rv: Add snroc per-task monitor

Add a per-task monitor as part of the sched model:

* snroc: set non runnable on its own context
Monitor to ensure set_state happens only in the respective task's context

To: Ingo Molnar <[e-mail]>
To: Peter Zijlstra <[e-mail]>
Cc: Juri Lelli <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: John Kacur <[e-mail]>
Cc: Clark Williams <[e-mail]>
Link: https://lore.kernel.org/[e-mail]
Signed-off-by: Gabriele Monaco <[e-mail]>
Signed-off-by: Steven Rostedt (Google) <[e-mail]>

kernel/trace/rv/Kconfig

···
 source "kernel/trace/rv/monitors/sched/Kconfig"
 source "kernel/trace/rv/monitors/tss/Kconfig"
 source "kernel/trace/rv/monitors/sco/Kconfig"
+source "kernel/trace/rv/monitors/snroc/Kconfig"
 # Add new monitors here
 
 config RV_REACTORS

kernel/trace/rv/Makefile

···
 obj-$(CONFIG_RV_MON_SCHED) += monitors/sched/sched.o
 obj-$(CONFIG_RV_MON_TSS) += monitors/tss/tss.o
 obj-$(CONFIG_RV_MON_SCO) += monitors/sco/sco.o
+obj-$(CONFIG_RV_MON_SNROC) += monitors/snroc/snroc.o
 # Add new monitors here
 obj-$(CONFIG_RV_REACTORS) += rv_reactors.o
 obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o

kernel/trace/rv/monitors/snroc/Kconfig

···
+# SPDX-License-Identifier: GPL-2.0-only
+#
+config RV_MON_SNROC
+	depends on RV
+	depends on RV_MON_SCHED
+	default y
+	select DA_MON_EVENTS_ID
+	bool "snroc monitor"
+	help
+	  Monitor to ensure sched_set_state happens only in the respective task's context.
+	  This monitor is part of the sched monitors collection.
+
+	  For further information, see:
+	    Documentation/trace/rv/monitor_sched.rst

kernel/trace/rv/monitors/snroc/snroc.c

···
+// 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 "snroc"
+
+#include <trace/events/sched.h>
+#include <rv_trace.h>
+#include <monitors/sched/sched.h>
+
+#include "snroc.h"
+
+static struct rv_monitor rv_snroc;
+DECLARE_DA_MON_PER_TASK(snroc, unsigned char);
+
+static void handle_sched_set_state(void *data, struct task_struct *tsk, int state)
+{
+	da_handle_event_snroc(tsk, sched_set_state_snroc);
+}
+
+static void handle_sched_switch(void *data, bool preempt,
+				struct task_struct *prev,
+				struct task_struct *next,
+				unsigned int prev_state)
+{
+	da_handle_start_event_snroc(prev, sched_switch_out_snroc);
+	da_handle_event_snroc(next, sched_switch_in_snroc);
+}
+
+static int enable_snroc(void)
+{
+	int retval;
+
+	retval = da_monitor_init_snroc();
+	if (retval)
+		return retval;
+
+	rv_attach_trace_probe("snroc", sched_set_state_tp, handle_sched_set_state);
+	rv_attach_trace_probe("snroc", sched_switch, handle_sched_switch);
+
+	return 0;
+}
+
+static void disable_snroc(void)
+{
+	rv_snroc.enabled = 0;
+
+	rv_detach_trace_probe("snroc", sched_set_state_tp, handle_sched_set_state);
+	rv_detach_trace_probe("snroc", sched_switch, handle_sched_switch);
+
+	da_monitor_destroy_snroc();
+}
+
+static struct rv_monitor rv_snroc = {
+	.name = "snroc",
+	.description = "set non runnable on its own context.",
+	.enable = enable_snroc,
+	.disable = disable_snroc,
+	.reset = da_monitor_reset_all_snroc,
+	.enabled = 0,
+};
+
+static int __init register_snroc(void)
+{
+	rv_register_monitor(&rv_snroc, &rv_sched);
+	return 0;
+}
+
+static void __exit unregister_snroc(void)
+{
+	rv_unregister_monitor(&rv_snroc);
+}
+
+module_init(register_snroc);
+module_exit(unregister_snroc);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Gabriele Monaco <[e-mail]>");
+MODULE_DESCRIPTION("snroc: set non runnable on its own context.");

kernel/trace/rv/monitors/snroc/snroc.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Automatically generated C representation of snroc automaton
+ * For further information about this format, see kernel documentation:
+ *   Documentation/trace/rv/deterministic_automata.rst
+ */
+
+enum states_snroc {
+	other_context_snroc = 0,
+	own_context_snroc,
+	state_max_snroc
+};
+
+#define INVALID_STATE state_max_snroc
+
+enum events_snroc {
+	sched_set_state_snroc = 0,
+	sched_switch_in_snroc,
+	sched_switch_out_snroc,
+	event_max_snroc
+};
+
+struct automaton_snroc {
+	char *state_names[state_max_snroc];
+	char *event_names[event_max_snroc];
+	unsigned char function[state_max_snroc][event_max_snroc];
+	unsigned char initial_state;
+	bool final_states[state_max_snroc];
+};
+
+static const struct automaton_snroc automaton_snroc = {
+	.state_names = {
+		"other_context",
+		"own_context"
+	},
+	.event_names = {
+		"sched_set_state",
+		"sched_switch_in",
+		"sched_switch_out"
+	},
+	.function = {
+		{      INVALID_STATE,  own_context_snroc,       INVALID_STATE },
+		{  own_context_snroc,      INVALID_STATE, other_context_snroc },
+	},
+	.initial_state = other_context_snroc,
+	.final_states = { 1, 0 },
+};

kernel/trace/rv/monitors/snroc/snroc_trace.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Snippet to be included in rv_trace.h
+ */
+
+#ifdef CONFIG_RV_MON_SNROC
+DEFINE_EVENT(event_da_monitor_id, event_snroc,
+	     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_snroc,
+	     TP_PROTO(int id, char *state, char *event),
+	     TP_ARGS(id, state, event));
+#endif /* CONFIG_RV_MON_SNROC */

kernel/trace/rv/rv_trace.h

···
 );
 
 #include <monitors/wwnr/wwnr_trace.h>
+#include <monitors/snroc/snroc_trace.h>
 // Add new monitors based on CONFIG_DA_MON_EVENTS_ID here
 
 #endif /* CONFIG_DA_MON_EVENTS_ID */

tools/verification/models/sched/snroc.dot

···
+digraph state_automaton {
+	center = true;
+	size = "7,11";
+	{node [shape = plaintext, style=invis, label=""] "__init_other_context"};
+	{node [shape = ellipse] "other_context"};
+	{node [shape = plaintext] "other_context"};
+	{node [shape = plaintext] "own_context"};
+	"__init_other_context" -> "other_context";
+	"other_context" [label = "other_context", color = green3];
+	"other_context" -> "own_context" [ label = "sched_switch_in" ];
+	"own_context" [label = "own_context"];
+	"own_context" -> "other_context" [ label = "sched_switch_out" ];
+	"own_context" -> "own_context" [ label = "sched_set_state" ];
+	{ rank = min ;
+		"__init_other_context";
+		"other_context";
+	}
+}