// SPDX-License-Identifier: GPL-2.0
/*
 * Base infrastructure for Linux-z/VM Monitor Stream, Stage 1.
 * Exports appldata_register_ops() and appldata_unregister_ops() for the
 * data gathering modules.
 *
 * Copyright IBM Corp. 2003, 2009
 *
 * Author: Gerald Schaefer <gerald.schaefer@de.ibm.com>
 */

#define pr_fmt(fmt) "appldata: " fmt

#include <linux/export.h>
#include <linux/module.h>
#include <linux/sched/stat.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/proc_fs.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
#include <linux/sysctl.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/workqueue.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <asm/appldata.h>
#include <asm/vtimer.h>
#include <asm/smp.h>

#include "appldata.h"


#define APPLDATA_CPU_INTERVAL   10000           /* default (CPU) time for
                                                   sampling interval in
                                                   milliseconds */

#define TOD_MICRO       0x01000                 /* nr. of TOD clock units
                                                   for 1 microsecond */

/*
 * /proc entries (sysctl)
 */
static const char appldata_proc_name[APPLDATA_PROC_NAME_LENGTH] = "appldata";
static int appldata_timer_handler(const struct ctl_table *ctl, int write,
                                  void *buffer, size_t *lenp, loff_t *ppos);
static int appldata_interval_handler(const struct ctl_table *ctl, int write,
                                     void *buffer, size_t *lenp, loff_t *ppos);

static struct ctl_table_header *appldata_sysctl_header;
static const struct ctl_table appldata_table[] = {
        {
                .procname       = "timer",
                .mode           = S_IRUGO | S_IWUSR,
                .proc_handler   = appldata_timer_handler,
        },
        {
                .procname       = "interval",
                .mode           = S_IRUGO | S_IWUSR,
                .proc_handler   = appldata_interval_handler,
        },
};

/*
 * Timer
 */
static struct vtimer_list appldata_timer;

static DEFINE_SPINLOCK(appldata_timer_lock);
static int appldata_interval = APPLDATA_CPU_INTERVAL;
static int appldata_timer_active;

/*
 * Work queue
 */
static struct workqueue_struct *appldata_wq;
static void appldata_work_fn(struct work_struct *work);
static DECLARE_WORK(appldata_work, appldata_work_fn);


/*
 * Ops list
 */
static DEFINE_MUTEX(appldata_ops_mutex);
static LIST_HEAD(appldata_ops_list);


/*************************** timer, work, DIAG *******************************/
/*
 * appldata_timer_function()
 *
 * schedule work and reschedule timer
 */
static void appldata_timer_function(unsigned long data)
{
        queue_work(appldata_wq, (struct work_struct *) data);
}

/*
 * appldata_work_fn()
 *
 * call data gathering function for each (active) module
 */
static void appldata_work_fn(struct work_struct *work)
{
        struct list_head *lh;
        struct appldata_ops *ops;

        mutex_lock(&appldata_ops_mutex);
        list_for_each(lh, &appldata_ops_list) {
                ops = list_entry(lh, struct appldata_ops, list);
                if (ops->active == 1) {
                        ops->callback(ops->data);
                }
        }
        mutex_unlock(&appldata_ops_mutex);
}

static struct appldata_product_id appldata_id = {
        .prod_nr    = {0xD3, 0xC9, 0xD5, 0xE4,
                       0xE7, 0xD2, 0xD9},       /* "LINUXKR" */
        .prod_fn    = 0xD5D3,                   /* "NL" */
        .version_nr = 0xF2F6,                   /* "26" */
        .release_nr = 0xF0F1,                   /* "01" */
};

/*
 * appldata_diag()
 *
 * prepare parameter list, issue DIAG 0xDC
 */
int appldata_diag(char record_nr, u16 function, unsigned long buffer,
                        u16 length, char *mod_lvl)
{
        struct appldata_parameter_list *parm_list;
        struct appldata_product_id *id;
        int rc;

        parm_list = kmalloc_obj(*parm_list);
        id = kmemdup(&appldata_id, sizeof(appldata_id), GFP_KERNEL);
        rc = -ENOMEM;
        if (parm_list && id) {
                id->record_nr = record_nr;
                id->mod_lvl = (mod_lvl[0]) << 8 | mod_lvl[1];
                rc = appldata_asm(parm_list, id, function,
                                  (void *) buffer, length);
        }
        kfree(id);
        kfree(parm_list);
        return rc;
}
/************************ timer, work, DIAG <END> ****************************/


/****************************** /proc stuff **********************************/

#define APPLDATA_ADD_TIMER      0
#define APPLDATA_DEL_TIMER      1
#define APPLDATA_MOD_TIMER      2

/*
 * __appldata_vtimer_setup()
 *
 * Add, delete or modify virtual timers on all online cpus.
 * The caller needs to get the appldata_timer_lock spinlock.
 */
static void __appldata_vtimer_setup(int cmd)
{
        u64 timer_interval = (u64) appldata_interval * 1000 * TOD_MICRO;

        switch (cmd) {
        case APPLDATA_ADD_TIMER:
                if (appldata_timer_active)
                        break;
                appldata_timer.expires = timer_interval;
                add_virt_timer_periodic(&appldata_timer);
                appldata_timer_active = 1;
                break;
        case APPLDATA_DEL_TIMER:
                del_virt_timer(&appldata_timer);
                if (!appldata_timer_active)
                        break;
                appldata_timer_active = 0;
                break;
        case APPLDATA_MOD_TIMER:
                if (!appldata_timer_active)
                        break;
                mod_virt_timer_periodic(&appldata_timer, timer_interval);
        }
}

/*
 * appldata_timer_handler()
 *
 * Start/Stop timer, show status of timer (0 = not active, 1 = active)
 */
static int
appldata_timer_handler(const struct ctl_table *ctl, int write,
                           void *buffer, size_t *lenp, loff_t *ppos)
{
        int timer_active = appldata_timer_active;
        int rc;
        struct ctl_table ctl_entry = {
                .procname       = ctl->procname,
                .data           = &timer_active,
                .maxlen         = sizeof(int),
                .extra1         = SYSCTL_ZERO,
                .extra2         = SYSCTL_ONE,
        };

        rc = proc_douintvec_minmax(&ctl_entry, write, buffer, lenp, ppos);
        if (rc < 0 || !write)
                return rc;

        spin_lock(&appldata_timer_lock);
        if (timer_active)
                __appldata_vtimer_setup(APPLDATA_ADD_TIMER);
        else
                __appldata_vtimer_setup(APPLDATA_DEL_TIMER);
        spin_unlock(&appldata_timer_lock);
        return 0;
}

/*
 * appldata_interval_handler()
 *
 * Set (CPU) timer interval for collection of data (in milliseconds), show
 * current timer interval.
 */
static int
appldata_interval_handler(const struct ctl_table *ctl, int write,
                           void *buffer, size_t *lenp, loff_t *ppos)
{
        int interval = appldata_interval;
        int rc;
        struct ctl_table ctl_entry = {
                .procname       = ctl->procname,
                .data           = &interval,
                .maxlen         = sizeof(int),
                .extra1         = SYSCTL_ONE,
        };

        rc = proc_dointvec_minmax(&ctl_entry, write, buffer, lenp, ppos);
        if (rc < 0 || !write)
                return rc;

        spin_lock(&appldata_timer_lock);
        appldata_interval = interval;
        __appldata_vtimer_setup(APPLDATA_MOD_TIMER);
        spin_unlock(&appldata_timer_lock);
        return 0;
}

/*
 * appldata_generic_handler()
 *
 * Generic start/stop monitoring and DIAG, show status of
 * monitoring (0 = not in process, 1 = in process)
 */
static int
appldata_generic_handler(const struct ctl_table *ctl, int write,
                           void *buffer, size_t *lenp, loff_t *ppos)
{
        struct appldata_ops *ops = NULL, *tmp_ops;
        struct list_head *lh;
        int rc, found;
        int active;
        struct ctl_table ctl_entry = {
                .data           = &active,
                .maxlen         = sizeof(int),
                .extra1         = SYSCTL_ZERO,
                .extra2         = SYSCTL_ONE,
        };

        found = 0;
        mutex_lock(&appldata_ops_mutex);
        list_for_each(lh, &appldata_ops_list) {
                tmp_ops = list_entry(lh, struct appldata_ops, list);
                if (&tmp_ops->ctl_table[0] == ctl) {
                        found = 1;
                }
        }
        if (!found) {
                mutex_unlock(&appldata_ops_mutex);
                return -ENODEV;
        }
        ops = ctl->data;
        if (!try_module_get(ops->owner)) {      // protect this function
                mutex_unlock(&appldata_ops_mutex);
                return -ENODEV;
        }
        mutex_unlock(&appldata_ops_mutex);

        active = ops->active;
        rc = proc_douintvec_minmax(&ctl_entry, write, buffer, lenp, ppos);
        if (rc < 0 || !write) {
                module_put(ops->owner);
                return rc;
        }

        mutex_lock(&appldata_ops_mutex);
        if (active && (ops->active == 0)) {
                // protect work queue callback
                if (!try_module_get(ops->owner)) {
                        mutex_unlock(&appldata_ops_mutex);
                        module_put(ops->owner);
                        return -ENODEV;
                }
                ops->callback(ops->data);       // init record
                rc = appldata_diag(ops->record_nr,
                                        APPLDATA_START_INTERVAL_REC,
                                        (unsigned long) ops->data, ops->size,
                                        ops->mod_lvl);
                if (rc != 0) {
                        pr_err("Starting the data collection for %s "
                               "failed with rc=%d\n", ops->name, rc);
                        module_put(ops->owner);
                } else
                        ops->active = 1;
        } else if (!active && (ops->active == 1)) {
                ops->active = 0;
                rc = appldata_diag(ops->record_nr, APPLDATA_STOP_REC,
                                (unsigned long) ops->data, ops->size,
                                ops->mod_lvl);
                if (rc != 0)
                        pr_err("Stopping the data collection for %s "
                               "failed with rc=%d\n", ops->name, rc);
                module_put(ops->owner);
        }
        mutex_unlock(&appldata_ops_mutex);
        module_put(ops->owner);
        return 0;
}

/*************************** /proc stuff <END> *******************************/


/************************* module-ops management *****************************/
/*
 * appldata_register_ops()
 *
 * update ops list, register /proc/sys entries
 */
int appldata_register_ops(struct appldata_ops *ops)
{
        if (ops->size > APPLDATA_MAX_REC_SIZE)
                return -EINVAL;

        ops->ctl_table = kzalloc_objs(struct ctl_table, 1);
        if (!ops->ctl_table)
                return -ENOMEM;

        mutex_lock(&appldata_ops_mutex);
        list_add(&ops->list, &appldata_ops_list);
        mutex_unlock(&appldata_ops_mutex);

        ops->ctl_table[0].procname = ops->name;
        ops->ctl_table[0].mode = S_IRUGO | S_IWUSR;
        ops->ctl_table[0].proc_handler = appldata_generic_handler;
        ops->ctl_table[0].data = ops;

        ops->sysctl_header = register_sysctl_sz(appldata_proc_name, ops->ctl_table, 1);
        if (!ops->sysctl_header)
                goto out;
        return 0;
out:
        mutex_lock(&appldata_ops_mutex);
        list_del(&ops->list);
        mutex_unlock(&appldata_ops_mutex);
        kfree(ops->ctl_table);
        return -ENOMEM;
}

/*
 * appldata_unregister_ops()
 *
 * update ops list, unregister /proc entries, stop DIAG if necessary
 */
void appldata_unregister_ops(struct appldata_ops *ops)
{
        mutex_lock(&appldata_ops_mutex);
        list_del(&ops->list);
        mutex_unlock(&appldata_ops_mutex);
        unregister_sysctl_table(ops->sysctl_header);
        kfree(ops->ctl_table);
}
/********************** module-ops management <END> **************************/


/******************************* init / exit *********************************/

/*
 * appldata_init()
 *
 * init timer, register /proc entries
 */
static int __init appldata_init(void)
{
        init_virt_timer(&appldata_timer);
        appldata_timer.function = appldata_timer_function;
        appldata_timer.data = (unsigned long) &appldata_work;
        appldata_wq = alloc_ordered_workqueue("appldata", 0);
        if (!appldata_wq)
                return -ENOMEM;
        appldata_sysctl_header = register_sysctl(appldata_proc_name, appldata_table);
        return 0;
}

__initcall(appldata_init);

/**************************** init / exit <END> ******************************/

EXPORT_SYMBOL_GPL(appldata_register_ops);
EXPORT_SYMBOL_GPL(appldata_unregister_ops);
EXPORT_SYMBOL_GPL(appldata_diag);

#ifdef CONFIG_SWAP
EXPORT_SYMBOL_GPL(si_swapinfo);
#endif
EXPORT_SYMBOL_GPL(nr_threads);
EXPORT_SYMBOL_GPL(nr_running);
EXPORT_SYMBOL_GPL(nr_iowait);