// SPDX-License-Identifier: GPL-2.0/* * Character device driver for reading z/VM *MONITOR service records. * * Copyright IBM Corp. 2004, 2009 * * Author: Gerald Schaefer <gerald.schaefer@de.ibm.com> */ #define pr_fmt(fmt) "monreader: " 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/machine.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_obj(struct mon_private);	if (!monpriv)		return NULL;	for (i = 0; i < MON_MSGLIM; i++) {		monpriv->msg_array[i] = kzalloc_obj(struct mon_msg);		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 )

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