[PATCH] arm64: trap implementation defined functionality in userspace

[Will Deacon]

On Wed, 22 Jun 2022 12:54:24 +0100, Kristina Martsenko wrote:
> The Arm v8.8 extension adds a new control FEAT_TIDCP1 that allows the
> kernel to disable all implementation-defined system registers and
> instructions in userspace. This can improve robustness against covert
> channels between processes, for example in cases where the firmware or
> hardware didn't disable that functionality by default.
> 
> The kernel does not currently support any implementation-defined
> features, as there are no hwcaps for any such features, so disable all
> imp-def features unconditionally. Any use of imp-def instructions will
> result in a SIGILL being delivered to the process (same as for undefined
> instructions).
> 
> [...]

Applied to arm64 (for-next/cpufeature), thanks!

[1/1] arm64: trap implementation defined functionality in userspace
      https://git.kernel.org/arm64/c/3a46b352a3e6

Cheers,
-- 
Will

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