6 ms·

Implementing a New CPU Architecture for Ghidra [slides]

75 points by guedou 7y ago

mappu 7y ago
This builds upon your previous https://news.ycombinator.com/item?id=17725189 https://news.ycombinator.com/item?id=17725189 ? I tried to read more about MeP architecture but there is very little "conventional" info about it - GCC 3.4 port abandoned http://people.redhat.com/dj/mep/ http://people.redhat.com/dj/mep/ , what compiler is commonly used? - Wikipedia page https://en.wikipedia.org/wiki/Media-embedded_processor https://en.wikipedia.org/wiki/Media-embedded_processor , well, compare it to RISC-V that contains assembly and microarchitecture details
- guedou 7y ago
  Yes,the idea is to use the Ghidra decompiler to ease reversing new parts of the FlashAir firmware. The MeP-c4 datasheet is available at https://www.datasheetarchive.com/pdf/download.php?id=6693e804e3df834cc0ce6f53df8c5cf03850f3&type=P&term=MeP%2520c-4 https://www.datasheetarchive.com/pdf/download.php?id=6693e80... I had success compiling GCC with MeP support using git and the commit before the removal. Yet, I believe that FlashAir are not compiled with gcc.
saagarjha 7y ago
As far as I'm aware, there's really no way to add support to IDA Pro's decompiler for custom architectures, so I'm really glad that Ghidra has the tools to do this!
- dmitrygr 7y ago
  That is false. I wrote an IDA plugin to support the VMU CPU. It is actually quite well documented in the IDA SDK. http://dmitry.gr/?r=05.Projects&proj=25.%20VMU%20Hacking http://dmitry.gr/?r=05.Projects&proj=25.%20VMU%20Hacking
  - arthurcolle 7y ago
    Impressive work! How hard was porting over Flappy Bird over to the VMU? Did you just hand-design the graphics?
    - dmitrygr 7y ago
      I wrote it in c. Source is on the site :)
      - arthurcolle 7y ago
        Unfortunately I can't run it locally. Do you have an alternative version for local dev? Ideally for macOS? I'd love to play around with it!
        dmitrygr 7y ago
        compile the source for SDL? or, i also published a VMU emulator (in source) which will build on macos. you can run the cortex-m23 emulator i wrote in it, and then the game in that
        arthurcolle 7y ago
        Awesome I'll give that a shot
  - souprock 7y ago
    I don't see any evidence there that you got the decompiler working, which would be quite a feat. The disassembler, and even graph view, is part of the IDA SDK as you mentioned.

75 points by guedou 7y ago

This builds upon your previous https://news.ycombinator.com/item?id=17725189 https://news.ycombinator.com/item?id=17725189 ? I tried to read more about MeP architecture but there is very little "conventional" info about it - GCC 3.4 port abandoned http://people.redhat.com/dj/mep/ http://people.redhat.com/dj/mep/ , what compiler is commonly used? - Wikipedia page https://en.wikipedia.org/wiki/Media-embedded_processor https://en.wikipedia.org/wiki/Media-embedded_processor , well, compare it to RISC-V that contains assembly and microarchitecture details

guedou 7y ago
Yes,the idea is to use the Ghidra decompiler to ease reversing new parts of the FlashAir firmware. The MeP-c4 datasheet is available at https://www.datasheetarchive.com/pdf/download.php?id=6693e804e3df834cc0ce6f53df8c5cf03850f3&type=P&term=MeP%2520c-4 https://www.datasheetarchive.com/pdf/download.php?id=6693e80... I had success compiling GCC with MeP support using git and the commit before the removal. Yet, I believe that FlashAir are not compiled with gcc.

saagarjha 7y ago

As far as I'm aware, there's really no way to add support to IDA Pro's decompiler for custom architectures, so I'm really glad that Ghidra has the tools to do this!

dmitrygr 7y ago
That is false. I wrote an IDA plugin to support the VMU CPU. It is actually quite well documented in the IDA SDK. http://dmitry.gr/?r=05.Projects&proj=25.%20VMU%20Hacking http://dmitry.gr/?r=05.Projects&proj=25.%20VMU%20Hacking
- arthurcolle 7y ago
  Impressive work! How hard was porting over Flappy Bird over to the VMU? Did you just hand-design the graphics?
  - dmitrygr 7y ago
    I wrote it in c. Source is on the site :)
    - arthurcolle 7y ago
      Unfortunately I can't run it locally. Do you have an alternative version for local dev? Ideally for macOS? I'd love to play around with it!
      - dmitrygr 7y ago
        compile the source for SDL? or, i also published a VMU emulator (in source) which will build on macos. you can run the cortex-m23 emulator i wrote in it, and then the game in that
        arthurcolle 7y ago
        Awesome I'll give that a shot
- souprock 7y ago
  I don't see any evidence there that you got the decompiler working, which would be quite a feat. The disassembler, and even graph view, is part of the IDA SDK as you mentioned.