Defending NVM Against Inconsistent Write Attack

Non-volatile Memory(NVM)such as Phase Change Memory(PCM)are vulnerable to malicious attacks due to limited write endurance.NVM cells usually demonstrate vast endurance variation due to Process Variation(PV).Uniform distribution of write traffic makes weak cells worn out early.To prolong the lifetime of NVM,PV-aware wear leveling schemes try to map intensive writes to cells with high endurance(strong cells).These schemes assume that the future write intensity distribution is consistent with the current observation window.They are vulnerable to Inconsistent Write Attack which reverses the write intensity distribution in two adjacent observation windows.Previous schemes randomly distribute writes traffic according to the endurance of cells to defend NVM against Inconsistent Write Attack but cause wrong page swapping.CLIMBER is proposed to neutralize Inconsistent Write Attack for NVM.CLIMBER dynamically changes harmful address mappings by address remapping so that intensive writes to weak cells are redirected to strong cells to defend NVM against Inconsistent Write Attack.The remapping threshold of different pages is set according to their endurance to make a tradeoff between overhead and lifetime.CLIMBER also conceals weak NVM cells from attackers by randomly mapping cold addresses to weak NVM regions.Experiment results show that CLIMBER is able to defend NVM against Inconsistent Write Attack efficiently.Compared with the state-of-the-art Toss-up Wear Leveling(TWL)scheme,CLIMBER can reduce maximum page wear rate under inconsistent write attack significantly by 43.2%,and prolong the lifetime of PCM under Inconsistent Write Attack from 4.19 years to 7.37 years.Compared with TWL,CLIMBER can also reduce maximum page wear rate under different benchmarks significantly by 55.4% on average with negligible performance and hardware overhead.