Re: [PATCH 3/6] kselftest/arm64: Corrupt P15 in the irritator when testing SSVE

On Wed, Nov 06, 2024 at 11:27:24AM +0000, Mark Rutland wrote:

...

+#ifndef SSVE // And FFR wrffr p15.b #endif

Both RDFFR and WRFFR are illegal in streaming mode unless FEAT_FA64 is implemented and enabled, so we cannot use DRFFR in the SSVE case.

Indeed, I'm surprised that managed to pass my testing...

Is there a different instruction we can use?

We could just trash p0 with something like a load or add.