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Python Ida Pro Hexag00n by programa-stic

Discussion in 'Plugins' started by storm shadow, Jul 8, 2016.

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  1. storm shadow

    Techbliss Owner Admin Ida Pro Expert Developer

    The plugin is a part of a collection of reverse engineering tools for the Qualcomm Digital Signal Proccesor (QDSP6)


    IDA Hexagon Processor Module

    IDA processor module for the Hexagon Qualcomm Hexagon architecture (v5) written in Python. It depends on the Qualcomm Hexagon Disassembler .
    The most reliable Hexagon processor module so far is from Willem Hengeveld (itsme@gsmk.de), written in C++ as a wrapper for Qualcomm's own objdump port for Hexagon. Another recently available processor module, also in C++, is nogaxeh.
    As this module is written in Python, it aims at platform independence, but as we only have a Windows license for IDA, this is the only platform where the module was tested.
    NOTE: There is a bug for Python 2.7.11 in IDA for Windows (when opening IDA: IDAPython: imporing "site" failed), Hex-Rays posted a fix in their blog.
    mce-anchor
    How to use it

    Install the Qualcomm Hexagon Disassembler.
    Copy hexagon.py to IDA's processor module directory, e.g., C:\Program Files (x86)\IDA 6.9\procs\ (administrator access required).
    In IDA's "Load a new file" window, under "Processor type", select Qualcomm Hexagon DSP v5[QDSP6V5]. When loading a binary for the first time IDA will complain with "Undefined or unknown machine type 164" (this can be avoided with theloader_elf_machine plugin), select "Yes", and ignore IDA's warning about unknown flag bits.
    The module (quite verbose) logging is turned off by default but setting the environment variable IDP_LOGGING will turn it on.
    By default the module outputs text highlighting the instruction operands, this can be disabled setting the environment variableIDP_OUT_SIMPLE_SYNTAX. Disabling text highlighting is recommended for programmatic processing of the module's output.
    Environment variables can be set through the OS or using IDA python console:

    Code (Text):
    import os; os.environ["IDP_LOGGING"] = "True"
    mce-anchor
    Notes on developing the module

    There are not many IDA processor modules written in Python, proctemplate.py was used as a base, and msp430.py served as an additional reference.
    The The IDA Pro Book was the main reference along with the IDA SDK online doc.
    For an easy modification of the IDA processor module file, a link can be created to the repo file, to avoid continually copying it, e.g., in Windows:
    mklink "C:\Program Files (x86)\IDA 6.9\procs\hexagon.py" "C:\Users\test\hexag00n\ida\hexagon.py"
    To make IDA take notice of the modifications in the module file the only way found was to restart IDA, so, as a convenience, IDA was started (and restarted) from the command line:

    C:\Program Files (x86)\IDA 6.9\idaq.exe -c example.elf

    With -c used to "disassemble a new file (delete the old database)".
    It is not clear which information populated by the processor module is used outside it. The cmd structure is handled apparently only in the cycle ana/emu/out. There is also not a clear warning for not doing everything in one of the three functions.
    The distinction between near and far doesn't apply in the Hexagon architecture, thus, according to the IDA documentation, everything should be referenced as near (e.g., jumps and calls).
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    Profiler

    Profiling is done in the main functions ana/emu/out and saved in the hexagondisasm module, to make it accessible from IDA's Python console (there should be a better way to do this):

    Code (Text):
    import hexagondisasm
    import pstats
    prof_stats = pstats.Stats(hexagondisasm.profiler)
    prof_stats.strip_dirs().sort_stats('cumulative').print_stats(20)
    mce-anchor
    Various notes

    In the IDA SDK terminology, a word is 2 bytes, whereas in Hexagon terminology it is 4 bytes, thus ua_next_long is used in the module (not ua_next_word).
    Nice and short explanation about IDA's algorithm to walk a binary:
    Useful Python regex tester: https://regex101.com/.
    mce-anchor
    TODOs

    • Identify fatal functions that do not return and mark them accordingly as instructions of type CF_STOP.
    • Identify indirect call functions: immext + jump instruction.
     

    Attached Files:

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