To use Oprofile, you need to tell oprofile where vmlinux corresponding to the kernel is located
This will allow you to profile the kernel along with your application. If you don't want to profile the kernel: opcontrol --no--vmlinux
This only needs to be done one time.
To run from the command line:
root@am335x-evm:~# opcontrol --vmlinux=/boot/vmlinux-[kernel version]