monwriter.c

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/*
 * Character device driver for writing z/VM *MONITOR service records.
 *
 * Copyright IBM Corp. 2006, 2009
 *
 * Author(s): Melissa Howland <[email protected]>
 */

#define KMSG_COMPONENT "monwriter"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/ctype.h>
#include <linux/poll.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <asm/ebcdic.h>
#include <asm/io.h>
#include <asm/appldata.h>
#include <asm/monwriter.h>

#define MONWRITE_MAX_DATALEN    4010

static int mon_max_bufs = 255;
static int mon_buf_count;

struct mon_buf {
    struct list_head list;
    struct monwrite_hdr hdr;
    int diag_done;
    char *data;
};

static LIST_HEAD(mon_priv_list);

struct mon_private {
    struct list_head priv_list;
    struct list_head list;
    struct monwrite_hdr hdr;
    size_t hdr_to_read;
    size_t data_to_read;
    struct mon_buf *current_buf;
    struct mutex thread_mutex;
};

/*
 * helper functions
 */

static int monwrite_diag(struct monwrite_hdr *myhdr, char *buffer, int fcn)
{
    struct appldata_product_id id;
    int rc;

    strcpy(id.prod_nr, "LNXAPPL");
    id.prod_fn = myhdr->applid;
    id.record_nr = myhdr->record_num;
    id.version_nr = myhdr->version;
    id.release_nr = myhdr->release;
    id.mod_lvl = myhdr->mod_level;
    rc = appldata_asm(&id, fcn, (void *) buffer, myhdr->datalen);
    if (rc <= 0)
        return rc;
    pr_err("Writing monitor data failed with rc=%i\n", rc);
    if (rc == 5)
        return -EPERM;
    return -EINVAL;
}

static struct mon_buf *monwrite_find_hdr(struct mon_private *monpriv,
                     struct monwrite_hdr *monhdr)
{
    struct mon_buf *entry, *next;

    list_for_each_entry_safe(entry, next, &monpriv->list, list)
        if ((entry->hdr.mon_function == monhdr->mon_function ||
             monhdr->mon_function == MONWRITE_STOP_INTERVAL) &&
            entry->hdr.applid == monhdr->applid &&
            entry->hdr.record_num == monhdr->record_num &&
            entry->hdr.version == monhdr->version &&
            entry->hdr.release == monhdr->release &&
            entry->hdr.mod_level == monhdr->mod_level)
            return entry;

    return NULL;
}

static int monwrite_new_hdr(struct mon_private *monpriv)
{
    struct monwrite_hdr *monhdr = &monpriv->hdr;
    struct mon_buf *monbuf;
    int rc = 0;

    if (monhdr->datalen > MONWRITE_MAX_DATALEN ||
        monhdr->mon_function > MONWRITE_START_CONFIG ||
        monhdr->hdrlen != sizeof(struct monwrite_hdr))
        return -EINVAL;
    monbuf = NULL;
    if (monhdr->mon_function != MONWRITE_GEN_EVENT)
        monbuf = monwrite_find_hdr(monpriv, monhdr);
    if (monbuf) {
        if (monhdr->mon_function == MONWRITE_STOP_INTERVAL) {
            monhdr->datalen = monbuf->hdr.datalen;
            rc = monwrite_diag(monhdr, monbuf->data,
                       APPLDATA_STOP_REC);
            list_del(&monbuf->list);
            mon_buf_count--;
            kfree(monbuf->data);
            kfree(monbuf);
            monbuf = NULL;
        }
    } else if (monhdr->mon_function != MONWRITE_STOP_INTERVAL) {
        if (mon_buf_count >= mon_max_bufs)
            return -ENOSPC;
        monbuf = kzalloc(sizeof(struct mon_buf), GFP_KERNEL);
        if (!monbuf)
            return -ENOMEM;
        monbuf->data = kzalloc(monhdr->datalen,
                       GFP_KERNEL | GFP_DMA);
        if (!monbuf->data) {
            kfree(monbuf);
            return -ENOMEM;
        }
        monbuf->hdr = *monhdr;
        list_add_tail(&monbuf->list, &monpriv->list);
        if (monhdr->mon_function != MONWRITE_GEN_EVENT)
            mon_buf_count++;
    }
    monpriv->current_buf = monbuf;
    return rc;
}

static int monwrite_new_data(struct mon_private *monpriv)
{
    struct monwrite_hdr *monhdr = &monpriv->hdr;
    struct mon_buf *monbuf = monpriv->current_buf;
    int rc = 0;

    switch (monhdr->mon_function) {
    case MONWRITE_START_INTERVAL:
        if (!monbuf->diag_done) {
            rc = monwrite_diag(monhdr, monbuf->data,
                       APPLDATA_START_INTERVAL_REC);
            monbuf->diag_done = 1;
        }
        break;
    case MONWRITE_START_CONFIG:
        if (!monbuf->diag_done) {
            rc = monwrite_diag(monhdr, monbuf->data,
                       APPLDATA_START_CONFIG_REC);
            monbuf->diag_done = 1;
        }
        break;
    case MONWRITE_GEN_EVENT:
        rc = monwrite_diag(monhdr, monbuf->data,
                   APPLDATA_GEN_EVENT_REC);
        list_del(&monpriv->current_buf->list);
        kfree(monpriv->current_buf->data);
        kfree(monpriv->current_buf);
        monpriv->current_buf = NULL;
        break;
    default:
        /* monhdr->mon_function is checked in monwrite_new_hdr */
        BUG();
    }
    return rc;
}

/*
 * file operations
 */

static int monwrite_open(struct inode *inode, struct file *filp)
{
    struct mon_private *monpriv;

    monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
    if (!monpriv)
        return -ENOMEM;
    INIT_LIST_HEAD(&monpriv->list);
    monpriv->hdr_to_read = sizeof(monpriv->hdr);
    mutex_init(&monpriv->thread_mutex);
    filp->private_data = monpriv;
    list_add_tail(&monpriv->priv_list, &mon_priv_list);
    return nonseekable_open(inode, filp);
}

static int monwrite_close(struct inode *inode, struct file *filp)
{
    struct mon_private *monpriv = filp->private_data;
    struct mon_buf *entry, *next;

    list_for_each_entry_safe(entry, next, &monpriv->list, list) {
        if (entry->hdr.mon_function != MONWRITE_GEN_EVENT)
            monwrite_diag(&entry->hdr, entry->data,
                      APPLDATA_STOP_REC);
        mon_buf_count--;
        list_del(&entry->list);
        kfree(entry->data);
        kfree(entry);
    }
    list_del(&monpriv->priv_list);
    kfree(monpriv);
    return 0;
}

static ssize_t monwrite_write(struct file *filp, const char __user *data,
                  size_t count, loff_t *ppos)
{
    struct mon_private *monpriv = filp->private_data;
    size_t len, written;
    void *to;
    int rc;

    mutex_lock(&monpriv->thread_mutex);
    for (written = 0; written < count; ) {
        if (monpriv->hdr_to_read) {
            len = min(count - written, monpriv->hdr_to_read);
            to = (char *) &monpriv->hdr +
                sizeof(monpriv->hdr) - monpriv->hdr_to_read;
            if (copy_from_user(to, data + written, len)) {
                rc = -EFAULT;
                goto out_error;
            }
            monpriv->hdr_to_read -= len;
            written += len;
            if (monpriv->hdr_to_read > 0)
                continue;
            rc = monwrite_new_hdr(monpriv);
            if (rc)
                goto out_error;
            monpriv->data_to_read = monpriv->current_buf ?
                monpriv->current_buf->hdr.datalen : 0;
        }

        if (monpriv->data_to_read) {
            len = min(count - written, monpriv->data_to_read);
            to = monpriv->current_buf->data +
                monpriv->hdr.datalen - monpriv->data_to_read;
            if (copy_from_user(to, data + written, len)) {
                rc = -EFAULT;
                goto out_error;
            }
            monpriv->data_to_read -= len;
            written += len;
            if (monpriv->data_to_read > 0)
                continue;
            rc = monwrite_new_data(monpriv);
            if (rc)
                goto out_error;
        }
        monpriv->hdr_to_read = sizeof(monpriv->hdr);
    }
    mutex_unlock(&monpriv->thread_mutex);
    return written;

out_error:
    monpriv->data_to_read = 0;
    monpriv->hdr_to_read = sizeof(struct monwrite_hdr);
    mutex_unlock(&monpriv->thread_mutex);
    return rc;
}

static const struct file_operations monwrite_fops = {
    .owner   = THIS_MODULE,
    .open    = &monwrite_open,
    .release = &monwrite_close,
    .write   = &monwrite_write,
    .llseek  = noop_llseek,
};

static struct miscdevice mon_dev = {
    .name   = "monwriter",
    .fops   = &monwrite_fops,
    .minor  = MISC_DYNAMIC_MINOR,
};

/*
 * suspend/resume
 */

static int monwriter_freeze(struct device *dev)
{
    struct mon_private *monpriv;
    struct mon_buf *monbuf;

    list_for_each_entry(monpriv, &mon_priv_list, priv_list) {
        list_for_each_entry(monbuf, &monpriv->list, list) {
            if (monbuf->hdr.mon_function != MONWRITE_GEN_EVENT)
                monwrite_diag(&monbuf->hdr, monbuf->data,
                          APPLDATA_STOP_REC);
        }
    }
    return 0;
}

static int monwriter_restore(struct device *dev)
{
    struct mon_private *monpriv;
    struct mon_buf *monbuf;

    list_for_each_entry(monpriv, &mon_priv_list, priv_list) {
        list_for_each_entry(monbuf, &monpriv->list, list) {
            if (monbuf->hdr.mon_function == MONWRITE_START_INTERVAL)
                monwrite_diag(&monbuf->hdr, monbuf->data,
                          APPLDATA_START_INTERVAL_REC);
            if (monbuf->hdr.mon_function == MONWRITE_START_CONFIG)
                monwrite_diag(&monbuf->hdr, monbuf->data,
                          APPLDATA_START_CONFIG_REC);
        }
    }
    return 0;
}

static int monwriter_thaw(struct device *dev)
{
    return monwriter_restore(dev);
}

static const struct dev_pm_ops monwriter_pm_ops = {
    .freeze     = monwriter_freeze,
    .thaw       = monwriter_thaw,
    .restore    = monwriter_restore,
};

static struct platform_driver monwriter_pdrv = {
    .driver = {
        .name   = "monwriter",
        .owner  = THIS_MODULE,
        .pm = &monwriter_pm_ops,
    },
};

static struct platform_device *monwriter_pdev;

/*
 * module init/exit
 */

static int __init mon_init(void)
{
    int rc;

    if (!MACHINE_IS_VM)
        return -ENODEV;

    rc = platform_driver_register(&monwriter_pdrv);
    if (rc)
        return rc;

    monwriter_pdev = platform_device_register_simple("monwriter", -1, NULL,
                            0);
    if (IS_ERR(monwriter_pdev)) {
        rc = PTR_ERR(monwriter_pdev);
        goto out_driver;
    }

    /*
     * misc_register() has to be the last action in module_init(), because
     * file operations will be available right after this.
     */
    rc = misc_register(&mon_dev);
    if (rc)
        goto out_device;
    return 0;

out_device:
    platform_device_unregister(monwriter_pdev);
out_driver:
    platform_driver_unregister(&monwriter_pdrv);
    return rc;
}

static void __exit mon_exit(void)
{
    misc_deregister(&mon_dev);
    platform_device_unregister(monwriter_pdev);
    platform_driver_unregister(&monwriter_pdrv);
}

module_init(mon_init);
module_exit(mon_exit);

module_param_named(max_bufs, mon_max_bufs, int, 0644);
MODULE_PARM_DESC(max_bufs, "Maximum number of sample monitor data buffers "
         "that can be active at one time");

MODULE_AUTHOR("Melissa Howland <[email protected]>");
MODULE_DESCRIPTION("Character device driver for writing z/VM "
           "APPLDATA monitor records.");
MODULE_LICENSE("GPL");