aboutsummaryrefslogtreecommitdiff
path: root/drivers/s390/char/monreader.c
blob: fb7bc9e5eebc90a20c09ae40f07b3df2a4c3e950 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
/*
 * drivers/s390/char/monreader.c
 *
 * Character device driver for reading z/VM *MONITOR service records.
 *
 * Copyright (C) 2004 IBM Corporation, IBM Deutschland Entwicklung GmbH.
 *
 * Author: Gerald Schaefer <geraldsc@de.ibm.com>
 */

#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 <asm/uaccess.h>
#include <asm/ebcdic.h>
#include <asm/extmem.h>
#include <linux/poll.h>
#include "../net/iucv.h"


//#define MON_DEBUG			/* Debug messages on/off */

#define MON_NAME "monreader"

#define P_INFO(x...)	printk(KERN_INFO MON_NAME " info: " x)
#define P_ERROR(x...)	printk(KERN_ERR MON_NAME " error: " x)
#define P_WARNING(x...)	printk(KERN_WARNING MON_NAME " warning: " x)

#ifdef MON_DEBUG
#define P_DEBUG(x...)   printk(KERN_DEBUG MON_NAME " debug: " x)
#else
#define P_DEBUG(x...)   do {} while (0)
#endif

#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;
	iucv_MessagePending local_eib;
	char msglim_reached;
	char replied_msglim;
};

struct mon_private {
	u16 pathid;
	iucv_handle_t iucv_handle;
	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 iucv_host[8] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

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 inline 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);
}

/*
 * print appropriate error message for segment_load()/segment_type()
 * return code
 */
static void
mon_segment_warn(int rc, char* seg_name)
{
	switch (rc) {
	case -ENOENT:
		P_WARNING("cannot load/query segment %s, does not exist\n",
			  seg_name);
		break;
	case -ENOSYS:
		P_WARNING("cannot load/query segment %s, not running on VM\n",
			  seg_name);
		break;
	case -EIO:
		P_WARNING("cannot load/query segment %s, hardware error\n",
			  seg_name);
		break;
	case -ENOTSUPP:
		P_WARNING("cannot load/query segment %s, is a multi-part "
			  "segment\n", seg_name);
		break;
	case -ENOSPC:
		P_WARNING("cannot load/query segment %s, overlaps with "
			  "storage\n", seg_name);
		break;
	case -EBUSY:
		P_WARNING("cannot load/query segment %s, overlaps with "
			  "already loaded dcss\n", seg_name);
		break;
	case -EPERM:
		P_WARNING("cannot load/query segment %s, already loaded in "
			  "incompatible mode\n", seg_name);
		break;
	case -ENOMEM:
		P_WARNING("cannot load/query segment %s, out of memory\n",
			  seg_name);
		break;
	case -ERANGE:
		P_WARNING("cannot load/query segment %s, exceeds kernel "
			  "mapping range\n", seg_name);
		break;
	default:
		P_WARNING("cannot load/query segment %s, return value %i\n",
			  seg_name, rc);
		break;
	}
}

static inline unsigned long
mon_mca_start(struct mon_msg *monmsg)
{
	return monmsg->local_eib.ln1msg1.iprmmsg1_u32;
}

static inline unsigned long
mon_mca_end(struct mon_msg *monmsg)
{
	return monmsg->local_eib.ln1msg2.ipbfln1f;
}

static inline u8
mon_mca_type(struct mon_msg *monmsg, u8 index)
{
	return *((u8 *) 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 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 4));
}

static inline u32
mon_rec_end(struct mon_msg *monmsg)
{
	return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 8));
}

static inline 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)))
	{
		P_DEBUG("READ, IGNORED INVALID MCA\n\n");
		return -EINVAL;
	}
	return 0;
}

static inline int
mon_send_reply(struct mon_msg *monmsg, struct mon_private *monpriv)
{
	u8 prmmsg[8];
	int rc;

	P_DEBUG("read, REPLY: pathid = 0x%04X, msgid = 0x%08X, trgcls = "
		"0x%08X\n\n",
		monmsg->local_eib.ippathid, monmsg->local_eib.ipmsgid,
		monmsg->local_eib.iptrgcls);
	rc = iucv_reply_prmmsg(monmsg->local_eib.ippathid,
				monmsg->local_eib.ipmsgid,
				monmsg->local_eib.iptrgcls,
				0, prmmsg);
	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) {
		P_ERROR("read, IUCV reply failed with rc = %i\n\n", rc);
		return -EIO;
	}
	return 0;
}

static inline struct mon_private *
mon_alloc_mem(void)
{
	int i,j;
	struct mon_private *monpriv;

	monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
	if (!monpriv) {
		P_ERROR("no memory for monpriv\n");
		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]) {
			P_ERROR("open, no memory for msg_array\n");
			for (j = 0; j < i; j++)
				kfree(monpriv->msg_array[j]);
			return NULL;
		}
	}
	return monpriv;
}

static inline void
mon_read_debug(struct mon_msg *monmsg, struct mon_private *monpriv)
{
#ifdef MON_DEBUG
	u8 msg_type[2], mca_type;
	unsigned long records_len;

	records_len = mon_rec_end(monmsg) - mon_rec_start(monmsg) + 1;

	memcpy(msg_type, &monmsg->local_eib.iptrgcls, 2);
	EBCASC(msg_type, 2);
	mca_type = mon_mca_type(monmsg, 0);
	EBCASC(&mca_type, 1);

	P_DEBUG("read, mon_read_index = %i, mon_write_index = %i\n",
		monpriv->read_index, monpriv->write_index);
	P_DEBUG("read, pathid = 0x%04X, msgid = 0x%08X, trgcls = 0x%08X\n",
		monmsg->local_eib.ippathid, monmsg->local_eib.ipmsgid,
		monmsg->local_eib.iptrgcls);
	P_DEBUG("read, msg_type = '%c%c', mca_type = '%c' / 0x%X / 0x%X\n",
		msg_type[0], msg_type[1], mca_type ? mca_type : 'X',
		mon_mca_type(monmsg, 1), mon_mca_type(monmsg, 2));
	P_DEBUG("read, MCA: start = 0x%lX, end = 0x%lX\n",
		mon_mca_start(monmsg), mon_mca_end(monmsg));
	P_DEBUG("read, REC: start = 0x%X, end = 0x%X, len = %lu\n\n",
		mon_rec_start(monmsg), mon_rec_end(monmsg), records_len);
	if (mon_mca_size(monmsg) > 12)
		P_DEBUG("READ, MORE THAN ONE MCA\n\n");
#endif
}

static inline void
mon_next_mca(struct mon_msg *monmsg)
{
	if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12))
		return;
	P_DEBUG("READ, NEXT MCA\n\n");
	monmsg->mca_offset += 12;
	monmsg->pos = 0;
}

static inline 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;
		P_WARNING("read, message limit reached\n");
		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_ConnectionComplete(iucv_ConnectionComplete *eib, void *pgm_data)
{
	struct mon_private *monpriv = (struct mon_private *) pgm_data;

	P_DEBUG("IUCV connection completed\n");
	P_DEBUG("IUCV ACCEPT (from *MONITOR): Version = 0x%02X, Event = "
		"0x%02X, Sample = 0x%02X\n",
		eib->ipuser[0], eib->ipuser[1], eib->ipuser[2]);
	atomic_set(&monpriv->iucv_connected, 1);
	wake_up(&mon_conn_wait_queue);
}

static void
mon_iucv_ConnectionSevered(iucv_ConnectionSevered *eib, void *pgm_data)
{
	struct mon_private *monpriv = (struct mon_private *) pgm_data;

	P_ERROR("IUCV connection severed with rc = 0x%X\n",
		(u8) eib->ipuser[0]);
	atomic_set(&monpriv->iucv_severed, 1);
	wake_up(&mon_conn_wait_queue);
	wake_up_interruptible(&mon_read_wait_queue);
}

static void
mon_iucv_MessagePending(iucv_MessagePending *eib, void *pgm_data)
{
	struct mon_private *monpriv = (struct mon_private *) pgm_data;

	P_DEBUG("IUCV message pending\n");
	memcpy(&monpriv->msg_array[monpriv->write_index]->local_eib, eib,
	       sizeof(iucv_MessagePending));
	if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) {
		P_WARNING("IUCV message pending, message limit (%i) reached\n",
			  MON_MSGLIM);
		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 iucv_interrupt_ops_t mon_iucvops = {
	.ConnectionComplete = mon_iucv_ConnectionComplete,
	.ConnectionSevered  = mon_iucv_ConnectionSevered,
	.MessagePending     = mon_iucv_MessagePending,
};

/******************************************************************************
 *                               file operations                              *
 *****************************************************************************/
static int
mon_open(struct inode *inode, struct file *filp)
{
	int rc, i;
	struct mon_private *monpriv;

	/*
	 * only one user allowed
	 */
	if (test_and_set_bit(MON_IN_USE, &mon_in_use))
		return -EBUSY;

	monpriv = mon_alloc_mem();
	if (!monpriv)
		return -ENOMEM;

	/*
	 * Register with IUCV and connect to *MONITOR service
	 */
	monpriv->iucv_handle = iucv_register_program("my_monreader    ",
							MON_SERVICE,
							NULL,
							&mon_iucvops,
							monpriv);
	if (!monpriv->iucv_handle) {
		P_ERROR("failed to register with iucv driver\n");
		rc = -EIO;
		goto out_error;
	}
	P_INFO("open, registered with IUCV\n");

	rc = iucv_connect(&monpriv->pathid, MON_MSGLIM, user_data_connect,
			  MON_SERVICE, iucv_host, IPRMDATA, NULL, NULL,
			  monpriv->iucv_handle, NULL);
	if (rc) {
		P_ERROR("iucv connection to *MONITOR failed with "
			"IPUSER SEVER code = %i\n", rc);
		rc = -EIO;
		goto out_unregister;
	}
	/*
	 * 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_unregister;
	}
	P_INFO("open, established connection to *MONITOR service\n\n");
	filp->private_data = monpriv;
	return nonseekable_open(inode, filp);

out_unregister:
	iucv_unregister_program(monpriv->iucv_handle);
out_error:
	for (i = 0; i < MON_MSGLIM; i++)
		kfree(monpriv->msg_array[i]);
	kfree(monpriv);
	clear_bit(MON_IN_USE, &mon_in_use);
	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
	 */
	rc = iucv_sever(monpriv->pathid, user_data_sever);
	if (rc)
		P_ERROR("close, iucv_sever failed with rc = %i\n", rc);
	else
		P_INFO("close, terminated connection to *MONITOR service\n");

	rc = iucv_unregister_program(monpriv->iucv_handle);
	if (rc)
		P_ERROR("close, iucv_unregister failed with rc = %i\n", rc);
	else
		P_INFO("close, unregistered with IUCV\n");

	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;
		mon_read_debug(monmsg, monpriv);
	}
	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, (void *) (unsigned long) 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, (void *) (unsigned long) 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 unsigned int
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 POLLERR;
	if (atomic_read(&monpriv->read_ready))
		return POLLIN | POLLRDNORM;
	return 0;
}

static struct file_operations mon_fops = {
	.owner   = THIS_MODULE,
	.open    = &mon_open,
	.release = &mon_close,
	.read    = &mon_read,
	.poll    = &mon_poll,
};

static struct miscdevice mon_dev = {
	.name       = "monreader",
	.devfs_name = "monreader",
	.fops       = &mon_fops,
	.minor      = MISC_DYNAMIC_MINOR,
};

/******************************************************************************
 *                              module init/exit                              *
 *****************************************************************************/
static int __init
mon_init(void)
{
	int rc;

	if (!MACHINE_IS_VM) {
		P_ERROR("not running under z/VM, driver not loaded\n");
		return -ENODEV;
	}

	rc = segment_type(mon_dcss_name);
	if (rc < 0) {
		mon_segment_warn(rc, mon_dcss_name);
		return rc;
	}
	if (rc != SEG_TYPE_SC) {
		P_ERROR("segment %s has unsupported type, should be SC\n",
			mon_dcss_name);
		return -EINVAL;
	}

	rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
			  &mon_dcss_start, &mon_dcss_end);
	if (rc < 0) {
		mon_segment_warn(rc, mon_dcss_name);
		return -EINVAL;
	}
	dcss_mkname(mon_dcss_name, &user_data_connect[8]);

	rc = misc_register(&mon_dev);
	if (rc < 0 ) {
		P_ERROR("misc_register failed, rc = %i\n", rc);
		goto out;
	}
	P_INFO("Loaded segment %s from %p to %p, size = %lu Byte\n",
		mon_dcss_name, (void *) mon_dcss_start, (void *) mon_dcss_end,
		mon_dcss_end - mon_dcss_start + 1);
	return 0;

out:
	segment_unload(mon_dcss_name);
	return rc;
}

static void __exit
mon_exit(void)
{
	segment_unload(mon_dcss_name);
	WARN_ON(misc_deregister(&mon_dev) != 0);
	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 <geraldsc@de.ibm.com>");
MODULE_DESCRIPTION("Character device driver for reading z/VM "
		   "monitor service records.");
MODULE_LICENSE("GPL");