Upgrading Nios Software - external flash

I think that my function "eraseflashsector" is loaded from external flash

memory and placed into internal memory.

This instruction erases the flash sector the NIOS is running from. From the moment the next instruction has to be executed, for example a print instruction (also declared by the section handler in internal memory), the NIOS tries to copy this instruction into internal memory. That is impossible, because the sector in which the instruction is stored is erased by the "eraseflashsector" instrcution.

Is my idea correct? Are the instructions loaded from external flash memory into internal memory from the moment they are called by the main program?

If yes, is it possible to save these instrcutions "always" in internal memory

Regards

Karel