arm64/sme: Flush foreign register state in do_sme_acc()
When do_sme_acc() runs with foreign FP state it does not do any updates of
the task structure, relying on the next return to userspace to reload the
register state appropriately, but leaves the task's last loaded CPU
untouched. This means that if the task returns to userspace on the last
CPU it ran on then the checks in fpsimd_bind_task_to_cpu() will incorrectly
determine that the register state on the CPU is current and suppress reload
of the floating point register state before returning to userspace. This
will result in spurious warnings due to SME access traps occuring for the
task after TIF_SME is set.
Call fpsimd_flush_task_state() to invalidate the last loaded CPU
recorded in the task, forcing detection of the task as foreign.
Fixes: 8bd7f91c03d8 ("arm64/sme: Implement traps and syscall handling for SME")Reported-by: Mark Rutlamd <mark.rutland@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
1 file changed
