mirror of
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214 lines
7.2 KiB
Python
214 lines
7.2 KiB
Python
from typing import Optional
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import pytest
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from isledecomp.compare.asm.parse import DisasmLiteInst, ParseAsm
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def mock_inst(mnemonic: str, op_str: str) -> DisasmLiteInst:
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"""Mock up the named tuple DisasmLite from just a mnemonic and op_str.
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To be used for tests on sanitize that do not require the instruction address
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or size. i.e. any non-jump instruction."""
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return DisasmLiteInst(0, 0, mnemonic, op_str)
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identity_cases = [
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("", ""),
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("sti", ""),
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("push", "ebx"),
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("ret", ""),
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("ret", "4"),
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("mov", "eax, 0x1234"),
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]
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@pytest.mark.parametrize("mnemonic, op_str", identity_cases)
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def test_identity(mnemonic, op_str):
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"""Confirm that nothing is substituted."""
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p = ParseAsm()
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inst = mock_inst(mnemonic, op_str)
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result = p.sanitize(inst)
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assert result == (mnemonic, op_str)
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ptr_replace_cases = [
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("byte ptr [0x5555]", "byte ptr [<OFFSET1>]"),
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("word ptr [0x5555]", "word ptr [<OFFSET1>]"),
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("dword ptr [0x5555]", "dword ptr [<OFFSET1>]"),
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("qword ptr [0x5555]", "qword ptr [<OFFSET1>]"),
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("eax, dword ptr [0x5555]", "eax, dword ptr [<OFFSET1>]"),
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("dword ptr [0x5555], eax", "dword ptr [<OFFSET1>], eax"),
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("dword ptr [0x5555], 0", "dword ptr [<OFFSET1>], 0"),
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("dword ptr [0x5555], 8", "dword ptr [<OFFSET1>], 8"),
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# Same value, assumed to be an addr in the first appearance
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# because it is designated as 'ptr', but we have not provided the
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# relocation table lookup method so we do not replace the second appearance.
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("dword ptr [0x5555], 0x5555", "dword ptr [<OFFSET1>], 0x5555"),
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]
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@pytest.mark.parametrize("start, end", ptr_replace_cases)
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def test_ptr_replace(start, end):
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"""Anything in square brackets (with the 'ptr' prefix) will always be replaced."""
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p = ParseAsm()
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inst = mock_inst("", start)
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(_, op_str) = p.sanitize(inst)
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assert op_str == end
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call_replace_cases = [
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("ebx", "ebx"),
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("0x1234", "<OFFSET1>"),
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("dword ptr [0x1234]", "dword ptr [<OFFSET1>]"),
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("dword ptr [ecx + 0x10]", "dword ptr [ecx + 0x10]"),
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]
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@pytest.mark.parametrize("start, end", call_replace_cases)
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def test_call_replace(start, end):
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"""Call with hex operand is always replaced.
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Otherwise, ptr replacement rules apply, but skip `this` calls."""
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p = ParseAsm()
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inst = mock_inst("call", start)
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(_, op_str) = p.sanitize(inst)
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assert op_str == end
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def test_jump_displacement():
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"""Display jump displacement (offset from end of jump instruction)
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instead of destination address."""
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p = ParseAsm()
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inst = DisasmLiteInst(0x1000, 2, "je", "0x1000")
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(_, op_str) = p.sanitize(inst)
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assert op_str == "-0x2"
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@pytest.mark.xfail(reason="Not implemented yet")
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def test_jmp_table():
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"""Should detect the characteristic jump table instruction
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(for a switch statement) and use placeholder."""
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p = ParseAsm()
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inst = mock_inst("jmp", "dword ptr [eax*4 + 0x5555]")
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(_, op_str) = p.sanitize(inst)
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assert op_str == "dword ptr [eax*4 + <OFFSET1>]"
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name_replace_cases = [
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("byte ptr [0x5555]", "byte ptr [_substitute_]"),
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("word ptr [0x5555]", "word ptr [_substitute_]"),
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("dword ptr [0x5555]", "dword ptr [_substitute_]"),
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("qword ptr [0x5555]", "qword ptr [_substitute_]"),
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]
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@pytest.mark.parametrize("start, end", name_replace_cases)
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def test_name_replace(start, end):
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"""Make sure the name lookup function is called if present"""
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def substitute(_: int) -> str:
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return "_substitute_"
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p = ParseAsm(name_lookup=substitute)
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inst = mock_inst("mov", start)
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(_, op_str) = p.sanitize(inst)
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assert op_str == end
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def test_replacement_cache():
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p = ParseAsm()
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inst = mock_inst("inc", "dword ptr [0x1234]")
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(_, op_str) = p.sanitize(inst)
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assert op_str == "dword ptr [<OFFSET1>]"
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(_, op_str) = p.sanitize(inst)
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assert op_str == "dword ptr [<OFFSET1>]"
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def test_replacement_numbering():
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"""If we can use the name lookup for the first address but not the second,
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the second replacement should be <OFFSET2> not <OFFSET1>."""
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def substitute_1234(addr: int) -> Optional[str]:
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return "_substitute_" if addr == 0x1234 else None
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p = ParseAsm(name_lookup=substitute_1234)
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(_, op_str) = p.sanitize(mock_inst("inc", "dword ptr [0x1234]"))
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assert op_str == "dword ptr [_substitute_]"
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(_, op_str) = p.sanitize(mock_inst("inc", "dword ptr [0x5555]"))
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assert op_str == "dword ptr [<OFFSET2>]"
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def test_relocate_lookup():
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"""Immediate values would be relocated if they are actually addresses.
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So we can use the relocation table to check whether a given value is an
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address or just some number."""
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def relocate_lookup(addr: int) -> bool:
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return addr == 0x1234
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p = ParseAsm(relocate_lookup=relocate_lookup)
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(_, op_str) = p.sanitize(mock_inst("mov", "eax, 0x1234"))
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assert op_str == "eax, <OFFSET1>"
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(_, op_str) = p.sanitize(mock_inst("mov", "eax, 0x5555"))
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assert op_str == "eax, 0x5555"
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def test_jump_to_function():
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"""A jmp instruction can lead us directly to a function. This can be found
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in the unwind section at the end of a function. However: we do not want to
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assume this is the case for all jumps. Only replace the jump with a name
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if we can find it using our lookup."""
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def substitute_1234(addr: int) -> Optional[str]:
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return "_substitute_" if addr == 0x1234 else None
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p = ParseAsm(name_lookup=substitute_1234)
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inst = DisasmLiteInst(0x1000, 2, "jmp", "0x1234")
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(_, op_str) = p.sanitize(inst)
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assert op_str == "_substitute_"
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# Should not replace this jump.
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# 0x1000 (start addr)
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# + 2 (size of jump instruction)
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# + 0x5555 (displacement, the value we want)
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# = 0x6557
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inst = DisasmLiteInst(0x1000, 2, "jmp", "0x6557")
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(_, op_str) = p.sanitize(inst)
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assert op_str == "0x5555"
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def test_float_replacement():
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"""Floating point constants often appear as pointers to data.
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A good example is ViewROI::IntrinsicImportance and the subclass override
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LegoROI::IntrinsicImportance. Both return 0.5, but this is done via the
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FLD instruction and a dword value at 0x100dbdec. In this case it is more
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valuable to just read the constant value rather than use a placeholder.
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The float constants don't appear to be deduplicated (like strings are)
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because there is another 0.5 at 0x100d40b0."""
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def substitute_float(addr: int, _: int) -> str:
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return "zero-point-five" if addr == 0x1234 else None
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p = ParseAsm(float_lookup=substitute_float)
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inst = DisasmLiteInst(0x1000, 6, "fld", "dword ptr [0x1234]")
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(_, op_str) = p.sanitize(inst)
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assert op_str == "dword ptr [zero-point-five (FLOAT)]"
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def test_float_variable():
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"""If there is a variable at the address referenced by a float instruction,
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use the name instead of calling into the float replacement handler."""
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def name_lookup(addr: int) -> Optional[str]:
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return "g_myFloatVariable" if addr == 0x1234 else None
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def substitute_float(_: int, __: int) -> str:
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return ""
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p = ParseAsm(name_lookup=name_lookup, float_lookup=substitute_float)
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inst = DisasmLiteInst(0x1000, 6, "fld", "dword ptr [0x1234]")
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(_, op_str) = p.sanitize(inst)
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assert op_str == "dword ptr [g_myFloatVariable]"
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