Import bios_extract fork source

bios_extract/microcode_extract.py

@@ -0,0 +1,126 @@
+#!/usr/bin/env python2
+# extract microcode updates from binary BIOS files
+# v 0.1 2012/07/23
+# v 0.2 2012/07/23 added VIA Nano support (relaxed some checks)
+# Licensed as Public Domain
+
+import ctypes
+import struct
+import sys
+import array
+
+uint8_t  = ctypes.c_ubyte
+char     = ctypes.c_char
+uint32_t = ctypes.c_uint
+uint64_t = ctypes.c_uint64
+uint16_t = ctypes.c_ushort
+
+def get_struct(str_, off, struct):
+    s = struct()
+    slen = ctypes.sizeof(s)
+    bytes = str_[off:off+slen]
+    fit = min(len(bytes), slen)
+    ctypes.memmove(ctypes.addressof(s), bytes, fit)
+    return s
+
+def DwordAt(f, off):
+    return struct.unpack("<I", f[off:off+4])[0]
+
+# Intel microcode update header
+class IntelUcUpdateHeader(ctypes.LittleEndianStructure):
+    _fields_ = [
+        ("HeaderVersion",       uint32_t), #
+        ("UpdateRevision",      uint32_t), #
+        ("Date",                uint32_t), #
+        ("ProcessorSignature",  uint32_t), #
+        ("Checksum",            uint32_t), #
+        ("LoaderRevision",      uint32_t), #
+        ("ProcessorFlags",      uint32_t), #
+        ("DataSize",            uint32_t), #
+        ("TotalSize",           uint32_t), #
+    ]
+
+def check_valid_mcode(f, off, maxoff, is_via = False):
+    hdr = get_struct(f, off, IntelUcUpdateHeader)
+    # on Intel, Total Size is always a multiple of 1024.
+    if not is_via and hdr.TotalSize & 0x3FF:
+        return
+
+    # For microcode updates with a data size field
+    # equal to 00000000H, the size of the microcode
+    # update is 2048 bytes.
+    if hdr.DataSize == 0:
+        check_len = 2048
+    else:
+        check_len = hdr.TotalSize
+        if check_len < 2048:
+            return False
+
+    # it should not run off the end of file or another update
+    if check_len + off > maxoff:
+        return
+
+    # update size must be a multiple of DWORD
+    if (hdr.DataSize & 3) or (hdr.TotalSize & 3):
+        return
+
+    # looks okay. let's check the checksum
+
+    mdata = f[off:off+check_len]
+    # make an array of DWORDs
+    arr = array.array("I", mdata)
+    # sum them
+    ck = sum(arr) & 0xFFFFFFFF
+    if ck == 0:
+        print "%08X: found a valid-looking update" % off
+        print ["Date: %02X/%02X/%4X", "Date: %02d/%02d/%4d"][is_via] % ((hdr.Date >> 24)&0xFF, (hdr.Date >> 16)&0xFF, hdr.Date & 0xFFFF)
+        print "Processor signature: %08X" % hdr.ProcessorSignature
+        if not is_via:
+            print "Processor flags:     %08X" % hdr.ProcessorFlags
+        print "Length:              %08X" % check_len
+        fname = "mcode_upd_%08X.bin" % off
+        print "Extracting to %s" % fname
+        open(fname, "wb").write(mdata)
+        return True
+    # nope
+    return False
+
+def find_ucode(f, is_via):
+    maxoff = len(f)
+    # minimal microcode update length is 2048 bytes
+    off = (maxoff-2048+8)&(~15)
+    # look for BCD date ddmmyyyy
+    # yyyy off-2
+    # dd   off-1
+    # mm   off
+    print "Scanning...\n%08X" % off
+    while off > 11:
+        # looks like a date?
+        m = ord(f[off])
+        if (1 <= m <= 0x12) and (1 <= ord(f[off-1]) <= 0x31):
+            if check_valid_mcode(f, off-11, maxoff, is_via):
+                maxoff = off-11
+                print "Scanning...\n%08X" % off
+        off -= 1
+        if (off & 0xFFFFF) == 0:
+            print "%08X" % off
+    print "\nDone"
+
+if len(sys.argv) < 2:
+    print "Usage: microcode_extract.py <file.rom> [-i|-v]"
+    print "  -i: look for Intel microcode (default)"
+    print "  -v: look for VIA Nano microcode"
+    sys.exit(1)
+else:
+    fn = None
+    is_via = False
+    for arg in sys.argv[1:]:
+        if arg == "-v":
+            is_via = True
+        elif arg == "-i":
+            is_via = False
+        else:
+            fn = arg
+
+    f = open(fn, "rb").read()
+    find_ucode(f, is_via)