class ArmTranslator(object):
"""ARM to IR Translator."""
def __init__(self, architecture_mode=ARCH_ARM_MODE_32, translation_mode=FULL_TRANSLATION):
# Set *Architecture Mode*. The translation of each instruction
# into the REIL language is based on this.
self._arch_mode = architecture_mode
# An instance of *ArchitectureInformation*.
self._arch_info = ArmArchitectureInformation(architecture_mode)
# Set *Translation Mode*.
self._translation_mode = translation_mode
# An instance of a *VariableNamer*. This is used so all the
# temporary REIL registers are unique.
self._ir_name_generator = VariableNamer("t", separator="")
self._builder = ReilInstructionBuilder()
self._flags = {
"nf" : ReilRegisterOperand("nf", 1),
"zf" : ReilRegisterOperand("zf", 1),
"cf" : ReilRegisterOperand("cf", 1),
"vf" : ReilRegisterOperand("vf", 1),
}
if self._arch_mode == ARCH_ARM_MODE_32:
self._sp = ReilRegisterOperand("r13", 32) # TODO: Implement alias
self._pc = ReilRegisterOperand("r15", 32)
self._lr = ReilRegisterOperand("r14", 32)
self._ws = ReilImmediateOperand(4, 32) # word size
elif self._arch_mode == ARCH_ARM_MODE_64:
self._sp = ReilRegisterOperand("r13", 64)
self._pc = ReilRegisterOperand("r15", 64)
self._lr = ReilRegisterOperand("r14", 64)
self._ws = ReilImmediateOperand(8, 64) # word size
def translate(self, instruction):
"""Return IR representation of an instruction.
"""
try:
trans_instrs = self._translate(instruction)
except NotImplementedError as e:
unkn_instr = self._builder.gen_unkn()
unkn_instr.address = instruction.address << 8 | (0x0 & 0xff)
trans_instrs = [unkn_instr]
self._log_not_supported_instruction(instruction)
except Exception as e:
self._log_translation_exception(instruction)
raise
# Some sanity check....
for instr in trans_instrs:
try:
check_operands_size(instr, self._arch_info.architecture_size)
except:
logger.error(
"Invalid operand size: %s (%s)",
instr,
instruction
)
raise
return trans_instrs
def _translate(self, instruction):
"""Translate a arm instruction into REIL language.
:param instruction: a arm instruction
:type instruction: ArmInstruction
"""
# Retrieve translation function.
translator_name = "_translate_" + instruction.mnemonic
translator_fn = getattr(self, translator_name, self._not_implemented)
# Translate instruction.
tb = ArmTranslationBuilder(self._ir_name_generator, self._arch_mode)
# Pre-processing: evaluate flags
nop_cc_lbl = tb.label('condition_code_not_met')
if (instruction.condition_code is not None):
self._evaluate_condition_code(tb, instruction, nop_cc_lbl)
translator_fn(tb, instruction)
tb.add(nop_cc_lbl)
tb.add(self._builder.gen_nop()) # Added NOP so there is a REIL instruction to jump to
return tb.instanciate(instruction.address)
def reset(self):
"""Restart IR register name generator.
"""
self._ir_name_generator.reset()
@property
def translation_mode(self):
"""Get translation mode.
"""
return self._translation_mode
@translation_mode.setter
def translation_mode(self, value):
"""Set translation mode.
"""
self._translation_mode = value
def _log_not_supported_instruction(self, instruction):
bytes_str = " ".join("%02x" % ord(b) for b in instruction.bytes)
logger.info(
"Instruction not supported: %s (%s [%s])",
instruction.mnemonic,
instruction,
bytes_str
)
def _log_translation_exception(self, instruction):
bytes_str = " ".join("%02x" % ord(b) for b in instruction.bytes)
logger.error(
"Failed to translate arm to REIL: %s (%s)",
instruction,
bytes_str,
exc_info=True
)
# ============================================================================ #
def _not_implemented(self, tb, instruction):
raise NotImplementedError("Instruction Not Implemented")
# Translators
# ============================================================================ #
# ============================================================================ #
# "Flags"
# ============================================================================ #
def _update_nf(self, tb, oprnd0, oprnd1, result):
sign = tb._extract_bit(result, oprnd0.size - 1)
tb.add(self._builder.gen_str(sign, self._flags["nf"]))
def _carry_from_uf(self, tb, oprnd0, oprnd1, result):
assert (result.size == oprnd0.size * 2)
carry = tb._extract_bit(result, oprnd0.size)
tb.add(self._builder.gen_str(carry, self._flags["cf"]))
def _borrow_from_uf(self, tb, oprnd0, oprnd1, result):
# BorrowFrom as defined in the ARM Reference Manual has the same implementation as CarryFrom
self._carry_from_uf(tb, oprnd0, oprnd1, result)
def _overflow_from_add_uf(self, tb, oprnd0, oprnd1, result):
op1_sign = tb._extract_bit(oprnd0, oprnd0.size - 1)
op2_sign = tb._extract_bit(oprnd1, oprnd0.size - 1)
res_sign = tb._extract_bit(result, oprnd0.size - 1)
overflow = tb._and_regs(tb._equal_regs(op1_sign, op2_sign), tb._unequal_regs(op1_sign, res_sign))
tb.add(self._builder.gen_str(overflow, self._flags["vf"]))
# Evaluate overflow and update the flag
def _overflow_from_sub_uf(self, tb, oprnd0, oprnd1, result):
tb.add(self._builder.gen_str(tb._overflow_from_sub(oprnd0, oprnd1, result), self._flags["vf"]))
def _update_zf(self, tb, oprnd0, oprnd1, result):
zf = self._flags["zf"]
imm0 = tb.immediate((2**oprnd0.size)-1, result.size)
tmp0 = tb.temporal(oprnd0.size)
tb.add(self._builder.gen_and(result, imm0, tmp0)) # filter low part of result
tb.add(self._builder.gen_bisz(tmp0, zf))
def _carry_out(self, tb, carry_operand, oprnd0, oprnd1, result):
if isinstance(carry_operand, ArmImmediateOperand):
return
elif isinstance(carry_operand, ArmRegisterOperand):
return
elif isinstance(carry_operand, ArmShiftedRegisterOperand):
base = ReilRegisterOperand(carry_operand.base_reg.name, carry_operand.size)
shift_type = carry_operand.shift_type
shift_amount = carry_operand.shift_amount
if (shift_type == 'lsl'):
if isinstance(shift_amount, ArmImmediateOperand):
if shift_amount.immediate == 0:
return
else:
# carry_out = Rm[32 - shift_imm]
shift_carry_out = tb._extract_bit(base, 32 - shift_amount.immediate)
elif isinstance(shift_amount, ArmRegisterOperand):
# Rs: register with shift amount
# if Rs[7:0] == 0 then
# carry_out = C Flag
# else if Rs[7:0] <= 32 then
# carry_out = Rm[32 - Rs[7:0]]
# else /* Rs[7:0] > 32 */
# carry_out = 0
shift_carry_out = tb.temporal(1)
tb.add(self._builder.gen_str(self._flags["cf"], shift_carry_out))
rs = ReilRegisterOperand(shift_amount.name, shift_amount.size)
rs_7_0 = tb._and_regs(rs, tb.immediate(0xFF, rs.size))
end_label = tb.label('end_label')
rs_greater_32_label = tb.label('rs_greater_32_label')
# if Rs[7:0] == 0 then
# carry_out = C Flag
tb._jump_if_zero(rs_7_0, end_label) # shift_carry_out already has the C flag set, so do nothing
tb.add(self._builder.gen_jcc(tb._greater_than_or_equal(rs_7_0, tb.immediate(33, rs_7_0.size)),
rs_greater_32_label))
# Rs > 0 and Rs <= 32
# carry_out = Rm[32 - Rs[7:0]]
extract_bit_number = tb.temporal(rs_7_0.size)
tb.add(self._builder.gen_sub(tb.immediate(32, rs_7_0.size), rs_7_0, extract_bit_number))
tb.add(self._builder.gen_str(tb._extract_bit_with_register(base, extract_bit_number),
shift_carry_out))
tb._jump_to(end_label)
# else /* Rs[7:0] > 32 */
# carry_out = 0
tb.add(rs_greater_32_label)
tb.add(self._builder.gen_str(tb.immediate(0, 1), shift_carry_out))
# tb._jump_to(end_label)
tb.add(end_label)
else:
raise Exception("carry_out: Unknown shift amount type.")
else:
# TODO: Implement other shift types
raise NotImplementedError("Instruction Not Implemented: carry_out: shift type " + carry_operand.shift_type)
else:
raise Exception("carry_out: Unknown operand type.")
tb.add(self._builder.gen_str(shift_carry_out, self._flags["cf"]))
def _update_flags_data_proc_add(self, tb, oprnd0, oprnd1, result):
self._update_zf(tb, oprnd0, oprnd1, result)
self._update_nf(tb, oprnd0, oprnd1, result)
self._carry_from_uf(tb, oprnd0, oprnd1, result)
self._overflow_from_add_uf(tb, oprnd0, oprnd1, result)
def _update_flags_data_proc_sub(self, tb, oprnd0, oprnd1, result):
self._update_zf(tb, oprnd0, oprnd1, result)
self._update_nf(tb, oprnd0, oprnd1, result)
self._borrow_from_uf(tb, oprnd0, oprnd1, result)
# C Flag = NOT BorrowFrom (to be used by subsequent instructions like SBC and RSC)
tb.add(self._builder.gen_str(tb._negate_reg(self._flags["cf"]), self._flags["cf"]))
self._overflow_from_sub_uf(tb, oprnd0, oprnd1, result)
def _update_flags_data_proc_other(self, tb, second_operand, oprnd0, oprnd1, result):
self._update_zf(tb, oprnd0, oprnd1, result)
self._update_nf(tb, oprnd0, oprnd1, result)
self._carry_out(tb, second_operand, oprnd0, oprnd1, result)
# Overflow Flag (V) unaffected
def _update_flags_other(self, tb, oprnd0, oprnd1, result):
self._update_zf(tb, oprnd0, oprnd1, result)
self._update_nf(tb, oprnd0, oprnd1, result)
# Carry Flag (C) unaffected
# Overflow Flag (V) unaffected
def _undefine_flag(self, tb, flag):
# NOTE: In every test I've made, each time a flag is leave
# undefined it is always set to 0.
imm = tb.immediate(0, flag.size)
tb.add(self._builder.gen_str(imm, flag))
def _clear_flag(self, tb, flag):
imm = tb.immediate(0, flag.size)
tb.add(self._builder.gen_str(imm, flag))
def _set_flag(self, tb, flag):
imm = tb.immediate(1, flag.size)
tb.add(self._builder.gen_str(imm, flag))
# EQ: Z set
def _evaluate_eq(self, tb):
return self._flags["zf"]
# NE: Z clear
def _evaluate_ne(self, tb):
return tb._negate_reg(self._flags["zf"])
# CS: C set
def _evaluate_cs(self, tb):
return self._flags["cf"]
# CC: C clear
def _evaluate_cc(self, tb):
return tb._negate_reg(self._flags["cf"])
# MI: N set
def _evaluate_mi(self, tb):
return self._flags["nf"]
# PL: N clear
def _evaluate_pl(self, tb):
return tb._negate_reg(self._flags["nf"])
# VS: V set
def _evaluate_vs(self, tb):
return self._flags["vf"]
# VC: V clear
def _evaluate_vc(self, tb):
return tb._negate_reg(self._flags["vf"])
# HI: C set and Z clear
def _evaluate_hi(self, tb):
return tb._and_regs(self._flags["cf"], tb._negate_reg(self._flags["zf"]))
# LS: C clear or Z set
def _evaluate_ls(self, tb):
return tb._or_regs(tb._negate_reg(self._flags["cf"]), self._flags["zf"])
# GE: N == V
def _evaluate_ge(self, tb):
return tb._equal_regs(self._flags["nf"], self._flags["vf"])
# LT: N != V
def _evaluate_lt(self, tb):
return tb._negate_reg(self._evaluate_ge(tb))
# GT: (Z == 0) and (N == V)
def _evaluate_gt(self, tb):
return tb._and_regs(tb._negate_reg(self._flags["zf"]), self._evaluate_ge(tb))
# LE: (Z == 1) or (N != V)
def _evaluate_le(self, tb):
return tb._or_regs(self._flags["zf"], self._evaluate_lt(tb))
def _evaluate_condition_code(self, tb, instruction, nop_label):
if (instruction.condition_code == ARM_COND_CODE_AL):
return
eval_cc_fn = {
ARM_COND_CODE_EQ : self._evaluate_eq,
ARM_COND_CODE_NE : self._evaluate_ne,
ARM_COND_CODE_CS : self._evaluate_cs,
ARM_COND_CODE_HS : self._evaluate_cs,
ARM_COND_CODE_CC : self._evaluate_cc,
ARM_COND_CODE_LO : self._evaluate_cc,
ARM_COND_CODE_MI : self._evaluate_mi,
ARM_COND_CODE_PL : self._evaluate_pl,
ARM_COND_CODE_VS : self._evaluate_vs,
ARM_COND_CODE_VC : self._evaluate_vc,
ARM_COND_CODE_HI : self._evaluate_hi,
ARM_COND_CODE_LS : self._evaluate_ls,
ARM_COND_CODE_GE : self._evaluate_ge,
ARM_COND_CODE_LT : self._evaluate_lt,
ARM_COND_CODE_GT : self._evaluate_gt,
ARM_COND_CODE_LE : self._evaluate_le,
}
neg_cond = tb._negate_reg(eval_cc_fn[instruction.condition_code](tb))
tb.add(self._builder.gen_jcc(neg_cond, nop_label))
return
# "Data-processing Instructions"
# ============================================================================ #
def _translate_mov(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
tb.write(instruction.operands[0], oprnd1)
if instruction.update_flags:
self._update_flags_data_proc_other(tb, instruction.operands[1], oprnd1, None, oprnd1)
def _translate_and(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size)
tb.add(self._builder.gen_and(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_other(tb, instruction.operands[2], oprnd1, oprnd2, result)
def _translate_orr(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size)
tb.add(self._builder.gen_or(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_other(tb, instruction.operands[2], oprnd1, oprnd2, result)
def _translate_eor(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size)
tb.add(self._builder.gen_xor(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_other(tb, instruction.operands[2], oprnd1, oprnd2, result)
def _translate_add(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_add(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_add(tb, oprnd1, oprnd2, result)
def _translate_sub(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_sub(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_sub(tb, oprnd1, oprnd2, result)
def _translate_mul(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_mul(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_zf(tb, oprnd1, oprnd2, result)
self._update_nf(tb, oprnd1, oprnd2, result)
def _translate_cmn(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[0])
oprnd2 = tb.read(instruction.operands[1])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_add(oprnd1, oprnd2, result))
self._update_flags_data_proc_add(tb, oprnd1, oprnd2, result) # S = 1 (implied in the instruction)
def _translate_cmp(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[0])
oprnd2 = tb.read(instruction.operands[1])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_sub(oprnd1, oprnd2, result))
self._update_flags_data_proc_sub(tb, oprnd1, oprnd2, result) # S = 1 (implied in the instruction)
# "Load/store word and unsigned byte Instructions"
# ============================================================================ #
def _translate_ldr(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
tb.write(instruction.operands[0], oprnd1)
def _translate_str(self, tb, instruction):
oprnd0 = tb.read(instruction.operands[0])
tb.write(instruction.operands[1], oprnd0)
# "Load/store multiple Instructions"
# ============================================================================ #
def _translate_ldm(self, tb, instruction):
self._translate_ldm_stm(tb, instruction, True)
def _translate_stm(self, tb, instruction):
self._translate_ldm_stm(tb, instruction, False)
# LDM and STM have exactly the same logic except one loads and the other stores
# It is assumed that the disassembler (for example Capstone) writes the register list in increasing order
def _translate_ldm_stm(self, tb, instruction, load = True):
base = tb.read(instruction.operands[0])
reg_list = tb.read(instruction.operands[1])
if instruction.ldm_stm_addr_mode == None:
instruction.ldm_stm_addr_mode = ARM_LDM_STM_IA # default mode for load and store
if load:
load_store_fn = self._load_value
# Convert stack addressing modes to non-stack addressing modes
if instruction.ldm_stm_addr_mode in ldm_stack_am_to_non_stack_am:
instruction.ldm_stm_addr_mode = ldm_stack_am_to_non_stack_am[instruction.ldm_stm_addr_mode]
else: # Store
load_store_fn = self._store_value
if instruction.ldm_stm_addr_mode in stm_stack_am_to_non_stack_am:
instruction.ldm_stm_addr_mode = stm_stack_am_to_non_stack_am[instruction.ldm_stm_addr_mode]
pointer = tb.temporal(base.size)
tb.add(self._builder.gen_str(base, pointer))
reg_list_size_bytes = ReilImmediateOperand(self._ws.immediate * len(reg_list), base.size)
if instruction.ldm_stm_addr_mode == ARM_LDM_STM_IA:
for reg in reg_list:
load_store_fn(tb, pointer, reg)
pointer = tb._add_to_reg(pointer, self._ws)
elif instruction.ldm_stm_addr_mode == ARM_LDM_STM_IB:
for reg in reg_list:
pointer = tb._add_to_reg(pointer, self._ws)
load_store_fn(tb, pointer, reg)
elif instruction.ldm_stm_addr_mode == ARM_LDM_STM_DA:
reg_list.reverse() # Assuming the registry list was in increasing registry number
for reg in reg_list:
load_store_fn(tb, pointer, reg)
pointer = tb._sub_to_reg(pointer, self._ws)
elif instruction.ldm_stm_addr_mode == ARM_LDM_STM_DB:
reg_list.reverse()
for reg in reg_list:
pointer = tb._sub_to_reg(pointer, self._ws)
load_store_fn(tb, pointer, reg)
else:
raise Exception("Unknown addressing mode.")
# Write-back
if instruction.operands[0].wb:
if instruction.ldm_stm_addr_mode == ARM_LDM_STM_IA or instruction.ldm_stm_addr_mode == ARM_LDM_STM_IB:
tmp = tb._add_to_reg(base, reg_list_size_bytes)
elif instruction.ldm_stm_addr_mode == ARM_LDM_STM_DA or instruction.ldm_stm_addr_mode == ARM_LDM_STM_DB:
tmp = tb._sub_to_reg(base, reg_list_size_bytes)
tb.add(self._builder.gen_str(tmp, base))
def _load_value(self, tb, mem_dir, value):
tb.add(self._builder.gen_ldm(mem_dir, value))
def _store_value(self, tb, mem_dir, value):
tb.add(self._builder.gen_stm(value, mem_dir))
# PUSH and POP are equivalent to STM and LDM in FD mode with the SP (and write-back)
# Instructions are modified to adapt it to the LDM/STM interface
def _translate_push_pop(self, tb, instruction, translate_fn):
sp_name = "r13" # TODO: Use self._sp
sp_size = instruction.operands[0].reg_list[0][0].size # Infer it from the registers list
sp_reg = ArmRegisterOperand(sp_name, sp_size)
sp_reg.wb = True
instruction.operands = [sp_reg, instruction.operands[0]]
instruction.ldm_stm_addr_mode = ARM_LDM_STM_FD
translate_fn(tb, instruction)
def _translate_push(self, tb, instruction):
self._translate_push_pop(tb, instruction, self._translate_stm)
def _translate_pop(self, tb, instruction):
self._translate_push_pop(tb, instruction, self._translate_ldm)
# "Branch Instructions"
# ============================================================================ #
def _translate_b(self, tb, instruction):
self._translate_branch(tb, instruction, link = False)
def _translate_bl(self, tb, instruction):
self._translate_branch(tb, instruction, link = True)
# TODO: Thumb
def _translate_bx(self, tb, instruction):
self._translate_branch(tb, instruction, link = False)
def _translate_blx(self, tb, instruction):
self._translate_branch(tb, instruction, link = True)
def _translate_branch(self, tb, instruction, link):
arm_operand = instruction.operands[0]
if isinstance(arm_operand, ArmImmediateOperand):
target = ReilImmediateOperand(arm_operand.immediate << 8, self._pc.size + 8)
elif isinstance(arm_operand, ArmRegisterOperand):
target = ReilRegisterOperand(arm_operand.name, arm_operand.size)
target = tb._and_regs(target, ReilImmediateOperand(0xFFFFFFFE, target.size))
tmp0 = tb.temporal(target.size + 8)
tmp1 = tb.temporal(target.size + 8)
tb.add(self._builder.gen_str(target, tmp0))
tb.add(self._builder.gen_bsh(tmp0, ReilImmediateOperand(8, target.size + 8), tmp1))
target = tmp1
else:
raise NotImplementedError("Instruction Not Implemented: Unknown operand for branch operation.")
if (link):
tb.add(self._builder.gen_str(ReilImmediateOperand(instruction.address + instruction.size, self._pc.size), self._lr))
tb._jump_to(target)
class TranslationBuilder(object):
def __init__(self, ir_name_generator, architecture_mode):
self._ir_name_generator = ir_name_generator
self._instructions = []
self._builder = ReilInstructionBuilder()
def add(self, instr):
self._instructions.append(instr)
def temporal(self, size):
return ReilRegisterOperand(self._ir_name_generator.get_next(), size)
def immediate(self, value, size):
return ReilImmediateOperand(value, size)
def label(self, name):
return Label(name)
def instanciate(self, address):
# Set instructions address.
instrs = self._instructions
for instr in instrs:
instr.address = address << 8
instrs = self._resolve_loops(instrs)
return instrs
# Auxiliary functions
# ======================================================================== #
def _resolve_loops(self, instrs):
idx_by_labels = {}
# Collect labels.
# curr = 0
# for index, instr in enumerate(instrs):
# if isinstance(instr, Label):
# idx_by_labels[instr.name] = curr
#
# del instrs[index]
# else:
# curr += 1
# TODO: Hack to avoid deleting while iterating
instrs_no_labels = []
curr = 0
for i in instrs:
if isinstance(i, Label):
idx_by_labels[i.name] = curr
else:
instrs_no_labels.append(i)
curr += 1
instrs[:] = instrs_no_labels
# Resolve instruction addresses and JCC targets.
for index, instr in enumerate(instrs):
assert isinstance(instr, ReilInstruction)
instr.address |= index
if instr.mnemonic == ReilMnemonic.JCC:
target = instr.operands[2]
if isinstance(target, Label):
idx = idx_by_labels[target.name]
address = (instr.address & ~0xff) | idx
instr.operands[2] = ReilImmediateOperand(address, self._arch_info.address_size + 8)
return instrs
def _all_ones_imm(self, reg):
return self.immediate((2**reg.size) - 1, reg.size)
def _negate_reg(self, reg):
neg = self.temporal(reg.size)
self.add(self._builder.gen_xor(reg, self._all_ones_imm(reg), neg))
return neg
def _and_regs(self, reg1, reg2):
ret = self.temporal(reg1.size)
self.add(self._builder.gen_and(reg1, reg2, ret))
return ret
def _or_regs(self, reg1, reg2):
ret = self.temporal(reg1.size)
self.add(self._builder.gen_or(reg1, reg2, ret))
return ret
def _xor_regs(self, reg1, reg2):
ret = self.temporal(reg1.size)
self.add(self._builder.gen_xor(reg1, reg2, ret))
return ret
def _equal_regs(self, reg1, reg2):
return self._negate_reg(self._xor_regs(reg1, reg2))
def _unequal_regs(self, reg1, reg2):
return self._xor_regs(reg1, reg2)
def _shift_reg(self, reg, sh):
ret = self.temporal(reg.size)
self.add(self._builder.gen_bsh(reg, sh, ret))
return ret
def _extract_bit(self, reg, bit):
assert(bit >= 0 and bit < reg.size)
tmp = self.temporal(reg.size)
ret = self.temporal(1)
self.add(self._builder.gen_bsh(reg, self.immediate(-bit, reg.size), tmp)) # shift to LSB
self.add(self._builder.gen_and(tmp, self.immediate(1, reg.size), ret)) # filter LSB
return ret
# Same as before but the bit number is indicated by a register and it will be resolved at runtime
def _extract_bit_with_register(self, reg, bit):
# assert(bit >= 0 and bit < reg.size2) # It is assumed, it is not checked
tmp = self.temporal(reg.size)
neg_bit = self.temporal(reg.size)
ret = self.temporal(1)
self.add(self._builder.gen_sub(self.immediate(0, bit.size), bit, neg_bit)) # as left bit is indicated by a negative number
self.add(self._builder.gen_bsh(reg, neg_bit, tmp)) # shift to LSB
self.add(self._builder.gen_and(tmp, self.immediate(1, reg.size), ret)) # filter LSB
return ret
def _extract_msb(self, reg):
return self._extract_bit(reg, reg.size - 1)
def _extract_sign_bit(self, reg):
return self._extract_msb(self, reg)
def _greater_than_or_equal(self, reg1, reg2):
assert(reg1.size == reg2.size)
result = self.temporal(reg1.size * 2)
self.add(self._builder.gen_sub(reg1, reg2, result))
sign = self._extract_bit(result, reg1.size - 1)
overflow = self._overflow_from_sub(reg1, reg2, result)
return self._equal_regs(sign, overflow)
def _jump_to(self, target):
self.add(self._builder.gen_jcc(self.immediate(1, 1), target))
def _jump_if_zero(self, reg, label):
is_zero = self.temporal(1)
self.add(self._builder.gen_bisz(reg, is_zero))
self.add(self._builder.gen_jcc(is_zero, label))
def _add_to_reg(self, reg, value):
res = self.temporal(reg.size)
self.add(self._builder.gen_add(reg, value, res))
return res
def _sub_to_reg(self, reg, value):
res = self.temporal(reg.size)
self.add(self._builder.gen_sub(reg, value, res))
return res
def _overflow_from_sub(self, oprnd0, oprnd1, result):
op1_sign = self._extract_bit(oprnd0, oprnd0.size - 1)
op2_sign = self._extract_bit(oprnd1, oprnd0.size - 1)
res_sign = self._extract_bit(result, oprnd0.size - 1)
return self._and_regs(self._unequal_regs(op1_sign, op2_sign), self._unequal_regs(op1_sign, res_sign))
class TranslationBuilder(object):
def __init__(self, ir_name_generator, architecture_mode):
self._ir_name_generator = ir_name_generator
self._instructions = []
self._builder = ReilInstructionBuilder()
def add(self, instr):
self._instructions.append(instr)
def temporal(self, size):
return ReilRegisterOperand(self._ir_name_generator.get_next(), size)
def immediate(self, value, size):
return ReilImmediateOperand(value, size)
def label(self, name):
return Label(name)
def instanciate(self, address):
# Set instructions address.
instrs = self._instructions
for instr in instrs:
instr.address = address << 8
instrs = self._resolve_loops(instrs)
return instrs
# Auxiliary functions
# ======================================================================== #
def _resolve_loops(self, instrs):
idx_by_labels = {}
# Collect labels.
# curr = 0
# for index, instr in enumerate(instrs):
# if isinstance(instr, Label):
# idx_by_labels[instr.name] = curr
#
# del instrs[index]
# else:
# curr += 1
# TODO: Hack to avoid deleting while iterating
instrs_no_labels = []
curr = 0
for i in instrs:
if isinstance(i, Label):
idx_by_labels[i.name] = curr
else:
instrs_no_labels.append(i)
curr += 1
instrs[:] = instrs_no_labels
# Resolve instruction addresses and JCC targets.
for index, instr in enumerate(instrs):
assert isinstance(instr, ReilInstruction)
instr.address |= index
if instr.mnemonic == ReilMnemonic.JCC:
target = instr.operands[2]
if isinstance(target, Label):
idx = idx_by_labels[target.name]
address = (instr.address & ~0xff) | idx
instr.operands[2] = ReilImmediateOperand(
address, self._arch_info.address_size + 8)
return instrs
def _all_ones_imm(self, reg):
return self.immediate((2**reg.size) - 1, reg.size)
def _negate_reg(self, reg):
neg = self.temporal(reg.size)
self.add(self._builder.gen_xor(reg, self._all_ones_imm(reg), neg))
return neg
def _and_regs(self, reg1, reg2):
ret = self.temporal(reg1.size)
self.add(self._builder.gen_and(reg1, reg2, ret))
return ret
def _or_regs(self, reg1, reg2):
ret = self.temporal(reg1.size)
self.add(self._builder.gen_or(reg1, reg2, ret))
return ret
def _xor_regs(self, reg1, reg2):
ret = self.temporal(reg1.size)
self.add(self._builder.gen_xor(reg1, reg2, ret))
return ret
def _equal_regs(self, reg1, reg2):
return self._negate_reg(self._xor_regs(reg1, reg2))
def _unequal_regs(self, reg1, reg2):
return self._xor_regs(reg1, reg2)
def _shift_reg(self, reg, sh):
ret = self.temporal(reg.size)
self.add(self._builder.gen_bsh(reg, sh, ret))
return ret
def _extract_bit(self, reg, bit):
assert (bit >= 0 and bit < reg.size)
tmp = self.temporal(reg.size)
ret = self.temporal(1)
self.add(
self._builder.gen_bsh(reg, self.immediate(-bit, reg.size),
tmp)) # shift to LSB
self.add(self._builder.gen_and(tmp, self.immediate(1, reg.size),
ret)) # filter LSB
return ret
# Same as before but the bit number is indicated by a register and it will be resolved at runtime
def _extract_bit_with_register(self, reg, bit):
# assert(bit >= 0 and bit < reg.size2) # It is assumed, it is not checked
tmp = self.temporal(reg.size)
neg_bit = self.temporal(reg.size)
ret = self.temporal(1)
self.add(
self._builder.gen_sub(
self.immediate(0, bit.size), bit,
neg_bit)) # as left bit is indicated by a negative number
self.add(self._builder.gen_bsh(reg, neg_bit, tmp)) # shift to LSB
self.add(self._builder.gen_and(tmp, self.immediate(1, reg.size),
ret)) # filter LSB
return ret
def _extract_msb(self, reg):
return self._extract_bit(reg, reg.size - 1)
def _extract_sign_bit(self, reg):
return self._extract_msb(self, reg)
def _greater_than_or_equal(self, reg1, reg2):
assert (reg1.size == reg2.size)
result = self.temporal(reg1.size * 2)
self.add(self._builder.gen_sub(reg1, reg2, result))
sign = self._extract_bit(result, reg1.size - 1)
overflow = self._overflow_from_sub(reg1, reg2, result)
return self._equal_regs(sign, overflow)
def _jump_to(self, target):
self.add(self._builder.gen_jcc(self.immediate(1, 1), target))
def _jump_if_zero(self, reg, label):
is_zero = self.temporal(1)
self.add(self._builder.gen_bisz(reg, is_zero))
self.add(self._builder.gen_jcc(is_zero, label))
def _add_to_reg(self, reg, value):
res = self.temporal(reg.size)
self.add(self._builder.gen_add(reg, value, res))
return res
def _sub_to_reg(self, reg, value):
res = self.temporal(reg.size)
self.add(self._builder.gen_sub(reg, value, res))
return res
def _overflow_from_sub(self, oprnd0, oprnd1, result):
op1_sign = self._extract_bit(oprnd0, oprnd0.size - 1)
op2_sign = self._extract_bit(oprnd1, oprnd0.size - 1)
res_sign = self._extract_bit(result, oprnd0.size - 1)
return self._and_regs(self._unequal_regs(op1_sign, op2_sign),
self._unequal_regs(op1_sign, res_sign))
class ArmTranslator(Translator):
"""ARM to IR Translator."""
def __init__(self,
architecture_mode=ARCH_ARM_MODE_THUMB,
translation_mode=FULL_TRANSLATION):
super(ArmTranslator, self).__init__()
# Set *Architecture Mode*. The translation of each instruction
# into the REIL language is based on this.
self._arch_mode = architecture_mode
# An instance of *ArchitectureInformation*.
self._arch_info = ArmArchitectureInformation(architecture_mode)
# Set *Translation Mode*.
self._translation_mode = translation_mode
# An instance of a *VariableNamer*. This is used so all the
# temporary REIL registers are unique.
self._ir_name_generator = VariableNamer("t", separator="")
self._builder = ReilInstructionBuilder()
self._flags = {
"nf": ReilRegisterOperand("nf", 1),
"zf": ReilRegisterOperand("zf", 1),
"cf": ReilRegisterOperand("cf", 1),
"vf": ReilRegisterOperand("vf", 1),
}
if self._arch_mode in [ARCH_ARM_MODE_ARM, ARCH_ARM_MODE_THUMB]:
self._sp = ReilRegisterOperand("r13", 32) # TODO: Implement alias
self._pc = ReilRegisterOperand("r15", 32)
self._lr = ReilRegisterOperand("r14", 32)
self._ws = ReilImmediateOperand(4, 32) # word size
# TODO: Remove this code?
# elif self._arch_mode == ARCH_ARM_MODE_64:
# self._sp = ReilRegisterOperand("r13", 64)
# self._pc = ReilRegisterOperand("r15", 64)
# self._lr = ReilRegisterOperand("r14", 64)
# self._ws = ReilImmediateOperand(8, 64) # word size
def translate(self, instruction):
"""Return IR representation of an instruction.
"""
try:
trans_instrs = self._translate(instruction)
except NotImplementedError as e:
unkn_instr = self._builder.gen_unkn()
unkn_instr.address = instruction.address << 8 | (0x0 & 0xff)
trans_instrs = [unkn_instr]
self._log_not_supported_instruction(instruction, str(e))
except Exception:
self._log_translation_exception(instruction)
raise
# Some sanity check....
for instr in trans_instrs:
try:
check_operands_size(instr, self._arch_info.architecture_size)
except:
logger.error("Invalid operand size: %s (%s)", instr,
instruction)
raise
return trans_instrs
def _translate(self, instruction):
"""Translate a arm instruction into REIL language.
:param instruction: a arm instruction
:type instruction: ArmInstruction
"""
# Retrieve translation function.
translator_name = "_translate_" + instruction.mnemonic
translator_fn = getattr(self, translator_name, self._not_implemented)
# Translate instruction.
tb = ArmTranslationBuilder(self._ir_name_generator, self._arch_mode)
# TODO: Improve this.
if instruction.mnemonic in [
"b", "bl", "bx", "blx", "bne", "beq", "bpl", "ble", "bcs",
"bhs", "blt", "bge", "bhi", "blo", "bls"
]:
if instruction.condition_code is None:
instruction.condition_code = ARM_COND_CODE_AL # TODO: unify translations
translator_fn(tb, instruction)
else:
# Pre-processing: evaluate flags
if instruction.condition_code is not None:
self._evaluate_condition_code(tb, instruction)
translator_fn(tb, instruction)
return tb.instanciate(instruction.address)
def reset(self):
"""Restart IR register name generator.
"""
self._ir_name_generator.reset()
@property
def translation_mode(self):
"""Get translation mode.
"""
return self._translation_mode
@translation_mode.setter
def translation_mode(self, value):
"""Set translation mode.
"""
self._translation_mode = value
def _log_not_supported_instruction(self, instruction, reason="unknown"):
bytes_str = " ".join("%02x" % ord(b) for b in instruction.bytes)
logger.info("Instruction not supported: %s (%s [%s]). Reason: %s",
instruction.mnemonic, instruction, bytes_str, reason)
def _log_translation_exception(self, instruction):
bytes_str = " ".join("%02x" % ord(b) for b in instruction.bytes)
logger.error("Failed to translate arm to REIL: %s (%s)",
instruction,
bytes_str,
exc_info=True)
def _not_implemented(self, tb, instruction):
raise NotImplementedError("Instruction Not Implemented")
# Translators
# ============================================================================ #
# ============================================================================ #
# "Flags"
# ============================================================================ #
def _update_nf(self, tb, oprnd0, oprnd1, result):
sign = tb._extract_bit(result, oprnd0.size - 1)
tb.add(self._builder.gen_str(sign, self._flags["nf"]))
def _carry_from_uf(self, tb, oprnd0, oprnd1, result):
assert (result.size == oprnd0.size * 2)
carry = tb._extract_bit(result, oprnd0.size)
tb.add(self._builder.gen_str(carry, self._flags["cf"]))
def _borrow_from_uf(self, tb, oprnd0, oprnd1, result):
# BorrowFrom as defined in the ARM Reference Manual has the same implementation as CarryFrom
self._carry_from_uf(tb, oprnd0, oprnd1, result)
def _overflow_from_add_uf(self, tb, oprnd0, oprnd1, result):
op1_sign = tb._extract_bit(oprnd0, oprnd0.size - 1)
op2_sign = tb._extract_bit(oprnd1, oprnd0.size - 1)
res_sign = tb._extract_bit(result, oprnd0.size - 1)
overflow = tb._and_regs(tb._equal_regs(op1_sign, op2_sign),
tb._unequal_regs(op1_sign, res_sign))
tb.add(self._builder.gen_str(overflow, self._flags["vf"]))
# Evaluate overflow and update the flag
def _overflow_from_sub_uf(self, tb, oprnd0, oprnd1, result):
tb.add(
self._builder.gen_str(
tb._overflow_from_sub(oprnd0, oprnd1, result),
self._flags["vf"]))
def _update_zf(self, tb, oprnd0, oprnd1, result):
zf = self._flags["zf"]
imm0 = tb.immediate((2**oprnd0.size) - 1, result.size)
tmp0 = tb.temporal(oprnd0.size)
tb.add(self._builder.gen_and(result, imm0,
tmp0)) # filter low part of result
tb.add(self._builder.gen_bisz(tmp0, zf))
def _carry_out(self, tb, carry_operand, oprnd0, oprnd1, result):
if isinstance(carry_operand, ArmImmediateOperand):
return
elif isinstance(carry_operand, ArmRegisterOperand):
return
elif isinstance(carry_operand, ArmShiftedRegisterOperand):
base = ReilRegisterOperand(carry_operand.base_reg.name,
carry_operand.size)
shift_type = carry_operand.shift_type
shift_amount = carry_operand.shift_amount
if shift_type == 'lsl':
if isinstance(shift_amount, ArmImmediateOperand):
if shift_amount.immediate == 0:
return
else:
# carry_out = Rm[32 - shift_imm]
shift_carry_out = tb._extract_bit(
base, 32 - shift_amount.immediate)
elif isinstance(shift_amount, ArmRegisterOperand):
# Rs: register with shift amount
# if Rs[7:0] == 0 then
# carry_out = C Flag
# else if Rs[7:0] <= 32 then
# carry_out = Rm[32 - Rs[7:0]]
# else /* Rs[7:0] > 32 */
# carry_out = 0
shift_carry_out = tb.temporal(1)
tb.add(
self._builder.gen_str(self._flags["cf"],
shift_carry_out))
rs = ReilRegisterOperand(shift_amount.name,
shift_amount.size)
rs_7_0 = tb._and_regs(rs, tb.immediate(0xFF, rs.size))
end_label = tb.label('end_label')
rs_greater_32_label = tb.label('rs_greater_32_label')
# if Rs[7:0] == 0 then
# carry_out = C Flag
tb._jump_if_zero(
rs_7_0, end_label
) # shift_carry_out already has the C flag set, so do nothing
tb.add(
self._builder.gen_jcc(
tb._greater_than_or_equal(
rs_7_0, tb.immediate(33, rs_7_0.size)),
rs_greater_32_label))
# Rs > 0 and Rs <= 32
# carry_out = Rm[32 - Rs[7:0]]
extract_bit_number = tb.temporal(rs_7_0.size)
tb.add(
self._builder.gen_sub(tb.immediate(32, rs_7_0.size),
rs_7_0, extract_bit_number))
tb.add(
self._builder.gen_str(
tb._extract_bit_with_register(
base, extract_bit_number), shift_carry_out))
tb._jump_to(end_label)
# else /* Rs[7:0] > 32 */
# carry_out = 0
tb.add(rs_greater_32_label)
tb.add(
self._builder.gen_str(tb.immediate(0, 1),
shift_carry_out))
# tb._jump_to(end_label)
tb.add(end_label)
else:
raise Exception("carry_out: Unknown shift amount type.")
else:
# TODO: Implement other shift types
raise NotImplementedError(
"Instruction Not Implemented: carry_out: shift type " +
carry_operand.shift_type)
else:
raise Exception("carry_out: Unknown operand type.")
tb.add(self._builder.gen_str(shift_carry_out, self._flags["cf"]))
def _update_flags_data_proc_add(self, tb, oprnd0, oprnd1, result):
self._update_zf(tb, oprnd0, oprnd1, result)
self._update_nf(tb, oprnd0, oprnd1, result)
self._carry_from_uf(tb, oprnd0, oprnd1, result)
self._overflow_from_add_uf(tb, oprnd0, oprnd1, result)
def _update_flags_data_proc_sub(self, tb, oprnd0, oprnd1, result):
self._update_zf(tb, oprnd0, oprnd1, result)
self._update_nf(tb, oprnd0, oprnd1, result)
self._borrow_from_uf(tb, oprnd0, oprnd1, result)
# C Flag = NOT BorrowFrom (to be used by subsequent instructions like SBC and RSC)
tb.add(
self._builder.gen_str(tb._negate_reg(self._flags["cf"]),
self._flags["cf"]))
self._overflow_from_sub_uf(tb, oprnd0, oprnd1, result)
def _update_flags_data_proc_other(self, tb, second_operand, oprnd0, oprnd1,
result):
self._update_zf(tb, oprnd0, oprnd1, result)
self._update_nf(tb, oprnd0, oprnd1, result)
self._carry_out(tb, second_operand, oprnd0, oprnd1, result)
# Overflow Flag (V) unaffected
def _update_flags_other(self, tb, oprnd0, oprnd1, result):
self._update_zf(tb, oprnd0, oprnd1, result)
self._update_nf(tb, oprnd0, oprnd1, result)
# Carry Flag (C) unaffected
# Overflow Flag (V) unaffected
def _undefine_flag(self, tb, flag):
# NOTE: In every test I've made, each time a flag is leave
# undefined it is always set to 0.
imm = tb.immediate(0, flag.size)
tb.add(self._builder.gen_str(imm, flag))
def _clear_flag(self, tb, flag):
imm = tb.immediate(0, flag.size)
tb.add(self._builder.gen_str(imm, flag))
def _set_flag(self, tb, flag):
imm = tb.immediate(1, flag.size)
tb.add(self._builder.gen_str(imm, flag))
def _evaluate_eq(self, tb):
# EQ: Z set
return self._flags["zf"]
def _evaluate_ne(self, tb):
# NE: Z clear
return tb._negate_reg(self._flags["zf"])
def _evaluate_cs(self, tb):
# CS: C set
return self._flags["cf"]
def _evaluate_cc(self, tb):
# CC: C clear
return tb._negate_reg(self._flags["cf"])
def _evaluate_mi(self, tb):
# MI: N set
return self._flags["nf"]
def _evaluate_pl(self, tb):
# PL: N clear
return tb._negate_reg(self._flags["nf"])
def _evaluate_vs(self, tb):
# VS: V set
return self._flags["vf"]
def _evaluate_vc(self, tb):
# VC: V clear
return tb._negate_reg(self._flags["vf"])
def _evaluate_hi(self, tb):
# HI: C set and Z clear
return tb._and_regs(self._flags["cf"],
tb._negate_reg(self._flags["zf"]))
def _evaluate_ls(self, tb):
# LS: C clear or Z set
return tb._or_regs(tb._negate_reg(self._flags["cf"]),
self._flags["zf"])
def _evaluate_ge(self, tb):
# GE: N == V
return tb._equal_regs(self._flags["nf"], self._flags["vf"])
def _evaluate_lt(self, tb):
# LT: N != V
return tb._negate_reg(self._evaluate_ge(tb))
def _evaluate_gt(self, tb):
# GT: (Z == 0) and (N == V)
return tb._and_regs(tb._negate_reg(self._flags["zf"]),
self._evaluate_ge(tb))
def _evaluate_le(self, tb):
# LE: (Z == 1) or (N != V)
return tb._or_regs(self._flags["zf"], self._evaluate_lt(tb))
def _evaluate_condition_code(self, tb, instruction):
if instruction.condition_code == ARM_COND_CODE_AL:
return
eval_cc_fn = {
ARM_COND_CODE_EQ: self._evaluate_eq,
ARM_COND_CODE_NE: self._evaluate_ne,
ARM_COND_CODE_CS: self._evaluate_cs,
ARM_COND_CODE_HS: self._evaluate_cs,
ARM_COND_CODE_CC: self._evaluate_cc,
ARM_COND_CODE_LO: self._evaluate_cc,
ARM_COND_CODE_MI: self._evaluate_mi,
ARM_COND_CODE_PL: self._evaluate_pl,
ARM_COND_CODE_VS: self._evaluate_vs,
ARM_COND_CODE_VC: self._evaluate_vc,
ARM_COND_CODE_HI: self._evaluate_hi,
ARM_COND_CODE_LS: self._evaluate_ls,
ARM_COND_CODE_GE: self._evaluate_ge,
ARM_COND_CODE_LT: self._evaluate_lt,
ARM_COND_CODE_GT: self._evaluate_gt,
ARM_COND_CODE_LE: self._evaluate_le,
}
neg_cond = tb._negate_reg(eval_cc_fn[instruction.condition_code](tb))
end_addr = ReilImmediateOperand(
(instruction.address + instruction.size) << 8,
self._arch_info.address_size + 8)
tb.add(self._builder.gen_jcc(neg_cond, end_addr))
return
# "Data-processing Instructions"
# ============================================================================ #
def _translate_mov(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
tb.write(instruction.operands[0], oprnd1)
if instruction.update_flags:
self._update_flags_data_proc_other(tb, instruction.operands[1],
oprnd1, None, oprnd1)
def _translate_mvn(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
tb.write(instruction.operands[0], tb._negate_reg(oprnd1))
if instruction.update_flags:
self._update_flags_data_proc_other(tb, instruction.operands[1],
oprnd1, None,
tb._negate_reg(oprnd1))
def _translate_movw(self, tb, instruction):
reil_operand = ReilRegisterOperand(instruction.operands[0].name,
instruction.operands[0].size)
word_mask = ReilImmediateOperand(0x0000FFFF, reil_operand.size)
and_temp = tb.temporal(reil_operand.size)
oprnd1 = tb.read(instruction.operands[1])
tb.write(instruction.operands[0], oprnd1)
tb.add(self._builder.gen_and(
reil_operand, word_mask,
and_temp)) # filter bits [7:0] part of result
tb.add(self._builder.gen_str(and_temp, reil_operand))
# It doesn't update flags
def _translate_and(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size)
tb.add(self._builder.gen_and(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_other(tb, instruction.operands[2],
oprnd1, oprnd2, result)
def _translate_orr(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size)
tb.add(self._builder.gen_or(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_other(tb, instruction.operands[2],
oprnd1, oprnd2, result)
def _translate_eor(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size)
tb.add(self._builder.gen_xor(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_other(tb, instruction.operands[2],
oprnd1, oprnd2, result)
def _translate_add(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_add(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_add(tb, oprnd1, oprnd2, result)
def _translate_sub(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_sub(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_sub(tb, oprnd1, oprnd2, result)
def _translate_rsb(self, tb, instruction):
instruction.operands[1], instruction.operands[
2] = instruction.operands[2], instruction.operands[1]
self._translate_sub(tb, instruction)
def _translate_mul(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_mul(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_zf(tb, oprnd1, oprnd2, result)
self._update_nf(tb, oprnd1, oprnd2, result)
def _translate_cmn(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[0])
oprnd2 = tb.read(instruction.operands[1])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_add(oprnd1, oprnd2, result))
self._update_flags_data_proc_add(
tb, oprnd1, oprnd2, result) # S = 1 (implied in the instruction)
def _translate_cmp(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[0])
oprnd2 = tb.read(instruction.operands[1])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_sub(oprnd1, oprnd2, result))
self._update_flags_data_proc_sub(
tb, oprnd1, oprnd2, result) # S = 1 (implied in the instruction)
def _translate_cbz(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[0])
arm_operand = instruction.operands[1]
if isinstance(arm_operand, ArmImmediateOperand):
target = ReilImmediateOperand(arm_operand.immediate << 8,
self._pc.size + 8)
elif isinstance(arm_operand, ArmRegisterOperand):
target = ReilRegisterOperand(arm_operand.name, arm_operand.size)
target = tb._and_regs(
target, ReilImmediateOperand(0xFFFFFFFE, target.size))
tmp0 = tb.temporal(target.size + 8)
tmp1 = tb.temporal(target.size + 8)
tb.add(self._builder.gen_str(target, tmp0))
tb.add(
self._builder.gen_bsh(tmp0,
ReilImmediateOperand(8, target.size + 8),
tmp1))
target = tmp1
else:
raise Exception()
tb._jump_if_zero(oprnd1, target)
def _translate_cbnz(self, tb, instruction):
oprnd0 = tb.read(instruction.operands[0])
arm_operand = instruction.operands[1]
if isinstance(arm_operand, ArmImmediateOperand):
target = ReilImmediateOperand(arm_operand.immediate << 8,
self._pc.size + 8)
elif isinstance(arm_operand, ArmRegisterOperand):
target = ReilRegisterOperand(arm_operand.name, arm_operand.size)
target = tb._and_regs(
target, ReilImmediateOperand(0xFFFFFFFE, target.size))
tmp0 = tb.temporal(target.size + 8)
tmp1 = tb.temporal(target.size + 8)
tb.add(self._builder.gen_str(target, tmp0))
tb.add(
self._builder.gen_bsh(tmp0,
ReilImmediateOperand(8, target.size + 8),
tmp1))
target = tmp1
else:
raise Exception()
neg_oprnd = tb._negate_reg(oprnd0)
tb._jump_if_zero(neg_oprnd, target)
def _translate_lsl(self, tb, instruction):
# LSL (register)
if len(instruction.operands) == 3 and isinstance(
instruction.operands[1], ArmRegisterOperand):
sh_op = ArmShiftedRegisterOperand(instruction.operands[1], "lsl",
instruction.operands[2],
instruction.operands[1].size)
disp = tb._compute_shifted_register(sh_op)
tb.write(instruction.operands[0], disp)
return
if len(instruction.operands) == 2 and isinstance(
instruction.operands[1], ArmShiftedRegisterOperand):
# Capstone is incorrectly packing <Rm>, #<imm5> into a shifted register, unpack it
instruction.operands.append(instruction.operands[1]._shift_amount)
instruction.operands[1] = instruction.operands[1]._base_reg
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size)
tb.add(self._builder.gen_bsh(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_zf(tb, oprnd1, oprnd2, result)
self._update_nf(tb, oprnd1, oprnd2, result)
# TODO: Encapsulate this new kind of flag update (different from the data proc instructions like add, and, orr)
if oprnd2.immediate == 0:
return
else:
# carry_out = Rm[32 - shift_imm]
shift_carry_out = tb._extract_bit(oprnd1,
32 - oprnd2.immediate)
tb.add(
self._builder.gen_str(shift_carry_out, self._flags["cf"]))
# "Load/store word and unsigned byte Instructions"
# ============================================================================ #
def _translate_ldr(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
tb.write(instruction.operands[0], oprnd1)
def _translate_str(self, tb, instruction):
oprnd0 = tb.read(instruction.operands[0])
tb.write(instruction.operands[1], oprnd0)
# TODO: Check if the byte suffix ('b') should be coded as extra information
# and removed from the mnemonic (handling all ldr/str translations in only
# two functions).
def _translate_ldrb(self, tb, instruction):
op0_reil = ReilRegisterOperand(instruction.operands[0].name,
instruction.operands[0].size)
addr_reg = tb._compute_memory_address(instruction.operands[1])
byte_reg = tb.temporal(8)
tb.add(tb._builder.gen_ldm(addr_reg, byte_reg))
tb.add(self._builder.gen_str(byte_reg, op0_reil))
def _translate_strb(self, tb, instruction):
reil_operand = ReilRegisterOperand(instruction.operands[0].name,
instruction.operands[0].size)
byte_reg = tb.temporal(8)
tb.add(self._builder.gen_str(
reil_operand, byte_reg)) # filter bits [7:0] part of result
addr = tb._compute_memory_address(instruction.operands[1])
tb.add(self._builder.gen_stm(byte_reg, addr))
# TODO: Generalize LDR to handle byte and half word in a single function
def _translate_ldrh(self, tb, instruction):
op0_reil = ReilRegisterOperand(instruction.operands[0].name,
instruction.operands[0].size)
addr_reg = tb._compute_memory_address(instruction.operands[1])
byte_reg = tb.temporal(16)
tb.add(tb._builder.gen_ldm(addr_reg, byte_reg))
tb.add(self._builder.gen_str(byte_reg, op0_reil))
def _translate_strh(self, tb, instruction):
reil_operand = ReilRegisterOperand(instruction.operands[0].name,
instruction.operands[0].size)
half_word_reg = tb.temporal(16)
tb.add(self._builder.gen_str(
reil_operand, half_word_reg)) # filter bits [15:0] part of result
addr = tb._compute_memory_address(instruction.operands[1])
tb.add(self._builder.gen_stm(half_word_reg, addr))
def _translate_ldrd(self, tb, instruction):
if len(instruction.operands
) > 2: # Rd2 has been specified (UAL syntax)
addr_reg = tb._compute_memory_address(instruction.operands[2])
else:
addr_reg = tb._compute_memory_address(instruction.operands[1])
reil_operand = ReilRegisterOperand(instruction.operands[0].name,
instruction.operands[0].size)
tb.add(tb._builder.gen_ldm(addr_reg, reil_operand))
addr_reg = tb._add_to_reg(addr_reg,
ReilImmediateOperand(4, reil_operand.size))
if len(instruction.operands
) > 2: # Rd2 has been specified (UAL syntax)
reil_operand = ReilRegisterOperand(instruction.operands[1].name,
instruction.operands[0].size)
else:
# TODO: Assuming the register is written in its number format
# (no alias like lr or pc).
reil_operand = ReilRegisterOperand(
'r' + str(int(reil_operand.name[1:]) + 1), reil_operand.size)
tb.add(tb._builder.gen_ldm(addr_reg, reil_operand))
def _translate_strd(self, tb, instruction):
if len(instruction.operands
) > 2: # Rd2 has been specified (UAL syntax)
addr_reg = tb._compute_memory_address(instruction.operands[2])
else:
addr_reg = tb._compute_memory_address(instruction.operands[1])
reil_operand = ReilRegisterOperand(instruction.operands[0].name,
instruction.operands[0].size)
tb.add(tb._builder.gen_stm(reil_operand, addr_reg))
addr_reg = tb._add_to_reg(addr_reg,
ReilImmediateOperand(4, reil_operand.size))
if len(instruction.operands
) > 2: # Rd2 has been specified (UAL syntax)
reil_operand = ReilRegisterOperand(instruction.operands[1].name,
instruction.operands[0].size)
else:
# TODO: Assuming the register is written in its number format
# (no alias like lr or pc).
reil_operand = ReilRegisterOperand(
'r' + str(int(reil_operand.name[1:]) + 1), reil_operand.size)
tb.add(tb._builder.gen_stm(reil_operand, addr_reg))
# "Load/store multiple Instructions"
# ============================================================================ #
def _translate_ldm(self, tb, instruction):
self._translate_ldm_stm(tb, instruction, True)
def _translate_stm(self, tb, instruction):
self._translate_ldm_stm(tb, instruction, False)
def _translate_ldm_stm(self, tb, instruction, load=True):
# LDM and STM have exactly the same logic except one loads and the
# other stores It is assumed that the disassembler (for example
# Capstone) writes the register list in increasing order
base = tb.read(instruction.operands[0])
reg_list = tb.read(instruction.operands[1])
if instruction.ldm_stm_addr_mode is None:
instruction.ldm_stm_addr_mode = ARM_LDM_STM_IA # default mode for load and store
if load:
load_store_fn = self._load_value
# Convert stack addressing modes to non-stack addressing modes
if instruction.ldm_stm_addr_mode in ldm_stack_am_to_non_stack_am:
instruction.ldm_stm_addr_mode = ldm_stack_am_to_non_stack_am[
instruction.ldm_stm_addr_mode]
else: # Store
load_store_fn = self._store_value
if instruction.ldm_stm_addr_mode in stm_stack_am_to_non_stack_am:
instruction.ldm_stm_addr_mode = stm_stack_am_to_non_stack_am[
instruction.ldm_stm_addr_mode]
pointer = tb.temporal(base.size)
tb.add(self._builder.gen_str(base, pointer))
reg_list_size_bytes = ReilImmediateOperand(
self._ws.immediate * len(reg_list), base.size)
if instruction.ldm_stm_addr_mode == ARM_LDM_STM_IA:
for reg in reg_list:
load_store_fn(tb, pointer, reg)
pointer = tb._add_to_reg(pointer, self._ws)
elif instruction.ldm_stm_addr_mode == ARM_LDM_STM_IB:
for reg in reg_list:
pointer = tb._add_to_reg(pointer, self._ws)
load_store_fn(tb, pointer, reg)
elif instruction.ldm_stm_addr_mode == ARM_LDM_STM_DA:
reg_list.reverse(
) # Assuming the registry list was in increasing registry number
for reg in reg_list:
load_store_fn(tb, pointer, reg)
pointer = tb._sub_to_reg(pointer, self._ws)
elif instruction.ldm_stm_addr_mode == ARM_LDM_STM_DB:
reg_list.reverse()
for reg in reg_list:
pointer = tb._sub_to_reg(pointer, self._ws)
load_store_fn(tb, pointer, reg)
else:
raise Exception("Unknown addressing mode.")
# Write-back
if instruction.operands[0].wb:
if instruction.ldm_stm_addr_mode == ARM_LDM_STM_IA or instruction.ldm_stm_addr_mode == ARM_LDM_STM_IB:
tmp = tb._add_to_reg(base, reg_list_size_bytes)
elif instruction.ldm_stm_addr_mode == ARM_LDM_STM_DA or instruction.ldm_stm_addr_mode == ARM_LDM_STM_DB:
tmp = tb._sub_to_reg(base, reg_list_size_bytes)
tb.add(self._builder.gen_str(tmp, base))
def _load_value(self, tb, mem_dir, value):
tb.add(self._builder.gen_ldm(mem_dir, value))
def _store_value(self, tb, mem_dir, value):
tb.add(self._builder.gen_stm(value, mem_dir))
def _translate_push_pop(self, tb, instruction, translate_fn):
# PUSH and POP are equivalent to STM and LDM in FD mode with the SP
# (and write-back) Instructions are modified to adapt it to the
# LDM/STM interface
sp_name = "r13" # TODO: Use self._sp
sp_size = instruction.operands[0].reg_list[0][
0].size # Infer it from the registers list
sp_reg = ArmRegisterOperand(sp_name, sp_size)
sp_reg.wb = True
instruction.operands = [sp_reg, instruction.operands[0]]
instruction.ldm_stm_addr_mode = ARM_LDM_STM_FD
translate_fn(tb, instruction)
def _translate_push(self, tb, instruction):
self._translate_push_pop(tb, instruction, self._translate_stm)
def _translate_pop(self, tb, instruction):
self._translate_push_pop(tb, instruction, self._translate_ldm)
# "Branch Instructions"
# ============================================================================ #
def _translate_b(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_bl(self, tb, instruction):
self._translate_branch(tb, instruction, link=True)
# TODO: Thumb
def _translate_bx(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_blx(self, tb, instruction):
self._translate_branch(tb, instruction, link=True)
def _translate_bne(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_beq(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_bpl(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_ble(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_bcs(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_bhs(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_blt(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_bge(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_bhi(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_blo(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_bls(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_branch(self, tb, instruction, link):
if instruction.condition_code == ARM_COND_CODE_AL:
cond = tb.immediate(1, 1)
else:
eval_cc_fn = {
ARM_COND_CODE_EQ: self._evaluate_eq,
ARM_COND_CODE_NE: self._evaluate_ne,
ARM_COND_CODE_CS: self._evaluate_cs,
ARM_COND_CODE_HS: self._evaluate_cs,
ARM_COND_CODE_CC: self._evaluate_cc,
ARM_COND_CODE_LO: self._evaluate_cc,
ARM_COND_CODE_MI: self._evaluate_mi,
ARM_COND_CODE_PL: self._evaluate_pl,
ARM_COND_CODE_VS: self._evaluate_vs,
ARM_COND_CODE_VC: self._evaluate_vc,
ARM_COND_CODE_HI: self._evaluate_hi,
ARM_COND_CODE_LS: self._evaluate_ls,
ARM_COND_CODE_GE: self._evaluate_ge,
ARM_COND_CODE_LT: self._evaluate_lt,
ARM_COND_CODE_GT: self._evaluate_gt,
ARM_COND_CODE_LE: self._evaluate_le,
}
cond = eval_cc_fn[instruction.condition_code](tb)
arm_operand = instruction.operands[0]
if isinstance(arm_operand, ArmImmediateOperand):
target = ReilImmediateOperand(arm_operand.immediate << 8,
self._pc.size + 8)
elif isinstance(arm_operand, ArmRegisterOperand):
target = ReilRegisterOperand(arm_operand.name, arm_operand.size)
target = tb._and_regs(
target, ReilImmediateOperand(0xFFFFFFFE, target.size))
tmp0 = tb.temporal(target.size + 8)
tmp1 = tb.temporal(target.size + 8)
tb.add(self._builder.gen_str(target, tmp0))
tb.add(
self._builder.gen_bsh(tmp0,
ReilImmediateOperand(8, target.size + 8),
tmp1))
target = tmp1
else:
raise NotImplementedError(
"Instruction Not Implemented: Unknown operand for branch operation."
)
if link:
tb.add(
self._builder.gen_str(
ReilImmediateOperand(
instruction.address + instruction.size, self._pc.size),
self._lr))
tb.add(self._builder.gen_jcc(cond, target))
return
class ArmTranslator(object):
"""ARM to IR Translator."""
def __init__(self,
architecture_mode=ARCH_ARM_MODE_32,
translation_mode=FULL_TRANSLATION):
# Set *Architecture Mode*. The translation of each instruction
# into the REIL language is based on this.
self._arch_mode = architecture_mode
# An instance of *ArchitectureInformation*.
self._arch_info = ArmArchitectureInformation(architecture_mode)
# Set *Translation Mode*.
self._translation_mode = translation_mode
# An instance of a *VariableNamer*. This is used so all the
# temporary REIL registers are unique.
self._ir_name_generator = VariableNamer("t", separator="")
self._builder = ReilInstructionBuilder()
self._flags = {
"nf": ReilRegisterOperand("nf", 1),
"zf": ReilRegisterOperand("zf", 1),
"cf": ReilRegisterOperand("cf", 1),
"vf": ReilRegisterOperand("vf", 1),
}
if self._arch_mode == ARCH_ARM_MODE_32:
self._sp = ReilRegisterOperand("r13", 32) # TODO: Implement alias
self._pc = ReilRegisterOperand("r15", 32)
self._lr = ReilRegisterOperand("r14", 32)
self._ws = ReilImmediateOperand(4, 32) # word size
elif self._arch_mode == ARCH_ARM_MODE_64:
self._sp = ReilRegisterOperand("r13", 64)
self._pc = ReilRegisterOperand("r15", 64)
self._lr = ReilRegisterOperand("r14", 64)
self._ws = ReilImmediateOperand(8, 64) # word size
def translate(self, instruction):
"""Return IR representation of an instruction.
"""
try:
trans_instrs = self._translate(instruction)
except NotImplementedError as e:
unkn_instr = self._builder.gen_unkn()
unkn_instr.address = instruction.address << 8 | (0x0 & 0xff)
trans_instrs = [unkn_instr]
self._log_not_supported_instruction(instruction)
except Exception as e:
self._log_translation_exception(instruction)
raise
# Some sanity check....
for instr in trans_instrs:
try:
check_operands_size(instr, self._arch_info.architecture_size)
except:
logger.error("Invalid operand size: %s (%s)", instr,
instruction)
raise
return trans_instrs
def _translate(self, instruction):
"""Translate a arm instruction into REIL language.
:param instruction: a arm instruction
:type instruction: ArmInstruction
"""
# Retrieve translation function.
translator_name = "_translate_" + instruction.mnemonic
translator_fn = getattr(self, translator_name, self._not_implemented)
# Translate instruction.
tb = ArmTranslationBuilder(self._ir_name_generator, self._arch_mode)
# Pre-processing: evaluate flags
nop_cc_lbl = tb.label('condition_code_not_met')
if (instruction.condition_code is not None):
self._evaluate_condition_code(tb, instruction, nop_cc_lbl)
translator_fn(tb, instruction)
tb.add(nop_cc_lbl)
tb.add(self._builder.gen_nop()
) # Added NOP so there is a REIL instruction to jump to
return tb.instanciate(instruction.address)
def reset(self):
"""Restart IR register name generator.
"""
self._ir_name_generator.reset()
@property
def translation_mode(self):
"""Get translation mode.
"""
return self._translation_mode
@translation_mode.setter
def translation_mode(self, value):
"""Set translation mode.
"""
self._translation_mode = value
def _log_not_supported_instruction(self, instruction):
bytes_str = " ".join("%02x" % ord(b) for b in instruction.bytes)
logger.info("Instruction not supported: %s (%s [%s])",
instruction.mnemonic, instruction, bytes_str)
def _log_translation_exception(self, instruction):
bytes_str = " ".join("%02x" % ord(b) for b in instruction.bytes)
logger.error("Failed to translate arm to REIL: %s (%s)",
instruction,
bytes_str,
exc_info=True)
# ============================================================================ #
def _not_implemented(self, tb, instruction):
raise NotImplementedError("Instruction Not Implemented")
# Translators
# ============================================================================ #
# ============================================================================ #
# "Flags"
# ============================================================================ #
def _update_nf(self, tb, oprnd0, oprnd1, result):
sign = tb._extract_bit(result, oprnd0.size - 1)
tb.add(self._builder.gen_str(sign, self._flags["nf"]))
def _carry_from_uf(self, tb, oprnd0, oprnd1, result):
assert (result.size == oprnd0.size * 2)
carry = tb._extract_bit(result, oprnd0.size)
tb.add(self._builder.gen_str(carry, self._flags["cf"]))
def _borrow_from_uf(self, tb, oprnd0, oprnd1, result):
# BorrowFrom as defined in the ARM Reference Manual has the same implementation as CarryFrom
self._carry_from_uf(tb, oprnd0, oprnd1, result)
def _overflow_from_add_uf(self, tb, oprnd0, oprnd1, result):
op1_sign = tb._extract_bit(oprnd0, oprnd0.size - 1)
op2_sign = tb._extract_bit(oprnd1, oprnd0.size - 1)
res_sign = tb._extract_bit(result, oprnd0.size - 1)
overflow = tb._and_regs(tb._equal_regs(op1_sign, op2_sign),
tb._unequal_regs(op1_sign, res_sign))
tb.add(self._builder.gen_str(overflow, self._flags["vf"]))
# Evaluate overflow and update the flag
def _overflow_from_sub_uf(self, tb, oprnd0, oprnd1, result):
tb.add(
self._builder.gen_str(
tb._overflow_from_sub(oprnd0, oprnd1, result),
self._flags["vf"]))
def _update_zf(self, tb, oprnd0, oprnd1, result):
zf = self._flags["zf"]
imm0 = tb.immediate((2**oprnd0.size) - 1, result.size)
tmp0 = tb.temporal(oprnd0.size)
tb.add(self._builder.gen_and(result, imm0,
tmp0)) # filter low part of result
tb.add(self._builder.gen_bisz(tmp0, zf))
def _carry_out(self, tb, carry_operand, oprnd0, oprnd1, result):
if isinstance(carry_operand, ArmImmediateOperand):
return
elif isinstance(carry_operand, ArmRegisterOperand):
return
elif isinstance(carry_operand, ArmShiftedRegisterOperand):
base = ReilRegisterOperand(carry_operand.base_reg.name,
carry_operand.size)
shift_type = carry_operand.shift_type
shift_amount = carry_operand.shift_amount
if (shift_type == 'lsl'):
if isinstance(shift_amount, ArmImmediateOperand):
if shift_amount.immediate == 0:
return
else:
# carry_out = Rm[32 - shift_imm]
shift_carry_out = tb._extract_bit(
base, 32 - shift_amount.immediate)
elif isinstance(shift_amount, ArmRegisterOperand):
# Rs: register with shift amount
# if Rs[7:0] == 0 then
# carry_out = C Flag
# else if Rs[7:0] <= 32 then
# carry_out = Rm[32 - Rs[7:0]]
# else /* Rs[7:0] > 32 */
# carry_out = 0
shift_carry_out = tb.temporal(1)
tb.add(
self._builder.gen_str(self._flags["cf"],
shift_carry_out))
rs = ReilRegisterOperand(shift_amount.name,
shift_amount.size)
rs_7_0 = tb._and_regs(rs, tb.immediate(0xFF, rs.size))
end_label = tb.label('end_label')
rs_greater_32_label = tb.label('rs_greater_32_label')
# if Rs[7:0] == 0 then
# carry_out = C Flag
tb._jump_if_zero(
rs_7_0, end_label
) # shift_carry_out already has the C flag set, so do nothing
tb.add(
self._builder.gen_jcc(
tb._greater_than_or_equal(
rs_7_0, tb.immediate(33, rs_7_0.size)),
rs_greater_32_label))
# Rs > 0 and Rs <= 32
# carry_out = Rm[32 - Rs[7:0]]
extract_bit_number = tb.temporal(rs_7_0.size)
tb.add(
self._builder.gen_sub(tb.immediate(32, rs_7_0.size),
rs_7_0, extract_bit_number))
tb.add(
self._builder.gen_str(
tb._extract_bit_with_register(
base, extract_bit_number), shift_carry_out))
tb._jump_to(end_label)
# else /* Rs[7:0] > 32 */
# carry_out = 0
tb.add(rs_greater_32_label)
tb.add(
self._builder.gen_str(tb.immediate(0, 1),
shift_carry_out))
# tb._jump_to(end_label)
tb.add(end_label)
else:
raise Exception("carry_out: Unknown shift amount type.")
else:
# TODO: Implement other shift types
raise NotImplementedError(
"Instruction Not Implemented: carry_out: shift type " +
carry_operand.shift_type)
else:
raise Exception("carry_out: Unknown operand type.")
tb.add(self._builder.gen_str(shift_carry_out, self._flags["cf"]))
def _update_flags_data_proc_add(self, tb, oprnd0, oprnd1, result):
self._update_zf(tb, oprnd0, oprnd1, result)
self._update_nf(tb, oprnd0, oprnd1, result)
self._carry_from_uf(tb, oprnd0, oprnd1, result)
self._overflow_from_add_uf(tb, oprnd0, oprnd1, result)
def _update_flags_data_proc_sub(self, tb, oprnd0, oprnd1, result):
self._update_zf(tb, oprnd0, oprnd1, result)
self._update_nf(tb, oprnd0, oprnd1, result)
self._borrow_from_uf(tb, oprnd0, oprnd1, result)
# C Flag = NOT BorrowFrom (to be used by subsequent instructions like SBC and RSC)
tb.add(
self._builder.gen_str(tb._negate_reg(self._flags["cf"]),
self._flags["cf"]))
self._overflow_from_sub_uf(tb, oprnd0, oprnd1, result)
def _update_flags_data_proc_other(self, tb, second_operand, oprnd0, oprnd1,
result):
self._update_zf(tb, oprnd0, oprnd1, result)
self._update_nf(tb, oprnd0, oprnd1, result)
self._carry_out(tb, second_operand, oprnd0, oprnd1, result)
# Overflow Flag (V) unaffected
def _update_flags_other(self, tb, oprnd0, oprnd1, result):
self._update_zf(tb, oprnd0, oprnd1, result)
self._update_nf(tb, oprnd0, oprnd1, result)
# Carry Flag (C) unaffected
# Overflow Flag (V) unaffected
def _undefine_flag(self, tb, flag):
# NOTE: In every test I've made, each time a flag is leave
# undefined it is always set to 0.
imm = tb.immediate(0, flag.size)
tb.add(self._builder.gen_str(imm, flag))
def _clear_flag(self, tb, flag):
imm = tb.immediate(0, flag.size)
tb.add(self._builder.gen_str(imm, flag))
def _set_flag(self, tb, flag):
imm = tb.immediate(1, flag.size)
tb.add(self._builder.gen_str(imm, flag))
# EQ: Z set
def _evaluate_eq(self, tb):
return self._flags["zf"]
# NE: Z clear
def _evaluate_ne(self, tb):
return tb._negate_reg(self._flags["zf"])
# CS: C set
def _evaluate_cs(self, tb):
return self._flags["cf"]
# CC: C clear
def _evaluate_cc(self, tb):
return tb._negate_reg(self._flags["cf"])
# MI: N set
def _evaluate_mi(self, tb):
return self._flags["nf"]
# PL: N clear
def _evaluate_pl(self, tb):
return tb._negate_reg(self._flags["nf"])
# VS: V set
def _evaluate_vs(self, tb):
return self._flags["vf"]
# VC: V clear
def _evaluate_vc(self, tb):
return tb._negate_reg(self._flags["vf"])
# HI: C set and Z clear
def _evaluate_hi(self, tb):
return tb._and_regs(self._flags["cf"],
tb._negate_reg(self._flags["zf"]))
# LS: C clear or Z set
def _evaluate_ls(self, tb):
return tb._or_regs(tb._negate_reg(self._flags["cf"]),
self._flags["zf"])
# GE: N == V
def _evaluate_ge(self, tb):
return tb._equal_regs(self._flags["nf"], self._flags["vf"])
# LT: N != V
def _evaluate_lt(self, tb):
return tb._negate_reg(self._evaluate_ge(tb))
# GT: (Z == 0) and (N == V)
def _evaluate_gt(self, tb):
return tb._and_regs(tb._negate_reg(self._flags["zf"]),
self._evaluate_ge(tb))
# LE: (Z == 1) or (N != V)
def _evaluate_le(self, tb):
return tb._or_regs(self._flags["zf"], self._evaluate_lt(tb))
def _evaluate_condition_code(self, tb, instruction, nop_label):
if (instruction.condition_code == ARM_COND_CODE_AL):
return
eval_cc_fn = {
ARM_COND_CODE_EQ: self._evaluate_eq,
ARM_COND_CODE_NE: self._evaluate_ne,
ARM_COND_CODE_CS: self._evaluate_cs,
ARM_COND_CODE_HS: self._evaluate_cs,
ARM_COND_CODE_CC: self._evaluate_cc,
ARM_COND_CODE_LO: self._evaluate_cc,
ARM_COND_CODE_MI: self._evaluate_mi,
ARM_COND_CODE_PL: self._evaluate_pl,
ARM_COND_CODE_VS: self._evaluate_vs,
ARM_COND_CODE_VC: self._evaluate_vc,
ARM_COND_CODE_HI: self._evaluate_hi,
ARM_COND_CODE_LS: self._evaluate_ls,
ARM_COND_CODE_GE: self._evaluate_ge,
ARM_COND_CODE_LT: self._evaluate_lt,
ARM_COND_CODE_GT: self._evaluate_gt,
ARM_COND_CODE_LE: self._evaluate_le,
}
neg_cond = tb._negate_reg(eval_cc_fn[instruction.condition_code](tb))
tb.add(self._builder.gen_jcc(neg_cond, nop_label))
return
# "Data-processing Instructions"
# ============================================================================ #
def _translate_mov(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
tb.write(instruction.operands[0], oprnd1)
if instruction.update_flags:
self._update_flags_data_proc_other(tb, instruction.operands[1],
oprnd1, None, oprnd1)
def _translate_and(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size)
tb.add(self._builder.gen_and(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_other(tb, instruction.operands[2],
oprnd1, oprnd2, result)
def _translate_orr(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size)
tb.add(self._builder.gen_or(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_other(tb, instruction.operands[2],
oprnd1, oprnd2, result)
def _translate_eor(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size)
tb.add(self._builder.gen_xor(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_other(tb, instruction.operands[2],
oprnd1, oprnd2, result)
def _translate_add(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_add(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_add(tb, oprnd1, oprnd2, result)
def _translate_sub(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_sub(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_flags_data_proc_sub(tb, oprnd1, oprnd2, result)
def _translate_mul(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
oprnd2 = tb.read(instruction.operands[2])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_mul(oprnd1, oprnd2, result))
tb.write(instruction.operands[0], result)
if instruction.update_flags:
self._update_zf(tb, oprnd1, oprnd2, result)
self._update_nf(tb, oprnd1, oprnd2, result)
def _translate_cmn(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[0])
oprnd2 = tb.read(instruction.operands[1])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_add(oprnd1, oprnd2, result))
self._update_flags_data_proc_add(
tb, oprnd1, oprnd2, result) # S = 1 (implied in the instruction)
def _translate_cmp(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[0])
oprnd2 = tb.read(instruction.operands[1])
result = tb.temporal(oprnd1.size * 2)
tb.add(self._builder.gen_sub(oprnd1, oprnd2, result))
self._update_flags_data_proc_sub(
tb, oprnd1, oprnd2, result) # S = 1 (implied in the instruction)
# "Load/store word and unsigned byte Instructions"
# ============================================================================ #
def _translate_ldr(self, tb, instruction):
oprnd1 = tb.read(instruction.operands[1])
tb.write(instruction.operands[0], oprnd1)
def _translate_str(self, tb, instruction):
oprnd0 = tb.read(instruction.operands[0])
tb.write(instruction.operands[1], oprnd0)
# "Load/store multiple Instructions"
# ============================================================================ #
def _translate_ldm(self, tb, instruction):
self._translate_ldm_stm(tb, instruction, True)
def _translate_stm(self, tb, instruction):
self._translate_ldm_stm(tb, instruction, False)
# LDM and STM have exactly the same logic except one loads and the other stores
# It is assumed that the disassembler (for example Capstone) writes the register list in increasing order
def _translate_ldm_stm(self, tb, instruction, load=True):
base = tb.read(instruction.operands[0])
reg_list = tb.read(instruction.operands[1])
if instruction.ldm_stm_addr_mode == None:
instruction.ldm_stm_addr_mode = ARM_LDM_STM_IA # default mode for load and store
if load:
load_store_fn = self._load_value
# Convert stack addressing modes to non-stack addressing modes
if instruction.ldm_stm_addr_mode in ldm_stack_am_to_non_stack_am:
instruction.ldm_stm_addr_mode = ldm_stack_am_to_non_stack_am[
instruction.ldm_stm_addr_mode]
else: # Store
load_store_fn = self._store_value
if instruction.ldm_stm_addr_mode in stm_stack_am_to_non_stack_am:
instruction.ldm_stm_addr_mode = stm_stack_am_to_non_stack_am[
instruction.ldm_stm_addr_mode]
pointer = tb.temporal(base.size)
tb.add(self._builder.gen_str(base, pointer))
reg_list_size_bytes = ReilImmediateOperand(
self._ws.immediate * len(reg_list), base.size)
if instruction.ldm_stm_addr_mode == ARM_LDM_STM_IA:
for reg in reg_list:
load_store_fn(tb, pointer, reg)
pointer = tb._add_to_reg(pointer, self._ws)
elif instruction.ldm_stm_addr_mode == ARM_LDM_STM_IB:
for reg in reg_list:
pointer = tb._add_to_reg(pointer, self._ws)
load_store_fn(tb, pointer, reg)
elif instruction.ldm_stm_addr_mode == ARM_LDM_STM_DA:
reg_list.reverse(
) # Assuming the registry list was in increasing registry number
for reg in reg_list:
load_store_fn(tb, pointer, reg)
pointer = tb._sub_to_reg(pointer, self._ws)
elif instruction.ldm_stm_addr_mode == ARM_LDM_STM_DB:
reg_list.reverse()
for reg in reg_list:
pointer = tb._sub_to_reg(pointer, self._ws)
load_store_fn(tb, pointer, reg)
else:
raise Exception("Unknown addressing mode.")
# Write-back
if instruction.operands[0].wb:
if instruction.ldm_stm_addr_mode == ARM_LDM_STM_IA or instruction.ldm_stm_addr_mode == ARM_LDM_STM_IB:
tmp = tb._add_to_reg(base, reg_list_size_bytes)
elif instruction.ldm_stm_addr_mode == ARM_LDM_STM_DA or instruction.ldm_stm_addr_mode == ARM_LDM_STM_DB:
tmp = tb._sub_to_reg(base, reg_list_size_bytes)
tb.add(self._builder.gen_str(tmp, base))
def _load_value(self, tb, mem_dir, value):
tb.add(self._builder.gen_ldm(mem_dir, value))
def _store_value(self, tb, mem_dir, value):
tb.add(self._builder.gen_stm(value, mem_dir))
# PUSH and POP are equivalent to STM and LDM in FD mode with the SP (and write-back)
# Instructions are modified to adapt it to the LDM/STM interface
def _translate_push_pop(self, tb, instruction, translate_fn):
sp_name = "r13" # TODO: Use self._sp
sp_size = instruction.operands[0].reg_list[0][
0].size # Infer it from the registers list
sp_reg = ArmRegisterOperand(sp_name, sp_size)
sp_reg.wb = True
instruction.operands = [sp_reg, instruction.operands[0]]
instruction.ldm_stm_addr_mode = ARM_LDM_STM_FD
translate_fn(tb, instruction)
def _translate_push(self, tb, instruction):
self._translate_push_pop(tb, instruction, self._translate_stm)
def _translate_pop(self, tb, instruction):
self._translate_push_pop(tb, instruction, self._translate_ldm)
# "Branch Instructions"
# ============================================================================ #
def _translate_b(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_bl(self, tb, instruction):
self._translate_branch(tb, instruction, link=True)
# TODO: Thumb
def _translate_bx(self, tb, instruction):
self._translate_branch(tb, instruction, link=False)
def _translate_blx(self, tb, instruction):
self._translate_branch(tb, instruction, link=True)
def _translate_branch(self, tb, instruction, link):
arm_operand = instruction.operands[0]
if isinstance(arm_operand, ArmImmediateOperand):
target = ReilImmediateOperand(arm_operand.immediate << 8,
self._pc.size + 8)
elif isinstance(arm_operand, ArmRegisterOperand):
target = ReilRegisterOperand(arm_operand.name, arm_operand.size)
target = tb._and_regs(
target, ReilImmediateOperand(0xFFFFFFFE, target.size))
tmp0 = tb.temporal(target.size + 8)
tmp1 = tb.temporal(target.size + 8)
tb.add(self._builder.gen_str(target, tmp0))
tb.add(
self._builder.gen_bsh(tmp0,
ReilImmediateOperand(8, target.size + 8),
tmp1))
target = tmp1
else:
raise NotImplementedError(
"Instruction Not Implemented: Unknown operand for branch operation."
)
if (link):
tb.add(
self._builder.gen_str(
ReilImmediateOperand(
instruction.address + instruction.size, self._pc.size),
self._lr))
tb._jump_to(target)