[PATCH v14 17/39] arm64/sme: Disable ZA and streaming mode when handling signals

Mark Brown
2022-04-19T11:24:41Z

The ABI requires that streaming mode and ZA are disabled when invoking
signal handlers, do this in setup_return() when we prepare the task state
for the signal handler.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm64/kernel/signal.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 4a4122ef6f39..42efa464e46e 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -759,6 +759,13 @@ static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
/* TCO (Tag Check Override) always cleared for signal handlers */
regs->pstate &= ~PSR_TCO_BIT;

+ /* Signal handlers are invoked with ZA and streaming mode disabled */
+ if (system_supports_sme()) {
+ current->thread.svcr &= ~(SYS_SVCR_EL0_ZA_MASK |
+ SYS_SVCR_EL0_SM_MASK);
+ sme_smstop();
+ }
+
if (ka->sa.sa_flags & SA_RESTORER)
sigtramp = ka->sa.sa_restorer;
else
--
2.30.2