[PATCH v9 18/40] arm64/sme: Disable ZA and streaming mode when handling signals

[Mark Brown]

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 at kernel.org>
---
 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 d8aaf4b6f432..cda04fd73333 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -758,6 +758,13 @@ 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