You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
678 lines
27 KiB
678 lines
27 KiB
#-------------------------------------------------------------------------------
|
|
# elftools: dwarf/callframe.py
|
|
#
|
|
# DWARF call frame information
|
|
#
|
|
# Eli Bendersky (eliben@gmail.com)
|
|
# This code is in the public domain
|
|
#-------------------------------------------------------------------------------
|
|
import copy
|
|
from collections import namedtuple
|
|
from ..common.utils import (struct_parse, dwarf_assert, preserve_stream_pos)
|
|
from ..common.py3compat import iterbytes, iterkeys
|
|
from ..construct import Struct, Switch
|
|
from .enums import DW_EH_encoding_flags
|
|
from .structs import DWARFStructs
|
|
from .constants import *
|
|
|
|
|
|
class CallFrameInfo(object):
|
|
""" DWARF CFI (Call Frame Info)
|
|
|
|
Note that this also supports unwinding information as found in .eh_frame
|
|
sections: its format differs slightly from the one in .debug_frame. See
|
|
<http://www.airs.com/blog/archives/460>.
|
|
|
|
stream, size:
|
|
A stream holding the .debug_frame section, and the size of the
|
|
section in it.
|
|
|
|
address:
|
|
Virtual address for this section. This is used to decode relative
|
|
addresses.
|
|
|
|
base_structs:
|
|
The structs to be used as the base for parsing this section.
|
|
Eventually, each entry gets its own structs based on the initial
|
|
length field it starts with. The address_size, however, is taken
|
|
from base_structs. This appears to be a limitation of the DWARFv3
|
|
standard, fixed in v4.
|
|
A discussion I had on dwarf-discuss confirms this.
|
|
So for DWARFv4 we'll take the address size from the CIE header,
|
|
but for earlier versions will use the elfclass of the containing
|
|
file; more sophisticated methods are used by libdwarf and others,
|
|
such as guessing which CU contains which FDEs (based on their
|
|
address ranges) and taking the address_size from those CUs.
|
|
"""
|
|
def __init__(self, stream, size, address, base_structs,
|
|
for_eh_frame=False):
|
|
self.stream = stream
|
|
self.size = size
|
|
self.address = address
|
|
self.base_structs = base_structs
|
|
self.entries = None
|
|
|
|
# Map between an offset in the stream and the entry object found at this
|
|
# offset. Useful for assigning CIE to FDEs according to the CIE_pointer
|
|
# header field which contains a stream offset.
|
|
self._entry_cache = {}
|
|
|
|
# The .eh_frame and .debug_frame section use almost the same CFI
|
|
# encoding, but there are tiny variations we need to handle during
|
|
# parsing.
|
|
self.for_eh_frame = for_eh_frame
|
|
|
|
def get_entries(self):
|
|
""" Get a list of entries that constitute this CFI. The list consists
|
|
of CIE or FDE objects, in the order of their appearance in the
|
|
section.
|
|
"""
|
|
if self.entries is None:
|
|
self.entries = self._parse_entries()
|
|
return self.entries
|
|
|
|
#-------------------------
|
|
|
|
def _parse_entries(self):
|
|
entries = []
|
|
offset = 0
|
|
while offset < self.size:
|
|
entries.append(self._parse_entry_at(offset))
|
|
offset = self.stream.tell()
|
|
return entries
|
|
|
|
def _parse_entry_at(self, offset):
|
|
""" Parse an entry from self.stream starting with the given offset.
|
|
Return the entry object. self.stream will point right after the
|
|
entry.
|
|
"""
|
|
if offset in self._entry_cache:
|
|
return self._entry_cache[offset]
|
|
|
|
entry_length = struct_parse(
|
|
self.base_structs.Dwarf_uint32(''), self.stream, offset)
|
|
|
|
if self.for_eh_frame and entry_length == 0:
|
|
return ZERO(offset)
|
|
|
|
dwarf_format = 64 if entry_length == 0xFFFFFFFF else 32
|
|
|
|
entry_structs = DWARFStructs(
|
|
little_endian=self.base_structs.little_endian,
|
|
dwarf_format=dwarf_format,
|
|
address_size=self.base_structs.address_size)
|
|
|
|
# Read the next field to see whether this is a CIE or FDE
|
|
CIE_id = struct_parse(
|
|
entry_structs.Dwarf_offset(''), self.stream)
|
|
|
|
if self.for_eh_frame:
|
|
is_CIE = CIE_id == 0
|
|
else:
|
|
is_CIE = (
|
|
(dwarf_format == 32 and CIE_id == 0xFFFFFFFF) or
|
|
CIE_id == 0xFFFFFFFFFFFFFFFF)
|
|
|
|
# Parse the header, which goes up to and excluding the sequence of
|
|
# instructions.
|
|
if is_CIE:
|
|
header_struct = (entry_structs.EH_CIE_header
|
|
if self.for_eh_frame else
|
|
entry_structs.Dwarf_CIE_header)
|
|
header = struct_parse(
|
|
header_struct, self.stream, offset)
|
|
else:
|
|
header = self._parse_fde_header(entry_structs, offset)
|
|
|
|
|
|
# If this is DWARF version 4 or later, we can have a more precise
|
|
# address size, read from the CIE header.
|
|
if not self.for_eh_frame and entry_structs.dwarf_version >= 4:
|
|
entry_structs = DWARFStructs(
|
|
little_endian=entry_structs.little_endian,
|
|
dwarf_format=entry_structs.dwarf_format,
|
|
address_size=header.address_size)
|
|
|
|
# If the augmentation string is not empty, hope to find a length field
|
|
# in order to skip the data specified augmentation.
|
|
if is_CIE:
|
|
aug_bytes, aug_dict = self._parse_cie_augmentation(
|
|
header, entry_structs)
|
|
else:
|
|
cie = self._parse_cie_for_fde(offset, header, entry_structs)
|
|
aug_bytes = self._read_augmentation_data(entry_structs)
|
|
|
|
# For convenience, compute the end offset for this entry
|
|
end_offset = (
|
|
offset + header.length +
|
|
entry_structs.initial_length_field_size())
|
|
|
|
# At this point self.stream is at the start of the instruction list
|
|
# for this entry
|
|
instructions = self._parse_instructions(
|
|
entry_structs, self.stream.tell(), end_offset)
|
|
|
|
if is_CIE:
|
|
self._entry_cache[offset] = CIE(
|
|
header=header, instructions=instructions, offset=offset,
|
|
augmentation_dict=aug_dict,
|
|
augmentation_bytes=aug_bytes,
|
|
structs=entry_structs)
|
|
|
|
else: # FDE
|
|
cie = self._parse_cie_for_fde(offset, header, entry_structs)
|
|
self._entry_cache[offset] = FDE(
|
|
header=header, instructions=instructions, offset=offset,
|
|
augmentation_bytes=aug_bytes,
|
|
structs=entry_structs, cie=cie)
|
|
return self._entry_cache[offset]
|
|
|
|
def _parse_instructions(self, structs, offset, end_offset):
|
|
""" Parse a list of CFI instructions from self.stream, starting with
|
|
the offset and until (not including) end_offset.
|
|
Return a list of CallFrameInstruction objects.
|
|
"""
|
|
instructions = []
|
|
while offset < end_offset:
|
|
opcode = struct_parse(structs.Dwarf_uint8(''), self.stream, offset)
|
|
args = []
|
|
|
|
primary = opcode & _PRIMARY_MASK
|
|
primary_arg = opcode & _PRIMARY_ARG_MASK
|
|
if primary == DW_CFA_advance_loc:
|
|
args = [primary_arg]
|
|
elif primary == DW_CFA_offset:
|
|
args = [
|
|
primary_arg,
|
|
struct_parse(structs.Dwarf_uleb128(''), self.stream)]
|
|
elif primary == DW_CFA_restore:
|
|
args = [primary_arg]
|
|
# primary == 0 and real opcode is extended
|
|
elif opcode in (DW_CFA_nop, DW_CFA_remember_state,
|
|
DW_CFA_restore_state):
|
|
args = []
|
|
elif opcode == DW_CFA_set_loc:
|
|
args = [
|
|
struct_parse(structs.Dwarf_target_addr(''), self.stream)]
|
|
elif opcode == DW_CFA_advance_loc1:
|
|
args = [struct_parse(structs.Dwarf_uint8(''), self.stream)]
|
|
elif opcode == DW_CFA_advance_loc2:
|
|
args = [struct_parse(structs.Dwarf_uint16(''), self.stream)]
|
|
elif opcode == DW_CFA_advance_loc4:
|
|
args = [struct_parse(structs.Dwarf_uint32(''), self.stream)]
|
|
elif opcode in (DW_CFA_offset_extended, DW_CFA_register,
|
|
DW_CFA_def_cfa, DW_CFA_val_offset):
|
|
args = [
|
|
struct_parse(structs.Dwarf_uleb128(''), self.stream),
|
|
struct_parse(structs.Dwarf_uleb128(''), self.stream)]
|
|
elif opcode in (DW_CFA_restore_extended, DW_CFA_undefined,
|
|
DW_CFA_same_value, DW_CFA_def_cfa_register,
|
|
DW_CFA_def_cfa_offset):
|
|
args = [struct_parse(structs.Dwarf_uleb128(''), self.stream)]
|
|
elif opcode == DW_CFA_def_cfa_offset_sf:
|
|
args = [struct_parse(structs.Dwarf_sleb128(''), self.stream)]
|
|
elif opcode == DW_CFA_def_cfa_expression:
|
|
args = [struct_parse(
|
|
structs.Dwarf_dw_form['DW_FORM_block'], self.stream)]
|
|
elif opcode in (DW_CFA_expression, DW_CFA_val_expression):
|
|
args = [
|
|
struct_parse(structs.Dwarf_uleb128(''), self.stream),
|
|
struct_parse(
|
|
structs.Dwarf_dw_form['DW_FORM_block'], self.stream)]
|
|
elif opcode in (DW_CFA_offset_extended_sf,
|
|
DW_CFA_def_cfa_sf, DW_CFA_val_offset_sf):
|
|
args = [
|
|
struct_parse(structs.Dwarf_uleb128(''), self.stream),
|
|
struct_parse(structs.Dwarf_sleb128(''), self.stream)]
|
|
else:
|
|
dwarf_assert(False, 'Unknown CFI opcode: 0x%x' % opcode)
|
|
|
|
instructions.append(CallFrameInstruction(opcode=opcode, args=args))
|
|
offset = self.stream.tell()
|
|
return instructions
|
|
|
|
def _parse_cie_for_fde(self, fde_offset, fde_header, entry_structs):
|
|
""" Parse the CIE that corresponds to an FDE.
|
|
"""
|
|
# Determine the offset of the CIE that corresponds to this FDE
|
|
if self.for_eh_frame:
|
|
# CIE_pointer contains the offset for a reverse displacement from
|
|
# the section offset of the CIE_pointer field itself (not from the
|
|
# FDE header offset).
|
|
cie_displacement = fde_header['CIE_pointer']
|
|
cie_offset = (fde_offset + entry_structs.dwarf_format // 8
|
|
- cie_displacement)
|
|
else:
|
|
cie_offset = fde_header['CIE_pointer']
|
|
|
|
# Then read it
|
|
with preserve_stream_pos(self.stream):
|
|
return self._parse_entry_at(cie_offset)
|
|
|
|
def _parse_cie_augmentation(self, header, entry_structs):
|
|
""" Parse CIE augmentation data from the annotation string in `header`.
|
|
|
|
Return a tuple that contains 1) the augmentation data as a string
|
|
(without the length field) and 2) the augmentation data as a dict.
|
|
"""
|
|
augmentation = header.get('augmentation')
|
|
if not augmentation:
|
|
return ('', {})
|
|
|
|
# Augmentation parsing works in minimal mode here: we need the length
|
|
# field to be able to skip unhandled augmentation fields.
|
|
assert augmentation.startswith(b'z'), (
|
|
'Unhandled augmentation string: {}'.format(repr(augmentation)))
|
|
|
|
available_fields = {
|
|
b'z': entry_structs.Dwarf_uleb128('length'),
|
|
b'L': entry_structs.Dwarf_uint8('LSDA_encoding'),
|
|
b'R': entry_structs.Dwarf_uint8('FDE_encoding'),
|
|
b'S': True,
|
|
b'P': Struct(
|
|
'personality',
|
|
entry_structs.Dwarf_uint8('encoding'),
|
|
Switch('function', lambda ctx: ctx.encoding & 0x0f, {
|
|
enc: fld_cons('function')
|
|
for enc, fld_cons
|
|
in self._eh_encoding_to_field(entry_structs).items()})),
|
|
}
|
|
|
|
# Build the Struct we will be using to parse the augmentation data.
|
|
# Stop as soon as we are not able to match the augmentation string.
|
|
fields = []
|
|
aug_dict = {}
|
|
|
|
for b in iterbytes(augmentation):
|
|
try:
|
|
fld = available_fields[b]
|
|
except KeyError:
|
|
break
|
|
|
|
if fld is True:
|
|
aug_dict[fld] = True
|
|
else:
|
|
fields.append(fld)
|
|
|
|
# Read the augmentation twice: once with the Struct, once for the raw
|
|
# bytes. Read the raw bytes last so we are sure we leave the stream
|
|
# pointing right after the augmentation: the Struct may be incomplete
|
|
# (missing trailing fields) due to an unknown char: see the KeyError
|
|
# above.
|
|
offset = self.stream.tell()
|
|
struct = Struct('Augmentation_Data', *fields)
|
|
aug_dict.update(struct_parse(struct, self.stream, offset))
|
|
self.stream.seek(offset)
|
|
aug_bytes = self._read_augmentation_data(entry_structs)
|
|
return (aug_bytes, aug_dict)
|
|
|
|
def _read_augmentation_data(self, entry_structs):
|
|
""" Read augmentation data.
|
|
|
|
This assumes that the augmentation string starts with 'z', i.e. that
|
|
augmentation data is prefixed by a length field, which is not returned.
|
|
"""
|
|
if not self.for_eh_frame:
|
|
return b''
|
|
|
|
augmentation_data_length = struct_parse(
|
|
Struct('Dummy_Augmentation_Data',
|
|
entry_structs.Dwarf_uleb128('length')),
|
|
self.stream)['length']
|
|
return self.stream.read(augmentation_data_length)
|
|
|
|
def _parse_fde_header(self, entry_structs, offset):
|
|
""" Compute a struct to parse the header of the current FDE.
|
|
"""
|
|
if not self.for_eh_frame:
|
|
return struct_parse(entry_structs.Dwarf_FDE_header, self.stream,
|
|
offset)
|
|
|
|
fields = [entry_structs.Dwarf_initial_length('length'),
|
|
entry_structs.Dwarf_offset('CIE_pointer')]
|
|
|
|
# Parse the couple of header fields that are always here so we can
|
|
# fetch the corresponding CIE.
|
|
minimal_header = struct_parse(Struct('eh_frame_minimal_header',
|
|
*fields), self.stream, offset)
|
|
cie = self._parse_cie_for_fde(offset, minimal_header, entry_structs)
|
|
initial_location_offset = self.stream.tell()
|
|
|
|
# Try to parse the initial location. We need the initial location in
|
|
# order to create a meaningful FDE, so assume it's there. Omission does
|
|
# not seem to happen in practice.
|
|
encoding = cie.augmentation_dict['FDE_encoding']
|
|
assert encoding != DW_EH_encoding_flags['DW_EH_PE_omit']
|
|
basic_encoding = encoding & 0x0f
|
|
encoding_modifier = encoding & 0xf0
|
|
|
|
# Depending on the specified encoding, complete the header Struct
|
|
formats = self._eh_encoding_to_field(entry_structs)
|
|
fields.append(formats[basic_encoding]('initial_location'))
|
|
fields.append(formats[basic_encoding]('address_range'))
|
|
|
|
result = struct_parse(Struct('Dwarf_FDE_header', *fields),
|
|
self.stream, offset)
|
|
|
|
if encoding_modifier == 0:
|
|
pass
|
|
|
|
elif encoding_modifier == DW_EH_encoding_flags['DW_EH_PE_pcrel']:
|
|
# Start address is relative to the address of the
|
|
# "initial_location" field.
|
|
result['initial_location'] += (
|
|
self.address + initial_location_offset)
|
|
else:
|
|
assert False, 'Unsupported encoding: {:#x}'.format(encoding)
|
|
|
|
return result
|
|
|
|
def _eh_encoding_to_field(self, entry_structs):
|
|
"""
|
|
Return a mapping from basic encodings (DW_EH_encoding_flags) the
|
|
corresponding field constructors (for instance
|
|
entry_structs.Dwarf_uint32).
|
|
"""
|
|
return {
|
|
DW_EH_encoding_flags['DW_EH_PE_absptr']:
|
|
entry_structs.Dwarf_uint32
|
|
if entry_structs.dwarf_format == 32 else
|
|
entry_structs.Dwarf_uint64,
|
|
DW_EH_encoding_flags['DW_EH_PE_uleb128']:
|
|
entry_structs.Dwarf_uleb128,
|
|
DW_EH_encoding_flags['DW_EH_PE_udata2']:
|
|
entry_structs.Dwarf_uint16,
|
|
DW_EH_encoding_flags['DW_EH_PE_udata4']:
|
|
entry_structs.Dwarf_uint32,
|
|
DW_EH_encoding_flags['DW_EH_PE_udata8']:
|
|
entry_structs.Dwarf_uint64,
|
|
|
|
DW_EH_encoding_flags['DW_EH_PE_sleb128']:
|
|
entry_structs.Dwarf_sleb128,
|
|
DW_EH_encoding_flags['DW_EH_PE_sdata2']:
|
|
entry_structs.Dwarf_int16,
|
|
DW_EH_encoding_flags['DW_EH_PE_sdata4']:
|
|
entry_structs.Dwarf_int32,
|
|
DW_EH_encoding_flags['DW_EH_PE_sdata8']:
|
|
entry_structs.Dwarf_int64,
|
|
}
|
|
|
|
|
|
def instruction_name(opcode):
|
|
""" Given an opcode, return the instruction name.
|
|
"""
|
|
primary = opcode & _PRIMARY_MASK
|
|
if primary == 0:
|
|
return _OPCODE_NAME_MAP[opcode]
|
|
else:
|
|
return _OPCODE_NAME_MAP[primary]
|
|
|
|
|
|
class CallFrameInstruction(object):
|
|
""" An instruction in the CFI section. opcode is the instruction
|
|
opcode, numeric - as it appears in the section. args is a list of
|
|
arguments (including arguments embedded in the low bits of some
|
|
instructions, when applicable), decoded from the stream.
|
|
"""
|
|
def __init__(self, opcode, args):
|
|
self.opcode = opcode
|
|
self.args = args
|
|
|
|
def __repr__(self):
|
|
return '%s (0x%x): %s' % (
|
|
instruction_name(self.opcode), self.opcode, self.args)
|
|
|
|
|
|
class CFIEntry(object):
|
|
""" A common base class for CFI entries.
|
|
Contains a header and a list of instructions (CallFrameInstruction).
|
|
offset: the offset of this entry from the beginning of the section
|
|
cie: for FDEs, a CIE pointer is required
|
|
augmentation_dict: Augmentation data as a parsed struct (dict): see
|
|
CallFrameInfo._parse_cie_augmentation and
|
|
http://www.airs.com/blog/archives/460.
|
|
augmentation_bytes: Augmentation data as a chain of bytes: see
|
|
CallFrameInfo._parse_cie_augmentation and
|
|
http://www.airs.com/blog/archives/460.
|
|
"""
|
|
def __init__(self, header, structs, instructions, offset,
|
|
augmentation_dict={}, augmentation_bytes=b'', cie=None):
|
|
self.header = header
|
|
self.structs = structs
|
|
self.instructions = instructions
|
|
self.offset = offset
|
|
self.cie = cie
|
|
self._decoded_table = None
|
|
self.augmentation_dict = augmentation_dict
|
|
self.augmentation_bytes = augmentation_bytes
|
|
|
|
def get_decoded(self):
|
|
""" Decode the CFI contained in this entry and return a
|
|
DecodedCallFrameTable object representing it. See the documentation
|
|
of that class to understand how to interpret the decoded table.
|
|
"""
|
|
if self._decoded_table is None:
|
|
self._decoded_table = self._decode_CFI_table()
|
|
return self._decoded_table
|
|
|
|
def __getitem__(self, name):
|
|
""" Implement dict-like access to header entries
|
|
"""
|
|
return self.header[name]
|
|
|
|
def _decode_CFI_table(self):
|
|
""" Decode the instructions contained in the given CFI entry and return
|
|
a DecodedCallFrameTable.
|
|
"""
|
|
if isinstance(self, CIE):
|
|
# For a CIE, initialize cur_line to an "empty" line
|
|
cie = self
|
|
cur_line = dict(pc=0, cfa=CFARule(reg=None, offset=0))
|
|
reg_order = []
|
|
else: # FDE
|
|
# For a FDE, we need to decode the attached CIE first, because its
|
|
# decoded table is needed. Its "initial instructions" describe a
|
|
# line that serves as the base (first) line in the FDE's table.
|
|
cie = self.cie
|
|
cie_decoded_table = cie.get_decoded()
|
|
if len(cie_decoded_table.table) > 0:
|
|
last_line_in_CIE = copy.copy(cie_decoded_table.table[-1])
|
|
cur_line = copy.copy(last_line_in_CIE)
|
|
else:
|
|
cur_line = dict(cfa=CFARule(reg=None, offset=0))
|
|
cur_line['pc'] = self['initial_location']
|
|
reg_order = copy.copy(cie_decoded_table.reg_order)
|
|
|
|
table = []
|
|
|
|
# Keeps a stack for the use of DW_CFA_{remember|restore}_state
|
|
# instructions.
|
|
line_stack = []
|
|
|
|
def _add_to_order(regnum):
|
|
if regnum not in cur_line:
|
|
reg_order.append(regnum)
|
|
|
|
for instr in self.instructions:
|
|
# Throughout this loop, cur_line is the current line. Some
|
|
# instructions add it to the table, but most instructions just
|
|
# update it without adding it to the table.
|
|
|
|
name = instruction_name(instr.opcode)
|
|
|
|
if name == 'DW_CFA_set_loc':
|
|
table.append(copy.copy(cur_line))
|
|
cur_line['pc'] = instr.args[0]
|
|
elif name in ( 'DW_CFA_advance_loc1', 'DW_CFA_advance_loc2',
|
|
'DW_CFA_advance_loc4', 'DW_CFA_advance_loc'):
|
|
table.append(copy.copy(cur_line))
|
|
cur_line['pc'] += instr.args[0] * cie['code_alignment_factor']
|
|
elif name == 'DW_CFA_def_cfa':
|
|
cur_line['cfa'] = CFARule(
|
|
reg=instr.args[0],
|
|
offset=instr.args[1])
|
|
elif name == 'DW_CFA_def_cfa_sf':
|
|
cur_line['cfa'] = CFARule(
|
|
reg=instr.args[0],
|
|
offset=instr.args[1] * cie['code_alignment_factor'])
|
|
elif name == 'DW_CFA_def_cfa_register':
|
|
cur_line['cfa'] = CFARule(
|
|
reg=instr.args[0],
|
|
offset=cur_line['cfa'].offset)
|
|
elif name == 'DW_CFA_def_cfa_offset':
|
|
cur_line['cfa'] = CFARule(
|
|
reg=cur_line['cfa'].reg,
|
|
offset=instr.args[0])
|
|
elif name == 'DW_CFA_def_cfa_expression':
|
|
cur_line['cfa'] = CFARule(expr=instr.args[0])
|
|
elif name == 'DW_CFA_undefined':
|
|
_add_to_order(instr.args[0])
|
|
cur_line[instr.args[0]] = RegisterRule(RegisterRule.UNDEFINED)
|
|
elif name == 'DW_CFA_same_value':
|
|
_add_to_order(instr.args[0])
|
|
cur_line[instr.args[0]] = RegisterRule(RegisterRule.SAME_VALUE)
|
|
elif name in ( 'DW_CFA_offset', 'DW_CFA_offset_extended',
|
|
'DW_CFA_offset_extended_sf'):
|
|
_add_to_order(instr.args[0])
|
|
cur_line[instr.args[0]] = RegisterRule(
|
|
RegisterRule.OFFSET,
|
|
instr.args[1] * cie['data_alignment_factor'])
|
|
elif name in ('DW_CFA_val_offset', 'DW_CFA_val_offset_sf'):
|
|
_add_to_order(instr.args[0])
|
|
cur_line[instr.args[0]] = RegisterRule(
|
|
RegisterRule.VAL_OFFSET,
|
|
instr.args[1] * cie['data_alignment_factor'])
|
|
elif name == 'DW_CFA_register':
|
|
_add_to_order(instr.args[0])
|
|
cur_line[instr.args[0]] = RegisterRule(
|
|
RegisterRule.REGISTER,
|
|
instr.args[1])
|
|
elif name == 'DW_CFA_expression':
|
|
_add_to_order(instr.args[0])
|
|
cur_line[instr.args[0]] = RegisterRule(
|
|
RegisterRule.EXPRESSION,
|
|
instr.args[1])
|
|
elif name == 'DW_CFA_val_expression':
|
|
_add_to_order(instr.args[0])
|
|
cur_line[instr.args[0]] = RegisterRule(
|
|
RegisterRule.VAL_EXPRESSION,
|
|
instr.args[1])
|
|
elif name in ('DW_CFA_restore', 'DW_CFA_restore_extended'):
|
|
_add_to_order(instr.args[0])
|
|
dwarf_assert(
|
|
isinstance(self, FDE),
|
|
'%s instruction must be in a FDE' % name)
|
|
if instr.args[0] in last_line_in_CIE:
|
|
cur_line[instr.args[0]] = last_line_in_CIE[instr.args[0]]
|
|
else:
|
|
cur_line.pop(instr.args[0], None)
|
|
elif name == 'DW_CFA_remember_state':
|
|
line_stack.append(copy.deepcopy(cur_line))
|
|
elif name == 'DW_CFA_restore_state':
|
|
pc = cur_line['pc']
|
|
cur_line = line_stack.pop()
|
|
cur_line['pc'] = pc
|
|
|
|
# The current line is appended to the table after all instructions
|
|
# have ended, if there were instructions.
|
|
if cur_line['cfa'].reg is not None or len(cur_line) > 2:
|
|
table.append(cur_line)
|
|
|
|
return DecodedCallFrameTable(table=table, reg_order=reg_order)
|
|
|
|
|
|
# A CIE and FDE have exactly the same functionality, except that a FDE has
|
|
# a pointer to its CIE. The functionality was wholly encapsulated in CFIEntry,
|
|
# so the CIE and FDE classes exists separately for identification (instead
|
|
# of having an explicit "entry_type" field in CFIEntry).
|
|
#
|
|
class CIE(CFIEntry):
|
|
pass
|
|
|
|
|
|
class FDE(CFIEntry):
|
|
pass
|
|
|
|
|
|
class ZERO(object):
|
|
""" End marker for the sequence of CIE/FDE.
|
|
|
|
This is specific to `.eh_frame` sections: this kind of entry does not exist
|
|
in pure DWARF. `readelf` displays these as "ZERO terminator", hence the
|
|
class name.
|
|
"""
|
|
def __init__(self, offset):
|
|
self.offset = offset
|
|
|
|
|
|
class RegisterRule(object):
|
|
""" Register rules are used to find registers in call frames. Each rule
|
|
consists of a type (enumeration following DWARFv3 section 6.4.1)
|
|
and an optional argument to augment the type.
|
|
"""
|
|
UNDEFINED = 'UNDEFINED'
|
|
SAME_VALUE = 'SAME_VALUE'
|
|
OFFSET = 'OFFSET'
|
|
VAL_OFFSET = 'VAL_OFFSET'
|
|
REGISTER = 'REGISTER'
|
|
EXPRESSION = 'EXPRESSION'
|
|
VAL_EXPRESSION = 'VAL_EXPRESSION'
|
|
ARCHITECTURAL = 'ARCHITECTURAL'
|
|
|
|
def __init__(self, type, arg=None):
|
|
self.type = type
|
|
self.arg = arg
|
|
|
|
def __repr__(self):
|
|
return 'RegisterRule(%s, %s)' % (self.type, self.arg)
|
|
|
|
|
|
class CFARule(object):
|
|
""" A CFA rule is used to compute the CFA for each location. It either
|
|
consists of a register+offset, or a DWARF expression.
|
|
"""
|
|
def __init__(self, reg=None, offset=None, expr=None):
|
|
self.reg = reg
|
|
self.offset = offset
|
|
self.expr = expr
|
|
|
|
def __repr__(self):
|
|
return 'CFARule(reg=%s, offset=%s, expr=%s)' % (
|
|
self.reg, self.offset, self.expr)
|
|
|
|
|
|
# Represents the decoded CFI for an entry, which is just a large table,
|
|
# according to DWARFv3 section 6.4.1
|
|
#
|
|
# DecodedCallFrameTable is a simple named tuple to group together the table
|
|
# and the register appearance order.
|
|
#
|
|
# table:
|
|
#
|
|
# A list of dicts that represent "lines" in the decoded table. Each line has
|
|
# some special dict entries: 'pc' for the location/program counter (LOC),
|
|
# and 'cfa' for the CFARule to locate the CFA on that line.
|
|
# The other entries are keyed by register numbers with RegisterRule values,
|
|
# and describe the rules for these registers.
|
|
#
|
|
# reg_order:
|
|
#
|
|
# A list of register numbers that are described in the table by the order of
|
|
# their appearance.
|
|
#
|
|
DecodedCallFrameTable = namedtuple(
|
|
'DecodedCallFrameTable', 'table reg_order')
|
|
|
|
|
|
#---------------- PRIVATE ----------------#
|
|
|
|
_PRIMARY_MASK = 0b11000000
|
|
_PRIMARY_ARG_MASK = 0b00111111
|
|
|
|
# This dictionary is filled by automatically scanning the constants module
|
|
# for DW_CFA_* instructions, and mapping their values to names. Since all
|
|
# names were imported from constants with `import *`, we look in globals()
|
|
_OPCODE_NAME_MAP = {}
|
|
for name in list(iterkeys(globals())):
|
|
if name.startswith('DW_CFA'):
|
|
_OPCODE_NAME_MAP[globals()[name]] = name
|
|
|