code: def sys_mprotect(self, start, size, prot):
          
          perms = perms_from_protflags(prot)
          ret = self.current.memory.mprotect(start, size, perms)
          return 0
docs: Sets protection on a region of memory. Changes protection for the calling process's
          memory page(s) containing any part of the address range in the interval [C{start}, C{start}+C{size}-1].
          :rtype: int
  
          :param start: the starting address to change the permissions.
          :param size: the size of the portion of memory to change the permissions.
          :param prot: the new access permission for the memory.
          :return: C{0} on success.