Android modifying code in ART

I am trying to implement self-modifying code in my android application using JNI.

I have the following method in my MainActivity class for my application:

public int methodToModify()
{       
    return 42;
}

      

        
        
        
      

    

And this is the bytecode of this method:

const/16 v0, 0x2A
return v0

      

        
        
        
      

    

The way this method is represented in the classes.dex file:

13 00 2A 00 0F 00

My goal here is to change the return value of a method methodToModify

at runtime from native code. So, this is a JNI method algorithm that implements self-modifying code:

• Read the process memory (here's more info on this Understanding Linux / proc / id / maps ):

  FILE *fp; fp = fopen("/proc/self/maps", "r");
  
  

• Determine the start and end addresses of the .dex file (or the .oat file in the case of ART):

  while (fgets(line, 2048, fp) != NULL) { // search for 'dex' or 'oat' if (strstr(line, ".oat") != NULL || strstr(line, ".dex") != NULL) // get starting and ending addresses of the DEX file region
  
  

• Find bytes methodToModify
  
  in .dex or .oat files.

• Use the function mprotect
  
  to set the permission to write the file.

• Modify the return method.

My problem is this approach works fine on my Nexus 7 running Android 4.2, but it doesn't work on a Nexus 5 running Android 5.1. I can implement self-modifying code with Dalvik, but I cannot do the same with ART.

So, is it possible to implement self-modifying code with ART?