// 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>

#define MODULE_NAME "opid"

#include <trace/events/sched.h>
#include <rv_trace.h>
#include <monitors/sched/sched.h>

#define RV_MON_TYPE RV_MON_PER_CPU
#include "opid.h"
#include <rv/ha_monitor.h>

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();
        else if (env == preempt_off_opid) {
                /*
                 * If CONFIG_PREEMPTION is enabled, then the tracepoint itself disables
                 * preemption (adding one to the preempt_count). Since we are
                 * interested in the preempt_count at the time the tracepoint was
                 * hit, we consider 1 as still enabled.
                 */
                if (IS_ENABLED(CONFIG_PREEMPTION))
                        return (preempt_count() & PREEMPT_MASK) > 1;
                return true;
        }
        return ENV_INVALID_VALUE;
}

static inline bool ha_verify_guards(struct ha_monitor *ha_mon,
                                    enum states curr_state, enum events event,
                                    enum states next_state, u64 time_ns)
{
        bool res = true;

        if (curr_state == any_opid && event == sched_need_resched_opid)
                res = ha_get_env(ha_mon, irq_off_opid, time_ns) == 1ull;
        else if (curr_state == any_opid && event == sched_waking_opid)
                res = ha_get_env(ha_mon, irq_off_opid, time_ns) == 1ull &&
                      ha_get_env(ha_mon, preempt_off_opid, time_ns) == 1ull;
        return res;
}

static bool ha_verify_constraint(struct ha_monitor *ha_mon,
                                 enum states curr_state, enum events event,
                                 enum states next_state, u64 time_ns)
{
        if (!ha_verify_guards(ha_mon, curr_state, event, next_state, time_ns))
                return false;

        return true;
}

static void handle_sched_need_resched(void *data, struct task_struct *tsk, int cpu, int tif)
{
        da_handle_start_run_event(sched_need_resched_opid);
}

static void handle_sched_waking(void *data, struct task_struct *p)
{
        da_handle_start_run_event(sched_waking_opid);
}

static int enable_opid(void)
{
        int retval;

        retval = da_monitor_init();
        if (retval)
                return retval;

        rv_attach_trace_probe("opid", sched_set_need_resched_tp, handle_sched_need_resched);
        rv_attach_trace_probe("opid", sched_waking, handle_sched_waking);

        return 0;
}

static void disable_opid(void)
{
        rv_this.enabled = 0;

        rv_detach_trace_probe("opid", sched_set_need_resched_tp, handle_sched_need_resched);
        rv_detach_trace_probe("opid", sched_waking, handle_sched_waking);

        da_monitor_destroy();
}

/*
 * This is the monitor register section.
 */
static struct rv_monitor rv_this = {
        .name = "opid",
        .description = "operations with preemption and irq disabled.",
        .enable = enable_opid,
        .disable = disable_opid,
        .reset = da_monitor_reset_all,
        .enabled = 0,
};

static int __init register_opid(void)
{
        return rv_register_monitor(&rv_this, &rv_sched);
}

static void __exit unregister_opid(void)
{
        rv_unregister_monitor(&rv_this);
}

module_init(register_opid);
module_exit(unregister_opid);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Gabriele Monaco <gmonaco@redhat.com>");
MODULE_DESCRIPTION("opid: operations with preemption and irq disabled.");