Re: [PATCH v10 19/40] arm64/gcs: Context switch GCS state for EL0

Mark Brown
2024-08-21T12:48:31Z

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On Wed, Aug 21, 2024 at 09:50:22AM +0100, Catalin Marinas wrote:
> On Tue, Aug 20, 2024 at 06:56:19PM +0100, Mark Brown wrote:

> > I forgot when writing the above that we always allow reads from
> > GCSPR_EL0 in order to avoid corner cases for unwinders in the case of
> > asynchronous disable. I'd expect that to be cheap to access though.

> But then gcs_preserve_current_state() doesn't save the GCSPR_EL0 value
> if the shadow stack was disabled. At the subsequent switch to this task,
> we write some stale value.

True, we should make the disable save the current value.

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