From: Mark Brown broonie@kernel.org
commit 7dde62f0687c8856b6c0660066c7ee83a6a6f033 upstream.
Currently we reject an attempt to restore a SVE signal frame on a system with SME but not SVE supported. This means that it is not possible to disable streaming mode via signal return as this is configured via the flags in the SVE signal context. Instead accept the signal frame, we will require it to have a vector length of 0 specified and no payload since the task will have no SVE vector length configured.
Fixes: 85ed24dad290 ("arm64/sme: Implement streaming SVE signal handling") Signed-off-by: Mark Brown broonie@kernel.org Link: https://lore.kernel.org/r/20221223-arm64-fix-sme-only-v1-2-938d663f69e5@kern... Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/kernel/signal.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -280,7 +280,12 @@ static int restore_sve_fpsimd_context(st
vl = task_get_sme_vl(current); } else { - if (!system_supports_sve()) + /* + * A SME only system use SVE for streaming mode so can + * have a SVE formatted context with a zero VL and no + * payload data. + */ + if (!system_supports_sve() && !system_supports_sme()) return -EINVAL;
vl = task_get_sve_vl(current);