From: Mark Brown broonie@kernel.org
commit ea64baacbc36a0d552aec0d87107182f40211131 upstream.
When handling a signal delivered to a context with streaming mode enabled we will disable streaming mode for the signal handler, when doing so we should also flush the saved FPSIMD register state like exiting streaming mode in the hardware would do so that if that state is reloaded we get the same behaviour. Without this we will reload whatever the last FPSIMD state that was saved for the task was.
Fixes: 40a8e87bb328 ("arm64/sme: Disable ZA and streaming mode when handling signals") Signed-off-by: Mark Brown broonie@kernel.org Reviewed-by: Catalin Marinas catalin.marinas@arm.com Link: https://lore.kernel.org/r/20220817182324.638214-3-broonie@kernel.org Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/kernel/signal.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
--- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -922,6 +922,16 @@ static void setup_return(struct pt_regs
/* Signal handlers are invoked with ZA and streaming mode disabled */ if (system_supports_sme()) { + /* + * If we were in streaming mode the saved register + * state was SVE but we will exit SM and use the + * FPSIMD register state - flush the saved FPSIMD + * register state in case it gets loaded. + */ + if (current->thread.svcr & SVCR_SM_MASK) + memset(¤t->thread.uw.fpsimd_state, 0, + sizeof(current->thread.uw.fpsimd_state)); + current->thread.svcr &= ~(SVCR_ZA_MASK | SVCR_SM_MASK); sme_smstop();