[PATCH] rv: Normalize opid IRQ state to a boolean

[PATCH] rv: Normalize opid IRQ state to a boolean

[Karl Mehltretter]

The opid hybrid-automaton guards compare irq_off with 1. However,
irqs_disabled() only guarantees zero or nonzero. On 32-bit Arm,
arch_irqs_disabled_flags() returns the CPSR I bit, 0x80. Consequently,
valid events with interrupts disabled fail the guard and spuriously
trigger the reactor.

Normalize the value before returning it. Add a KUnit regression test
that handles a need-resched event with local interrupts disabled.
Without the normalization, the test triggers a reaction on Arm.

Fixes: 2b406fdb33387 ("rv: Convert the opid monitor to a hybrid automaton")
Assisted-by: LLM
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
---
Tested with an ARMv7 GCC 16 W=1 build and targeted SMP1 QEMU run:
rv_test_opid and the RV KUnit suite pass.

 kernel/trace/rv/monitors/opid/opid.c       | 2 +-
 kernel/trace/rv/monitors/opid/opid_kunit.c | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/rv/monitors/opid/opid.c b/kernel/trace/rv/monitors/opid/opid.c
index 9ae619f176fa1..a14532cc41778 100644
--- a/kernel/trace/rv/monitors/opid/opid.c
+++ b/kernel/trace/rv/monitors/opid/opid.c
@@ -20,7 +20,7 @@
 static u64 ha_get_env(struct ha_monitor *ha_mon, enum envs_opid env, u64 time_ns)
 {
 	if (env == irq_off_opid)
-		return irqs_disabled();
+		return !!irqs_disabled();
 	else if (env == preempt_off_opid) {
 		if (IS_ENABLED(CONFIG_PREEMPTION))
 			return (preempt_count() & PREEMPT_MASK) > 0;
diff --git a/kernel/trace/rv/monitors/opid/opid_kunit.c b/kernel/trace/rv/monitors/opid/opid_kunit.c
index 3cb087a74241e..8aa1fb9c62344 100644
--- a/kernel/trace/rv/monitors/opid/opid_kunit.c
+++ b/kernel/trace/rv/monitors/opid/opid_kunit.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/kernel.h>
+#include <linux/irqflags.h>
 #include <linux/rv.h>
 #include <rv/kunit.h>
 #include <trace/events/sched.h>
@@ -17,6 +18,11 @@ static void rv_test_opid(struct kunit *test)
 	guard(migrate)();
 	KUNIT_EXPECT_TRUE(test, preemptible());
 
+	/* Need resched with interrupts disabled */
+	scoped_guard(irq)
+		rv_opid_ops.handle_sched_need_resched(NULL, NULL, 0, TIF_NEED_RESCHED);
+	RV_KUNIT_EXPECT_NO_REACTION(test, ctx);
+
 	/* Wakeup with preemption and interrupts enabled */
 	RV_KUNIT_EXPECT_REACTION_HERE(test, ctx)
 		rv_opid_ops.handle_sched_waking(NULL, NULL);

base-commit: c03c1a14507dfaf8b856c2608f9ac216021fc222
-- 
2.39.5 (Apple Git-154)

Re: [PATCH] rv: Normalize opid IRQ state to a boolean

[Gabriele Monaco]

On Tue Oct 20, 2026 at 5:51 AM CEST, Karl Mehltretter wrote:
> The opid hybrid-automaton guards compare irq_off with 1. However,
> irqs_disabled() only guarantees zero or nonzero. On 32-bit Arm,
> arch_irqs_disabled_flags() returns the CPSR I bit, 0x80. Consequently,
> valid events with interrupts disabled fail the guard and spuriously
> trigger the reactor.
>
> Normalize the value before returning it. Add a KUnit regression test
> that handles a need-resched event with local interrupts disabled.
> Without the normalization, the test triggers a reaction on Arm.
>
> Fixes: 2b406fdb33387 ("rv: Convert the opid monitor to a hybrid automaton")
> Assisted-by: LLM
> Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
> ---

Looks reasonable, thanks!

Acked-by: Gabriele Monaco <gmonaco@redhat.com>

> Tested with an ARMv7 GCC 16 W=1 build and targeted SMP1 QEMU run:
> rv_test_opid and the RV KUnit suite pass.
>
>  kernel/trace/rv/monitors/opid/opid.c       | 2 +-
>  kernel/trace/rv/monitors/opid/opid_kunit.c | 6 ++++++
>  2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/trace/rv/monitors/opid/opid.c b/kernel/trace/rv/monitors/opid/opid.c
> index 9ae619f176fa1..a14532cc41778 100644
> --- a/kernel/trace/rv/monitors/opid/opid.c
> +++ b/kernel/trace/rv/monitors/opid/opid.c
> @@ -20,7 +20,7 @@
>  static u64 ha_get_env(struct ha_monitor *ha_mon, enum envs_opid env, u64 time_ns)
>  {
>  	if (env == irq_off_opid)
> -		return irqs_disabled();
> +		return !!irqs_disabled();
>  	else if (env == preempt_off_opid) {
>  		if (IS_ENABLED(CONFIG_PREEMPTION))
>  			return (preempt_count() & PREEMPT_MASK) > 0;
> diff --git a/kernel/trace/rv/monitors/opid/opid_kunit.c b/kernel/trace/rv/monitors/opid/opid_kunit.c
> index 3cb087a74241e..8aa1fb9c62344 100644
> --- a/kernel/trace/rv/monitors/opid/opid_kunit.c
> +++ b/kernel/trace/rv/monitors/opid/opid_kunit.c
> @@ -1,5 +1,6 @@
>  // SPDX-License-Identifier: GPL-2.0
>  #include <linux/kernel.h>
> +#include <linux/irqflags.h>
>  #include <linux/rv.h>
>  #include <rv/kunit.h>
>  #include <trace/events/sched.h>
> @@ -17,6 +18,11 @@ static void rv_test_opid(struct kunit *test)
>  	guard(migrate)();
>  	KUNIT_EXPECT_TRUE(test, preemptible());
>  
> +	/* Need resched with interrupts disabled */
> +	scoped_guard(irq)
> +		rv_opid_ops.handle_sched_need_resched(NULL, NULL, 0, TIF_NEED_RESCHED);
> +	RV_KUNIT_EXPECT_NO_REACTION(test, ctx);
> +
>  	/* Wakeup with preemption and interrupts enabled */
>  	RV_KUNIT_EXPECT_REACTION_HERE(test, ctx)
>  		rv_opid_ops.handle_sched_waking(NULL, NULL);
>
> base-commit: c03c1a14507dfaf8b856c2608f9ac216021fc222