// SPDX-License-Identifier: GPL-2.0
/*
* Character device driver for reading z/VM *MONITOR service records.
*
* Copyright IBM Corp. 2004, 2009
*
* Author: Gerald Schaefer <[email protected]>
*/
#define KMSG_COMPONENT "monreader"
#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/spinlock.h>
#include <linux/interrupt.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <net/iucv/iucv.h>
#include <linux/uaccess.h>
#include <asm/ebcdic.h>
#include <asm/extmem.h>
#define MON_COLLECT_SAMPLE 0x80
#define MON_COLLECT_EVENT 0x40
#define MON_SERVICE "*MONITOR"
#define MON_IN_USE 0x01
#define MON_MSGLIM 255
static char mon_dcss_name[9] = "MONDCSS\0";
struct mon_msg {
u32 pos;
u32 mca_offset;
struct iucv_message msg;
char msglim_reached;
char replied_msglim;
};
struct mon_private {
struct iucv_path *path;
struct mon_msg *msg_array[MON_MSGLIM];
unsigned int write_index;
unsigned int read_index;
atomic_t msglim_count;
atomic_t read_ready;
atomic_t iucv_connected;
atomic_t iucv_severed;
};
static unsigned long mon_in_use = 0;
static unsigned long mon_dcss_start;
static unsigned long mon_dcss_end;
static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue);
static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue);
static u8 user_data_connect[16] = {
/* Version code, must be 0x01 for shared mode */
0x01,
/* what to collect */
MON_COLLECT_SAMPLE | MON_COLLECT_EVENT,
/* DCSS name in EBCDIC, 8 bytes padded with blanks */
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
};
static u8 user_data_sever[16] = {
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
};
/******************************************************************************
* helper functions *
*****************************************************************************/
/*
* Create the 8 bytes EBCDIC DCSS segment name from
* an ASCII name, incl. padding
*/
static void dcss_mkname(char *ascii_name, char *ebcdic_name)
{
int i;
for (i = 0; i < 8; i++) {
if (ascii_name[i] == '\0')
break;
ebcdic_name[i] = toupper(ascii_name[i]);
}
for (; i < 8; i++)
ebcdic_name[i] = ' ';
ASCEBC(ebcdic_name, 8);
}
static inline unsigned long mon_mca_start(struct mon_msg *monmsg)
{
return *(u32 *) &monmsg->msg.rmmsg;
}
static inline unsigned long mon_mca_end(struct mon_msg *monmsg)
{
return *(u32 *) &monmsg->msg.rmmsg[4];
}
static inline u8 mon_mca_type(struct mon_msg *monmsg, u8 index)
{
return *((u8 *)__va(mon_mca_start(monmsg)) + monmsg->mca_offset + index);
}
static inline u32 mon_mca_size(struct mon_msg *monmsg)
{
return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
}
static inline u32 mon_rec_start(struct mon_msg *monmsg)
{
return *((u32 *)(__va(mon_mca_start(monmsg)) + monmsg->mca_offset + 4));
}
static inline u32 mon_rec_end(struct mon_msg *monmsg)
{
return *((u32 *)(__va(mon_mca_start(monmsg)) + monmsg->mca_offset + 8));
}
static int mon_check_mca(struct mon_msg *monmsg)
{
if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) ||
(mon_rec_start(monmsg) < mon_dcss_start) ||
(mon_rec_end(monmsg) > mon_dcss_end) ||
(mon_mca_type(monmsg, 0) == 0) ||
(mon_mca_size(monmsg) % 12 != 0) ||
(mon_mca_end(monmsg) <= mon_mca_start(monmsg)) ||
(mon_mca_end(monmsg) > mon_dcss_end) ||
(mon_mca_start(monmsg) < mon_dcss_start) ||
((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0)))
return -EINVAL;
return 0;
}
static int mon_send_reply(struct mon_msg *monmsg,
struct mon_private *monpriv)
{
int rc;
rc = iucv_message_reply(monpriv->path, &monmsg->msg,
IUCV_IPRMDATA, NULL, 0);
atomic_dec(&monpriv->msglim_count);
if (likely(!monmsg->msglim_reached)) {
monmsg->pos = 0;
monmsg->mca_offset = 0;
monpriv->read_index = (monpriv->read_index + 1) %
MON_MSGLIM;
atomic_dec(&monpriv->read_ready);
} else
monmsg->replied_msglim = 1;
if (rc) {
pr_err("Reading monitor data failed with rc=%i\n", rc);
return -EIO;
}
return 0;
}
static void mon_free_mem(struct mon_private *monpriv)
{
int i;
for (i = 0; i < MON_MSGLIM; i++)
kfree(monpriv->msg_array[i]);
kfree(monpriv);
}
static struct mon_private *mon_alloc_mem(void)
{
int i;
struct mon_private *monpriv;
monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
if (!monpriv)
return NULL;
for (i = 0; i < MON_MSGLIM; i++) {
monpriv->msg_array[i] = kzalloc(sizeof(struct mon_msg),
GFP_KERNEL);
if (!monpriv->msg_array[i]) {
mon_free_mem(monpriv);
return NULL;
}
}
return monpriv;
}
static inline void mon_next_mca(struct mon_msg *monmsg)
{
if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12))
return;
monmsg->mca_offset += 12;
monmsg->pos = 0;
}
static struct mon_msg *mon_next_message(struct mon_private *monpriv)
{
struct mon_msg *monmsg;
if (!atomic_read(&monpriv->read_ready))
return NULL;
monmsg = monpriv->msg_array[monpriv->read_index];
if (unlikely(monmsg->replied_msglim)) {
monmsg->replied_msglim = 0;
monmsg->msglim_reached = 0;
monmsg->pos = 0;
monmsg->mca_offset = 0;
monpriv->read_index = (monpriv->read_index + 1) %
MON_MSGLIM;
atomic_dec(&monpriv->read_ready);
return ERR_PTR(-EOVERFLOW);
}
return monmsg;
}
/******************************************************************************
* IUCV handler *
*****************************************************************************/
static void mon_iucv_path_complete(struct iucv_path *path, u8 *ipuser)
{
struct mon_private *monpriv = path->private;
atomic_set(&monpriv->iucv_connected, 1);
wake_up(&mon_conn_wait_queue);
}
static void mon_iucv_path_severed(struct iucv_path *path, u8 *ipuser)
{
struct mon_private *monpriv = path->private;
pr_err("z/VM *MONITOR system service disconnected with rc=%i\n",
ipuser[0]);
iucv_path_sever(path, NULL);
atomic_set(&monpriv->iucv_severed, 1);
wake_up(&mon_conn_wait_queue);
wake_up_interruptible(&mon_read_wait_queue);
}
static void mon_iucv_message_pending(struct iucv_path *path,
struct iucv_message *msg)
{
struct mon_private *monpriv = path->private;
memcpy(&monpriv->msg_array[monpriv->write_index]->msg,
msg, sizeof(*msg));
if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) {
pr_warn("The read queue for monitor data is full\n");
monpriv->msg_array[monpriv->write_index]->msglim_reached = 1;
}
monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM;
atomic_inc(&monpriv->read_ready);
wake_up_interruptible(&mon_read_wait_queue);
}
static struct iucv_handler monreader_iucv_handler = {
.path_complete = mon_iucv_path_complete,
.path_severed = mon_iucv_path_severed,
.message_pending = mon_iucv_message_pending,
};
/******************************************************************************
* file operations *
*****************************************************************************/
static int mon_open(struct inode *inode, struct file *filp)
{
struct mon_private *monpriv;
int rc;
/*
* only one user allowed
*/
rc = -EBUSY;
if (test_and_set_bit(MON_IN_USE, &mon_in_use))
goto out;
rc = -ENOMEM;
monpriv = mon_alloc_mem();
if (!monpriv)
goto out_use;
/*
* Connect to *MONITOR service
*/
monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
if (!monpriv->path)
goto out_priv;
rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
MON_SERVICE, NULL, user_data_connect, monpriv);
if (rc) {
pr_err("Connecting to the z/VM *MONITOR system service "
"failed with rc=%i\n", rc);
rc = -EIO;
goto out_path;
}
/*
* Wait for connection confirmation
*/
wait_event(mon_conn_wait_queue,
atomic_read(&monpriv->iucv_connected) ||
atomic_read(&monpriv->iucv_severed));
if (atomic_read(&monpriv->iucv_severed)) {
atomic_set(&monpriv->iucv_severed, 0);
atomic_set(&monpriv->iucv_connected, 0);
rc = -EIO;
goto out_path;
}
filp->private_data = monpriv;
return nonseekable_open(inode, filp);
out_path:
iucv_path_free(monpriv->path);
out_priv:
mon_free_mem(monpriv);
out_use:
clear_bit(MON_IN_USE, &mon_in_use);
out:
return rc;
}
static int mon_close(struct inode *inode, struct file *filp)
{
int rc, i;
struct mon_private *monpriv = filp->private_data;
/*
* Close IUCV connection and unregister
*/
if (monpriv->path) {
rc = iucv_path_sever(monpriv->path, user_data_sever);
if (rc)
pr_warn("Disconnecting the z/VM *MONITOR system service failed with rc=%i\n",
rc);
iucv_path_free(monpriv->path);
}
atomic_set(&monpriv->iucv_severed, 0);
atomic_set(&monpriv->iucv_connected, 0);
atomic_set(&monpriv->read_ready, 0);
atomic_set(&monpriv->msglim_count, 0);
monpriv->write_index = 0;
monpriv->read_index = 0;
for (i = 0; i < MON_MSGLIM; i++)
kfree(monpriv->msg_array[i]);
kfree(monpriv);
clear_bit(MON_IN_USE, &mon_in_use);
return 0;
}
static ssize_t mon_read(struct file *filp, char __user *data,
size_t count, loff_t *ppos)
{
struct mon_private *monpriv = filp->private_data;
struct mon_msg *monmsg;
int ret;
u32 mce_start;
monmsg = mon_next_message(monpriv);
if (IS_ERR(monmsg))
return PTR_ERR(monmsg);
if (!monmsg) {
if (filp->f_flags & O_NONBLOCK)
return -EAGAIN;
ret = wait_event_interruptible(mon_read_wait_queue,
atomic_read(&monpriv->read_ready) ||
atomic_read(&monpriv->iucv_severed));
if (ret)
return ret;
if (unlikely(atomic_read(&monpriv->iucv_severed)))
return -EIO;
monmsg = monpriv->msg_array[monpriv->read_index];
}
if (!monmsg->pos)
monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
if (mon_check_mca(monmsg))
goto reply;
/* read monitor control element (12 bytes) first */
mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
count = min(count, (size_t) mce_start + 12 - monmsg->pos);
ret = copy_to_user(data, __va(monmsg->pos), count);
if (ret)
return -EFAULT;
monmsg->pos += count;
if (monmsg->pos == mce_start + 12)
monmsg->pos = mon_rec_start(monmsg);
goto out_copy;
}
/* read records */
if (monmsg->pos <= mon_rec_end(monmsg)) {
count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
+ 1);
ret = copy_to_user(data, __va(monmsg->pos), count);
if (ret)
return -EFAULT;
monmsg->pos += count;
if (monmsg->pos > mon_rec_end(monmsg))
mon_next_mca(monmsg);
goto out_copy;
}
reply:
ret = mon_send_reply(monmsg, monpriv);
return ret;
out_copy:
*ppos += count;
return count;
}
static __poll_t mon_poll(struct file *filp, struct poll_table_struct *p)
{
struct mon_private *monpriv = filp->private_data;
poll_wait(filp, &mon_read_wait_queue, p);
if (unlikely(atomic_read(&monpriv->iucv_severed)))
return EPOLLERR;
if (atomic_read(&monpriv->read_ready))
return EPOLLIN | EPOLLRDNORM;
return 0;
}
static const struct file_operations mon_fops = {
.owner = THIS_MODULE,
.open = &mon_open,
.release = &mon_close,
.read = &mon_read,
.poll = &mon_poll,
.llseek = noop_llseek,
};
static struct miscdevice mon_dev = {
.name = "monreader",
.fops = &mon_fops,
.minor = MISC_DYNAMIC_MINOR,
};
/******************************************************************************
* module init/exit *
*****************************************************************************/
static int __init mon_init(void)
{
int rc;
if (!MACHINE_IS_VM) {
pr_err("The z/VM *MONITOR record device driver cannot be "
"loaded without z/VM\n");
return -ENODEV;
}
/*
* Register with IUCV and connect to *MONITOR service
*/
rc = iucv_register(&monreader_iucv_handler, 1);
if (rc) {
pr_err("The z/VM *MONITOR record device driver failed to "
"register with IUCV\n");
return rc;
}
rc = segment_type(mon_dcss_name);
if (rc < 0) {
segment_warning(rc, mon_dcss_name);
goto out_iucv;
}
if (rc != SEG_TYPE_SC) {
pr_err("The specified *MONITOR DCSS %s does not have the "
"required type SC\n", mon_dcss_name);
rc = -EINVAL;
goto out_iucv;
}
rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
&mon_dcss_start, &mon_dcss_end);
if (rc < 0) {
segment_warning(rc, mon_dcss_name);
rc = -EINVAL;
goto out_iucv;
}
dcss_mkname(mon_dcss_name, &user_data_connect[8]);
/*
* 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 < 0 )
goto out;
return 0;
out:
segment_unload(mon_dcss_name);
out_iucv:
iucv_unregister(&monreader_iucv_handler, 1);
return rc;
}
static void __exit mon_exit(void)
{
segment_unload(mon_dcss_name);
misc_deregister(&mon_dev);
iucv_unregister(&monreader_iucv_handler, 1);
return;
}
module_init(mon_init);
module_exit(mon_exit);
module_param_string(mondcss, mon_dcss_name, 9, 0444);
MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
"service, max. 8 chars. Default is MONDCSS");
MODULE_AUTHOR("Gerald Schaefer <[email protected]>");
MODULE_DESCRIPTION("Character device driver for reading z/VM "
"monitor service records.");
MODULE_LICENSE("GPL");
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