一句话：提出分析/变换工具 cio，在二进制代码上自动检测并缓解未来指令中心微架构优化引入的时序侧信道。
随着摩尔定律放缓，以指令为中心的微架构优化可能引入新的时序侧信道。这类侧信道源于硬件而非源代码，传统常量时间编程难以消除。本文关注两类尚未部署的优化：静默存储（silent stores）在写无效时丢弃在途存储，从而泄漏待写秘密；计算简化（computation simplification）运行时短路平凡计算，泄漏算术操作数。传统常量时间技术无法处理寄存器溢出、地址计算和复杂指令微操作等泄漏点。为此，作者设计、实现并评估了 cio：一个面向密码代码、检测并缓解上述侧信道的分析与二进制变换工具/流程。在专用缓解不可用时，cio 可作为提供受验证缓解的后备方案。
With the end of Moore's Law-based scaling, novel microarchitectural optimizations are being patented, researched, and implemented at an increasing rate. Previous research has examined recently published patents and papers and demonstrated ways these upcoming optimizations present new security risks via novel side channels. As these side channels are introduced by microarchitectural optimization, they are not generically solvable in source code. In this paper, we build program analysis and transformation tools for automatically mitigating the security risks introduced by future instruction-centric microarchitectural optimizations. We focus on two classes of optimizations that are not yet deployed: silent stores and computation simplification. Silent stores are known to leak secret data being written to memory by dropping in-flight stores that will have no effect. Computation simplification is known to leak operands to arithmetic instructions by shortcutting trivial computations at execution time. This presents problems that classical constant-time techniques cannot handle: register spills, address calculations, and the micro-ops of complex instructions are all potentially leaky. To address these problems, we design, implement, and evaluate a process and tool, cio, for detecting and mitigating these types of side channels in cryptographic code. cio is a backstop, providing verified mitigation for novel microarchitectural side-channels when more specialized and efficient hardware or software tools, such as microcode patches, are not yet available.
@inproceedings{FlandersSMGK24,
title = {Avoiding Instruction-Centric Microarchitectural Timing Channels Via Binary-Code Transformations},
author = {Michael Flanders and Reshabh K Sharma and Alexandra E. Michael and Dan Grossman and David Kohlbrenner},
booktitle = {ASPLOS},
year = {2024},
doi = {10.1145/3620665.3640400}
}