Efficient Hardware Support for Deterministic Replay Debugging of Memory Races, Interrupts and Self Modifying Code

Significant time is spent by companies trying to reproduce and fix bugs. BugNet is a recent architecture proposal that provides architecture support for debugging. It focuses on continuously recording information about the program execution which can be communicated back to the developer on encountering an abrupt program termination. Using that information the developer can deterministically replay the program execution and can reproduce and fix the bugs. To enable deterministic replay for multi-threaded programs BugNet assumed hardware support to record the ordering between the memory operations executed across all the threads. In this paper, we significantly reduce the hardware support required for logging multi-threaded programs by exploiting an important property in BugNet checkpointing scheme that allows one to independently replay each thread without explicitly logging shared memory dependences. During offline debugging, we independently replay each thread to collect memory traces for their execution. Given these traces, we show how one can infer the memory ordering across the threads. In addition, we present a set of optimizations to improve the complexity and functionality of the BugNet architecture. Those optimizations include supporting self-modifying code and reducing the log size in the presence of frequent interrupts.Pre-2018 CSE ID: CS2005-084