[Example] Windows KDMP Emulation (#12)

Adds an example for emulation using `kdmp-parser`

Plus fixing an issue with building bochscpu with recent version,
reverting to bochs-emu/Bochs@c48a501
for now that is known to work

Author: hugsy

.github/build-bochscpu.bat

@@ -12,7 +12,7 @@ mkdir bxbuild
 cd bxbuild
 
 REM Use WSL to configure / clone the repositories.
-bash -c "git clone https://github.com/yrp604/bochscpu-build.git && git clone https://github.com/yrp604/bochscpu && git clone https://github.com/yrp604/bochscpu-ffi && cd bochscpu-build && bash prep.sh && cd Bochs/bochs && bash .conf.cpu-msvc"
+bash -c "git clone https://github.com/yrp604/bochscpu-build.git && git clone https://github.com/yrp604/bochscpu && git clone https://github.com/yrp604/bochscpu-ffi && cd bochscpu-build && BOCHS_REV=c48a50141b6ade6c6b0744280a598b55d906bb9e bash prep.sh && cd Bochs/bochs && bash .conf.cpu-msvc"
 
 REM Build bochs; libinstrument.a is expected to fail to build so don't freak out.
 REM You can run nmake all-clean to clean up the build.

.github/build-bochscpu.sh

@@ -16,11 +16,12 @@ git clone https://github.com/yrp604/bochscpu
 git clone https://github.com/yrp604/bochscpu-ffi
 
 cd bochscpu-build
+export BOCHS_REV=c48a50141b6ade6c6b0744280a598b55d906bb9e
 bash prep.sh && cd Bochs/bochs && sh .conf.cpu && make || true
 
 # Remove old files in bochscpu.
 rm -rf ../../../bochscpu/bochs
-rm -rf ../../../bochscpu/libs
+rm -rf ../../../bochscpu/lib
 
 # Create the libs directory where we stuff all the libs.
 mkdir ../../../bochscpu/lib

examples/long_mode_emulate_windows_kdump.py

@@ -0,0 +1,292 @@
+from typing import Optional
+
+import ctypes
+import logging
+import os
+import pathlib
+import sys
+
+import capstone
+import kdmp_parser
+
+import bochscpu
+import bochscpu.cpu
+import bochscpu.memory
+import bochscpu.utils
+
+
+kernel32 = ctypes.windll.kernel32
+kernel32.GetModuleHandleW.argtypes = [ctypes.c_wchar_p]
+kernel32.GetModuleHandleW.restype = ctypes.c_void_p
+kernel32.GetProcAddress.argtypes = [ctypes.c_void_p, ctypes.c_char_p]
+kernel32.GetProcAddress.restype = ctypes.c_void_p
+
+
+cs = capstone.Cs(capstone.CS_ARCH_X86, capstone.CS_MODE_64)
+
+emulation_end_address = 0
+
+hvas: list[int] = []
+dmp: Optional[kdmp_parser.KernelDumpParser] = None
+session: Optional[bochscpu.Session] = None
+
+
+def hexdump(
+    source: bytes, length: int = 0x10, separator: str = ".", base: int = 0x00
+) -> str:
+    result = []
+    align = 0x8 * 2 + 2
+
+    def chunk2hexstr(chunk: bytes):
+        return " ".join(map(lambda x: f"{x:02X}", chunk))
+
+    def chunk2ascii(chunk: bytes):
+        return "".join([chr(b) if 0x20 <= b < 0x7F else separator for b in chunk])
+
+    for i in range(0, len(source), length):
+        chunk = bytearray(source[i : i + length])
+        hexa = chunk2hexstr(chunk)
+        text = chunk2ascii(chunk)
+        result.append(f"{base + i:#0{align}x}   {hexa:<{3 * length}}    {text}")
+    return os.linesep.join(result)
+
+
+def missing_page_cb(pa):
+    global session, dmp, hvas
+    assert dmp and session
+
+    gpa = kdmp_parser.page.align(pa)
+    logging.debug(f"Missing GPA={gpa:#x}")
+
+    if gpa in dmp.pages:
+        # lazily handle missing page: first try to look into the dump, if found load it to mem
+        hva = bochscpu.memory.allocate_host_page()
+        page = dmp.read_physical_page(gpa)
+        if hva and page:
+            bochscpu.memory.page_insert(gpa, hva)
+            bochscpu.memory.phy_write(gpa, page)
+            logging.debug(f"{gpa=:#x} -> {hva=:#x}")
+            hvas.append(hva)
+            # we've successfully mapped it
+            return
+
+    # otherwise the page is really missing, bail
+    session.stop()
+    raise Exception
+
+
+def phy_access_cb(
+    sess: bochscpu.Session, cpu_id: int, lin: int, phy: int, len: int, rw: int
+):
+    logging.debug(f"{lin=:#x} -> {phy=:#x}, {len=:#x}, {bool(rw)=}")
+
+
+def exception_cb(
+    sess: bochscpu.Session,
+    cpu_id: int,
+    vector: int,
+    error_code: int,
+):
+    excpt = bochscpu.cpu.ExceptionType(vector)
+    match excpt:
+        case bochscpu.cpu.ExceptionType.BreakPoint:
+            logging.info("breakpoint hit")
+
+        case bochscpu.cpu.ExceptionType.PageFault:
+            logging.warning(
+                f"pagefault on VA={sess.cpu.cr2:#016x} at IP={sess.cpu.rip:#016x}"
+            )
+
+        case _:
+            logging.error(
+                f"cpu#{cpu_id} received exception({excpt=}, {error_code=:d}) "
+            )
+    sess.stop()
+
+
+def before_execution_cb(sess: bochscpu.Session, cpu_id: int, _: int):
+    state = sess.cpu.state
+    raw = bytes(bochscpu.memory.virt_read(state.cr3, state.rip, 16))
+    insn = next(cs.disasm(raw, state.rip))
+    logging.debug(
+        f"[CPU#{cpu_id}] PC={state.rip:#x} {insn.bytes.hex()} - {insn.mnemonic} {insn.op_str}"
+    )
+
+
+def after_execution_cb(sess: bochscpu.Session, cpu_id: int, _: int):
+    global emulation_end_address
+    if not emulation_end_address:
+        return
+
+    if emulation_end_address == sess.cpu.state.rip:
+        logging.info(
+            f"Reaching end address @ {emulation_end_address}, ending emulation"
+        )
+        sess.stop()
+
+
+def resolve_function(symbol: str) -> int:
+    dll, func = symbol.split("!", 1)
+    if not dll.lower().endswith(".dll"):
+        dll += ".dll"
+    logging.info(f"Looking up {func} in {dll}")
+    handle = kernel32.GetModuleHandleW(dll)
+    address: int = kernel32.GetProcAddress(handle, func.encode())
+    if not address:
+        raise RuntimeError(f"Failed to resolve {symbol}")
+    logging.info(f"Resolved '{symbol:s}' -> {address:#x}")
+    return address
+
+
+def emulate(dmp_path: pathlib.Path):
+    global session, dmp
+
+    assert session is None
+
+    logging.info(f"Parsing {dmp_path}")
+    dmp = kdmp_parser.KernelDumpParser(dmp_path)
+    assert dmp
+
+    logging.info(f"Successfully parsed {dmp_path}")
+
+    session = bochscpu.Session()
+    session.missing_page_handler = missing_page_cb
+
+    logging.debug("Preparing CPU state")
+    state = bochscpu.State()
+    bochscpu.cpu.set_long_mode(state)
+
+    logging.debug("Enabling MMX (SSE/AVX) instructions")
+    cr0 = bochscpu.utils.cpu.CR0(state.cr0)
+    cr4 = bochscpu.utils.cpu.CR4(state.cr4)
+    xcr0 = bochscpu.utils.cpu.XCR0(state.xcr0)
+    # See AMD Vol2 - 11.3
+    cr0.MP = True
+    cr0.EM = False
+    cr4.OSFXSR = True
+    cr4.OSXSAVE = True
+    # See AMD Vol2 - 11.5.2
+    xcr0.x87 = True
+    xcr0.SSE = True
+    xcr0.YMM = True
+
+    # TODO use bdump.js::regs.json instead
+    logging.debug(f"Setting {cr0=:}")
+    logging.debug(f"Setting {cr4=:}")
+    logging.debug(f"Setting {xcr0=:}")
+    state.cr0 = int(cr0)
+    state.cr4 = int(cr4)
+    state.xcr0 = int(xcr0)
+
+    cr3 = dmp._KernelDumpParser__dump.GetDirectoryTableBase()  # type: ignore #  HACK
+    logging.debug(f"Setting CR3={cr3:#x}")
+    state.cr3 = cr3
+
+    logging.debug(f"Setting the flag register")
+    state.rflags = dmp.context.ContextFlags
+
+    logging.debug(f"Setting the other GPRs")
+    for regname in (
+        "rax",
+        "rbx",
+        "rcx",
+        "rdx",
+        "rsi",
+        "rdi",
+        "rip",
+        "rsp",
+        "rbp",
+        "r8",
+        "r9",
+        "r10",
+        "r11",
+        "r12",
+        "r13",
+        "r14",
+        "r15",
+    ):
+        value = int(getattr(dmp.context, regname.capitalize()))
+        setattr(state, regname, value)
+
+    logging.debug(f"Setting the segment selectors")
+    _cs = bochscpu.Segment()
+    _cs.base = 0
+    _cs.limit = 0xFFFF_FFFF
+    _cs.selector = dmp.context.SegCs
+    _cs_attr = bochscpu.cpu.SegmentFlags()
+    _cs_attr.A = True
+    _cs_attr.R = True
+    _cs_attr.E = True
+    _cs_attr.S = True
+    _cs_attr.P = True
+    _cs_attr.L = True
+    _cs.attr = int(_cs_attr)
+    _ds = bochscpu.Segment()
+    _ds.base = 0
+    _ds.limit = 0xFFFF_FFFF
+    _ds.selector = dmp.context.SegDs
+    _ds.attr = 0xCF3
+    _es = bochscpu.Segment()
+    _es.base = 0
+    _es.limit = 0xFFFF_FFFF
+    _es.selector = dmp.context.SegEs
+    _es.attr = 0xCF3
+    _ss = bochscpu.Segment()
+    _ss.base = 0
+    _ss.limit = 0xFFFF_FFFF
+    _ss.selector = dmp.context.SegSs
+    _ss.attr = 0xCF3
+    _fs = bochscpu.Segment()
+    _fs.base = 0
+    _fs.limit = 0xFFFF_FFFF
+    _fs.selector = dmp.context.SegFs
+    _fs.present = True
+    _fs.attr = 0x4F3
+    _gs = bochscpu.Segment()
+    _gs.base = 0  # TODO: missing curprocess TEB
+    _gs.limit = 0xFFFF_FFFF
+    _gs.selector = dmp.context.SegGs
+    _gs.present = True
+    _gs.attr = 0xCF3
+
+    state.ss = _ss
+    state.cs = _cs
+    state.ds = _ds
+    state.es = _es
+    state.fs = _fs
+    state.gs = _gs
+
+    logging.debug(f"Apply the created state to the session CPU")
+    session.cpu.state = state
+
+    logging.debug("Preparing hooks")
+    hook = bochscpu.Hook()
+    hook.exception = exception_cb
+    hook.before_execution = before_execution_cb
+    hook.after_execution = after_execution_cb
+
+    logging.debug("Initial register state")
+    bochscpu.utils.dump_registers(session.cpu.state)
+
+    logging.debug("Let's go baby!")
+    session.run(
+        [
+            hook,
+        ]
+    )
+
+    session.stop()
+
+    logging.debug("Final register state")
+    bochscpu.utils.dump_registers(session.cpu.state)
+
+
+if __name__ == "__main__":
+    logging.basicConfig(format="%(levelname)s:%(message)s", level=logging.DEBUG)
+    arg = pathlib.Path(sys.argv[1]).resolve()
+    assert arg.exists()
+    emulate(arg)
+
+    logging.debug("Cleanup")
+    for hva in hvas:
+        bochscpu.memory.release_host_page(hva)