4 files changed, 244 insertions, 0 deletions
diff --git a/kernel/trace/rv/monitors/nrp/Kconfig b/kernel/trace/rv/monitors/nrp/Kconfig
new file mode 100644
index 000000000000..f5ec08f65535
--- /dev/null
+++ b/kernel/trace/rv/monitors/nrp/Kconfig
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+config RV_MON_NRP
+	depends on RV
+	depends on RV_MON_SCHED
+	default y if !ARM64
+	select DA_MON_EVENTS_ID
+	bool "nrp monitor"
+	help
+	  Monitor to ensure preemption requires need resched.
+	  This monitor is part of the sched monitors collection.
+
+	  This monitor is unstable on arm64, say N unless you are testing it.
+
+	  For further information, see:
+	    Documentation/trace/rv/monitor_sched.rst
diff --git a/kernel/trace/rv/monitors/nrp/nrp.c b/kernel/trace/rv/monitors/nrp/nrp.c
new file mode 100644
index 000000000000..5a83b7171432
--- /dev/null
+++ b/kernel/trace/rv/monitors/nrp/nrp.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/ftrace.h>
+#include <linux/tracepoint.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/rv.h>
+#include <rv/instrumentation.h>
+#include <rv/da_monitor.h>
+
+#define MODULE_NAME "nrp"
+
+#include <trace/events/irq.h>
+#include <trace/events/sched.h>
+#include <rv_trace.h>
+#include <monitors/sched/sched.h>
+
+#include "nrp.h"
+
+static struct rv_monitor rv_nrp;
+DECLARE_DA_MON_PER_TASK(nrp, unsigned char);
+
+#ifdef CONFIG_X86_LOCAL_APIC
+#include <asm/trace/irq_vectors.h>
+
+static void handle_vector_irq_entry(void *data, int vector)
+{
+	da_handle_event_nrp(current, irq_entry_nrp);
+}
+
+static void attach_vector_irq(void)
+{
+	rv_attach_trace_probe("nrp", local_timer_entry, handle_vector_irq_entry);
+	if (IS_ENABLED(CONFIG_IRQ_WORK))
+		rv_attach_trace_probe("nrp", irq_work_entry, handle_vector_irq_entry);
+	if (IS_ENABLED(CONFIG_SMP)) {
+		rv_attach_trace_probe("nrp", reschedule_entry, handle_vector_irq_entry);
+		rv_attach_trace_probe("nrp", call_function_entry, handle_vector_irq_entry);
+		rv_attach_trace_probe("nrp", call_function_single_entry, handle_vector_irq_entry);
+	}
+}
+
+static void detach_vector_irq(void)
+{
+	rv_detach_trace_probe("nrp", local_timer_entry, handle_vector_irq_entry);
+	if (IS_ENABLED(CONFIG_IRQ_WORK))
+		rv_detach_trace_probe("nrp", irq_work_entry, handle_vector_irq_entry);
+	if (IS_ENABLED(CONFIG_SMP)) {
+		rv_detach_trace_probe("nrp", reschedule_entry, handle_vector_irq_entry);
+		rv_detach_trace_probe("nrp", call_function_entry, handle_vector_irq_entry);
+		rv_detach_trace_probe("nrp", call_function_single_entry, handle_vector_irq_entry);
+	}
+}
+
+#else
+/* We assume irq_entry tracepoints are sufficient on other architectures */
+static void attach_vector_irq(void) { }
+static void detach_vector_irq(void) { }
+#endif
+
+static void handle_irq_entry(void *data, int irq, struct irqaction *action)
+{
+	da_handle_event_nrp(current, irq_entry_nrp);
+}
+
+static void handle_sched_need_resched(void *data, struct task_struct *tsk,
+				      int cpu, int tif)
+{
+	/*
+	 * Although need_resched leads to both the rescheduling and preempt_irq
+	 * states, it is safer to start the monitor always in preempt_irq,
+	 * which may not mirror the system state but makes the monitor simpler,
+	 */
+	if (tif == TIF_NEED_RESCHED)
+		da_handle_start_event_nrp(tsk, sched_need_resched_nrp);
+}
+
+static void handle_schedule_entry(void *data, bool preempt)
+{
+	if (preempt)
+		da_handle_event_nrp(current, schedule_entry_preempt_nrp);
+	else
+		da_handle_event_nrp(current, schedule_entry_nrp);
+}
+
+static int enable_nrp(void)
+{
+	int retval;
+
+	retval = da_monitor_init_nrp();
+	if (retval)
+		return retval;
+
+	rv_attach_trace_probe("nrp", irq_handler_entry, handle_irq_entry);
+	rv_attach_trace_probe("nrp", sched_set_need_resched_tp, handle_sched_need_resched);
+	rv_attach_trace_probe("nrp", sched_entry_tp, handle_schedule_entry);
+	attach_vector_irq();
+
+	return 0;
+}
+
+static void disable_nrp(void)
+{
+	rv_nrp.enabled = 0;
+
+	rv_detach_trace_probe("nrp", irq_handler_entry, handle_irq_entry);
+	rv_detach_trace_probe("nrp", sched_set_need_resched_tp, handle_sched_need_resched);
+	rv_detach_trace_probe("nrp", sched_entry_tp, handle_schedule_entry);
+	detach_vector_irq();
+
+	da_monitor_destroy_nrp();
+}
+
+static struct rv_monitor rv_nrp = {
+	.name = "nrp",
+	.description = "need resched preempts.",
+	.enable = enable_nrp,
+	.disable = disable_nrp,
+	.reset = da_monitor_reset_all_nrp,
+	.enabled = 0,
+};
+
+static int __init register_nrp(void)
+{
+	return rv_register_monitor(&rv_nrp, &rv_sched);
+}
+
+static void __exit unregister_nrp(void)
+{
+	rv_unregister_monitor(&rv_nrp);
+}
+
+module_init(register_nrp);
+module_exit(unregister_nrp);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Gabriele Monaco <gmonaco@redhat.com>");
+MODULE_DESCRIPTION("nrp: need resched preempts.");
diff --git a/kernel/trace/rv/monitors/nrp/nrp.h b/kernel/trace/rv/monitors/nrp/nrp.h
new file mode 100644
index 000000000000..c9f12207cbf6
--- /dev/null
+++ b/kernel/trace/rv/monitors/nrp/nrp.h
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Automatically generated C representation of nrp automaton
+ * For further information about this format, see kernel documentation:
+ *   Documentation/trace/rv/deterministic_automata.rst
+ */
+
+enum states_nrp {
+	preempt_irq_nrp = 0,
+	any_thread_running_nrp,
+	nested_preempt_nrp,
+	rescheduling_nrp,
+	state_max_nrp
+};
+
+#define INVALID_STATE state_max_nrp
+
+enum events_nrp {
+	irq_entry_nrp = 0,
+	sched_need_resched_nrp,
+	schedule_entry_nrp,
+	schedule_entry_preempt_nrp,
+	event_max_nrp
+};
+
+struct automaton_nrp {
+	char *state_names[state_max_nrp];
+	char *event_names[event_max_nrp];
+	unsigned char function[state_max_nrp][event_max_nrp];
+	unsigned char initial_state;
+	bool final_states[state_max_nrp];
+};
+
+static const struct automaton_nrp automaton_nrp = {
+	.state_names = {
+		"preempt_irq",
+		"any_thread_running",
+		"nested_preempt",
+		"rescheduling"
+	},
+	.event_names = {
+		"irq_entry",
+		"sched_need_resched",
+		"schedule_entry",
+		"schedule_entry_preempt"
+	},
+	.function = {
+		{
+			preempt_irq_nrp,
+			preempt_irq_nrp,
+			nested_preempt_nrp,
+			nested_preempt_nrp
+		},
+		{
+			any_thread_running_nrp,
+			rescheduling_nrp,
+			any_thread_running_nrp,
+			INVALID_STATE
+		},
+		{
+			nested_preempt_nrp,
+			preempt_irq_nrp,
+			any_thread_running_nrp,
+			any_thread_running_nrp
+		},
+		{
+			preempt_irq_nrp,
+			rescheduling_nrp,
+			any_thread_running_nrp,
+			any_thread_running_nrp
+		},
+	},
+	.initial_state = preempt_irq_nrp,
+	.final_states = { 0, 1, 0, 0 },
+};
diff --git a/kernel/trace/rv/monitors/nrp/nrp_trace.h b/kernel/trace/rv/monitors/nrp/nrp_trace.h
new file mode 100644
index 000000000000..2e13497de3b6
--- /dev/null
+++ b/kernel/trace/rv/monitors/nrp/nrp_trace.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Snippet to be included in rv_trace.h
+ */
+
+#ifdef CONFIG_RV_MON_NRP
+DEFINE_EVENT(event_da_monitor_id, event_nrp,
+	     TP_PROTO(int id, char *state, char *event, char *next_state, bool final_state),
+	     TP_ARGS(id, state, event, next_state, final_state));
+
+DEFINE_EVENT(error_da_monitor_id, error_nrp,
+	     TP_PROTO(int id, char *state, char *event),
+	     TP_ARGS(id, state, event));
+#endif /* CONFIG_RV_MON_NRP */