Machine code

The task requires poking machine code directly into memory and executing it.

This is strictly for x86 (32 bit) architectures.

The machine code is the opcodes of the following simple program:

which translates into the following opcodes: (139 68 36 4 3 68 36 8 195) and in Hex this would correspond to the following: ("8B" "44" "24" "4" "3" "44" "24" "8" "C3")

Task

Implement the following in your favorite programming language (take the common lisp code as an example if you wish):

Poke the above opcodes into a memory pointer
Execute it with the following arguments: [ESP+4] => unsigned-byte argument of value 7; [ESP+8] => unsigned-byte argument of value 12; The result would be 19.
Free the Pointer

BBC BASIC

Works with: BBC BASIC for Windows

Note that BBC BASIC for Windows includes an 80386/80486 assembler as standard!

<lang bbcbasic> REM Claim 9 bytes of memory

     SYS "GlobalAlloc",0,9 TO code%

     REM Poke machine code into it
     P%=code%
     [OPT 0
     mov EAX, [ESP+4]
     add EAX, [ESP+8]
     ret
     ]

     REM Run code
     SYS code%,7,12 TO result%
     PRINT result%

     REM Free memory
     SYS "GlobalFree",code%
     END</lang>

COBOL

This solution is a 64-bit adaptation of the task, using the macOS ABI and 64-bit instructions. The assembly code in question is:

<lang Assembler>pushq %rbp movq %rsp, %rbp movl %edi, -0x4(%rbp) movl %esi, -0x8(%rbp) movl -0x4(%rbp), %esi addl -0x8(%rbp), %esi movl %esi, -0xc(%rbp) movl -0xc(%rbp), %eax popq %rbp retq </lang> The 64-bit "wrapper code" used by the PicoLisp and Go implementations have the parameters 7 and 12 baked into it, so I opted for a pure 64-bit implementation rather than manipulating the 64-bit stack to support the 32-bit instructions. <lang COBOL> >>SOURCE FORMAT IS FIXED

      IDENTIFICATION DIVISION.
      PROGRAM-ID. MC.
      DATA DIVISION.
      WORKING-STORAGE SECTION.
          01 INSTRUCTIONS.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'55'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'48'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'89'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'E5'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'89'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'7D'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'FC'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'89'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'75'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'F8'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'8B'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'75'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'FC'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'03'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'75'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'F8'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'89'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'75'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'F4'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'8B'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'45'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'F4'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'5D'.
             03 USAGE BINARY-CHAR UNSIGNED VALUE H'C3'.
          01 MMAP.
             03 MMAP-ADDR   USAGE POINTER VALUE NULL.
             03 MMAP-LEN    USAGE BINARY-LONG UNSIGNED VALUE 24.
             03 MMAP-PROT   USAGE BINARY-INT VALUE H'0007'.
             03 MMAP-FLAGS  USAGE BINARY-INT VALUE H'1002'.
             03 MMAP-FD     USAGE BINARY-INT VALUE -1.
             03 MMAP-OFFSET USAGE BINARY-LONG VALUE 0.
          03 CODE-PTR USAGE PROCEDURE-POINTER.
          01 ARG-A USAGE BINARY-INT VALUE 7.
          01 ARG-B USAGE BINARY-INT VALUE 12.
          01 RESULT USAGE BINARY-INT.
      LINKAGE SECTION.
          01 MACHINE-CODE PIC X(24).
      PROCEDURE DIVISION.
      MAIN SECTION.
          PERFORM SET-UP.
          CALL CODE-PTR USING
             BY VALUE ARG-A
             BY VALUE ARG-B
             RETURNING RESULT.
          DISPLAY RESULT.
          PERFORM TEAR-DOWN.
          STOP RUN.

      SET-UP SECTION.
          CALL 'mmap' USING
             BY VALUE MMAP-ADDR
             BY VALUE MMAP-LEN
             BY VALUE MMAP-PROT
             BY VALUE MMAP-FLAGS
             BY VALUE MMAP-FD
             BY VALUE MMAP-OFFSET
             RETURNING CODE-PTR.
          SET ADDRESS OF MACHINE-CODE TO CODE-PTR.
          MOVE INSTRUCTIONS TO MACHINE-CODE.

      TEAR-DOWN SECTION.
          SET ADDRESS OF MACHINE-CODE TO NULL.
          CALL 'munmap' USING
             BY VALUE CODE-PTR
             BY VALUE MMAP-LEN.

</lang>

Output:

+0000000019

Common Lisp

<lang lisp>;;Note that by using the 'CFFI' library, one can apply this procedure portably in any lisp implementation;

in this code however I chose to demonstrate only the implementation-dependent programs.

CCL Allocate a memory pointer and poke the opcode into it

(defparameter ptr (ccl::malloc 9))

(loop for i in '(139 68 36 4 3 68 36 8 195)

  for j from 0 do
  (setf (ccl::%get-unsigned-byte ptr j) i))

Execute with the required arguments and return the result as an unsigned-byte

(ccl::ff-call ptr :UNSIGNED-BYTE 7 :UNSIGNED-BYTE 12 :UNSIGNED-BYTE)

Output = 19

Free the pointer

(ccl::free ptr)

SBCL

(defparameter mmap (list 139 68 36 4 3 68 36 8 195))

(defparameter pointer (sb-alien:make-alien sb-alien:unsigned-char (length mmap)))

(defparameter callp (loop for byte in mmap

                         for i from 0

do (setf (sb-alien:deref pointer i) byte) finally (return (sb-alien:cast pointer (function integer integer integer)))))

(sb-alien:alien-funcall callp 7 12)

(loop for i from 0 below 18 collect (sb-alien:deref ptr i))

(sb-alien:free-alien pointer)

CLISP

(defparameter mmap (list 139 68 36 4 3 68 36 8 195))

(defparameter POINTER (FFI:FOREIGN-ADDRESS (FFI:FOREIGN-ALLOCATE 'FFI:UINT8 :COUNT 9)))

(loop for i in mmap

  for j from 0 do
  (FUNCALL #'(SETF FFI:MEMORY-AS) i POINTER 'FFI:INT j))

(FUNCALL

(FFI:FOREIGN-FUNCTION POINTER

(LOAD-TIME-VALUE (FFI:PARSE-C-TYPE '(FFI:C-FUNCTION (:ARGUMENTS 'FFI:INT 'FFI:INT) (:RETURN-TYPE FFI:INT) (:LANGUAGE :STDC)))))

7 12)

(FFI:FOREIGN-FREE POINTER) </lang>

Cowgol

<lang cowgol>include "cowgol.coh";

Run machine code at cptr, given two 32-bit arguments,
return the value returned from EAX.

sub RunCode(cptr: [uint8], arg1: uint32, arg2: uint32): (rslt: uint32) is

   # Inline assembly is supported, so this whole rigmarole
   # is not even necessary. 
   # Though note that this (obviously) depends on the assembly back-end used.
   # Linux as uses AT&T syntax, so that's what I'm doing here.
   # Cowgol supports many processors but this will, obviously, only work
   # on x86. 
   
   @asm "pushl (",arg1,")";      # Push the two arguments on the stack
   @asm "pushl (",arg2,")";
   @asm "call *(",cptr,")";      # Call the code at the pointer
   @asm "movl %eax, (",rslt,")"; # Store the result in rslt
   @asm "popl %eax";             # Clean up the stack
   @asm "popl %eax";

end sub;

Store code in an array. This is enough to make it available.

var code: uint8[] := {139, 68, 36, 4, 3, 68, 36, 8, 195};

Use the function

print_i32(RunCode(&code as [uint8], 7, 12)); # this prints 7+12 = 19 print_nl();

As a demonstration, this shows it can be patched at runtime to multiply instead

code[4] := 247; code[5] := 100; print_i32(RunCode(&code as [uint8], 7, 12)); # this prints 7*12 = 84 print_nl();</lang>

Output:

19
84

D

In D you usually use a nicer asm {} statement for similar purposes.

Generally new operating systems forbid execution of any address unless it's known to contain executable code. This is a basic version that unlike the C entry executes from array memory. This may crash on some operating systems. <lang d>int test(in int a, in int b) pure nothrow @nogc {

   /*
   mov EAX, [ESP+4]
   add EAX, [ESP+8]
   ret
   */
   immutable ubyte[9] code = [0x8B, 0x44, 0x24, 0x4, 0x3, 0x44, 0x24, 0x8, 0xC3];
   alias F = extern(C) int function(int, int) pure nothrow @nogc;
   immutable f = cast(F)code.ptr;
   return f(a, b); // Run code.

}

void main() {

   import std.stdio;

   test(7, 12).writeln;

}</lang>

Output:

Go

Translation of: C

This task requires the use of 'cgo' which enables Go to interface with C code by importing a pseudo-package called "C".

Although Go supports both 32-bit and 64-bit architectures, I'm writing this on a 64-bit Ubuntu 16.04 system. I've therefore utilized the PicoLisp entry's 'glue code' to enable the 32-bit code to run on it.

There doesn't appear to be a way to cast a pointer to a native buffer to a Go function pointer so that the machine code can be run directly. I've therefore written a C function to perform this step and embedded it in the program which 'cgo' allows us to do. <lang go>package main

import "fmt"

/*

include <stdio.h>
include <stdlib.h>
include <sys/mman.h>
include <string.h>

typedef unsigned char byte; typedef byte (*mcfunc) (byte, byte);

void runMachineCode(void *buf, byte a, byte b) {

   mcfunc fp = (mcfunc)buf;
   printf("%d\n", fp(a, b));

}

/

import "C"

func main() {

   code := []byte{
       144, // Align
       144,
       106, 12, // Prepare stack
       184, 7, 0, 0, 0,
       72, 193, 224, 32,
       80,
       139, 68, 36, 4, 3, 68, 36, 8, // Rosetta task code
       76, 137, 227, // Get result
       137, 195,
       72, 193, 227, 4,
       128, 203, 2,
       72, 131, 196, 16, // Clean up stack
       195, // Return
   }
   le := len(code)
   buf := C.mmap(nil, C.size_t(le), C.PROT_READ|C.PROT_WRITE|C.PROT_EXEC,
       C.MAP_PRIVATE|C.MAP_ANON, -1, 0)
   codePtr := C.CBytes(code)
   C.memcpy(buf, codePtr, C.size_t(le))
   var a, b byte = 7, 12
   fmt.Printf("%d + %d = ", a, b)
   C.runMachineCode(buf, C.byte(a), C.byte(b))
   C.munmap(buf, C.size_t(le))
   C.free(codePtr)

}</lang>

Output:

7 + 12 = 19

Julia

Translation of: C

Julia cannot execute machine code directly, but can embed C and C++ with the Cxx library. <lang julia>using Cxx

cxx"""

include <stdio.h>
include <sys/mman.h>
include <string.h>

int test (int a, int b) {

 /*
      mov EAX, [ESP+4]
      add EAX, [ESP+8]
      ret
 */
 char code[] = {0x8B, 0x44, 0x24, 0x4, 0x3, 0x44, 0x24, 0x8, 0xC3};
 void *buf;
 int c;
 /* copy code to executable buffer */
 buf = mmap (0,sizeof(code),PROT_READ|PROT_WRITE|PROT_EXEC,
            MAP_PRIVATE|MAP_ANON,-1,0);

 memcpy (buf, code, sizeof(code));
 /* run code */
 c = ((int (*) (int, int))buf)(a, b);
 /* free buffer */
 munmap (buf, sizeof(code));
 return c;

}

int main () {

 printf("%d\n", test(7,12));
 return 0;

} """

julia_function = @cxx main() julia_function() </lang>

Kotlin

Translation of: C

This task presents a number of issues for Kotlin Native which at the time of writing (August 2017) is still in the earlier stages of development:-

1. The language doesn't (yet) have an unsigned Byte type, though this is easily solved by subtracting 256 from unsigned values between 128 and 255 inclusive and then using the signed Byte type.

2. As far as x86 is concerned, the language is currently only targetting 64-bit platforms including Ubuntu 14.04 on which I'm writing this. Rather than rewrite the task using x64 opcodes, I've used the PicoLisp entry's 'glue code' to enable the 32-bit machine code to run on a 64-bit system.

3. There doesn't appear to be a way to cast a pointer to a native buffer to a Kotlin function pointer so that the machine code can be run. I've therefore written a 'one line' C helper function (in mcode.def) to perform this step and compiled it to a library (mcode.klib) so that it can be called from Kotlin code. <lang C>// mcode.def ---

static inline unsigned char runMachineCode(void *code, unsigned char a, unsigned char b) {

   return ((unsigned char (*) (unsigned char, unsigned char))code)(a, b);

}</lang>

<lang scala>// Kotlin Native version 0.3

import kotlinx.cinterop.* import string.* import mman.* import mcode.*

fun main(args: Array<String>) {

   memScoped {        
       val bytes = byteArrayOf(
           144 - 256,                            // Align
           144 - 256,
           106, 12,                              // Prepare stack
           184 - 256, 7, 0, 0, 0, 
           72, 193 - 256, 224 - 256, 32,
           80,
           139 - 256, 68, 36, 4, 3, 68, 36, 8,   // Rosetta task code
           76, 137 - 256, 227 - 256,             // Get result
           137 - 256, 195 - 256,
           72, 193 - 256, 227 - 256, 4,
           128 - 256, 203 - 256, 2,
           72, 131 - 256, 196 - 256, 16,         // Clean up stack 
           195 - 256                             // Return
       )
       val len = bytes.size    
       val code = allocArray<ByteVar>(len)
       for (i in 0 until len) code[i] = bytes[i]
       val buf = mmap(null, len.toLong(), PROT_READ or PROT_WRITE or PROT_EXEC,
                      MAP_PRIVATE or MAP_ANON, -1, 0) 
       memcpy(buf, code, len.toLong())
       val a: Byte = 7
       val b: Byte = 12
       val c = runMachineCode(buf, a, b)
       munmap(buf, len.toLong()) 
       println("$a + $b = ${if(c >= 0) c.toInt() else c + 256}")
   }

}</lang>

Output:

7 + 12 = 19

Lua

Thankfully, native Lua has no such provisions. This task should probably be marked "omit from|Lua", except that the task is not explicit whether or not only native facilities may be used. The task cites the Common Lisp example as reference, which does use an external FFI library to accomplish the task, so implies that external facilities may be used. If such tactics are allowed, then the LuaJIT distribution includes FFI. Or, wrap the "test" function of the C example, and expose it to Lua as an external library - that is well within Lua's capabilities (one of Lua's strengths, actually). Or take the modified approach used in the Kotlin example - Lua can easily build the raw byte array, then pass it to an external C library to execute. Or, simply compile the C example, then call it via os.execute("cexample.exe"). No code is given, as the task is outside the scope of pure/native Lua, but it would be easy to accomplish if external support were allowed.

M2000 Interpreter

We can execute machine code, in a buffer for code. We can't push to stack and then call, we can use a buffer for data. If eax is non zero then error raised, with error number the eax number. When execute code the code buffer can't be used to write over. so we have to use a buffer for data for read/write data. This example perform these: At Datamem(1) put 500, eax=5100, eax add Datamem(1), eax add 5, store eax to Datamem(0). We have an option to clear eax, or use it to return value as error code. We have to leave all other registers, and stack as we found it. Both running in Wine (Linux 64bit) too

<lang M2000 Interpreter> Module Checkit {

     Buffer DataMem as Long*10
     Return DataMem, 1:=500    ' second Long
     Print Eval(DataMem, 1)+5100+5=5605
     \\ Now we do math executing machine code
     Buffer Code ExecMem as byte*1024
     Address=0
     EmbLong(0xb8, 5100) ' mov eax,5100
     EmbByteByte(0x83, 0xC0, 5) ' add  eax,0x5
     EmbByteLong(0x3,0x5, DataMem(1)) ' add eax, [DataMem(1)] 
     EmbLong(0xa3, DataMem(0)) ' mov [DataMem(0)], eax
     \\ split rem to execute xor eax eax (eax=0)
     Rem : EmbByte(0x31, 0xC0) ' xor eax, eax 
     Ret() ' Return
     \\  
     Try ok {
           Execute Code ExecMem, 0
     }
     \\If  Eax <>0 then we get error, so we read error as Uint()
     \\ Error read once then change to zero
     m=Uint(Error)
     \\ Hex is Print Hexadecimal for unsigned numbers
     Hex m
     Print m=5605
     Print Error=0, ok=False
     
     Print Eval(DataMem, 0)=5605,  Eval(DataMem, 0)
     \\ sub used as Exit here
     Sub Ret()
           Return ExecMem, Address:=0xC3
           Address++
     End Sub
     Sub EmbByteByte()
           Return ExecMem, Address:=Number, Address+1:=Number, Address+2:=Number
           Address+=3
     End Sub
     Sub EmbByte()
           Return ExecMem, Address:=Number, Address+1:=Number
           Address+=2
     End Sub
     Sub EmbLong()
           Return ExecMem, Address:=Number, Address+1:=Number as Long
           Address+=5
     End Sub
     Sub EmbByteLong()
           Return ExecMem, Address:=Number, Address+1:=Number, Address+2:=Number as Long
           Address+=6
     End Sub

} CheckIt </lang>

Using a lambda function with closures two buffers (buffers are objects in M2000 to handle memory blocks). This also add 12 +7 as the task want (but with no pushing to stack, but poke to data buffer)

<lang M2000 Interpreter> Function MyAdd {

     Buffer DataMem as Long*2
     Buffer Code ExecMem as byte*32
     Address=0
     EmbByte(0x31, 0xC0)
     EmbByteLong(0x3,0x5, DataMem(0)) ' add eax, [DataMem(0)] 
     EmbByteLong(0x3,0x5, DataMem(1)) ' add eax, [DataMem(1)] 
     EmbLong(0xa3, DataMem(0)) ' mov [DataMem(0)], eax
     Rem :
     EmbByte(0x31, 0xC0) ' xor eax, eax 
     Ret() ' Return
     =lambda ExecMem, DataMem (a as double, b as double)-> {
           Return DataMem, 0:=a, 1:=b
           Try ok  {
                 Execute Code ExecMem, 0
           }
           If not ok then {
                 =Uint(Error)   
           }  Else {
                 =Eval(DataMem, 0)
           }
     }
     Sub Ret()
           Return ExecMem, Address:=0xC3
           Address++
     End Sub
     Sub EmbByte()
           Return ExecMem, Address:=Number, Address+1:=Number
           Address+=2
     End Sub
     Sub EmbLong()
           Return ExecMem, Address:=Number, Address+1:=Number as Long
           Address+=5
     End Sub
     Sub EmbByteLong()
           Return ExecMem, Address:=Number, Address+1:=Number, Address+2:=Number as Long
           Address+=6
     End Sub

} \\ Produce a lambda function with machine code inside UnsingedAdd=MyAdd() Print UnsingedAdd(12, 7), UnsingedAdd(500, 100) </lang>

Nim

Translation of: C

<lang nim>import posix

when defined(macosx) or defined(bsd):

 const MAP_ANONYMOUS = 0x1000

elif defined(solaris):

 const MAP_ANONYMOUS = 0x100

else:

 var
   MAP_ANONYMOUS {.importc: "MAP_ANONYMOUS", header: "<sys/mman.h>".}: cint

proc test(a, b: cint): cint =

 # mov EAX, [ESP+4]
 # add EAX, [ESP+8]
 var code = [0x8B'u8, 0x44, 0x24, 0x4, 0x3, 0x44, 0x24, 0x8, 0xC3]

 # create executable buffer
 var buf = mmap(nil, sizeof(code), PROT_READ or PROT_WRITE or PROT_EXEC,
   MAP_PRIVATE or MAP_ANONYMOUS, -1, 0)

 # copy code to buffer
 copyMem(addr buf, addr code[0], sizeof(code))

 # run code
 {.emit: "`result` = ((int (*) (int, int))&`buf`)(`a`,`b`);".}

 # free buffer
 discard munmap(buf, sizeof(code))

echo test(7, 12)</lang>

PARI/GP

GP can't peek and poke into memory, but PARI can add in those capabilities via C.

Translation of: C

<lang c>#include <stdio.h>

include <sys/mman.h>
include <string.h>
include <pari/pari.h>

int test(int a, int b) {

 char code[] = {0x8B, 0x44, 0x24, 0x4, 0x3, 0x44, 0x24, 0x8, 0xC3};
 void *buf;
 int c;
 /* copy code to executable buffer */
 buf = mmap (0,sizeof(code),PROT_READ|PROT_WRITE|PROT_EXEC,
            MAP_PRIVATE|MAP_ANON,-1,0);

 memcpy (buf, code, sizeof(code));
 /* run code */
 c = ((int (*) (int, int))buf)(a, b);
 /* free buffer */
 munmap (buf, sizeof(code));
 return c;

}

void init_auto(void) {

 pari_printf("%d\n", test(7,12));
 return 0;

}</lang>

Pascal

Tested under Linux with Freepascal 2.6.4-32BIt ( like the Code used ) cdecl doesn't work in Freepascal under Linux 64-bit <lang pascal>Program Example66; {Inspired... program to demonstrate the MMap function. Freepascal docs } Uses

 BaseUnix,Unix;

const

 code : array[0..9] of byte = ($8B, $44, $24, $4, $3, $44, $24, $8, $C3, $00);
 a :longInt= 12; 
 b :longInt=  7;

type

 tDummyFunc = function(a,b:LongInt):LongInt;cdecl;

Var

   Len,k  : cint;
   P    : Pointer;

begin

 len := sizeof(code);
 P:= fpmmap(nil,
            len+1 ,
            PROT_READ OR PROT_WRITE OR PROT_EXEC,
            MAP_ANONYMOUS OR MAP_PRIVATE,
            -1, // for MAP_ANONYMOUS
            0);
 If P =  Pointer(-1) then
   Halt(4);

 for k := 0 to len-1 do
   pChar(p)[k] := char(code[k]);

 k := tDummyFunc(P)(a,b);

 Writeln(a,'+',b,' = ',k);
 if fpMUnMap(P,Len)<>0 Then
   Halt(fpgeterrno);

end.</lang>

output

12+7 = 19

Phix

<lang Phix>atom mem = allocate(9) poke(mem,{#8B,#44,#24,#04,#03,#44,#24,#08,#C3}) constant mfunc = define_c_func({},mem,{C_INT,C_INT},C_INT) ?c_func(mfunc,{12,7}) free(mem)</lang> In Phix the #ilASM statement (which has guards to allow 32/64/WIN/LNX variants) is usually used for inline assembly, for example (but sticking to the task): <lang Phix>atom mem = allocate(9) poke(mem,{#8B,#44,#24,#04,#03,#44,#24,#08,#C3}) integer res

ilASM{ mov eax,[mem]

       call :%pLoadMint -- eax:=(int32)eax, in case mem>#3FFFFFFF
       push 12
       push 7
       call eax
       add esp,8
       mov [res],eax }

?res free(mem)</lang> Better yet, albeit deviating somewhat from the task (and this runs on both 32 and 64 bit): <lang Phix>integer res

ilASM{ jmp @f

     ::add
   [32]
       mov eax,[esp+4]
       add eax,[esp+8]
   [64]
       mov rax,[rsp+8]
       add rax,[rsp+16]
   []  
       ret
     @@:
       push 12
       push 7
       call :add
   [32]
       add esp,8
       mov [res],eax
   [64]
       add rsp,16
       mov [res],rax
   []
     }

?res</lang> All three cases output 19

PicoLisp

The following runs on 64-bit PicoLisp. Therefore we need some glue code to interface to the task's 32-bit code. <lang PicoLisp>(setq P

  (struct (native "@" "malloc" 'N 39) 'N
     # Align
     144                  # nop
     144                  # nop

     # Prepare stack
     106 12               # pushq $12
     184 7 0 0 0          # mov $7, %eax
     72 193 224 32        # shl $32, %rax
     80                   # pushq %rax

     # Rosetta task code
     139 68 36 4 3 68 36 8

     # Get result
     76 137 227           # mov %r12, %rbx
     137 195              # mov %eax, %ebx
     72 193 227 4         # shl $4, %rbx
     128 203 2            # orb $2, %bl

     # Clean up stack
     72 131 196 16        # add $16, %rsp

     # Return 
     195 )                # ret
  foo (>> 4 P) )

Execute

(println (foo))

Free memory

(native "@" "free" NIL P)</lang> Output:

PureBasic

Using the Windows API:

<lang PureBasic>CompilerIf #PB_Compiler_Processor <> #PB_Processor_x86

 CompilerError "Code requires a 32-bit processor."

CompilerEndIf

Machine code using the Windows API

Procedure MachineCodeVirtualAlloc(a,b)

vm = VirtualAlloc_(#Null,?ecode-?scode,#MEM_COMMIT,#PAGE_EXECUTE_READWRITE)

   If(*vm)
       CopyMemory(?scode, *vm, ?ecode-?scode)
       eax_result=CallFunctionFast(*vm,a,b)
       VirtualFree_(*vm,0,#MEM_RELEASE)
       ProcedureReturn eax_result
   EndIf

EndProcedure

rv=MachineCodeVirtualAlloc( 7, 12) MessageRequester("MachineCodeVirtualAlloc",Str(rv)+Space(50),#PB_MessageRequester_Ok)

HEAP_CREATE_ENABLE_EXECUTE=$00040000

Procedure MachineCodeHeapCreate(a,b) hHeap=HeapCreate_(#HEAP_CREATE_ENABLE_EXECUTE,?ecode-?scode,?ecode-?scode)

   If(hHeap)
       CopyMemory(?scode, hHeap, ?ecode-?scode)
       eax_result=CallFunctionFast(hHeap,a,b)
       HeapDestroy_(hHeap)
       ProcedureReturn eax_result
   EndIf

EndProcedure

rv=MachineCodeHeapCreate(7,12) MessageRequester("MachineCodeHeapCreate",Str(rv)+Space(50),#PB_MessageRequester_Ok) End

8B442404 mov eax,[esp+4]
03442408 add eax,[esp+8]
C20800 ret 8

DataSection scode: Data.a $8B,$44,$24,$04,$03,$44,$24,$08,$C2,$08,$00 ecode: EndDataSection</lang>

Python

Works with: CPython version 3.x

The ctypes module is meant for calling existing native code from Python, but you can get it to execute your own bytes with some tricks. The bulk of the code is spent establishing an executable memory area - once that's done, the actual execution takes just a few lines.

<lang Python>import ctypes import os from ctypes import c_ubyte, c_int

code = bytes([0x8b, 0x44, 0x24, 0x04, 0x03, 0x44, 0x24, 0x08, 0xc3])

code_size = len(code)

copy code into an executable buffer

if (os.name == 'posix'):

   import mmap
   executable_map = mmap.mmap(-1, code_size, mmap.MAP_PRIVATE | mmap.MAP_ANON, mmap.PROT_READ | mmap.PROT_WRITE | mmap.PROT_EXEC)
   # we must keep a reference to executable_map until the call, to avoid freeing the mapped memory
   executable_map.write(code)
   # the mmap object won't tell us the actual address of the mapping, but we can fish it out by allocating
   # some ctypes object over its buffer, then asking the address of that
   func_address = ctypes.addressof(c_ubyte.from_buffer(executable_map))

elif (os.name == 'nt'):

   # the mmap module doesn't support protection flags on Windows, so execute VirtualAlloc instead
   code_buffer = ctypes.create_string_buffer(code)
   PAGE_EXECUTE_READWRITE = 0x40  # Windows constants that would usually come from header files
   MEM_COMMIT = 0x1000
   executable_buffer_address = ctypes.windll.kernel32.VirtualAlloc(0, code_size, MEM_COMMIT, PAGE_EXECUTE_READWRITE)
   if (executable_buffer_address == 0):
       print('Warning: Failed to enable code execution, call will likely cause a protection fault.')
       func_address = ctypes.addressof(code_buffer)
   else:
       ctypes.memmove(executable_buffer_address, code_buffer, code_size)
       func_address = executable_buffer_address

else:

   # for other platforms, we just hope DEP isn't enabled
   code_buffer = ctypes.create_string_buffer(code)
   func_address = ctypes.addressof(code_buffer)

prototype = ctypes.CFUNCTYPE(c_int, c_ubyte, c_ubyte) # build a function prototype from return type and argument types func = prototype(func_address) # build an actual function from the prototype by specifying the address res = func(7,12) print(res) </lang>

Racket

<lang racket>#lang racket/base

(require ffi/unsafe)

set up access to racket internals

(define scheme-malloc-code

 (get-ffi-obj 'scheme_malloc_code #f (_fun (len : _intptr) -> _pointer)))

(define scheme-free-code

 (get-ffi-obj 'scheme_free_code #f (_fun _pointer -> _void)))

(define opcodes '(139 68 36 4 3 68 36 8 195))

(define code (scheme-malloc-code 64))

(for ([byte opcodes]

     [i (in-naturals)])
 (ptr-set! code _ubyte i byte))

(define function (cast code _pointer (_fun _ubyte _ubyte -> _ubyte)))

(function 7 12)

(scheme-free-code code)</lang>

Raku

I don't know how to translate this C line <lang C>c = ((int (*) (int, int))buf)(a, b);</lang> so cannot solve the task with an idiomatic solution. I have also tried with Go's approach by adding a helper program but it also doesn't work out. Nonetheless I just present the attempt here so perhaps someone can fix that in 10 seconds. <lang perl6>use NativeCall;

constant PROT_READ = 0x1; # constant PROT_WRITE = 0x2; # constant PROT_EXEC = 0x4; # from local /usr/include/bits/mman.h constant MAP_PRIVATE = 0x02; # constant MAP_ANON = 0x20; #

sub mmap(Pointer $addr, size_t $length, int32 $prot, int32 $flags,

  int32 $fd, size_t $offset --> Pointer) is native { * };

sub memcpy(Pointer $dest, Pointer $src, size_t $size --> Pointer) is native {*} sub munmap(Pointer $addr, size_t $length) is native { * };

sub test (uint8 $a, uint8 $b) {

  my $code = CArray[uint8].new(
     0x90, 0x90, 0x6A, 0xC, 0xB8, 0x7, 0x0, 0x0, 0x0, 0x48, 0xC1, 0xE0, 0x20,
     0x50, 0x8B, 0x44, 0x24, 0x4, 0x3, 0x44, 0x24, 0x8, 0x4C, 0x89, 0xE3, 0x89,
     0xC3, 0x48, 0xC1, 0xE3, 0x4, 0x80, 0xCB, 0x2, 0x48, 0x83, 0xC4, 0x10, 0xC3   
  );
  my $buf =
     mmap(Pointer, nativesizeof($code), PROT_READ +| PROT_WRITE +| PROT_EXEC,
     MAP_PRIVATE +| MAP_ANON, -1, 0);

  memcpy($buf, nativecast(Pointer,$code), nativesizeof($code));

  my $c; # = ((int (*) (int, int))buf)(a, b);

  munmap($buf, nativesizeof($code));

  return $c = "Incomplete Attempt";

}

say test 7, 12;</lang>

In the mean time, here is a less desirable approach by writing a wrapper for the C entry, with the 64 bit instructions from PicoLisp ..

Translation of: C

test.c

<lang C>#include <stdio.h>

include <stdlib.h>
include <sys/mman.h>
include <string.h>

int test (int a, int b) {

 char code[] = {
    0x90, 0x90, 0x6A, 0xC, 0xB8, 0x7, 0x0, 0x0, 0x0, 0x48, 0xC1, 0xE0, 0x20,
    0x50, 0x8B, 0x44, 0x24, 0x4, 0x3, 0x44, 0x24, 0x8, 0x4C, 0x89, 0xE3, 0x89,
    0xC3, 0x48, 0xC1, 0xE3, 0x4, 0x80, 0xCB, 0x2, 0x48, 0x83, 0xC4, 0x10, 0xC3
 };

 void *buf;
 int c;
 /* copy code to executable buffer */
 buf = mmap (0,sizeof(code),PROT_READ|PROT_WRITE|PROT_EXEC,
            MAP_PRIVATE|MAP_ANON,-1,0);
 memcpy (buf, code, sizeof(code));
 /* run code */
 c = ((int (*) (int, int))buf)(a, b);
 /* free buffer */
 munmap (buf, sizeof(code));
 return c;

}</lang> mcode.raku <lang perl6>#!/usr/bin/env raku

20200501 Raku programming solution

use NativeCall;

constant LIBTEST = '/home/user/LibTest.so';

sub test(uint8 $a, uint8 $b) returns uint8 is native(LIBTEST) { * };

say test 7, 12; </lang>

Output:

gcc -Wall -fPIC -shared -o LibTest.so test.c

file LibTest.so LibTest.so: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, BuildID[sha1]=90d2695df9a56b88a57144147fb9288ac07b172f, not stripped ./mcode.raku

19

Rust

This is heavily inspired by https://www.jonathanturner.org/2015/12/building-a-simple-jit-in-rust.html
Hence, only working on Linux (the only other way to disable memory execution protection on other OSes was to use other crates, which kind of defeats the purpose.) <lang Rust>extern crate libc;

[cfg(all(

   target_os = "linux",
   any(target_pointer_width = "32", target_pointer_width = "64")

))] fn main() {

   use std::mem;
   use std::ptr;

   let page_size: usize = 4096;
   let (bytes, size): (Vec<u8>, usize) = if cfg!(target_pointer_width = "32") {
       (
           vec![0x8b, 0x44, 0x24, 0x04, 0x03, 0x44, 0x24, 0x08, 0xc3],
           9,
       )
   } else {
       (vec![0x48, 0x89, 0xf8, 0x48, 0x01, 0xf0, 0xc3], 7)
   };
   let f: fn(u8, u8) -> u8 = unsafe {
       let mut page: *mut libc::c_void = ptr::null_mut();
       libc::posix_memalign(&mut page, page_size, size);
       libc::mprotect(
           page,
           size,
           libc::PROT_EXEC | libc::PROT_READ | libc::PROT_WRITE,
       );
       let contents: *mut u8 = page as *mut u8;
       ptr::copy(bytes.as_ptr(), contents, 9);
       mem::transmute(contents)
   };

   let return_value = f(7, 12);
   println!("Returned value: {}", return_value);
   assert_eq!(return_value, 19);

}

[cfg(any(

   not(target_os = "linux"),
   not(any(target_pointer_width = "32", target_pointer_width = "64"))

))] fn main() {

   println!("Not supported on this platform.");

} </lang>

Scala

PEEK, POKE and inserting machine opcode makes your system vulnerable which is not quite professional.

Considered to be more harmful than useful.

Smalltalk

I agree that this is more harmful than useful. The only target audience are compiler writers and Smalltalk-core developers (of which I guess are not too many around).

Also, this is highly cpu specific, the task is for an x86 and also assuming a particular calling convention; both is probably (definitely) not the case (most, incl. myself are on 64bit machines these days).

Anyway, as a sketch, here is how to do it (I won't waste time in making an x86_64 version for the particular calling convention used on my machine; and yes: it is even different between Unix and Windows systems!):

First we need a way to allocate executable memory (btw. we should probably also care to flush any instruction caches, which I won't go into here); This is very Smalltalk dialect specific, and probably not supported on other Smalltalks; in ST/X, where inline C-code can be compiled dynamically, we can define it as:

Works with: Smalltalk/X

<lang smalltalk>!ExternalBytes class methods!

mapExecutableBytes:size %{

include <sys/mman.h>

   void *mem;
   OBJ retVal;
   int nBytes = __intVal(size);

   mem = mmap(nil, nBytes, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANON, -1, 0);
   if (mem != MAP_FAILED) {
       RETURN( __MKEXTERNALBYTES_N(mem, nBytes));
   }

%}.

   self primitiveFailed

! !</lang>

next, we need the correct code; the following presents the x86 version (but do not expect this code to NOT crash the Smalltalk VM, as the calling convention is certainly wrong..) <lang smalltalk>OperatingSystem getCPUType = #'x86' ifTrue:[

   code := #[0x8B 0x44 0x24 0x04 0x03 0x44 0x24 0x08 0xC3].

] ifFalse:[

   self error:'unsupported cpu'

].

handle := ExternalBytes mapExecutableBytes:100. handle replaceFrom:1 with:code.

" dump it (debugging only)... " e'code at {handle address hexPrintString} is:' printCR. (handle copyFrom:1 to:50) asByteArray hexPrintString printCR.

" create an ExternalFunction for it " func := ExternalLibraryFunction new code:handle address. func name:'unnamed' module:nil returnType:#int argumentTypes:#(int int). func beCallTypeC. func printCR.

" now call it " result := func invokeWithArguments:{10 . 20} </lang> With a few more tricks, it is even possible to install that function as a method in a class; but additional code needs to be generated, to assert that the passed data is correctly boxed/unboxed.

Swift

Translation of: C

Using 64-bit glue code since Swift has limited 32-bit support on x86.

<lang swift>import Foundation

typealias TwoIntsOneInt = @convention(c) (Int, Int) -> Int

let code = [

 144, // Align
 144,
 106, 12, // Prepare stack
 184, 7, 0, 0, 0,
 72, 193, 224, 32,
 80,
 139, 68, 36, 4, 3, 68, 36, 8, // Rosetta task code
 76, 137, 227, // Get result
 137, 195,
 72, 193, 227, 4,
 128, 203, 2,
 72, 131, 196, 16, // Clean up stack
 195, // Return

] as [UInt8]

func fudge(x: Int, y: Int) -> Int {

 let buf = mmap(nil, code.count, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANON, -1, 0)

 memcpy(buf, code, code.count)

 let fun = unsafeBitCast(buf, to: TwoIntsOneInt.self)
 let ret = fun(x, y)

 munmap(buf, code.count)

 return ret

}

print(fudge(x: 7, y: 12)) </lang>

Tcl

Translation of: C

Library: Critcl

<lang tcl>package require critcl

critcl::ccode {

   #include <sys/mman.h>

}

Define a command using C. The C is embedded in Tcl, and will be
built into a shared library at runtime. Note that Tcl does not
provide a native way of doing this sort of thing; this thunk is
mandatory.

critcl::cproc runMachineCode {Tcl_Obj* codeObj int a int b} int {

   int size, result;
   unsigned char *code = Tcl_GetByteArrayFromObj(codeObj, &size);
   void *buf;

   /* copy code to executable buffer */
   buf = mmap(0, (size_t) size, PROT_READ|PROT_WRITE|PROT_EXEC,
           MAP_PRIVATE|MAP_ANON, -1, 0); 
   memcpy(buf, code, (size_t) size);
   /* run code */
   result = ((int (*) (int, int)) buf)(a, b);
   /* dispose buffer */
   munmap(buf, (size_t) size);

   return result;

}

But now we have our thunk, we can execute arbitrary binary blobs

set code [binary format c* {0x8B 0x44 0x24 0x4 0x3 0x44 0x24 0x8 0xC3}] puts [runMachineCode $code 7 12]</lang> Note that it would be more common to put that thunk in its own package (e.g., machineCodeThunk) and then just do something like this: <lang tcl>package require machineCodeThunk 1.0

set code [binary format c* {0x8B 0x44 0x24 0x4 0x3 0x44 0x24 0x8 0xC3}] puts [runMachineCode $code 7 12]</lang>