HammerSim: A System-Level Tool to Model RowHammer

2026-05-26

AI Summary

This work addresses the critical gap in existing simulators, which lack system-level modeling capabilities to accurately assess the complex impact of RowHammer vulnerabilities across operating systems and cross-layer defenses, thereby threatening the reliability and security of modern computing platforms. To bridge this gap, the authors develop a full-system simulation framework based on gem5, incorporating for the first time a scalable, probabilistic DRAM bit-flip model that faithfully captures RowHammer effects. The framework integrates both Target Row Refresh (TRR) hardware mitigations and selective ECC-based software protections. Model fidelity is validated against real DDR4 memory behavior using Jensen–Shannon divergence, demonstrating its effectiveness in evaluating attack success rates, defense mechanisms, and susceptibility of benign workloads to RowHammer-induced errors.

Abstract

Modern architecture research relies on simulators to evaluate system security, yet analyzing emerging hardware vulnerabilities like RowHammer requires full-system visibility. As RowHammer vulnerabilities worsen with continuous technology scaling, existing simulators lack the system-level models needed to study complex OS effects and cross-layer mitigations. This tool deficiency leaves modern computing platforms exposed to severe reliability and security risks. In this work, we present HammerSim, a gem5-based framework for modeling RowHammer at the full-system level. HammerSim integrates probability-driven bitflip modeling to realistically capture the behavior of RowHammer. It further enables evaluation of hardware and software mitigations such as TRR and selective ECC. We validate HammerSim's bitflip modeling against real DDR4 DIMMs using JS divergence, demonstrating its utility in studying attacks, defenses, and benign workload susceptibility. Our framework provides an extensible platform to bridge the gap between hardware experiments and architectural simulation.

Problem

• RowHammer
• system-level simulation
• hardware vulnerability
• security risk
• reliability

Innovation

• RowHammer
• full-system simulation
• bitflip modeling
• cross-layer mitigation
• gem5