[PATCH dovetail v5 03/12] riscv: irq_pipeline: enable hard IRQs during in-band trap handling

When running with interrupt pipelining, re-enable hard interrupts
while handling traps on the in-band stage so that out-of-band events
can be delivered promptly.

Signed-off-by: Tobias Schaffner <[email protected]>
---
 arch/riscv/kernel/traps.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 267b8ec5a1bf..5b84e1ff0eeb 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -112,10 +112,30 @@ void die(struct pt_regs *regs, const char *str)
 		make_task_dead(SIGSEGV);
 }
 
+static __always_inline
+bool mark_trap_entry(int signo, struct pt_regs *regs)
+{
+	if (likely(running_inband())) {
+		hard_cond_local_irq_enable();
+		return true;
+	}
+
+	return false;
+}
+
+static __always_inline
+void mark_trap_exit(int signo, struct pt_regs *regs)
+{
+	hard_cond_local_irq_disable();
+}
+
 void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)
 {
 	struct task_struct *tsk = current;
 
+	if (!mark_trap_entry(signo, regs))
+		return;
+
 	if (show_unhandled_signals && unhandled_signal(tsk, signo)
 	    && printk_ratelimit()) {
 		pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x" REG_FMT,
@@ -127,6 +147,8 @@ void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)
 	}
 
 	force_sig_fault(signo, code, (void __user *)addr);
+
+	mark_trap_exit(signo, regs);
 }
 
 static void do_trap_error(struct pt_regs *regs, int signo, int code,
@@ -137,6 +159,12 @@ static void do_trap_error(struct pt_regs *regs, int signo, int code,
 	if (user_mode(regs)) {
 		do_trap(regs, signo, code, addr);
 	} else {
+		/*
+		 * Dovetail: If we trapped from kernel space, either
+		 * we can fix up the situation, or we can't and we may
+		 * happily crash with hard irqs off. Either way, don't
+		 * bother.
+		 */
 		if (!fixup_exception(regs))
 			die(regs, str);
 	}
-- 
2.43.0