arm64: mte: initialize RGSR_EL1.SEED in __cpu_setup
A valid implementation choice for the ChooseRandomNonExcludedTag() pseudocode function used by IRG is to behave in the same way as with GCR_EL1.RRND=0. This would mean that RGSR_EL1.SEED is used as an LFSR which must have a non-zero value in order for IRG to properly produce pseudorandom numbers. However, RGSR_EL1 is reset to an UNKNOWN value on soft reset and thus may reset to 0. Therefore we must initialize RGSR_EL1.SEED to a non-zero value in order to ensure that IRG behaves as expected. Signed-off-by:Peter Collingbourne <pcc@google.com> Fixes: 3b714d24 ("arm64: mte: CPU feature detection and initial sysreg configuration") Cc: <stable@vger.kernel.org> # 5.10 Link: https://linux-review.googlesource.com/id/I2b089b6c7d6f17ee37e2f0db7df5ad5bcc04526c Acked-by:
Mark Rutland <mark.rutland@arm.com> Link: https://lore.kernel.org/r/20210507185905.1745402-1-pcc@google.com Signed-off-by:
Catalin Marinas <catalin.marinas@arm.com>
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a1bed090
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