290 lines
10 KiB
Python
290 lines
10 KiB
Python
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# Support for DWARF v1.1 in a way that will be more or less compatible with pyelftools
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from io import BytesIO
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from collections import OrderedDict, namedtuple
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from bisect import bisect_left
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from elftools.dwarf.dwarfinfo import DwarfConfig, DebugSectionDescriptor
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from elftools.dwarf.die import AttributeValue
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from elftools.dwarf.structs import DWARFStructs
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from elftools.common.utils import struct_parse, bytelist2string
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from elftools.dwarf.enums import ENUM_DW_TAG, ENUM_DW_AT, ENUM_DW_FORM
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from elftools.construct import CString
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from elftools.dwarf.lineprogram import LineProgramEntry, LineState
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from elftools.dwarf.dwarf_expr import DWARFExprOp
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LineTableHeader = namedtuple('LineTableHeader', 'version file_entry')
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CUv1Header = namedtuple('CUv1Header', 'version unit_length debug_abbrev_offset address_size')
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TAG_reverse = dict((v, k) for k, v in ENUM_DW_TAG.items())
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ATTR_reverse = dict((v, k) for k, v in ENUM_DW_AT.items())
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FORM_reverse = dict((v, k) for k, v in ENUM_DW_FORM.items())
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DW_OP_name2opcode = dict(
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DW_OP_reg = 0x01,
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DW_OP_basereg = 0x02,
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DW_OP_addr = 0x03,
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DW_OP_const = 0x04,
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DW_OP_deref2 = 0x05,
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DW_OP_deref = 0x06,
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DW_OP_deref4 = 0x06,
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DW_OP_add = 0x07,
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DW_OP_user_0x80 = 0x80 #Extension op, not sure what's the deal with that
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)
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DW_OP_opcode2name = dict((v, k) for k, v in DW_OP_name2opcode.items())
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class DIEV1(object):
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def __init__(self, stm, cu, di):
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self.cu = cu
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self.dwarfinfo = di
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self.stream = stm
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self.offset = stm.tell()
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self.attributes = OrderedDict()
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self.tag = None
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self.has_children = None
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self.abbrev_code = None
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self.size = 0
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# Null DIE terminator. It can be used to obtain offset range occupied
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# by this DIE including its whole subtree.
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self._terminator = None
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self._parent = None
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structs = self.dwarfinfo.structs
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self.size = struct_parse(structs.Dwarf_uint32(''), stm)
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if self.size < 8:
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self.tag = 'DW_TAG_padding'
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self.has_children = False
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else:
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tag_code = struct_parse(structs.Dwarf_uint16(''), stm)
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if tag_code not in TAG_reverse:
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raise ValueError("%d not a known tag" % (tag_code))
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self.tag = TAG_reverse[tag_code]
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if self.tag == 'DW_TAG_null': # TAG_padding in DWARF1 spec
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# No attributes, just advance the stream
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stm.seek(self.size-6, 1)
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self.has_children = False
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else:
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while stm.tell() < self.offset + self.size:
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attr_offset = self.stream.tell()
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attr = struct_parse(structs.Dwarf_uint16(''), stm)
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form = FORM_reverse[attr & 0xf]
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attr >>= 4
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if attr in ATTR_reverse:
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name = ATTR_reverse[attr]
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elif 0x200 <= attr <= 0x3ff: #DW_AT_MIPS represented as 0x204???
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name = 'DW_AT_user_0x%x' % attr
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else:
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raise ValueError("%d not a known attribute" % (attr))
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raw_value = struct_parse(structs.Dwarf_dw_form[form], stm)
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value = raw_value
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self.attributes[name] = AttributeValue(
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name=name,
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form=form,
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value=value,
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raw_value=raw_value,
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offset=attr_offset)
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self.has_children = self.attributes['DW_AT_sibling'].value >= self.offset + self.size + 8
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def get_parent(self):
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return self._parent
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def is_null(self):
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return self.tag == 'DW_TAG_padding'
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def iter_children(self):
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return self.cu.iter_children(self)
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def sibling(self):
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return self.attributes['DW_AT_sibling'].value
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class CompileUnitV1(object):
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def __init__(self, di, top_die):
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self.dwarfinfo = di
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self.structs = di.structs
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self.header = CUv1Header(version = 1, unit_length = None, debug_abbrev_offset = None, address_size = 4)
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self._dielist = [top_die]
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self._diemap = [top_die.offset]
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def get_top_DIE(self):
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return self._dielist[0]
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def __getitem__(self, name):
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return self.header._asdict()[name]
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# Caches
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def DIE_at_offset(self, offset):
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i = bisect_left(self._diemap, offset)
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if i < len(self._diemap) and offset == self._diemap[i]:
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die = self._dielist[i]
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else:
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die = self.dwarfinfo.DIE_at_offset(offset, self)
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self._dielist.insert(i, die)
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self._diemap.insert(i, offset)
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return die
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# pyelftools' iter_DIEs sets parent on discovered DIEs, we should too
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def iter_DIEs(self):
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offset = self.cu_offset
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parent = None
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parent_stack = list()
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end_offset = self.get_top_DIE().attributes['DW_AT_sibling'].value
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while offset < end_offset:
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die = self.DIE_at_offset(offset)
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if die._parent is None:
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die._parent = parent
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if not die.is_null():
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yield die
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offset += die.size
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if offset != die.sibling(): # Start of a subtree
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parent_stack.append(parent)
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parent = die
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else: # padding - end of a sibling chain
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parent = parent_stack.pop()
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offset += die.size
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def iter_children(self, parent_die):
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offset = parent_die.offset + parent_die.size
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while offset < self.dwarfinfo.section_size:
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die = self.DIE_at_offset(offset)
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if die._parent is None:
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die._parent = parent_die
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if not die.is_null():
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yield die
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# Troubleshooting #1497
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tag = die.tag
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attr = die.attributes
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off = die.offset
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size = die.size
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has_children = die.has_children
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offset = die.sibling()
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else:
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break
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class LineTableV1(object):
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def __init__(self, stm, structs, len, pc):
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self.stm = stm
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self.structs = structs
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self.len = len
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self.pc = pc
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self._decoded_entries = None
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self.header = LineTableHeader(1, (None))
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def get_entries(self):
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if self._decoded_entries is None:
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stm = self.stm
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offset = stm.tell()
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end_offset = offset + self.len
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structs = self.structs
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entries = []
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pc = self.pc
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while offset < end_offset:
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line = struct_parse(structs.Dwarf_uint32(''), stm)
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col = struct_parse(structs.Dwarf_uint16(''), stm)
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pc_delta = struct_parse(structs.Dwarf_uint32(''), stm)
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if line == 0:
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break
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state = LineState(True)
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state.file = 0
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state.line = line
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state.column = col if col != 0xffff else None
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state.address = pc
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entries.append(LineProgramEntry(0, False, [], state))
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pc += pc_delta
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self._decoded_entries = entries
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return self._decoded_entries
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class DWARFExprParserV1(object):
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def __init__(self, structs):
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self.structs = structs
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def parse_expr(self, expr):
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stm = BytesIO(bytelist2string(expr))
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parsed = []
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while True:
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# Get the next opcode from the stream. If nothing is left in the
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# stream, we're done.
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byte = stm.read(1)
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if len(byte) == 0:
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break
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# Decode the opcode and its name.
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op = ord(byte)
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op_name = DW_OP_opcode2name.get(op, 'OP:0x%x' % op)
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if op <= 4 or op == 0x80:
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args = [struct_parse(self.structs.Dwarf_target_addr(''), stm),]
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else:
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args = []
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parsed.append(DWARFExprOp(op=op, op_name=op_name, args=args, offset=stm.tell()))
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return parsed
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class DWARFInfoV1(object):
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def __init__(self, elffile):
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section = elffile.get_section_by_name(".debug")
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section_data = section.data()
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self.section_size = len(section_data)
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self.stm = BytesIO()
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self.stm.write(section_data)
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self.stm.seek(0, 0)
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lsection = elffile.get_section_by_name(".line")
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if lsection:
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self.linestream = BytesIO()
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self.linestream.write(lsection.data())
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self.linestream.seek(0, 0)
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self.config = DwarfConfig(
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little_endian = elffile.little_endian,
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default_address_size = elffile.elfclass // 8,
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machine_arch = elffile.get_machine_arch()
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)
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self.structs = DWARFStructs(
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little_endian = self.config.little_endian,
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dwarf_format = 32,
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address_size = self.config.default_address_size)
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def iter_CUs(self):
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offset = 0
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while offset < self.section_size:
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die = self.DIE_at_offset(offset, None)
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if die.tag != 'DW_TAG_padding':
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if die.cu is None:
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die.cu = cu = CompileUnitV1(self, die)
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cu.cu_offset = offset
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yield die.cu
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offset = die.attributes['DW_AT_sibling'].value
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else:
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break
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# Does not cache
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def DIE_at_offset(self, offset, cu):
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self.stm.seek(offset, 0)
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return DIEV1(self.stm, cu, self)
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def location_lists(self):
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return None
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def line_program_for_CU(self, cu):
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top_DIE = cu.get_top_DIE()
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if 'DW_AT_stmt_list' in top_DIE.attributes:
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stm = self.linestream
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stm.seek(top_DIE.attributes['DW_AT_stmt_list'].value, 0)
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structs = self.structs
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len = struct_parse(structs.Dwarf_uint32(''), stm)
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pc = struct_parse(structs.Dwarf_target_addr(''), stm)
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return LineTableV1(stm, structs, len, pc)
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else:
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return None
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def parse_dwarf1(elffile):
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return DWARFInfoV1(elffile)
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