tools: Add support for data symbol checking for GOT entries

data/data_symbols.csv

@@ -1,3 +1,4 @@
+0x00000071023556B0,_ZTVN4sead14SafeStringBaseIcEE
 0x000000710246F9E0,_ZN4ksys3gdt6detail13sCommonFlags0E
 0x00000071024709E0,_ZN4ksys3gdt6detail13sCommonFlags1E
 0x00000071024719E0,_ZN4ksys3gdt6detail13sCommonFlags2E

tools/util/checker.py

@@ -1,5 +1,6 @@
+import struct
 from collections import defaultdict
-from typing import Set, DefaultDict, Dict, Optional
+from typing import Set, DefaultDict, Dict, Optional, Tuple
 
 import capstone as cs
 
@@ -18,6 +19,9 @@ class FunctionChecker:
         self._mismatch_addr1 = -1
         self._mismatch_addr2 = -1
         self._mismatch_cause = ""
+        self._base_got_section = elf.base_elf.get_section_by_name(".got")
+        self._decomp_glob_data_table = elf.build_glob_data_table(elf.my_elf)
+        self._got_data_symbol_check_cache: Dict[Tuple[int, int], bool] = dict()
 
         self.load_data_for_project()
 
@@ -113,7 +117,7 @@ class FunctionChecker:
 
                 gprs1[reg] += i1.operands[1].value.mem.disp
                 gprs2[reg] += i2.operands[1].value.mem.disp
-                if not self._check_data_symbol(i1, i2, gprs1[reg], gprs2[reg]):
+                if not self._check_data_symbol_load(i1, i2, gprs1[reg], gprs2[reg]):
                     return False
 
                 adrp_pair_registers.remove(reg)
@@ -130,9 +134,9 @@ class FunctionChecker:
                 if reg not in adrp_pair_registers:
                     return False
 
-                gprs1[reg] += i1.operands[1].value.mem.disp
-                gprs2[reg] += i2.operands[1].value.mem.disp
-                if not self._check_data_symbol(i1, i2, gprs1[reg], gprs2[reg]):
+                gprs1[reg] += i1.operands[2].value.mem.disp
+                gprs2[reg] += i2.operands[2].value.mem.disp
+                if not self._check_data_symbol_load(i1, i2, gprs1[reg], gprs2[reg]):
                     return False
 
                 adrp_pair_registers.remove(reg)
@@ -174,10 +178,30 @@ class FunctionChecker:
             return True
 
         if self._log_mismatch_cause:
-            self._set_mismatch_cause(i1, i2, f"data symbol mismatch: {symbol.name} (original address: {orig_addr:#x})")
+            self._set_mismatch_cause(i1, i2, f"data symbol mismatch: {symbol.name} (original address: {orig_addr:#x}, "
+                                             f"expected: {decomp_symbol.addr:#x}, "
+                                             f"actual: {decomp_addr:#x})")
 
         return False
 
+    def _check_data_symbol_load(self, i1, i2, orig_addr: int, decomp_addr: int) -> bool:
+        cached_result = self._got_data_symbol_check_cache.get((orig_addr, decomp_addr), None)
+        if cached_result is not None:
+            return cached_result
+
+        if not elf.is_in_section(self._base_got_section, orig_addr, 8):
+            return True
+
+        ptr1, = struct.unpack("<Q", elf.read_from_elf(elf.base_elf, orig_addr, 8))
+        if self.dsymtab.get_symbol(ptr1) is None:
+            return True
+
+        ptr2 = self._decomp_glob_data_table[decomp_addr]
+
+        result = self._check_data_symbol(i1, i2, ptr1, ptr2)
+        self._got_data_symbol_check_cache[(orig_addr, decomp_addr)] = result
+        return result
+
     def _check_function_call(self, i1, i2, orig_addr: int, decomp_addr: int) -> bool:
         name = self.decompiled_fns.get(orig_addr, None)
         if name is None:

tools/util/elf.py

@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
-
-from typing import Any, Dict, NamedTuple
 import io
+from typing import Any, Dict, NamedTuple
 
 from elftools.elf.elffile import ELFFile
+from elftools.elf.relocation import RelocationSection
+from elftools.elf.sections import Section
 
 import diff_settings
 from util import utils
@@ -40,7 +40,13 @@ def get_file_offset(elf, addr: int) -> int:
             continue
         if seg["p_vaddr"] <= addr < seg["p_vaddr"] + seg["p_filesz"]:
             return addr - seg["p_vaddr"] + seg["p_offset"]
-    assert False
+    raise KeyError(f"No segment found for {addr:#x}")
+
+
+def is_in_section(section: Section, addr: int, size: int) -> bool:
+    begin = section["sh_addr"]
+    end = begin + section["sh_size"]
+    return begin <= addr < end and begin <= addr + size < end
 
 
 def get_symbol(table, name: str) -> Symbol:
@@ -69,14 +75,34 @@ def build_name_to_symbol_table(symtab) -> Dict[str, Symbol]:
     return {sym.name: Symbol(sym["st_value"], sym.name, sym["st_size"]) for sym in symtab.iter_symbols()}
 
 
+def read_from_elf(elf: ELFFile, addr: int, size: int) -> bytes:
+    offset: int = get_file_offset(elf, addr)
+    elf.stream.seek(offset)
+    return elf.stream.read(size)
+
+
 def get_fn_from_base_elf(addr: int, size: int) -> Function:
-    offset = get_file_offset(base_elf, addr)
-    base_elf.stream.seek(offset)
-    return Function(base_elf.stream.read(size), addr)
+    return Function(read_from_elf(base_elf, addr, size), addr)
 
 
 def get_fn_from_my_elf(name: str) -> Function:
     sym = get_symbol(my_symtab, name)
-    offset = get_file_offset(my_elf, sym.addr)
-    my_elf.stream.seek(offset)
-    return Function(my_elf.stream.read(sym.size), sym.addr)
+    return Function(read_from_elf(my_elf, sym.addr, sym.size), sym.addr)
+
+
+R_AARCH64_GLOB_DAT = 1025
+
+
+def build_glob_data_table(elf: ELFFile) -> Dict[int, int]:
+    table: Dict[int, int] = dict()
+    section = elf.get_section_by_name(".rela.dyn")
+    assert isinstance(section, RelocationSection)
+
+    symtab = elf.get_section(section["sh_link"])
+
+    for reloc in section.iter_relocations():
+        sym_value = symtab.get_symbol(reloc["r_info_sym"])["st_value"]
+        if reloc["r_info_type"] == R_AARCH64_GLOB_DAT:
+            table[reloc["r_offset"]] = sym_value + reloc["r_addend"]
+
+    return table