Row access strobe (RAS) clobber and row hammer failure mitigation
There are provided systems and methods that include at least one memory that has a plurality of memory cells. The cells may be disposed in rows and columns. The device can further include a controller that is communicatively coupled to the at least one memory, and the controller may be configured by its hardware topology and its instruction set and/or by a communicatively coupled processor or higher-level system or subsystem to maintain data integrity in the at least one memory and/or to prevent or mitigate malicious access patterns that may compromise the at least one memory. The controller may be configured to execute a deterministic protocol in conjunction with or sequentially to a probabilistic protocol to achieve one or more of the above-noted functions.
1. A memory device comprising:
at least one memory including a plurality of memory cells disposed in rows and columns; and
a controller, communicatively coupled to the at least one memory;
wherein the controller maintains data integrity in the at least one memory by executing operations comprising:
receiving a row activation (ACT) command for a row;
starting a RAS counter and incrementing the RAS counter in a subsequent instance of an edge of a clock;
determining if a pre-charge (PRE) command has been received for the row, and if said pre-charge command has been received, setting the RAS counter to zero;
determining whether the RAS counter is greater than a RAS clobber counter threshold (RCCT) if said pre-charge command was not received;
triggering another row activation command for a second row (ACT+1) and setting the RAS counter to zero; and
incrementing the RAS counter at another edge of the clock when the RAS counter is greater than the RCCT.
2. The memory device of claim 1 , wherein the memory device comprises a DRAM.
3. The memory device of claim 1 , wherein the controller is further configured to execute a base protocol including a probabilistic protocol configured to mitigate a native risk of failure of the at least one memory.
4. The memory device of claim 1 , wherein the controller is configured to mitigate a RH1 risk (+/1 rows), a RH2 risk (+/−2 rows), and a RAS clobber risk as risk of failure of the at least one memory.
5. The memory device of claim 3 , wherein the base protocol includes at least one of a RH refresh (RHR) protocol, an address sampling (AS) protocol, and a content addressable memory (CAM) protocol.
6. The memory device of claim 3 , wherein the base protocol includes an activity tracking (AT) protocol.
7. The memory device of claim 3 , wherein the base protocol further includes a native deterministic RH risk mitigation protocol.
8. The memory device of claim 7 , wherein the native deterministic RH risk mitigation protocol is based on a DRFM servicing protocol.
9. The memory device of claim 3 , wherein the base protocol includes at least one of a space saving (SS) RH protocol, a Revised Misra-Grise RH protocol, and a lockout SS RH protocol.
10. The memory device of claim 3 , wherein the base protocol includes a Ping-Pong protocol.
11. A method for mitigating risk of failure in a memory device including at least one memory, the method comprising:
executing, by a controller configured to maintain data integrity in the at least one, operations comprising:
receiving a row activation (ACT) command for a row;
starting a RAS counter and incrementing said RAS counter in a subsequent instance of an edge of a clock;
determining if a pre-charge command has been received for the row, and if said pre-charge command has been received, setting the RAS counter zero;
determining whether the RAS counter is greater than a RAS clobber counter threshold (RCCT) if said pre-charge command was not received; and
triggering another row activation command for a second row (ACT+1) and setting the RAS counter to zero, and subsequently, incrementing the RAS counter at another edge of the clock, when the RAS counter is greater than the RCCT.
12. The method of claim 11 , wherein the memory device comprises a DRAM.
13. The method of claim 11 , wherein the operations further include executing a base protocol to mitigate a risk of failure selected from the set of failure risks consisting of a Row Hammer (RH) failure risk, and a RAS Clobber failure risk.
14. The method of claim 13 , wherein when the failure risk is a RH failure risk, the deterministic protocol is configured to mitigate a RH1 risk (+/1 rows), a RH2 risk (+/−2 rows), a RAS clobber risk, and an inverse hammer risk.
15. The method of claim 14 , wherein the inverse hammer risk is a DRFM-induced RH failure risk consisting of a RH/3/4 (+/−3, 4) risk.
16. The method of claim 13 , wherein the base protocol includes at least one of a RH refresh (RHR) protocol, an address sampling (AS) protocol, and a content addressable memory (CAM) protocol.
17. The method of claim 13 , wherein the base protocol includes an activity tracking (AT) protocol; and
wherein the base protocol further includes a native deterministic RH risk mitigation protocol.
18. The method of claim 13 , wherein the controller is configured to mitigate failure risks deterministically.
19. The method of claim 13 , wherein the controller is configured to mitigate failure risks deterministically in conjunction with addressing native failure risks using a probabilistic mitigation protocol.
20. A non-transitory computer readable medium having stored thereon computer executable instructions that, if executed by a computing device, cause the computing device to perform a method for mitigating risk of failure in a memory device including at least one memory, the method comprising:
executing, by a controller configured to maintain data integrity in the at least one, operations comprising:
receiving a row activation (ACT) command for a row;
starting a RAS counter and incrementing said RAS counter in a subsequent instance of an edge of a clock;
determining if a pre-charge command has been received for the row, and if said pre-charge command has been received, setting the RAS counter zero;
determining whether the RAS counter is greater than a RAS clobber counter threshold (RCCT) if said pre-charge command was not received; and
triggering another row activation command for a second row (ACT+1) and setting the RAS counter to zero, and subsequently, incrementing the RAS counter at another edge of the clock, when the RAS counter is greater than the RCCT.