Biblio

Today, most embedded systems use Dynamic Voltage and Frequency Scaling (DVFS) to minimize energy consumption and maximize performance. The DVFS technique works by regulating the important parameters that govern the amount of energy consumed in a system, voltage and frequency. For the implementation of this technique, the operating system (OS) includes software applications that dynamically control a voltage regulator or a frequency regulator or both. In this paper, we demonstrate for the first time a malicious use of the frequency regulator against a TrustZone-enabled System-on-Chip (SoC). We demonstrate a use of frequency scaling to create covert channel in a TrustZone-enabled heterogeneous SoC. We present four proofs of concept to transfer sensitive data from a secure entity in the SoC to a non-secure one. The first proof of concept is from a secure ARM core to outside of SoC. The second is from a secure ARM core to a non-secure one. The third is from a non-trusted third party IP embedded in the programmable logic part of the SoC to a non-secure ARM core. And the last proof of concept is from a secure third party IP to a non-secure ARM core.

Power is increasingly the limiting factor in High Performance Computing (HPC) at Exascale and will continue to influence future advancements in supercomputing. Recent processors equipped with on-board hardware counters allow real time monitoring of operating conditions such as energy and temperature, in addition to performance measures such as instructions retired and memory accesses. An experimental memory study presented on modern CPU architectures, Intel Sandybridge and Haswell, identifies a metric, TORo\_core, that detects bandwidth saturation and increased latency. TORo-Core is used to construct a dynamic policy applied at coarse and fine-grained levels to modulate per-core power controls on Haswell machines. The coarse and fine-grained application of dynamic policy shows best energy savings of 32.1% and 19.5% with a 2% slowdown in both cases. On average for six MPI applications, the fine-grained dynamic policy speeds execution by 1% while the coarse-grained application results in a 3% slowdown. Energy savings through frequency reduction not only provide cost advantages, they also reduce resource contention and create additional thermal headroom for non-throttled cores improving performance.