Making operand an offset in IDA Python

Question

I working with ARM executable. Sometimes I have something like this MOV instruction:

MOV R0, #0xCD548A40

where the number #0xCD548A40 is a valid offset but IDA doesn't recognize it as such automatically. I tried to reanalyze the executable with enabled option "Automatically convert data to offsets" without of any suitable result. I also tried to write IDAPython script to fix this, but the only possibility of conversion to offset that I found was:

idaapi.jumpto(address)
idaapi.process_ui_action("OpOffset", 0)

Which is not too much convenient to use.

Question

Given an instruction at specific address and one of its operands in a valid offset range is it possible to convert such numbers to offsets using IDA Python ?

Which IDAPython API should I use for it ?

Answer 1

I've been using the Ida OpOff function for that. That was idc, not idapython, but https://www.hex-rays.com/products/ida/support/idapython_docs/idc-module.html#OpOff says there's OpOff in idapython as well. In addition, there's another function, OpOffEx, that lets you specify more details. I think one of those is what you need.

Answer 2

I happen to just run into this exact issue.

Here's what I did. Replace the for bits with the if bits to just test it on a small bit.

from idautils import *
from idaapi import *
from idc import *

#if True:
#    if True:
#        if True:
#            startea = 0x0F9109DC
#            endea = 0x0F9109F
for segea in Segments():
    for funcea in Functions(segea, SegEnd(segea)):
        functionName = GetFunctionName(funcea)
        for (startea, endea) in Chunks(funcea):
            for ea in Heads(startea, endea):
                if idc.GetMnem(ea) != "MOV" or idc.get_operand_type(ea, 1) != 5 or  idc.get_str_type(idc.get_operand_value(ea, 1)) != 0:
                    continue
                print "0x%08x"%(ea), ":", idc.GetOpnd(ea, 1), idc.get_operand_type(ea, 1)
                idc.op_plain_offset(ea,1,0)

```