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9eecef05 |
| 15-Nov-2023 |
Andrew Turner <andrew@FreeBSD.org> |
Add an Armv8 rndr random number provider
Armv8.5 adds an optional random number generator. This is implemented as two special registers one to read a random number, the other to re-seed the entropy
Add an Armv8 rndr random number provider
Armv8.5 adds an optional random number generator. This is implemented as two special registers one to read a random number, the other to re-seed the entropy pool before reading a random number. Both registers will set the condition flags to tell the caller they can't produce a random number in a reasonable amount of time.
Without a signal to reseed the entropy pool use the latter register to provide random numbers to the kernel pool. If at a later time we had a way to tell the provider if it needs to reseed or not we could use the former.
On an Amazon AWS Graviton3 VM this never failed, however this may not be the case on low end CPUs so retry reading the random number 10 times before returning an error.
Reviewed by: imp, delphij (csprng) Sponsored by: The FreeBSD Foundation Sponsored by: Arm Ltd Differential Revision: https://reviews.freebsd.org/D35411
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