Today, incorporating a new hardware feature into a modern microprocessor is extremely difficult largely due to the long design cycle and the cost of design and verification. This paper proposes to address this problem utilizing an on-chip FPGA that is tightly coupled with a processing core. A new hardware feature can be implemented and evaluated on the FPGA fabric without requiring a re-design or a fabrication of a new chip. To evaluate this FPGA co-processing approach, we implemented Dynamic Information Flow Tracking (DIFT), which is arguably one of the most powerful security features against software attacks, on the FPGA fabric. The synthesis results of the DIFT extension demonstrate that DIFT can indeed be implemented on the FPGA fabric and provide the performance that is close to the dedicated hardware.