[PATCH v3 1/2] arm64: Move handling of erratum 1418040 into C code

[Stephen Boyd]

Quoting Marc Zyngier (2020-07-31 10:38:23)
> Instead of dealing with erratum 1418040 on each entry and exit,
> let's move the handling to __switch_to() instead, which has
> several advantages:
> 
> - It can be applied when it matters (switching between 32 and 64
>   bit tasks).
> - It is written in C (yay!)
> - It can rely on static keys rather than alternatives
> 
> Tested-by: Sai Prakash Ranjan <saiprakash.ranjan at codeaurora.org>
> Acked-by: Will Deacon <will at kernel.org>
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---

Reviewed-by: Stephen Boyd <swboyd at chromium.org>