual(
            """Disassemble of BPF program b'test_func':
   0: (b7) r0 = 1
   1: (95) exit""",
            b.disassemble_func(b"test_func"))
        
        def _assert_equal_ignore_fd_id(s1, s2):
            # In first line of string like
            #    Layout of BPF map test_map (type HASH, FD 3, ID 0):
            # Ignore everything from FD to end-of-line
            # Compare rest of string normally
            s1_lines = s1.split('\n')
            s2_lines = s2.split('\n')
            s1_first_cut = s1_lines[0]
            s1_first_cut = s1_first_cut[0:s1_first_cut.index("FD")]
            s2_first_cut = s2_lines[0]
            s2_first_cut = s2_first_cut[0:s2_first_cut.index("FD")]

            self.assertEqual(s1_first_cut, s2_first_cut)

            s1_rest = '\n'.join(s1_lines[1:])
            s2_rest = '\n'.join(s2_lines[1:])
            self.assertEqual(s1_rest, s2_rest)

        _assert_equal_ignore_fd_id(
            """Layout of BPF map b'test_map' (type HASH, FD 3, ID 0):
  struct {
    int a;
    short b;
    struct {
      int c:4;
      int d:8;
    } e;
  } key;
  unsigned long long value;""",
            b.decode_table(b"test_map"))
    
    def test_bpf_isa(self):
        for op, instr_fmt in self.opcodes:
            instr_fmt
            if instr_fmt is None:
                continue
            instr = self.build_instr(op)
            instr_str = ct.string_at(ct.addressof(instr), ct.sizeof(instr))
            target_text = self.format_instr(instr, instr_fmt)
            self.assertEqual(disassembler.disassemble_str(instr_str)[0],
                             "%4d: (%02x) %s" % (0, op, target_text))
        
if __name__ == "__main__":
    main()