Skip to content

Instantly share code, notes, and snippets.

@analyticsearch
Forked from susMdT/Program.cs
Created March 3, 2023 01:04
Show Gist options
  • Save analyticsearch/d5d79f7c498ef7e303dd9a87a8f20856 to your computer and use it in GitHub Desktop.
Save analyticsearch/d5d79f7c498ef7e303dd9a87a8f20856 to your computer and use it in GitHub Desktop.
haha funny jit go brrrr
using System;
using System.Runtime.CompilerServices;
using System.Reflection;
using System.Reflection.Emit;
namespace FunkyJit
{
class Program
{
public static void Nothing() { Console.WriteLine(); }
static void Main(string[] args)
{
IntPtr pMem = GenerateRWXMemory(4096); // Doesn't divide cleanly so we get 4113 (17 extra bytes) of space
Console.WriteLine("Method Table: 0x{0:X}", (long)typeof(Program).TypeHandle.Value);
Console.WriteLine("JIT: 0x{0:X} ?", (long)pMem);
Console.ReadKey();
}
public static IntPtr GenerateRWXMemory(int ByteCount)
{
AssemblyName AssemblyName = new AssemblyName("Assembly");
AssemblyBuilder AssemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(AssemblyName, AssemblyBuilderAccess.Run);
ModuleBuilder ModuleBuilder = AssemblyBuilder.DefineDynamicModule("Module");
MethodBuilder MethodBuilder = ModuleBuilder.DefineGlobalMethod(
"MethodName",
MethodAttributes.Public | MethodAttributes.Static,
typeof(void), //arbitrary return type hehexd
new Type[] { }); // no args, but no real reason
ILGenerator il = MethodBuilder.GetILGenerator();
// sub rsp,28h (0x48, 0x83, 0xec, 0x28) [4]
// Every Emit.WriteLine results in 18 bytes
// mov rcx,1D3E2F736A8h (0xe8, 0x7a, 0x07, 0x45, 0x5e) [5]
// rcx,qword ptr [rcx] (0x48, 0x8b, 0x09) [3]
// call mscorlib_ni!System.Console.WriteLine (0x48, 0xb9, 0xa8, 0x36, 0xf7, 0xe2, 0x2d, 0x30, 0x10, 0x00) [10]
// Ends with
// ret (0xc3) [1]
while (ByteCount > 0)
{
il.EmitWriteLine("bruh");
ByteCount -= 18;
}
il.Emit(OpCodes.Ret); // JIT to 0xc3
ModuleBuilder.CreateGlobalFunctions();
RuntimeMethodHandle mh = ModuleBuilder.GetMethods()[0].MethodHandle;
RuntimeHelpers.PrepareMethod(mh);
return mh.GetFunctionPointer();
}
}
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment