On Wed, Oct 23, 2024 at 09:38:31PM +0100, Mark Brown wrote:
> When building for streaming SVE the irritator for SVE skips updates of both
> P15 and FFR. While FFR is skipped since it might not be present there is no
> reason to skip corrupting P15 so move the ifdef appropriately.
I think you mean P0 rather than P15 here?
rdffr p0.b
... reads from the FFR and writes to P0, modifying P0.
wrffr p15.b
... reads from P15 and writes to the FRR, leaving P15 unchanged.
> Signed-off-by: Mark Brown <broo...@kernel.org>
> ---
> tools/testing/selftests/arm64/fp/sve-test.S | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/arm64/fp/sve-test.S
> b/tools/testing/selftests/arm64/fp/sve-test.S
> index
> f1fb9745c681786f686f1fafcb7e1154f3c8e1a3..3c88dfe9c8cad29f44217314aeaffa984bac05e5
> 100644
> --- a/tools/testing/selftests/arm64/fp/sve-test.S
> +++ b/tools/testing/selftests/arm64/fp/sve-test.S
> @@ -302,9 +302,9 @@ function irritator_handler
> movi v0.8b, #1
> movi v9.16b, #2
> movi v31.8b, #3
> -#ifndef SSVE
> // And P0
> rdffr p0.b
> +#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.
Is there a different instruction we can use?
Mark.
