def __eval_offset(self):
bitoffset = get_attr_val(self.die, 'DW_AT_data_bit_offset')
if bitoffset is not None:
# Bit offset is given directly
return bitoffset
location = get_attr_val(self.die, 'DW_AT_data_member_location')
if location is None:
# no offset attribute exists -- the member is located at the beginning of its parent
return 0
elif isinstance(location, (int, long)):
# the attribute is a number -- this is the offset in bytes
return location * 8
elif isinstance(location, list):
# the attribute is an expression
dwxpr = location
if dwxpr[0] == dwarf_expr.DW_OP_name2opcode['DW_OP_plus_uconst']:
# Right now we only support location descriptions in the form [DW_OP_plus_uconst, <ULEB128>].
# This is the only form GCC and clang produce.
return LEB.decode(BytesIO(bytearray(dwxpr[1:]))) * 8
else:
opcode = dwarf_expr.DW_OP_opcode2name.get(
dwxpr[0], '<unknown>')
raise NotImplementedError(
'Unsupported opcode in data member location %s (%02x)' %
(opcode, dwxpr[0]))
assert False, 'Unreachable code.'
def __eval_offset(self):
bitoffset = get_attr_val(self.die, 'DW_AT_data_bit_offset')
if bitoffset is not None:
# Bit offset is given directly
return bitoffset
location = get_attr_val(self.die, 'DW_AT_data_member_location')
if location is None:
# no offset attribute exists -- the member is located at the beginning of its parent
return 0
elif isinstance(location, (int, long)):
# the attribute is a number -- this is the offset in bytes
return location * 8
elif isinstance(location, list):
# the attribute is an expression
dwxpr = location
if dwxpr[0] == dwarf_expr.DW_OP_name2opcode['DW_OP_plus_uconst']:
# Right now we only support location descriptions in the form [DW_OP_plus_uconst, <ULEB128>].
# This is the only form GCC and clang produce.
return LEB.decode(BytesIO(bytearray(dwxpr[1:]))) * 8
else:
opcode = dwarf_expr.DW_OP_opcode2name.get(dwxpr[0], '<unknown>')
raise NotImplementedError('Unsupported opcode in data member location %s (%02x)' % (opcode, dwxpr[0]))
assert False, 'Unreachable code.'
def decode_offset(member_location):
'''Convert dwarf expression in DW_AT_data_member_location to offset from structure start.'''
if member_location is None:
# the attribute does not exist -- the member is located at the beginning of its parent
return 0
elif isinstance(member_location, int):
# the attribute is a number -- this is the offset
return member_location
elif isinstance(member_location, list):
# the attribute is an expression
dwxpr = member_location
if dwxpr[0] == dwarf_expr.DW_OP_name2opcode['DW_OP_plus_uconst']:
# Right now we only support location descriptions in the form [DW_OP_plus_uconst, <ULEB128>].
# This is the only form GCC and clang produce.
return LEB.decode(BytesIO(bytearray(dwxpr[1:])))
else:
opcode = dwarf_expr.DW_OP_opcode2name.get(dwxpr[0], '<unknown>')
raise NotImplementedError('Unsupported opcode in data member location %s (%02x)' % (opcode, dwxpr[0]))
def iter_entries():
if not self.debug_info.dwarf.has_CFI():
logging.warn('ELF has no call frame information.')
return
for fde in self.debug_info.dwarf.CFI_entries():
if not isinstance(fde, FDE):
continue
low = fde.header.initial_location
high = low + fde.header.address_range
invalid = False
decoded = fde.get_decoded().table
for n, each in enumerate(decoded, 0):
try:
entry_low = debug_info.addr2fo(each['pc'])
entry_high = debug_info.addr2fo(
high if n >= len(decoded) -
1 else decoded[n + 1]['pc'])
except ValueError:
invalid = True
continue
cfa_rule = each['cfa']
if cfa_rule.expr is not None:
# CFA is a regular DWARF expressions
expr = cfa_rule.expr
else:
assert cfa_rule.reg is not None
# CFA is a register + offset -- convert it to a DWARF expression
expr = bytearray([0x92]) # DW_OP_bregx
expr += LEB.encode(cfa_rule.reg) # Register index
expr += SLEB.encode(
cfa_rule.offset) # Offset from register
yield CallFrameInfoEntry(entry_low, entry_high,
b64encode(expr))
if invalid:
logging.warn(
'Invalid call frame information entry encountered in FDE at %#x.',
fde.offset)
def decode_offset(member_location):
'''Convert dwarf expression in DW_AT_data_member_location to offset from structure start.'''
if member_location is None:
# the attribute does not exist -- the member is located at the beginning of its parent
return 0
elif isinstance(member_location, int):
# the attribute is a number -- this is the offset
return member_location
elif isinstance(member_location, list):
# the attribute is an expression
dwxpr = member_location
if dwxpr[0] == dwarf_expr.DW_OP_name2opcode['DW_OP_plus_uconst']:
# Right now we only support location descriptions in the form [DW_OP_plus_uconst, <ULEB128>].
# This is the only form GCC and clang produce.
return LEB.decode(BytesIO(bytearray(dwxpr[1:])))
else:
opcode = dwarf_expr.DW_OP_opcode2name.get(dwxpr[0], '<unknown>')
raise NotImplementedError(
'Unsupported opcode in data member location %s (%02x)' %
(opcode, dwxpr[0]))
def iter_entries():
if not self.debug_info.dwarf.has_CFI():
logging.warn('ELF has no call frame information.')
return
for fde in self.debug_info.dwarf.CFI_entries():
if not isinstance(fde, FDE):
continue
low = fde.header.initial_location
high = low + fde.header.address_range
invalid = False
decoded = fde.get_decoded().table
for n, each in enumerate(decoded, 0):
try:
entry_low = debug_info.addr2fo(each['pc'])
entry_high = debug_info.addr2fo(high if n >= len(decoded) - 1 else decoded[n + 1]['pc'])
except ValueError:
invalid = True
continue
cfa_rule = each['cfa']
if cfa_rule.expr is not None:
# CFA is a regular DWARF expressions
expr = cfa_rule.expr
else:
assert cfa_rule.reg is not None
# CFA is a register + offset -- convert it to a DWARF expression
expr = bytearray([0x92]) # DW_OP_bregx
expr += LEB.encode(cfa_rule.reg) # Register index
expr += SLEB.encode(cfa_rule.offset) # Offset from register
yield CallFrameInfoEntry(entry_low, entry_high, b64encode(expr))
if invalid:
logging.warn('Invalid call frame information entry encountered in FDE at %#x.', fde.offset)
def regx(self):
regnum = LEB.decode(self.expression)
return 'get_reg(%i)' % regnum
def bregx(self):
'''The DW_OP_bregx operation has two operands: a register which is specified by an unsigned LEB128 number,
followed by a signed LEB128 offset.'''
regnum = LEB.decode(self.expression)
return self.bregN(regnum)
def constu(self):
'''The single operand of the DW_OP_constu operation provides an unsigned LEB128 integer constant.'''
val = LEB.decode(self.expression)
self.push('%#x' % val)
def regx(self):
regnum = LEB.decode(self.expression)
return 'get_reg(%i)' % regnum
def bregx(self):
'''The DW_OP_bregx operation has two operands: a register which is specified by an unsigned LEB128 number,
followed by a signed LEB128 offset.'''
regnum = LEB.decode(self.expression)
return self.bregN(regnum)
def constu(self):
'''The single operand of the DW_OP_constu operation provides an unsigned LEB128 integer constant.'''
val = LEB.decode(self.expression)
self.push('%#x' % val)
