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ffcb9ccb19
Add support for evaluating a DWARF location description and translating it into a drgn object. In this commit, this is just used for global variables, but an upcoming commit will wire this up to stack traces for parameters and local variables. There are a few locations that drgn's object model can't represent yet. DW_OP_piece/DW_OP_bit_piece can describe objects that are only partially known or partially in memory; we approximate these where we can. We don't have a good way to support DW_OP_implicit_pointer at all yet. This also adds test cases for DWARF expressions, which we couldn't easily test before. Signed-off-by: Omar Sandoval <osandov@osandov.com>
63 lines
2.0 KiB
Python
63 lines
2.0 KiB
Python
# Copyright (c) Facebook, Inc. and its affiliates.
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# SPDX-License-Identifier: GPL-3.0-or-later
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from collections import namedtuple
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def _append_uleb128(buf, value):
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while True:
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byte = value & 0x7F
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value >>= 7
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if value:
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buf.append(byte | 0x80)
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else:
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buf.append(byte)
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break
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def _append_sleb128(buf, value):
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while True:
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byte = value & 0x7F
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value >>= 7
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if (not value and not (byte & 0x40)) or (value == -1 and (byte & 0x40)):
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buf.append(byte)
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break
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else:
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buf.append(byte | 0x80)
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U8 = namedtuple("U8", ["value"])
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U8._append = lambda self, buf, byteorder: buf.append(self.value)
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S8 = namedtuple("S8", ["value"])
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S8._append = lambda self, buf, byteorder: buf.append(self.value & 0xFF)
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U16 = namedtuple("U16", ["value"])
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U16._append = lambda self, buf, byteorder: buf.extend(self.value.to_bytes(2, byteorder))
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S16 = namedtuple("S16", ["value"])
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S16._append = lambda self, buf, byteorder: buf.extend(
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self.value.to_bytes(2, byteorder, signed=True)
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)
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U32 = namedtuple("U32", ["value"])
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U32._append = lambda self, buf, byteorder: buf.extend(self.value.to_bytes(4, byteorder))
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S32 = namedtuple("S32", ["value"])
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S32._append = lambda self, buf, byteorder: buf.extend(
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self.value.to_bytes(4, byteorder, signed=True)
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)
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U64 = namedtuple("U64", ["value"])
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U64._append = lambda self, buf, byteorder: buf.extend(self.value.to_bytes(8, byteorder))
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S64 = namedtuple("S64", ["value"])
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S64._append = lambda self, buf, byteorder: buf.extend(
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self.value.to_bytes(8, byteorder, signed=True)
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)
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ULEB128 = namedtuple("ULEB128", ["value"])
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ULEB128._append = lambda self, buf, byteorder: _append_uleb128(buf, self.value)
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SLEB128 = namedtuple("SLEB128", ["value"])
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SLEB128._append = lambda self, buf, byteorder: _append_sleb128(buf, self.value)
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def assemble(*args, little_endian=True):
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byteorder = "little" if little_endian else "big"
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buf = bytearray()
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for arg in args:
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arg._append(buf, byteorder)
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return buf
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