115 lines
3.6 KiB
Python
115 lines
3.6 KiB
Python
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import sys
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import idaapi
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import idc
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# -----------------------------------------------------------------------
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def accept_file(li, filename):
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# ignore any trailer; align on 64KB boundary
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size = li.size()
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if (size & 0xFFF) != 0:
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size &= ~0xFFFF
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if size < 16:
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return 0
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# check the code at F000:FFF0
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li.seek(size-16);
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jump = li.read(16)
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# skip any nops
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while jump[:1] == b'\x90':
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jump = jump[1:]
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# skip wbinvd
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if jump.startswith(b'\x0F\x09'):
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jump = jump[2:]
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_byte = ord if sys.version_info.major < 3 else lambda t: t
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# is it a jump?
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if (
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jump.startswith(b'\xEA') # jmp ptr16:16 EA oo oo ss ss
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and len(jump) >= 5
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and 0xF0 <= _byte(jump[4]) <= 0xFE # segment should be above F000
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) or (
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jump.startswith(b'\xE9') # jmp rel16 E9 ll hh
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and len(jump) >= 3
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# and (_byte(jump[2]) & 0x80) != 0 # jump backwards
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) or (
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jump.startswith(b'\xEB') # jmp rel8 EB dd
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and len(jump) >= 2
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and (_byte(jump[1]) & 0x80) != 0 # jump backwards
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):
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return {'format': "BIOS Image", 'processor':'metapc'} # accept the file
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return 0
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def myAddSeg(startea, endea, base, use32, name, clas):
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s = idaapi.segment_t()
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s.start_ea = startea
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s.end_ea = endea
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s.sel = idaapi.setup_selector(base)
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s.bitness = use32
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s.align = idaapi.saRelPara
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s.comb = idaapi.scPub
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idaapi.add_segm_ex(s, name, clas, idaapi.ADDSEG_NOSREG|idaapi.ADDSEG_OR_DIE)
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# -----------------------------------------------------------------------
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def load_file(li, neflags, format):
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chunksize = 0x10000
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base = 0xF000
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start = base << 4;
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size = li.size()
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if (size & 0xFFF) != 0:
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size &= ~0xFFFF
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offs = size - chunksize
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idaapi.set_processor_type("metapc", idaapi.SETPROC_LOADER)
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if size < chunksize:
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offs = 0
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start += (chunksize - size)
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chunksize = size
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# make E and F segments for real-mode part
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myAddSeg(start, start+chunksize, base, 0, "BIOS_F", "CODE")
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li.file2base(offs, start, start+chunksize, 1)
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if offs > 0 and base > 0xE000:
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base -= 0x1000
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start -= chunksize
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offs -= chunksize
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myAddSeg(start, start+chunksize, base, 0, "BIOS_%X" % (base>>12), "CODE")
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li.file2base(offs, start, start+chunksize, 1)
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# set default ds to point to the current segment
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idc.set_default_sreg_value(start, "ds", base)
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if offs > 0:
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# file is bigger than 128KB
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# make a flat 32-bit segment for the flash alias area
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start = (-size) & 0xFFFFFFFF # place it so that it ends at 4GB
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chunksize = size
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if not idc.__EA64__:
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chunksize -= 2 # truncate last two bytes to avoid address space overlap
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# map the whole file
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offs = 0
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base = 0
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myAddSeg(start, start+chunksize, base, 1, "BIOS_FLASH", "CODE")
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li.file2base(offs, start, start+chunksize, 1)
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# set the entry registers to F000:FFF0
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idc.set_inf_attr(idc.INF_START_IP, 0xFFF0)
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idc.set_inf_attr(idc.INF_START_CS, 0xF000)
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# turn off "Convert 32bit instruction operand to offset", too many false positives in high areas
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idc.set_inf_attr(idc.INF_AF, idc.get_inf_attr(idc.INF_AF) & ~idc.AF_IMMOFF)
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# turn off "Create function tails"
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idc.set_inf_attr(idc.INF_AF, idc.get_inf_attr(idc.INF_AF) & ~idc.AF_FTAIL)
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return 1
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# -----------------------------------------------------------------------
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def move_segm(frm, to, sz, fileformatname):
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idc.warning("move_segm(from=%s, to=%s, sz=%d, formatname=%s" % (hex(frm), hex(to), sz, fileformatname))
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return 0
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