Power side-channel attacks exploit the correlation of power consumption with the instructions and data being processed to extract secrets from a device (e.g., cryptographic keys). Prior work primarily focused on protecting small embedded micro-controllers and in-order processors rather than high-performance, out-of-order desktop and server CPUs. In this article, we present Paradise , a general-purpose out-of-order processor with always-on protection, that implements a novel dynamic instruction scheduler to provide obfuscated execution and mitigate power analysis attacks. To achieve this, we exploit the time between operand availability of critical instructions ( slack ) and create high-performance random schedules. Further, we highlight the dangers of using incorrect adversarial assumptions, which can often lead to a false sense of security. Therefore, we perform an extended security analysis on AES-128 using different levels of adversaries, from basic to advanced, including a convolution neural networks–based attack. Our advanced security evaluation assumes a strong adversary with full knowledge of the countermeasure and demonstrates a significant security improvement of 556 × when combined with Boolean Masking over a baseline only protected by masking and 62,500× over an unprotected baseline. The resulting overhead in performance, power, and area of Paradise is 3.2%, 1.2%, and 0.8% respectively. 1

Spectre-type attacks have exposed a major class of vulnerabilities arising from speculative execution of instructions, the main performance enabler of modern CPUs. These attacks speculatively leak secrets that have been either speculatively loaded (seen in sand-boxed programs) or non-speculatively loaded (seen in constant-time programs). Various hardware-only defenses have been proposed to mitigate both speculative and non-speculative secrets via all potential transmission channels. However, limited program knowledge is exposed to the hardware and these solutions conservatively restrict the execution of all instructions that can potentially leak.

Hardware Trojans, malicious components that attempt to prevent a chip from operating as expected, are carefully crafted to circumvent detection during the pre-deployment silicon design and verification stages. They are an emerging threat being investigated by academia, the military, and industry. Therefore, run-time hardware Trojan detection is critically needed as the final layer of defense during chip deployment, and in this work, we focus on hardware Trojans that target the processor’s performance. Current state-of-the-art detectors watch hardware counters for anomalies using complex machine-learning models, which require a dedicated off-chip processor and must be trained extensively for each target processor. In this work, we propose a lightweight solution that uses data from a single reference run to accurately determine whether a Trojan is slowing processor performance, across CPU configurations, without the need for new profiles. To accomplish this, we use an analytical model based on the application’s inherent microarchitecturally-independent characteristics. Such models determine the expected microarchitectural events across different processor configurations without requiring reference values for each application-hardware configuration pair. By comparing predicted values to actual hardware events, one can quickly check for unexpected application slowdowns that are the key signatures of many hardware Trojans. The proposed methodology achieves a higher true positive rate compared to prior works while having no false positives. The proposed detector incurs no run-time performance penalty and only adds a negligible power overhead of 0.005%.

In this work, we extend the auto-tuning process of the state-of-the-art TVM framework with XFeatur; a tool that extracts new meaningful hardware-related features that improve the quality of the representation of the search space and consequently improve the accuracy of its prediction algorithm. These new features provide information about the amount of thread-level parallelism, shared memory usage, register usage, dynamic instruction count and memory access dependencies. Optimizing ResNet-18 with the proposed features improves the quality of the search space representation by 63% on average and a maximum of 2× for certain tasks, while it reduces the tuning time by 9% (approximately 1.1 hours) and produces configurations that have equal or better performance (up to 92.7%) than the baseline.

Issue time prediction processors use dataflow dependencies and predefined instruction latencies to predict issue times of repeated instructions. In this work, we make two key observations: (1) memory accesses often take additional time to arrive than the static, predefined access latency that is used to describe these systems. This is due to contention in the memory hierarchy and variability in DRAM access times, and (2) we find that these memory access delays often repeat across iterations of the same code. We propose a new processor microarchitecture that replaces a complex reservation-station-based scheduler with an efficient, scalable alternative. Our scheduling technique tracks real-time delays of loads to accurately predict instruction issue times and uses a reordering mechanism to prioritize instructions based on that prediction. To accomplish this in an energy-efficient manner we introduce (1) an instruction delay learning mechanism that monitors repeated load instructions and learns their latest delay, (2) an issue time predictor that uses learned delays and dataflow dependencies to predict instruction issue times, and (3) priority queues that reorder instructions based on their issue time prediction. Our processor achieves 86.2% of the performance of a traditional out-of-order processor, higher than previous efficient scheduler proposals, while consuming 30% less power.

Modern superscalar processors execute instructions out-of-order, but commit them in program order to provide precise exception handling and safe instruction retirement. However, in-order instruction commit is highly conservative and holds on to critical resources far longer than necessary, severely limiting the reach of general-purpose processors, ultimately reducing performance. Solutions that allow for efficient, early reclamation of these critical resources could seize the opportunity to improve performance. One such solution is out-of-order commit, which has traditionally been challenging due to inefficient, complex hardware used to guarantee safe instruction retirement and provide precise exception handling.

Laser fault injection in integrated circuits is a powerful information leakage technique due to its high precision, timing accuracy and repeatability. Countermeasures to these attacks have been studied extensively. However, with most current design flows, security tests against these attacks can only be realized after chip fabrication. Restarting the complete silicon design cycle in order to address these vulnerabilities is thus both time-consuming and costly. To overcome these limitations, this paper proposes an open-source benchmark suite that allows chip designers to simulate laser attacks, and evaluate the security of their designs, both hardware-based and software-based, against laser fault injection early on during design time. The proposed benchmark suite consists of a tool that automatically integrates hardware-based spatial, temporal and hybrid redundancy techniques into a target design. With the tools used in this work, we demonstrate how the attacks can be simulated on a Verilog simulator, and run on an FPGA with a design equipped with hardware-based redundancy techniques without manual modifications. This work consists of four attacks, and four hardware-based redundancy techniques. The attacks and defenses together that the benchmark suite provides will automate the entire early design evaluation flow against laser fault injection attacks.

The explosive growth of Internet-connected devices will soon result in a flood of generated data, which will increase the demand for network bandwidth as well as compute power to process the generated data. Consequently, there is a need for more energy efficient servers to empower traditional centralized Cloud data-centers as well as emerging decentralized data-centers at the Edges of the Cloud. In this paper, we present our approach, which aims at developing a new class of micro-servers - the UniServer - that exceed the conservative energy and performance scaling boundaries by introducing novel mechanisms at all layers of the design stack. The main idea lies on the realization of the intrinsic hardware heterogeneity and the development of mechanisms that will automatically expose the unique varying capabilities of each hardware. Low overhead schemes are employed to monitor and predict the hardware behavior and report it to the system software. The system software including a virtualization and resource management layer is responsible for optimizing the system operation in terms of energy or performance, while guaranteeing non-disruptive operation under the extended operating points. Our characterization results on a 64-bit ARMv8 micro-server in 28nm process reveal large voltage margins in terms of Vmin variation among the 8 cores of the CPU chip, among three different sigma chips, and among different benchmarks with the potential to obtain up-to 38.8% energy savings. Similarly, DRAM characterizations show that refresh rate and voltage can be relaxed by 35x and 5%, respectively, leading to 23.2% power savings on average.

SWITCHES is a task-based dataflow runtime that implements a lightweight distributed triggering system for runtime dependence resolution and uses static scheduling and compile-time assignment policies to reduce runtime overheads. Unlike other systems, the granularity of loop-tasks can be increased to favor data-locality, even when having dependences across different loops. SWITCHES introduces explicit task resource allocation mechanisms for efficient allocation of resources and adopts the latest OpenMP Application Programming Interface (API), as to maintain high levels of programming productivity. It provides a source-to-source tool that automatically produces thread-based code. Performance on an Intel Xeon-Phi shows good scalability and surpasses OpenMP by an average of 32%.

Our target in this work is to study ways of exploring the parallelism offered by vectorization on accelerators with very wide vector units. To this end, we implemented two kernels that derive from the Wilson Dslash operator and investigate several data layout techniques for increasing the scalability of lattice QCD scientific kernels suitable for the Intel Xeon Phi. In parts of the application where real numbers are used for computation, we see a 6.6x increase in bandwidth compared to scalar code, thanks to the auto-vectorization by the compiler. In other kernels where arithmetic operations on complex numbers dominate, our hand-vectorized code out-performs the auto-vectorization of the compiler. In this paper we find that our proposed Hopping Vector-friendly Ordering allows for more efficient vectorization of complex arithmetic floating point operations. Using this data layout, we manage to increase the sustained bandwidth by approximately 1.8x.

The current trend in processor design is to increase the number of cores as to achieve a desired performance. While having a large number of cores on a chip seems to be feasible in terms of the hardware, the development of the software that is able to exploit that parallelism is one of the biggest challenges. In this paper we propose a Data-Flow based system that can be used to exploit the parallelism in large-scale many-core processors in an effective and efficient way. Our proposed system - TFlux SCC - is an extension of the TFlux Data-Driven Multithreading (DDM), which evolved to exploit the parallelism of the 48-core Intel Single-chip Cloud Computing (SCC) processor. With TFlux SCC we achieve scalable performance using a global address space without the need of cache-coherency support. Our scalability study shows that application's performance can scale, with speedup results reaching up to 48x for 48 cores. The findings of this work provide insight towards what a Data-Flow implementation requires and what not from a many-core architecture in order to scale the performance.

Decision Support System (DSS) workloads are known to be one of the most time-consuming database workloads that process large data sets. Traditionally, DSS queries have been accelerated using large-scale multiprocessors. In this work we exploit the benefits of using future many-core architectures, more specifically on-chip clustered many-core architectures. To achieve this goal we propose different representative data parallel versions of the original database scan and join algorithms. We also study the impact on the performance when on-chip memory, shared among all cores, is used as a prefetching buffer. For our experiments we study the behaviour of three queries from the standard DSS benchmark TPC-H executing on the Intel Single chip Cloud Computer experimental processor (Intel SCC). Our results show that parallelism can be well exploited by such architectures and how important it is to have a balance between computation and data intensity. Moreover, from our experimental results we show that performance improvement of 5x and 10x for the corresponding query implementation without data prefetching. Finally we show how we could efficiently use the system in order to achieve high power-performance efficiency when using the proposed prefetching buffer.

Low-Density Parity-Check (LDPC) codes are powerful error correcting codes used today in communication standards such as DVB-S2 and WiMAX to transmit data inside noisy channels with high error probability. LDPC decoding is computationally demanding and requires irregular accesses to memory which makes it suitable for parallelization. The recent introduction of the many-core Single-chip Cloud Computer (SCC) from Intel research Labs has created new opportunities and also new challenges for programmers that wish to exploit conveniently the high level of parallelism available in the architecture. In this paper we propose three different implementations: a distributed, a shared and a multi-codeword implementation, for LDPC decoding algorithms that explore the Intel SCC scaling opportunities. From the experimental results we observed that the distributed memory model couldn't scale due to the large number of messages exchanged by the parallel kernels, while the shared memory model had a limited scaling due to the overhead added by the uncacheable shared memory. On the other hand, the multi-codeword implementation scales almost linearly acheving a relative throughput of 28 for 32 cores.