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Data memory-dependent prefetcher

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A data memory-dependent prefetcher is a memory prefetcher that looks at cache memory content for possible pointer values, and prefetches the data at those locations into cache if it sees memory access patterns that suggest following those pointers would be useful.[1][2]

As of 2022, data prefetching was already a common feature in CPUs,[3] but most prefetchers do not inspect the data within the cache for pointers, instead working by monitoring memory access patterns. Data memory-dependent prefetchers take this one step further.

The data memory-dependent prefetcher in Apple's M1 computer architecture was demonstrated to be capable of being used as a memory side-channel in work first reported in 2024.[4] As of the time of its announcement, no practical attacks using the side-channel were yet known to exist.[1]

Some Intel Core CPUs feature what Intel calls "Data Dependent Prefetcher" functionality which appears to be similar, but Intel states that they have features to prevent them being used for side-channel attacks.[5]

References

  1. ^ a b "Augury". www.prefetchers.info. 2022-05-02. Retrieved 2024-03-21.
  2. ^ Vicarte, Jose Rodrigo Sanchez; Flanders, Michael; Paccagnella, Riccardo; Garrett-Grossman, Grant; Morrison, Adam; Fletcher, Christopher W.; Kohlbrenner, David (May 2022). "Augury: Using Data Memory-Dependent Prefetchers to Leak Data at Rest". IEEE: 1491–1505. doi:10.1109/SP46214.2022.9833570. ISBN 978-1-6654-1316-9. {{cite journal}}: Cite journal requires |journal= (help)
  3. ^ Bakhshalipour, Mohammad; Shakerinava, Mehran; Golshan, Fatemeh; Ansari, Ali; Lotfi-Karman, Pejman; Sarbazi-Azad, Hamid (2020-09-01), A Survey on Recent Hardware Data Prefetching Approaches with An Emphasis on Servers, doi:10.48550/arXiv.2009.00715, retrieved 2024-03-21
  4. ^ Goodin, Dan (2024-03-21). "Unpatchable vulnerability in Apple chip leaks secret encryption keys". Ars Technica. Retrieved 2024-03-21.
  5. ^ "Data Dependent Prefetcher". Intel. Retrieved 2024-03-21.