Customized Interfaces for Modern Storage Devices

In the past decade, we have seen two major evolutions on storage technologies: flash storage and non-volatile memory. These storage technologies are both vastly different in their properties and implementations than the disk-based storage devices that current soft- ware stacks and applications have been built for and optimized over several decades. The second major trend that the industry has been witnessing is new classes of applications that are moving away from the conventional ACID (SQL) database access to storage. The resulting new class of NoSQL and in-memory storage applications consume storage using entirely new application programmer interfaces than their predecessors. The most significant outcome given these trends is that there is a great mismatch in terms of both application access interfaces and implementations of storage stacks when consuming these new technologies. In this work, we study the unique, intrinsic properties of current and next-generation storage technologies and propose new interfaces that allow application developers to get the most out of these storage technologies without having to become storage experts them- selves. We first build a new type of NoSQL key-value (KV) store that is FTL-aware rather than flash optimized. Our novel FTL cooperative design for KV store proofed to simplify development and outperformed state of the art KV stores, while reducing write amplification. Next, to address the growing relevance of byte-addressable persistent memory, we build a new type of KV store that is customized and optimized for persistent memory. The resulting KV store illustrates how to program persistent effectively while exposing a simpler interface and performing better than more general solutions. As the final component of the thesis, we build a generic, native storage solution for byte-addressable persistent memory. This new solution provides the most generic interface to applications, allow- ing applications to store and manipulate arbitrarily structured data with strong durability and consistency properties. With this new solution, existing applications as well as new “green field” applications will get to experience native performance and interfaces that are customized for the next storage technology evolution

Architectural Techniques to Enable Reliable and Scalable Memory Systems

High capacity and scalable memory systems play a vital role in enabling our desktops, smartphones, and pervasive technologies like Internet of Things (IoT). Unfortunately, memory systems are becoming increasingly prone to faults. This is because we rely on technology scaling to improve memory density, and at small feature sizes, memory cells tend to break easily. Today, memory reliability is seen as the key impediment towards using high-density devices, adopting new technologies, and even building the next Exascale supercomputer. To ensure even a bare-minimum level of reliability, present-day solutions tend to have high performance, power and area overheads. Ideally, we would like memory systems to remain robust, scalable, and implementable while keeping the overheads to a minimum. This dissertation describes how simple cross-layer architectural techniques can provide orders of magnitude higher reliability and enable seamless scalability for memory systems while incurring negligible overheads.Comment: PhD thesis, Georgia Institute of Technology (May 2017

Secure execution environments through reconfigurable lightweight cryptographic components

Software protection is one of the most important problems in the area of computing as it affects a multitude of players like software vendors, digital content providers, users, and government agencies. There are multiple dimensions to this broad problem of software protection. The most important ones are: (1) protecting software from reverse engineering. (2) protecting software from tamper (or modification). (3) preventing software piracy. (4) verification of integrity of the software;In this thesis we focus on these areas of software protection. The basic requirement to achieve these goals is to provide a secure execution environment, which ensures that the programs behave in the same way as it was designed, and the execution platforms respect certain types of wishes specified by the program;We take the approach of providing secure execution environment through architecture support. We exploit the power of reconfigurable components in achieving this. The first problem we consider is to provide architecture support for obfuscation. This also achieves the goals of tamper resistance, copy protection, and IP protection indirectly. Our approach is based on the intuition that the software is a sequence of instructions (and data) and if the sequence as well the contents are obfuscated then all the required goals can be achieved;The second problem we solve is integrity verification of the software particularly in embedded devices. Our solution is based on the intuition that an obfuscated (permuted) binary image without any dynamic traces reveals very little information about the IP of the program. Moreover, if this obfuscation function becomes a shared secret between the verifier and the embedded device then verification can be performed in a trustworthy manner;Cryptographic components form the underlying building blocks/primitives of any secure execution environment. Our use of reconfigurable components to provide software protection in both Arc 3 D and TIVA led us to an interesting observation about the power of reconfigurable components. Reconfigurable components provide the ability to use the secret (or key) in a much stronger way than the conventional cryptographic designs. This opened up an opportunity for us to explore the use of reconfigurable gates to build cryptographic functions