HARDROID: Transparent Integration of Crypto Accelerators in Android
Luca Piccolboni, Giuseppe Di Guglielmo, Simha Sethumadhavan, Luca P. Carloni · 2021
Accelerators have become fundamental building blocks of any modern architecture. Accelerators are often deployed on a platform by evaluating performance and energy consumption, while assuming that the software applications can be modified to invoke the accelerators. In some contexts, however, this is impractical. For instance, in an Android-based platform changing the applications to invoke an accelerator can affect their portability. We present Hardroid, a heterogeneous platform that allows an Android application to offload tasks to loosely-coupled accelerators on an FPGA in a transparent way, i.e., without modifying the code of the application. To demonstrate the Hardroid capabilities, we design four accelerators for cryptography with high-level synthesis (HLS) and we compare their efficiency with two libraries for cryptography, by executing 29 Android applications. While we use FPGAs to implement and evaluate Hardroid, our accelerators are designed so that they can be integrated in a system-on-chip (SoC) and we report their energy efficiency also for an ASIC implementation. The experimental results show that Hardroid is an effective platform that can be used to evaluate the costs and benefits of integrating accelerators, when these are called by real-world Android applications. We show that invoking accelerators without modifying the code of the applications can affect the energy efficiency of the accelerators.