建立 MAG160C 逆向工程交接仓库

2026-08-11 19:08:44 +08:00
commit 8409b27ba3
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+# -------------------------------------------------------------------------------
+# elftools: ehabi/ehabiinfo.py
+#
+# Decoder for ARM exception handler bytecode.
+#
+# LeadroyaL (leadroyal@qq.com)
+# This code is in the public domain
+# -------------------------------------------------------------------------------
+from __future__ import annotations
+
+from functools import cached_property
+from typing import TYPE_CHECKING
+
+from ..common.utils import struct_parse
+
+from .decoder import EHABIBytecodeDecoder
+from .constants import EHABI_INDEX_ENTRY_SIZE
+from .structs import EHABIStructs
+
+if TYPE_CHECKING:
+    from ..elf.sections import Section
+    from .decoder import MnemonicItem
+
+
+class EHABIInfo:
+    """ ARM exception handler abi information class.
+
+        Parameters:
+
+            arm_idx_section:
+                elf.sections.Section object, section which type is SHT_ARM_EXIDX.
+
+            little_endian:
+                bool, endianness of elf file.
+    """
+
+    def __init__(self, arm_idx_section: Section, little_endian: bool) -> None:
+        self._arm_idx_section = arm_idx_section
+        self._struct = EHABIStructs(little_endian)
+
+    def section_name(self) -> str:
+        return self._arm_idx_section.name
+
+    def section_offset(self) -> int:
+        return self._arm_idx_section['sh_offset']
+
+    def num_entry(self) -> int:
+        """ Number of exception handler entry in the section.
+        """
+        return self._num_entry
+
+    @cached_property
+    def _num_entry(self) -> int:
+        return self._arm_idx_section['sh_size'] // EHABI_INDEX_ENTRY_SIZE
+
+    def get_entry(self, n: int) -> EHABIEntry:
+        """ Get the exception handler entry at index #n. (EHABIEntry object or a subclass)
+        """
+        if n >= self.num_entry():
+            raise IndexError('Invalid entry %d/%d' % (n, self.num_entry()))
+        eh_index_entry_offset = self.section_offset() + n * EHABI_INDEX_ENTRY_SIZE
+        eh_index_data = struct_parse(self._struct.EH_index_struct, self._arm_idx_section.stream, eh_index_entry_offset)
+        word0, word1 = eh_index_data['word0'], eh_index_data['word1']
+
+        if word0 & 0x80000000 != 0:
+            return CorruptEHABIEntry('Corrupt ARM exception handler table entry: %x' % n)
+
+        function_offset = arm_expand_prel31(word0, self.section_offset() + n * EHABI_INDEX_ENTRY_SIZE)
+
+        if word1 == 1:
+            # 0x1 means cannot unwind
+            return CannotUnwindEHABIEntry(function_offset)
+        elif word1 & 0x80000000 == 0:
+            # highest bit is zero, point to .ARM.extab data
+            eh_table_offset = arm_expand_prel31(word1, self.section_offset() + n * EHABI_INDEX_ENTRY_SIZE + 4)
+            eh_index_data = struct_parse(self._struct.EH_table_struct, self._arm_idx_section.stream, eh_table_offset)
+            word0 = eh_index_data['word0']
+            if word0 & 0x80000000 == 0:
+                # highest bit is one, generic model
+                return GenericEHABIEntry(function_offset, arm_expand_prel31(word0, eh_table_offset))
+            else:
+                # highest bit is one, arm compact model
+                # highest half must be 0b1000 for compact model
+                if word0 & 0x70000000 != 0:
+                    return CorruptEHABIEntry('Corrupt ARM compact model table entry: %x' % n)
+                per_index = (word0 >> 24) & 0x7f
+                if per_index == 0:
+                    # arm compact model 0
+                    opcode = [(word0 & 0xFF0000) >> 16, (word0 & 0xFF00) >> 8, word0 & 0xFF]
+                    return EHABIEntry(function_offset, per_index, opcode)
+                elif per_index == 1 or per_index == 2:
+                    # arm compact model 1/2
+                    more_word = (word0 >> 16) & 0xff
+                    opcode = [(word0 >> 8) & 0xff, (word0 >> 0) & 0xff]
+                    self._arm_idx_section.stream.seek(eh_table_offset + 4)
+                    for i in range(more_word):
+                        r = struct_parse(self._struct.EH_table_struct, self._arm_idx_section.stream)['word0']
+                        opcode.append((r >> 24) & 0xFF)
+                        opcode.append((r >> 16) & 0xFF)
+                        opcode.append((r >> 8) & 0xFF)
+                        opcode.append((r >> 0) & 0xFF)
+                    return EHABIEntry(function_offset, per_index, opcode, eh_table_offset=eh_table_offset)
+                else:
+                    return CorruptEHABIEntry('Unknown ARM compact model %d at table entry: %x' % (per_index, n))
+        else:
+            # highest bit is one, compact model must be 0
+            if word1 & 0x7f000000 != 0:
+                return CorruptEHABIEntry('Corrupt ARM compact model table entry: %x' % n)
+            opcode = [(word1 & 0xFF0000) >> 16, (word1 & 0xFF00) >> 8, word1 & 0xFF]
+            return EHABIEntry(function_offset, 0, opcode)
+
+
+class EHABIEntry:
+    """ Exception handler abi entry.
+
+        Accessible attributes:
+
+            function_offset:
+                Integer.
+                None if corrupt. (Reference: CorruptEHABIEntry)
+
+            personality:
+                Integer.
+                None if corrupt or unwindable. (Reference: CorruptEHABIEntry, CannotUnwindEHABIEntry)
+                0/1/2 for ARM personality compact format.
+                Others for generic personality.
+
+            bytecode_array:
+                Integer array.
+                None if corrupt or unwindable or generic personality.
+                (Reference: CorruptEHABIEntry, CannotUnwindEHABIEntry, GenericEHABIEntry)
+
+            eh_table_offset:
+                Integer.
+                Only entries who point to .ARM.extab contains this field, otherwise return None.
+
+            unwindable:
+                bool. Whether this function is unwindable.
+
+            corrupt:
+                bool. Whether this entry is corrupt.
+
+    """
+
+    def __init__(
+        self,
+        function_offset: int | None,
+        personality: int | None,
+        bytecode_array: list[int] | None,
+        eh_table_offset: int | None = None,
+        unwindable: bool = True,
+        corrupt: bool = False,
+    ) -> None:
+        self.function_offset = function_offset
+        self.personality = personality
+        self.bytecode_array = bytecode_array
+        self.eh_table_offset = eh_table_offset
+        self.unwindable = unwindable
+        self.corrupt = corrupt
+
+    def mnmemonic_array(self) -> list[MnemonicItem] | None:
+        if self.bytecode_array:
+            return EHABIBytecodeDecoder(self.bytecode_array).mnemonic_array
+        else:
+            return None
+
+    def __repr__(self) -> str:
+        fo = self.function_offset
+        to = self.eh_table_offset
+        return (
+            "<EHABIEntry"
+            f" function_offset={'' if fo is None else '{fo:#x}'}"
+            f", personaality={self.personality}"
+            f"{', eh_table_offset={to:#x}' if to else ''}"
+            f", bytecode={self.bytecode_array}"
+            ">"
+        )
+
+
+class CorruptEHABIEntry(EHABIEntry):
+    """ This entry is corrupt. Attribute #corrupt will be True.
+    """
+
+    def __init__(self, reason: str) -> None:
+        super().__init__(function_offset=None, personality=None, bytecode_array=None,
+                                                corrupt=True)
+        self.reason = reason
+
+    def __repr__(self) -> str:
+        return "<CorruptEHABIEntry reason=%s>" % self.reason
+
+
+class CannotUnwindEHABIEntry(EHABIEntry):
+    """ This function cannot be unwind. Attribute #unwindable will be False.
+    """
+
+    if TYPE_CHECKING:
+        function_offset: int  # instead of `int|None` to save `is None` checks everywhere
+
+    def __init__(self, function_offset: int) -> None:
+        super().__init__(function_offset, personality=None, bytecode_array=None,
+                                                     unwindable=False)
+
+    def __repr__(self) -> str:
+        return "<CannotUnwindEHABIEntry function_offset=0x%x>" % self.function_offset
+
+
+class GenericEHABIEntry(EHABIEntry):
+    """ This entry is generic model rather than ARM compact model.Attribute #bytecode_array will be None.
+    """
+
+    if TYPE_CHECKING:
+        function_offset: int  # instead of `int|None` to save `is None` checks everywhere
+        personality: int
+
+    def __init__(self, function_offset: int, personality: int) -> None:
+        super().__init__(function_offset, personality, bytecode_array=None)
+
+    def __repr__(self) -> str:
+        return "<GenericEHABIEntry function_offset=0x%x, personality=0x%x>" % (self.function_offset, self.personality)
+
+
+def arm_expand_prel31(address: int, place: int) -> int:
+    """
+       address: uint32
+       place: uint32
+       return: uint64
+    """
+    location = address & 0x7fffffff
+    if location & 0x04000000:
+        location |= 0xffffffff80000000
+    return location + place & 0xffffffffffffffff