From bdf36bee7a72ebb9a2b27430f701cea5abd507ba Mon Sep 17 00:00:00 2001
From: He Zhe <zhe.he@windriver.com>
Date: Tue, 12 Oct 2021 16:44:21 +0800
Subject: [PATCH 139/184] arm64: signal: Use ARCH_RT_DELAYS_SIGNAL_SEND.

The software breakpoint is handled via do_debug_exception() which
disables preemption. On PREEMPT_RT spinlock_t become sleeping locks and
must not be acquired with disabled preemption.

Use ARCH_RT_DELAYS_SIGNAL_SEND so the signal (from send_user_sigtrap())
is sent delayed in return to userland.

Cc: stable-rt@vger.kernel.org
Signed-off-by: He Zhe <zhe.he@windriver.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20211012084421.35136-1-zhe.he@windriver.com
---
 arch/arm64/include/asm/signal.h | 4 ++++
 arch/arm64/kernel/signal.c      | 8 ++++++++
 2 files changed, 12 insertions(+)

diff --git a/arch/arm64/include/asm/signal.h b/arch/arm64/include/asm/signal.h
index ef449f5f4ba80..5e535c3e49260 100644
--- a/arch/arm64/include/asm/signal.h
+++ b/arch/arm64/include/asm/signal.h
@@ -22,4 +22,8 @@ static inline void __user *arch_untagged_si_addr(void __user *addr,
 }
 #define arch_untagged_si_addr arch_untagged_si_addr
 
+#if defined(CONFIG_PREEMPT_RT)
+#define ARCH_RT_DELAYS_SIGNAL_SEND
+#endif
+
 #endif
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 8422536289577..70c4496c54b7a 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -933,6 +933,14 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags)
 		} else {
 			local_daif_restore(DAIF_PROCCTX);
 
+#ifdef ARCH_RT_DELAYS_SIGNAL_SEND
+			if (unlikely(current->forced_info.si_signo)) {
+				struct task_struct *t = current;
+				force_sig_info(&t->forced_info);
+				t->forced_info.si_signo = 0;
+			}
+#endif
+
 			if (thread_flags & _TIF_UPROBE)
 				uprobe_notify_resume(regs);
 
-- 
2.55.0

