RISC-V-ELF-Interpreter

Here is a simple implementation of RISC-V instructions interpreter with ELF files' parsing.

There are the following features of the project:

• Firstly ELF file is parsed and checked for correctness.
• The program in ELF file is loaded into virtual memory (paging memory), as it usually OS does.
• The interpreter supports all instructions from RV32I set, except ECALL, EBREAK and FENCE instructions.

How to compile

First of all make sure you have git, cmake, libelf on your device. Then do the following:

git clone https://github.com/Vokerlee/RISC-V-ELF-Interpreter.git
cd RISC-V-ELF-Interpreter
mkdir build
cd build
cmake ..
make

Now you have compiled program in build folder with name RISC-V-Interpreter.

How to use

The usage is plain: you are to create ELF file (with RISC-V architecture) and next launch RISC-V-Interpreter as follows:

./RISC-V-Interpreter elf_file_name.out

All information about executed instructions is placed in stdoutstream. It is recommended to redirect stream to another file, using the launch of the program in the following form:

./RISC-V-Interpreter elf_file_name.out > log_instructions.log

Mind that you cannot use any library while compiling your ELF program, otherwise the interpreter will not work (it doesn't support system calls).

How to create ELF file with RISC-V architecture

Normally compilers generate ELF files of x86/64 architecture. To change it you are to install another compiler: download and install https://github.com/riscv-collab/riscv-gnu-toolchain RISC-V GNU Compiler Toolchain (mind to disable RVC extension!).] with RV32 configuration.

Now you let's look at an example how to compile a simple program:

int mult(int a, int b);

int main()
{
    int a = 19;
    int b = 8;
    int c = mult(a, b);
    
    return 0;
}

int mult(int a, int b)
{
    int result = 0;

    while (b != 0)
    {
        if (b & 0x1 == 0x1)
        result += a;

        b >>= 1;
        a <<= 1;
    }

    return result;
}

riscv32-unknown-elf-gcc -S test_prog.c -o test_prog.s
riscv32-unknown-elf-as test_prog.s -o test_prog.o
riscv32-unknown-elf-ld test_prog.o -o test_prog.out

Also you can use objdump to check for correctness ELF file:

riscv32-unknown-elf-objdump -S test_prog.out > test_prog.dump

Different examples of compilation and usage of the program you can see in examples folder.