Rubix: Reducing the Overhead of Secure Rowhammer Mitigations via Randomized Line-to-Row Mapping

Modern systems mitigate Rowhammer using victim refresh, which refreshes neighbours of an aggressor row when it encounters a specified number of activations. Unfortunately, complex attack patterns like Half-Double break victim-refresh, rendering current systems vulnerable. Instead, recently proposed secure Rowhammer mitigations perform mitigative action on the aggressor rather than the victims. Such schemes employ mitigative actions such as row-migration or access-control and include AQUA, SRS, and Blockhammer. While these schemes incur only modest slowdowns at Rowhammer thresholds of few thousand, they incur prohibitive slowdowns (15%-600%) for lower thresholds that are likely in the near future. The goal of our paper is to make secure Rowhammer mitigations practical at such low thresholds.