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Introduction

This tool statically (AOT) translates (or raises) binaries to LLVM IR.

Current Status

Llvm-mctoll is capable of raising X86-64 and Arm32 Linux/ELF libraries and executables to LLVM IR. Raising Windows, OS X and C++ binaries needs to be added. At this time X86-64 support is more mature than Arm32.

Development and testing are done on Ubuntu 18.04. Other platforms that are expected to work are Ubuntu 16.04, Ubuntu 17.04, Ubuntu 17.10, CentOS 7.5, Debian 10, Windows 10, and OS X.

Triple VarArgs FuncProto StackFrame JumpTables SharedLibs C++
x86_64-linux X X X X X
arm-linux X X X X X
  • VarArgs: function calls with variable arguments (such as printf)
  • FuncProto: function prototype discovery
  • StackFrame: stack frame abstraction
  • JumpTables: switch statements with jump tables
  • SharedLibs: shared libraries
  • C++: vtables, name mangling and exception handling

Known Issues

SIMD instructions such as SSE, AVX, and Neon cannot be raised at this time. For X86-64 you can sometimes work around this issue by compiling the binary to raise with SSE disabled (clang -mno-sse).

Most testing is done using binaries compiled for Linux using LLVM. We have done only limited testing with GCC compiled code.

Getting Started

There are no dependencies outside of LLVM to build llvm-mctoll. The following instructions assume you will build LLVM with Ninja.

Support for raising X86-64 and Arm32 binaries is enabled by building LLVM's X86 and ARM targets. The tool is not built unless one of the X86 or ARM LLVM targets are built.

Building as part of the LLVM tree

  1. On Linux and OS X build from a command prompt such as a bash shell. On Windows build from an x64 Native Tools Command Prompt. See LLVM's Visual Studio guide.

  2. Clone the LLVM and mctoll git repositories

git clone --depth 500 -b master https://github.com/llvm/llvm-project.git
cd llvm-project && git clone -b master https://github.com/microsoft/llvm-mctoll.git llvm/tools/llvm-mctoll
  1. The commit recorded in LLVMVersion.txt is the tested version of LLVM to build against. If you use a different version LLVM you might encounter build errors.
git checkout <hash from LLVMVersion.txt>
  1. Run cmake to create a ninja project then build the llvm-mctoll target. See LLVM CMake Variables for more information on LLVM's cmake options.
mkdir build && cd build
cmake -G "Ninja" -DLLVM_TARGETS_TO_BUILD="X86;ARM" -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_ENABLE_ASSERTIONS=true -DCMAKE_BUILD_TYPE=Release ../llvm
ninja llvm-mctoll
  1. Run the unit tests (Linux only)
ninja check-mctoll

Usage

Command Description
-d <binary> Generate LLVM IR for a binary and place the result in <binary>-dis.ll
--filter-functions-file=<file> Text file with C functions to exclude or include during raising
-print-after-all Print the LLVM IR after each pass of the raiser

Raising a binary to LLVM IR

This is what you came here for :-). Please file an issue if you find a problem.

llvm-mctoll -d a.out

Raising specific functions in a binary

You can specify the C functions to include or exclude during raising with the --filter-functions-file option.

llvm-mctoll -d --filter-functions-file=restrict.txt a.out

Provide a plain text file with exclude-functions and include-functions sections. Inside each section list the file and function prototype seperated by a colon. Use LLVM IR function types when defining the return and argument types for a function prototype. Here is a simple example.

; exclude `int bar(int)` defined in a.out
exclude-functions {
  a.out:i32 bar(i32)   
}

; include `int foo(void)` defined in a.out
include-functions {
  a.out:i32 foo(void)   
}

Debugging the raiser

If you build llvm-mctoll with assertions enabled you can print the LLVM IR after each pass of the raiser to assist with debugging.

llvm-mctoll -d -print-after-all a.out

Checking a translation is correct

The easiest way to check the raised LLVM IR <binary>-dis.ll is correct is to compile the IR to an executable using clang and run the resulting executable. The tests in the repository follow this methodology.

Acknowledgements

Please use the following reference when citing llvm-mctoll in your work:

  • Raising Binaries to LLVM IR with MCTOLL (WIP), S. Bharadwaj Yadavalli and Aaron Smith, LCTES 2019

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit https://cla.microsoft.com.

When you submit a pull request, a CLA-bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., label, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.