Biblio

GPUs have been widely used to accelerate big-data inference applications and scientific computing through their parallelized hardware resources and programming model. Their extreme parallelism increases the possibility of bugs such as data races and un-coalesced memory accesses, and thus verifying program correctness is critical. State-of-the-art GPU program verification efforts mainly focus on analyzing application-level programs, e.g., in C, and suffer from the following limitations: (1) high false-positive rate due to coarse-grained abstraction of synchronization primitives, (2) high complexity of reasoning about pointer arithmetic, and (3) keeping up with an evolving API for developing application-level programs. In this paper, we address these limitations by modeling GPUs and reasoning about programs at the instruction level. We formally model the Nvidia GPU at the parallel execution thread (PTX) level using the recently proposed Instruction-Level Abstraction (ILA) model for accelerators. PTX is analogous to the Instruction-Set Architecture (ISA) of a general-purpose processor. Our formal ILA model of the GPU includes non-synchronization instructions as well as all synchronization primitives, enabling us to verify multithreaded programs. We demonstrate the applicability of our ILA model in scalable GPU program verification of data-race checking. The evaluation shows that our checker outperforms state-of-the-art GPU data race checkers with fewer false-positives and improved scalability.

Formal security verification of firmware interacting with hardware in modern Systems-on-Chip (SoCs) is a critical research problem. This faces the following challenges: (1) design complexity and heterogeneity, (2) semantics gaps between software and hardware, (3) concurrency between firmware/hardware and between Intellectual Property Blocks (IPs), and (4) expensive bit-precise reasoning. In this paper, we present a co-verification methodology to address these challenges. We model hardware using the Instruction-Level Abstraction (ILA), capturing firmware-visible behavior at the architecture level. This enables integrating hardware behavior with firmware in each IP into a single thread. The co-verification with multiple firmware across IPs is formulated as a multi-threaded program verification problem, for which we leverage software verification techniques. We also propose an optimization using abstraction to prevent expensive bit-precise reasoning. The evaluation of our methodology on an industry SoC Secure Boot design demonstrates its applicability in SoC security verification.