1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Character device driver for reading z/VM *MONITOR service records.
4 *
5 * Copyright IBM Corp. 2004, 2009
6 *
7 * Author: Gerald Schaefer <gerald.schaefer@de.ibm.com>
8 */
9
10#define KMSG_COMPONENT "monreader"
11#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
12
13#include <linux/module.h>
14#include <linux/moduleparam.h>
15#include <linux/init.h>
16#include <linux/errno.h>
17#include <linux/types.h>
18#include <linux/kernel.h>
19#include <linux/miscdevice.h>
20#include <linux/ctype.h>
21#include <linux/spinlock.h>
22#include <linux/interrupt.h>
23#include <linux/poll.h>
24#include <linux/device.h>
25#include <linux/slab.h>
26#include <net/iucv/iucv.h>
27#include <linux/uaccess.h>
28#include <asm/ebcdic.h>
29#include <asm/extmem.h>
30
31
32#define MON_COLLECT_SAMPLE 0x80
33#define MON_COLLECT_EVENT  0x40
34#define MON_SERVICE	   "*MONITOR"
35#define MON_IN_USE	   0x01
36#define MON_MSGLIM	   255
37
38static char mon_dcss_name[9] = "MONDCSS\0";
39
40struct mon_msg {
41	u32 pos;
42	u32 mca_offset;
43	struct iucv_message msg;
44	char msglim_reached;
45	char replied_msglim;
46};
47
48struct mon_private {
49	struct iucv_path *path;
50	struct mon_msg *msg_array[MON_MSGLIM];
51	unsigned int   write_index;
52	unsigned int   read_index;
53	atomic_t msglim_count;
54	atomic_t read_ready;
55	atomic_t iucv_connected;
56	atomic_t iucv_severed;
57};
58
59static unsigned long mon_in_use = 0;
60
61static unsigned long mon_dcss_start;
62static unsigned long mon_dcss_end;
63
64static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue);
65static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue);
66
67static u8 user_data_connect[16] = {
68	/* Version code, must be 0x01 for shared mode */
69	0x01,
70	/* what to collect */
71	MON_COLLECT_SAMPLE | MON_COLLECT_EVENT,
72	/* DCSS name in EBCDIC, 8 bytes padded with blanks */
73	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
74	0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
75};
76
77static u8 user_data_sever[16] = {
78	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
79	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
80};
81
82static struct device *monreader_device;
83
84/******************************************************************************
85 *                             helper functions                               *
86 *****************************************************************************/
87/*
88 * Create the 8 bytes EBCDIC DCSS segment name from
89 * an ASCII name, incl. padding
90 */
91static void dcss_mkname(char *ascii_name, char *ebcdic_name)
92{
93	int i;
94
95	for (i = 0; i < 8; i++) {
96		if (ascii_name[i] == '\0')
97			break;
98		ebcdic_name[i] = toupper(ascii_name[i]);
99	}
100	for (; i < 8; i++)
101		ebcdic_name[i] = ' ';
102	ASCEBC(ebcdic_name, 8);
103}
104
105static inline unsigned long mon_mca_start(struct mon_msg *monmsg)
106{
107	return *(u32 *) &monmsg->msg.rmmsg;
108}
109
110static inline unsigned long mon_mca_end(struct mon_msg *monmsg)
111{
112	return *(u32 *) &monmsg->msg.rmmsg[4];
113}
114
115static inline u8 mon_mca_type(struct mon_msg *monmsg, u8 index)
116{
117	return *((u8 *) mon_mca_start(monmsg) + monmsg->mca_offset + index);
118}
119
120static inline u32 mon_mca_size(struct mon_msg *monmsg)
121{
122	return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
123}
124
125static inline u32 mon_rec_start(struct mon_msg *monmsg)
126{
127	return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 4));
128}
129
130static inline u32 mon_rec_end(struct mon_msg *monmsg)
131{
132	return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 8));
133}
134
135static int mon_check_mca(struct mon_msg *monmsg)
136{
137	if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) ||
138	    (mon_rec_start(monmsg) < mon_dcss_start) ||
139	    (mon_rec_end(monmsg) > mon_dcss_end) ||
140	    (mon_mca_type(monmsg, 0) == 0) ||
141	    (mon_mca_size(monmsg) % 12 != 0) ||
142	    (mon_mca_end(monmsg) <= mon_mca_start(monmsg)) ||
143	    (mon_mca_end(monmsg) > mon_dcss_end) ||
144	    (mon_mca_start(monmsg) < mon_dcss_start) ||
145	    ((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0)))
146		return -EINVAL;
147	return 0;
148}
149
150static int mon_send_reply(struct mon_msg *monmsg,
151			  struct mon_private *monpriv)
152{
153	int rc;
154
155	rc = iucv_message_reply(monpriv->path, &monmsg->msg,
156				IUCV_IPRMDATA, NULL, 0);
157	atomic_dec(&monpriv->msglim_count);
158	if (likely(!monmsg->msglim_reached)) {
159		monmsg->pos = 0;
160		monmsg->mca_offset = 0;
161		monpriv->read_index = (monpriv->read_index + 1) %
162				      MON_MSGLIM;
163		atomic_dec(&monpriv->read_ready);
164	} else
165		monmsg->replied_msglim = 1;
166	if (rc) {
167		pr_err("Reading monitor data failed with rc=%i\n", rc);
168		return -EIO;
169	}
170	return 0;
171}
172
173static void mon_free_mem(struct mon_private *monpriv)
174{
175	int i;
176
177	for (i = 0; i < MON_MSGLIM; i++)
178		kfree(monpriv->msg_array[i]);
179	kfree(monpriv);
180}
181
182static struct mon_private *mon_alloc_mem(void)
183{
184	int i;
185	struct mon_private *monpriv;
186
187	monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
188	if (!monpriv)
189		return NULL;
190	for (i = 0; i < MON_MSGLIM; i++) {
191		monpriv->msg_array[i] = kzalloc(sizeof(struct mon_msg),
192						    GFP_KERNEL);
193		if (!monpriv->msg_array[i]) {
194			mon_free_mem(monpriv);
195			return NULL;
196		}
197	}
198	return monpriv;
199}
200
201static inline void mon_next_mca(struct mon_msg *monmsg)
202{
203	if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12))
204		return;
205	monmsg->mca_offset += 12;
206	monmsg->pos = 0;
207}
208
209static struct mon_msg *mon_next_message(struct mon_private *monpriv)
210{
211	struct mon_msg *monmsg;
212
213	if (!atomic_read(&monpriv->read_ready))
214		return NULL;
215	monmsg = monpriv->msg_array[monpriv->read_index];
216	if (unlikely(monmsg->replied_msglim)) {
217		monmsg->replied_msglim = 0;
218		monmsg->msglim_reached = 0;
219		monmsg->pos = 0;
220		monmsg->mca_offset = 0;
221		monpriv->read_index = (monpriv->read_index + 1) %
222				      MON_MSGLIM;
223		atomic_dec(&monpriv->read_ready);
224		return ERR_PTR(-EOVERFLOW);
225	}
226	return monmsg;
227}
228
229
230/******************************************************************************
231 *                               IUCV handler                                 *
232 *****************************************************************************/
233static void mon_iucv_path_complete(struct iucv_path *path, u8 *ipuser)
234{
235	struct mon_private *monpriv = path->private;
236
237	atomic_set(&monpriv->iucv_connected, 1);
238	wake_up(&mon_conn_wait_queue);
239}
240
241static void mon_iucv_path_severed(struct iucv_path *path, u8 *ipuser)
242{
243	struct mon_private *monpriv = path->private;
244
245	pr_err("z/VM *MONITOR system service disconnected with rc=%i\n",
246	       ipuser[0]);
247	iucv_path_sever(path, NULL);
248	atomic_set(&monpriv->iucv_severed, 1);
249	wake_up(&mon_conn_wait_queue);
250	wake_up_interruptible(&mon_read_wait_queue);
251}
252
253static void mon_iucv_message_pending(struct iucv_path *path,
254				     struct iucv_message *msg)
255{
256	struct mon_private *monpriv = path->private;
257
258	memcpy(&monpriv->msg_array[monpriv->write_index]->msg,
259	       msg, sizeof(*msg));
260	if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) {
261		pr_warn("The read queue for monitor data is full\n");
262		monpriv->msg_array[monpriv->write_index]->msglim_reached = 1;
263	}
264	monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM;
265	atomic_inc(&monpriv->read_ready);
266	wake_up_interruptible(&mon_read_wait_queue);
267}
268
269static struct iucv_handler monreader_iucv_handler = {
270	.path_complete	 = mon_iucv_path_complete,
271	.path_severed	 = mon_iucv_path_severed,
272	.message_pending = mon_iucv_message_pending,
273};
274
275/******************************************************************************
276 *                               file operations                              *
277 *****************************************************************************/
278static int mon_open(struct inode *inode, struct file *filp)
279{
280	struct mon_private *monpriv;
281	int rc;
282
283	/*
284	 * only one user allowed
285	 */
286	rc = -EBUSY;
287	if (test_and_set_bit(MON_IN_USE, &mon_in_use))
288		goto out;
289
290	rc = -ENOMEM;
291	monpriv = mon_alloc_mem();
292	if (!monpriv)
293		goto out_use;
294
295	/*
296	 * Connect to *MONITOR service
297	 */
298	monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
299	if (!monpriv->path)
300		goto out_priv;
301	rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
302			       MON_SERVICE, NULL, user_data_connect, monpriv);
303	if (rc) {
304		pr_err("Connecting to the z/VM *MONITOR system service "
305		       "failed with rc=%i\n", rc);
306		rc = -EIO;
307		goto out_path;
308	}
309	/*
310	 * Wait for connection confirmation
311	 */
312	wait_event(mon_conn_wait_queue,
313		   atomic_read(&monpriv->iucv_connected) ||
314		   atomic_read(&monpriv->iucv_severed));
315	if (atomic_read(&monpriv->iucv_severed)) {
316		atomic_set(&monpriv->iucv_severed, 0);
317		atomic_set(&monpriv->iucv_connected, 0);
318		rc = -EIO;
319		goto out_path;
320	}
321	filp->private_data = monpriv;
322	dev_set_drvdata(monreader_device, monpriv);
323	return nonseekable_open(inode, filp);
324
325out_path:
326	iucv_path_free(monpriv->path);
327out_priv:
328	mon_free_mem(monpriv);
329out_use:
330	clear_bit(MON_IN_USE, &mon_in_use);
331out:
332	return rc;
333}
334
335static int mon_close(struct inode *inode, struct file *filp)
336{
337	int rc, i;
338	struct mon_private *monpriv = filp->private_data;
339
340	/*
341	 * Close IUCV connection and unregister
342	 */
343	if (monpriv->path) {
344		rc = iucv_path_sever(monpriv->path, user_data_sever);
345		if (rc)
346			pr_warn("Disconnecting the z/VM *MONITOR system service failed with rc=%i\n",
347				rc);
348		iucv_path_free(monpriv->path);
349	}
350
351	atomic_set(&monpriv->iucv_severed, 0);
352	atomic_set(&monpriv->iucv_connected, 0);
353	atomic_set(&monpriv->read_ready, 0);
354	atomic_set(&monpriv->msglim_count, 0);
355	monpriv->write_index  = 0;
356	monpriv->read_index   = 0;
357	dev_set_drvdata(monreader_device, NULL);
358
359	for (i = 0; i < MON_MSGLIM; i++)
360		kfree(monpriv->msg_array[i]);
361	kfree(monpriv);
362	clear_bit(MON_IN_USE, &mon_in_use);
363	return 0;
364}
365
366static ssize_t mon_read(struct file *filp, char __user *data,
367			size_t count, loff_t *ppos)
368{
369	struct mon_private *monpriv = filp->private_data;
370	struct mon_msg *monmsg;
371	int ret;
372	u32 mce_start;
373
374	monmsg = mon_next_message(monpriv);
375	if (IS_ERR(monmsg))
376		return PTR_ERR(monmsg);
377
378	if (!monmsg) {
379		if (filp->f_flags & O_NONBLOCK)
380			return -EAGAIN;
381		ret = wait_event_interruptible(mon_read_wait_queue,
382					atomic_read(&monpriv->read_ready) ||
383					atomic_read(&monpriv->iucv_severed));
384		if (ret)
385			return ret;
386		if (unlikely(atomic_read(&monpriv->iucv_severed)))
387			return -EIO;
388		monmsg = monpriv->msg_array[monpriv->read_index];
389	}
390
391	if (!monmsg->pos)
392		monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
393	if (mon_check_mca(monmsg))
394		goto reply;
395
396	/* read monitor control element (12 bytes) first */
397	mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
398	if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
399		count = min(count, (size_t) mce_start + 12 - monmsg->pos);
400		ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
401				   count);
402		if (ret)
403			return -EFAULT;
404		monmsg->pos += count;
405		if (monmsg->pos == mce_start + 12)
406			monmsg->pos = mon_rec_start(monmsg);
407		goto out_copy;
408	}
409
410	/* read records */
411	if (monmsg->pos <= mon_rec_end(monmsg)) {
412		count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
413					    + 1);
414		ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
415				   count);
416		if (ret)
417			return -EFAULT;
418		monmsg->pos += count;
419		if (monmsg->pos > mon_rec_end(monmsg))
420			mon_next_mca(monmsg);
421		goto out_copy;
422	}
423reply:
424	ret = mon_send_reply(monmsg, monpriv);
425	return ret;
426
427out_copy:
428	*ppos += count;
429	return count;
430}
431
432static __poll_t mon_poll(struct file *filp, struct poll_table_struct *p)
433{
434	struct mon_private *monpriv = filp->private_data;
435
436	poll_wait(filp, &mon_read_wait_queue, p);
437	if (unlikely(atomic_read(&monpriv->iucv_severed)))
438		return EPOLLERR;
439	if (atomic_read(&monpriv->read_ready))
440		return EPOLLIN | EPOLLRDNORM;
441	return 0;
442}
443
444static const struct file_operations mon_fops = {
445	.owner   = THIS_MODULE,
446	.open    = &mon_open,
447	.release = &mon_close,
448	.read    = &mon_read,
449	.poll    = &mon_poll,
450	.llseek  = noop_llseek,
451};
452
453static struct miscdevice mon_dev = {
454	.name       = "monreader",
455	.fops       = &mon_fops,
456	.minor      = MISC_DYNAMIC_MINOR,
457};
458
459
460/******************************************************************************
461 *				suspend / resume			      *
462 *****************************************************************************/
463static int monreader_freeze(struct device *dev)
464{
465	struct mon_private *monpriv = dev_get_drvdata(dev);
466	int rc;
467
468	if (!monpriv)
469		return 0;
470	if (monpriv->path) {
471		rc = iucv_path_sever(monpriv->path, user_data_sever);
472		if (rc)
473			pr_warn("Disconnecting the z/VM *MONITOR system service failed with rc=%i\n",
474				rc);
475		iucv_path_free(monpriv->path);
476	}
477	atomic_set(&monpriv->iucv_severed, 0);
478	atomic_set(&monpriv->iucv_connected, 0);
479	atomic_set(&monpriv->read_ready, 0);
480	atomic_set(&monpriv->msglim_count, 0);
481	monpriv->write_index  = 0;
482	monpriv->read_index   = 0;
483	monpriv->path = NULL;
484	return 0;
485}
486
487static int monreader_thaw(struct device *dev)
488{
489	struct mon_private *monpriv = dev_get_drvdata(dev);
490	int rc;
491
492	if (!monpriv)
493		return 0;
494	rc = -ENOMEM;
495	monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
496	if (!monpriv->path)
497		goto out;
498	rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
499			       MON_SERVICE, NULL, user_data_connect, monpriv);
500	if (rc) {
501		pr_err("Connecting to the z/VM *MONITOR system service "
502		       "failed with rc=%i\n", rc);
503		goto out_path;
504	}
505	wait_event(mon_conn_wait_queue,
506		   atomic_read(&monpriv->iucv_connected) ||
507		   atomic_read(&monpriv->iucv_severed));
508	if (atomic_read(&monpriv->iucv_severed))
509		goto out_path;
510	return 0;
511out_path:
512	rc = -EIO;
513	iucv_path_free(monpriv->path);
514	monpriv->path = NULL;
515out:
516	atomic_set(&monpriv->iucv_severed, 1);
517	return rc;
518}
519
520static int monreader_restore(struct device *dev)
521{
522	int rc;
523
524	segment_unload(mon_dcss_name);
525	rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
526			  &mon_dcss_start, &mon_dcss_end);
527	if (rc < 0) {
528		segment_warning(rc, mon_dcss_name);
529		panic("fatal monreader resume error: no monitor dcss\n");
530	}
531	return monreader_thaw(dev);
532}
533
534static const struct dev_pm_ops monreader_pm_ops = {
535	.freeze  = monreader_freeze,
536	.thaw	 = monreader_thaw,
537	.restore = monreader_restore,
538};
539
540static struct device_driver monreader_driver = {
541	.name = "monreader",
542	.bus  = &iucv_bus,
543	.pm   = &monreader_pm_ops,
544};
545
546
547/******************************************************************************
548 *                              module init/exit                              *
549 *****************************************************************************/
550static int __init mon_init(void)
551{
552	int rc;
553
554	if (!MACHINE_IS_VM) {
555		pr_err("The z/VM *MONITOR record device driver cannot be "
556		       "loaded without z/VM\n");
557		return -ENODEV;
558	}
559
560	/*
561	 * Register with IUCV and connect to *MONITOR service
562	 */
563	rc = iucv_register(&monreader_iucv_handler, 1);
564	if (rc) {
565		pr_err("The z/VM *MONITOR record device driver failed to "
566		       "register with IUCV\n");
567		return rc;
568	}
569
570	rc = driver_register(&monreader_driver);
571	if (rc)
572		goto out_iucv;
573	monreader_device = kzalloc(sizeof(struct device), GFP_KERNEL);
574	if (!monreader_device) {
575		rc = -ENOMEM;
576		goto out_driver;
577	}
578
579	dev_set_name(monreader_device, "monreader-dev");
580	monreader_device->bus = &iucv_bus;
581	monreader_device->parent = iucv_root;
582	monreader_device->driver = &monreader_driver;
583	monreader_device->release = (void (*)(struct device *))kfree;
584	rc = device_register(monreader_device);
585	if (rc) {
586		put_device(monreader_device);
587		goto out_driver;
588	}
589
590	rc = segment_type(mon_dcss_name);
591	if (rc < 0) {
592		segment_warning(rc, mon_dcss_name);
593		goto out_device;
594	}
595	if (rc != SEG_TYPE_SC) {
596		pr_err("The specified *MONITOR DCSS %s does not have the "
597		       "required type SC\n", mon_dcss_name);
598		rc = -EINVAL;
599		goto out_device;
600	}
601
602	rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
603			  &mon_dcss_start, &mon_dcss_end);
604	if (rc < 0) {
605		segment_warning(rc, mon_dcss_name);
606		rc = -EINVAL;
607		goto out_device;
608	}
609	dcss_mkname(mon_dcss_name, &user_data_connect[8]);
610
611	/*
612	 * misc_register() has to be the last action in module_init(), because
613	 * file operations will be available right after this.
614	 */
615	rc = misc_register(&mon_dev);
616	if (rc < 0 )
617		goto out;
618	return 0;
619
620out:
621	segment_unload(mon_dcss_name);
622out_device:
623	device_unregister(monreader_device);
624out_driver:
625	driver_unregister(&monreader_driver);
626out_iucv:
627	iucv_unregister(&monreader_iucv_handler, 1);
628	return rc;
629}
630
631static void __exit mon_exit(void)
632{
633	segment_unload(mon_dcss_name);
634	misc_deregister(&mon_dev);
635	device_unregister(monreader_device);
636	driver_unregister(&monreader_driver);
637	iucv_unregister(&monreader_iucv_handler, 1);
638	return;
639}
640
641
642module_init(mon_init);
643module_exit(mon_exit);
644
645module_param_string(mondcss, mon_dcss_name, 9, 0444);
646MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
647		 "service, max. 8 chars. Default is MONDCSS");
648
649MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>");
650MODULE_DESCRIPTION("Character device driver for reading z/VM "
651		   "monitor service records.");
652MODULE_LICENSE("GPL");
653