Runtime Detection of a Bandwidth Denial Attack from a Rogue Network-on-Chip

Chips with high computational power are the crux of today’s pervasive complex digital systems. Microprocessor circuits are evolving towards many core designs with the integration of hundreds of processing cores, memory elements and other devices on a single chip to sustain high performance computing while maintaining low design costs. Two decisive paradigm shifts in the semiconductor industry have made this evolution possible: (a) architectural and (b) organizational. At the heart of the architectural innovation is a scalable high speed data communication structure, the network-on-chip (NoC). NoC is an interconnect network for the glueless integration of on-chip components in the modern complex communication centric designs. In the recent days, NoC has replaced the traditional bus based architecture owing to its structured and modular design, scalability and low design cost. The organizational revolution has resulted in a globalized and collaborative supply chain with pervasive use of third party intellectual properties to reduce the time-to-market and overall design costs. Despite the advantages of these paradigm shifts, modern system-on-chips pose a plethora of security vulnerabilities. This work explores a threat model arising from a malicious NoC IP embedded with a hardware trojan affecting the resource availability of on-chip components. A rigorous simulation infrastructure is established to evaluate the feasibility and potency of such an attack. Further, a non-invasive runtime monitoring technique is proposed and thoroughly investigated to ensure the trustworthiness of a third party NoC IP with low overheads

Toward Reliable, Secure, and Energy-Efficient Multi-Core System Design

Computer hardware researchers have perennially focussed on improving the performance of computers while stipulating the energy consumption under a strict budget. While several innovations over the years have led to high performance and energy efficient computers, more challenges have also emerged as a fallout. For example, smaller transistor devices in modern multi-core systems are afflicted with several reliability and security concerns, which were inconceivable even a decade ago. Tackling these bottlenecks happens to negatively impact the power and performance of the computers. This dissertation explores novel techniques to gracefully solve some of the pressing challenges of the modern computer design. Specifically, the proposed techniques improve the reliability of on-chip communication fabric under a high power supply noise, increase the energy-efficiency of low-power graphics processing units, and demonstrate an unprecedented security loophole of the low-power computing paradigm through rigorous hardware-based experiments

Adaptive Routing Approaches for Networked Many-Core Systems

Through advances in technology, System-on-Chip design is moving towards integrating tens to hundreds of intellectual property blocks into a single chip. In such a many-core system, on-chip communication becomes a performance bottleneck for high performance designs. Network-on-Chip (NoC) has emerged as a viable solution for the communication challenges in highly complex chips. The NoC architecture paradigm, based on a modular packet-switched mechanism, can address many of the on-chip communication challenges such as wiring complexity, communication latency, and bandwidth. Furthermore, the combined benefits of 3D IC and NoC schemes provide the possibility of designing a high performance system in a limited chip area. The major advantages of 3D NoCs are the considerable reductions in average latency and power consumption. There are several factors degrading the performance of NoCs. In this thesis, we investigate three main performance-limiting factors: network congestion, faults, and the lack of efficient multicast support. We address these issues by the means of routing algorithms. Congestion of data packets may lead to increased network latency and power consumption. Thus, we propose three different approaches for alleviating such congestion in the network. The first approach is based on measuring the congestion information in different regions of the network, distributing the information over the network, and utilizing this information when making a routing decision. The second approach employs a learning method to dynamically find the less congested routes according to the underlying traffic. The third approach is based on a fuzzy-logic technique to perform better routing decisions when traffic information of different routes is available. Faults affect performance significantly, as then packets should take longer paths in order to be routed around the faults, which in turn increases congestion around the faulty regions. We propose four methods to tolerate faults at the link and switch level by using only the shortest paths as long as such path exists. The unique characteristic among these methods is the toleration of faults while also maintaining the performance of NoCs. To the best of our knowledge, these algorithms are the first approaches to bypassing faults prior to reaching them while avoiding unnecessary misrouting of packets. Current implementations of multicast communication result in a significant performance loss for unicast traffic. This is due to the fact that the routing rules of multicast packets limit the adaptivity of unicast packets. We present an approach in which both unicast and multicast packets can be efficiently routed within the network. While suggesting a more efficient multicast support, the proposed approach does not affect the performance of unicast routing at all. In addition, in order to reduce the overall path length of multicast packets, we present several partitioning methods along with their analytical models for latency measurement. This approach is discussed in the context of 3D mesh networks.Siirretty Doriast

ENOC : rede-em-chip expansível

Orientador: Luiz Carlos Pessoa AlbiniCoorientador: Marco Antonio Zanata AlvesTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Informática. Defesa : Curitiba, 10/02/2018Inclui referências: p. 71-81Resumo: Os sistemas multiprocessados integrados em chip têm emergido como uma importante tendência para projetos de sistemas em chip. Estes sistemas são formados por vários elementos de processamento conectados originalmente por um barramento compartilhado. Este barramento possui restrições à crescente integração de mais elementos de processamento em um único chip, pois não permite a comunicação paralela e à medida que os elementos aumentam o barramento apresenta menor desempenho na comunicação devido a capacidade fixa. A rede em chip, do inglês Network-on-Chip (NoC), é uma alternativa ao barramento que permite a comunicação paralela e escalável entre os diferentes elementos de processamento de um chip. Tradicionalmente, a NoC é composta por interligações metálicas entre os roteadores e cada roteador é ligado a um elemento de processamento, a comunicação acontece por encaminhamento de pacotes seguindo um determinado algoritmo de roteamento. Esta comunicação pode ser estendida de ligações metálicas para ligações sem fio principalmente para mitigar a latência resultante dos diversos saltos necessários para comunicar elementos de processamento de um chip, em especial dos mais distantes, uma vez que na comunicação sem fio o pacote é transmitido com apenas um salto. Entretanto, há sobrecustos em utilizar esta tecnologia, e por isto várias pesquisas abordam a interligação de apenas regiões do chip, e não todos os elementos. Mesmo com a evolução das formas de comunicação em um chip, a capacidade de um sistema em chip estava limitada aos seus elementos inseridos em momento de fabricação. Esta tese apresenta a ENoC, uma rede em chip expansível capaz de interligar sistemas em chip distintos reconfigurando-se para oferecer uma visão única de sistema com processamento paralelo distribuído por passagem de mensagem. A arquitetura e a comunicação na ENoC são apresentadas juntamente com uma discussão sobre o uso de sistema operacional e organização da memória. A avaliação é realizada por meio de simulações e análise de desempenho. A segurança da comunicação entre os chips é discutida e sistemas de criptografias são avaliados para manter a confidencialidade da informação. Com os resultados dos experimentos concluímos que a ENoC é uma abordagem adequada para a expandir os recursos entre chips e que cada sistema de criptografia possui vantagens e desvantagens próprias para proteger a comunicação sem fio entre as ENoCs, e a escolha de qual criptossistema é uma decisão de projeto. Palavras-chave: sistema em chip, rede em chip, criptografia.Abstract: Multiprocessor Systems-on-Chip has emerged as an important trend for System-on-Chip designs. These systems consists in several processing elements interconnected, originally, by a shared bus. This bus has restrictions to the increasing integration of many processing elements in a single chip, due to does not allow the parallel communication and as the elements increase the bus presents fewer communication performance because its capacity is fixed. The Network-on-Chip (NoC) is an alternative to the bus that allows parallel and scalable communication among all processing elements on chip. Traditionally, the NoC is made up of metallic wired interconnecting the routers and each router is connected to a processing element, the communication is performed by packets routing following a routing algorithm. This communication may be extended from metal wired links to wireless links, mainly to mitigate the latency from several needed hops to communicate processing elements, in special, the more distant ones, once in wireless communication the packet is transmitted by a single hop. However, there are additional costs in using this technology, and for this reason several researches focus on interconnecting only chip regions, not all elements. Even with the evolution of communication on NoC, the capacity of a system-on-chip was limited to its elements at manufacture time. This thesis presents the ENoC, an Expansible Network-on-Chip capable of interconnecting distinct reconfigurable SoCs to provide a single system view with parallel processing distributed by message passing. The architecture and communication of ENoC are presented within a discussion of operational system and memory organization. The evaluation is performed by simulation and performance analysis. The security of inter-chip communication is discussed and cryptography systems are evaluated to offer a confidentiality of the information. With the results, we conclude that the ENoC is a suitable approach to expand the resources between chips and that each encryption system has its own advantages and disadvantages in order to protect the wireless inter-chip communication, in such way, the choice of which criptosystem is a design decision. Keywords: system-on-chip, network-on-chip, cryptography

Software-based and regionally-oriented traffic management in Networks-on-Chip

Since the introduction of chip-multiprocessor systems, the number of integrated cores has been steady growing and workload applications have been adapted to exploit the increasing parallelism. This changed the importance of efficient on-chip communication significantly and the infrastructure has to keep step with these new requirements. The work at hand makes significant contributions to the state-of-the-art of the latest generation of such solutions, called Networks-on-Chip, to improve the performance, reliability, and flexible management of these on-chip infrastructures

Multistage Packet-Switching Fabrics for Data Center Networks

Recent applications have imposed stringent requirements within the Data Center Network (DCN) switches in terms of scalability, throughput and latency. In this thesis, the architectural design of the packet-switches is tackled in different ways to enable the expansion in both the number of connected endpoints and traffic volume. A cost-effective Clos-network switch with partially buffered units is proposed and two packet scheduling algorithms are described. The first algorithm adopts many simple and distributed arbiters, while the second approach relies on a central arbiter to guarantee an ordered packet delivery. For an improved scalability, the Clos switch is build using a Network-on-Chip (NoC) fabric instead of the common crossbar units. The Clos-UDN architecture made with Input-Queued (IQ) Uni-Directional NoC modules (UDNs) simplifies the input line cards and obviates the need for the costly Virtual Output Queues (VOQs). It also avoids the need for complex, and synchronized scheduling processes, and offers speedup, load balancing, and good path diversity. Under skewed traffic, a reliable micro load-balancing contributes to boosting the overall network performance. Taking advantage of the NoC paradigm, a wrapped-around multistage switch with fully interconnected Central Modules (CMs) is proposed. The architecture operates with a congestion-aware routing algorithm that proactively distributes the traffic load across the switching modules, and enhances the switch performance under critical packet arrivals. The implementation of small on-chip buffers has been made perfectly feasible using the current technology. This motivated the implementation of a large switching architecture with an Output-Queued (OQ) NoC fabric. The design merges assets of the output queuing, and NoCs to provide high throughput, and smooth latency variations. An approximate analytical model of the switch performance is also proposed. To further exploit the potential of the NoC fabrics and their modularity features, a high capacity Clos switch with Multi-Directional NoC (MDN) modules is presented. The Clos-MDN switching architecture exhibits a more compact layout than the Clos-UDN switch. It scales better and faster in port count and traffic load. Results achieved in this thesis demonstrate the high performance, expandability and programmability features of the proposed packet-switches which makes them promising candidates for the next-generation data center networking infrastructure