Revisiting row hammer: A deep dive into understanding and resolving the issue

Abstract

Row hammer is a vulnerability in Dynamic Random Access Memory (DRAM) chips, whereby repeatedly accessing a specific row in the DRAM chip may cause bit flips in memory cells. As the DRAM fabrication process scales down, DRAM chips are becoming more susceptible to row hammer. To gain a comprehensive understanding of the row hammer vulnerability, we investigate its mechanisms, attack patterns, simulation methodology and tools, as well as mitigation techniques. We also summarize several impact factors of row hammer, including timing parameters, temperature, DRAM fabrication process, radiation effects, voltage level, and data patterns. Finally, we point out future research directions, such as exploring how radiation effects and temperature impact row hammer, modeling and simulation methodology under advanced technology nodes, and deep-learning-based mitigation solutions.