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Also important to mention that PAC is a new ARMv8.2 feature and previous versions of ARM have no PAC system at all. The only ARM chips with PAC are from Apple a
by gjsman-1000 4y ago
Also important to mention that PAC is a new ARMv8.2 feature and previous versions of ARM have no PAC system at all. The only ARM chips with PAC are from Apple and AWS Graviton3 - any other chip has no hardware protections against this.
So ultimately, right now, it's just downgrading a very new protection to as if it didn't exist, which is exactly how 98% of ARM chips in the world operate right now. Not great, not terrible, A for effort, was worth a shot, speculative execution breaks everything.
- gjsman-1000 4y agoEdit: Correction, ARMv8.3, not ARMv8.2.
- adrian_b 4y agoBesides the Apple CPUs and Graviton 3 (Armv8.4-A), the cores introduced by ARM in 2021 and present in some 2022 smartphones (Cortex-X2, Cortex-A710, Cortex-A510), which implement Armv9.0-A, also support PAC.
- fulafel 4y agoThe doc in the kernel tree is dated 2017, so it's percolated to products quite slowly: https://www.kernel.org/doc/html/latest/arm64/pointer-authentication.html https://www.kernel.org/doc/html/latest/arm64/pointer-authent...
- shp0ngle 4y agoAh thanks, this finally makes sense in context