xref: /openbmc/linux/drivers/s390/char/monreader.c (revision 67ce50ce)
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/slab.h>
25 #include <net/iucv/iucv.h>
26 #include <linux/uaccess.h>
27 #include <asm/ebcdic.h>
28 #include <asm/extmem.h>
29 
30 
31 #define MON_COLLECT_SAMPLE 0x80
32 #define MON_COLLECT_EVENT  0x40
33 #define MON_SERVICE	   "*MONITOR"
34 #define MON_IN_USE	   0x01
35 #define MON_MSGLIM	   255
36 
37 static char mon_dcss_name[9] = "MONDCSS\0";
38 
39 struct mon_msg {
40 	u32 pos;
41 	u32 mca_offset;
42 	struct iucv_message msg;
43 	char msglim_reached;
44 	char replied_msglim;
45 };
46 
47 struct mon_private {
48 	struct iucv_path *path;
49 	struct mon_msg *msg_array[MON_MSGLIM];
50 	unsigned int   write_index;
51 	unsigned int   read_index;
52 	atomic_t msglim_count;
53 	atomic_t read_ready;
54 	atomic_t iucv_connected;
55 	atomic_t iucv_severed;
56 };
57 
58 static unsigned long mon_in_use = 0;
59 
60 static unsigned long mon_dcss_start;
61 static unsigned long mon_dcss_end;
62 
63 static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue);
64 static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue);
65 
66 static u8 user_data_connect[16] = {
67 	/* Version code, must be 0x01 for shared mode */
68 	0x01,
69 	/* what to collect */
70 	MON_COLLECT_SAMPLE | MON_COLLECT_EVENT,
71 	/* DCSS name in EBCDIC, 8 bytes padded with blanks */
72 	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
73 	0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
74 };
75 
76 static u8 user_data_sever[16] = {
77 	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
78 	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
79 };
80 
81 /******************************************************************************
82  *                             helper functions                               *
83  *****************************************************************************/
84 /*
85  * Create the 8 bytes EBCDIC DCSS segment name from
86  * an ASCII name, incl. padding
87  */
dcss_mkname(char * ascii_name,char * ebcdic_name)88 static void dcss_mkname(char *ascii_name, char *ebcdic_name)
89 {
90 	int i;
91 
92 	for (i = 0; i < 8; i++) {
93 		if (ascii_name[i] == '\0')
94 			break;
95 		ebcdic_name[i] = toupper(ascii_name[i]);
96 	}
97 	for (; i < 8; i++)
98 		ebcdic_name[i] = ' ';
99 	ASCEBC(ebcdic_name, 8);
100 }
101 
mon_mca_start(struct mon_msg * monmsg)102 static inline unsigned long mon_mca_start(struct mon_msg *monmsg)
103 {
104 	return *(u32 *) &monmsg->msg.rmmsg;
105 }
106 
mon_mca_end(struct mon_msg * monmsg)107 static inline unsigned long mon_mca_end(struct mon_msg *monmsg)
108 {
109 	return *(u32 *) &monmsg->msg.rmmsg[4];
110 }
111 
mon_mca_type(struct mon_msg * monmsg,u8 index)112 static inline u8 mon_mca_type(struct mon_msg *monmsg, u8 index)
113 {
114 	return *((u8 *)__va(mon_mca_start(monmsg)) + monmsg->mca_offset + index);
115 }
116 
mon_mca_size(struct mon_msg * monmsg)117 static inline u32 mon_mca_size(struct mon_msg *monmsg)
118 {
119 	return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
120 }
121 
mon_rec_start(struct mon_msg * monmsg)122 static inline u32 mon_rec_start(struct mon_msg *monmsg)
123 {
124 	return *((u32 *)(__va(mon_mca_start(monmsg)) + monmsg->mca_offset + 4));
125 }
126 
mon_rec_end(struct mon_msg * monmsg)127 static inline u32 mon_rec_end(struct mon_msg *monmsg)
128 {
129 	return *((u32 *)(__va(mon_mca_start(monmsg)) + monmsg->mca_offset + 8));
130 }
131 
mon_check_mca(struct mon_msg * monmsg)132 static int mon_check_mca(struct mon_msg *monmsg)
133 {
134 	if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) ||
135 	    (mon_rec_start(monmsg) < mon_dcss_start) ||
136 	    (mon_rec_end(monmsg) > mon_dcss_end) ||
137 	    (mon_mca_type(monmsg, 0) == 0) ||
138 	    (mon_mca_size(monmsg) % 12 != 0) ||
139 	    (mon_mca_end(monmsg) <= mon_mca_start(monmsg)) ||
140 	    (mon_mca_end(monmsg) > mon_dcss_end) ||
141 	    (mon_mca_start(monmsg) < mon_dcss_start) ||
142 	    ((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0)))
143 		return -EINVAL;
144 	return 0;
145 }
146 
mon_send_reply(struct mon_msg * monmsg,struct mon_private * monpriv)147 static int mon_send_reply(struct mon_msg *monmsg,
148 			  struct mon_private *monpriv)
149 {
150 	int rc;
151 
152 	rc = iucv_message_reply(monpriv->path, &monmsg->msg,
153 				IUCV_IPRMDATA, NULL, 0);
154 	atomic_dec(&monpriv->msglim_count);
155 	if (likely(!monmsg->msglim_reached)) {
156 		monmsg->pos = 0;
157 		monmsg->mca_offset = 0;
158 		monpriv->read_index = (monpriv->read_index + 1) %
159 				      MON_MSGLIM;
160 		atomic_dec(&monpriv->read_ready);
161 	} else
162 		monmsg->replied_msglim = 1;
163 	if (rc) {
164 		pr_err("Reading monitor data failed with rc=%i\n", rc);
165 		return -EIO;
166 	}
167 	return 0;
168 }
169 
mon_free_mem(struct mon_private * monpriv)170 static void mon_free_mem(struct mon_private *monpriv)
171 {
172 	int i;
173 
174 	for (i = 0; i < MON_MSGLIM; i++)
175 		kfree(monpriv->msg_array[i]);
176 	kfree(monpriv);
177 }
178 
mon_alloc_mem(void)179 static struct mon_private *mon_alloc_mem(void)
180 {
181 	int i;
182 	struct mon_private *monpriv;
183 
184 	monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
185 	if (!monpriv)
186 		return NULL;
187 	for (i = 0; i < MON_MSGLIM; i++) {
188 		monpriv->msg_array[i] = kzalloc(sizeof(struct mon_msg),
189 						    GFP_KERNEL);
190 		if (!monpriv->msg_array[i]) {
191 			mon_free_mem(monpriv);
192 			return NULL;
193 		}
194 	}
195 	return monpriv;
196 }
197 
mon_next_mca(struct mon_msg * monmsg)198 static inline void mon_next_mca(struct mon_msg *monmsg)
199 {
200 	if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12))
201 		return;
202 	monmsg->mca_offset += 12;
203 	monmsg->pos = 0;
204 }
205 
mon_next_message(struct mon_private * monpriv)206 static struct mon_msg *mon_next_message(struct mon_private *monpriv)
207 {
208 	struct mon_msg *monmsg;
209 
210 	if (!atomic_read(&monpriv->read_ready))
211 		return NULL;
212 	monmsg = monpriv->msg_array[monpriv->read_index];
213 	if (unlikely(monmsg->replied_msglim)) {
214 		monmsg->replied_msglim = 0;
215 		monmsg->msglim_reached = 0;
216 		monmsg->pos = 0;
217 		monmsg->mca_offset = 0;
218 		monpriv->read_index = (monpriv->read_index + 1) %
219 				      MON_MSGLIM;
220 		atomic_dec(&monpriv->read_ready);
221 		return ERR_PTR(-EOVERFLOW);
222 	}
223 	return monmsg;
224 }
225 
226 
227 /******************************************************************************
228  *                               IUCV handler                                 *
229  *****************************************************************************/
mon_iucv_path_complete(struct iucv_path * path,u8 * ipuser)230 static void mon_iucv_path_complete(struct iucv_path *path, u8 *ipuser)
231 {
232 	struct mon_private *monpriv = path->private;
233 
234 	atomic_set(&monpriv->iucv_connected, 1);
235 	wake_up(&mon_conn_wait_queue);
236 }
237 
mon_iucv_path_severed(struct iucv_path * path,u8 * ipuser)238 static void mon_iucv_path_severed(struct iucv_path *path, u8 *ipuser)
239 {
240 	struct mon_private *monpriv = path->private;
241 
242 	pr_err("z/VM *MONITOR system service disconnected with rc=%i\n",
243 	       ipuser[0]);
244 	iucv_path_sever(path, NULL);
245 	atomic_set(&monpriv->iucv_severed, 1);
246 	wake_up(&mon_conn_wait_queue);
247 	wake_up_interruptible(&mon_read_wait_queue);
248 }
249 
mon_iucv_message_pending(struct iucv_path * path,struct iucv_message * msg)250 static void mon_iucv_message_pending(struct iucv_path *path,
251 				     struct iucv_message *msg)
252 {
253 	struct mon_private *monpriv = path->private;
254 
255 	memcpy(&monpriv->msg_array[monpriv->write_index]->msg,
256 	       msg, sizeof(*msg));
257 	if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) {
258 		pr_warn("The read queue for monitor data is full\n");
259 		monpriv->msg_array[monpriv->write_index]->msglim_reached = 1;
260 	}
261 	monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM;
262 	atomic_inc(&monpriv->read_ready);
263 	wake_up_interruptible(&mon_read_wait_queue);
264 }
265 
266 static struct iucv_handler monreader_iucv_handler = {
267 	.path_complete	 = mon_iucv_path_complete,
268 	.path_severed	 = mon_iucv_path_severed,
269 	.message_pending = mon_iucv_message_pending,
270 };
271 
272 /******************************************************************************
273  *                               file operations                              *
274  *****************************************************************************/
mon_open(struct inode * inode,struct file * filp)275 static int mon_open(struct inode *inode, struct file *filp)
276 {
277 	struct mon_private *monpriv;
278 	int rc;
279 
280 	/*
281 	 * only one user allowed
282 	 */
283 	rc = -EBUSY;
284 	if (test_and_set_bit(MON_IN_USE, &mon_in_use))
285 		goto out;
286 
287 	rc = -ENOMEM;
288 	monpriv = mon_alloc_mem();
289 	if (!monpriv)
290 		goto out_use;
291 
292 	/*
293 	 * Connect to *MONITOR service
294 	 */
295 	monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
296 	if (!monpriv->path)
297 		goto out_priv;
298 	rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
299 			       MON_SERVICE, NULL, user_data_connect, monpriv);
300 	if (rc) {
301 		pr_err("Connecting to the z/VM *MONITOR system service "
302 		       "failed with rc=%i\n", rc);
303 		rc = -EIO;
304 		goto out_path;
305 	}
306 	/*
307 	 * Wait for connection confirmation
308 	 */
309 	wait_event(mon_conn_wait_queue,
310 		   atomic_read(&monpriv->iucv_connected) ||
311 		   atomic_read(&monpriv->iucv_severed));
312 	if (atomic_read(&monpriv->iucv_severed)) {
313 		atomic_set(&monpriv->iucv_severed, 0);
314 		atomic_set(&monpriv->iucv_connected, 0);
315 		rc = -EIO;
316 		goto out_path;
317 	}
318 	filp->private_data = monpriv;
319 	return nonseekable_open(inode, filp);
320 
321 out_path:
322 	iucv_path_free(monpriv->path);
323 out_priv:
324 	mon_free_mem(monpriv);
325 out_use:
326 	clear_bit(MON_IN_USE, &mon_in_use);
327 out:
328 	return rc;
329 }
330 
mon_close(struct inode * inode,struct file * filp)331 static int mon_close(struct inode *inode, struct file *filp)
332 {
333 	int rc, i;
334 	struct mon_private *monpriv = filp->private_data;
335 
336 	/*
337 	 * Close IUCV connection and unregister
338 	 */
339 	if (monpriv->path) {
340 		rc = iucv_path_sever(monpriv->path, user_data_sever);
341 		if (rc)
342 			pr_warn("Disconnecting the z/VM *MONITOR system service failed with rc=%i\n",
343 				rc);
344 		iucv_path_free(monpriv->path);
345 	}
346 
347 	atomic_set(&monpriv->iucv_severed, 0);
348 	atomic_set(&monpriv->iucv_connected, 0);
349 	atomic_set(&monpriv->read_ready, 0);
350 	atomic_set(&monpriv->msglim_count, 0);
351 	monpriv->write_index  = 0;
352 	monpriv->read_index   = 0;
353 
354 	for (i = 0; i < MON_MSGLIM; i++)
355 		kfree(monpriv->msg_array[i]);
356 	kfree(monpriv);
357 	clear_bit(MON_IN_USE, &mon_in_use);
358 	return 0;
359 }
360 
mon_read(struct file * filp,char __user * data,size_t count,loff_t * ppos)361 static ssize_t mon_read(struct file *filp, char __user *data,
362 			size_t count, loff_t *ppos)
363 {
364 	struct mon_private *monpriv = filp->private_data;
365 	struct mon_msg *monmsg;
366 	int ret;
367 	u32 mce_start;
368 
369 	monmsg = mon_next_message(monpriv);
370 	if (IS_ERR(monmsg))
371 		return PTR_ERR(monmsg);
372 
373 	if (!monmsg) {
374 		if (filp->f_flags & O_NONBLOCK)
375 			return -EAGAIN;
376 		ret = wait_event_interruptible(mon_read_wait_queue,
377 					atomic_read(&monpriv->read_ready) ||
378 					atomic_read(&monpriv->iucv_severed));
379 		if (ret)
380 			return ret;
381 		if (unlikely(atomic_read(&monpriv->iucv_severed)))
382 			return -EIO;
383 		monmsg = monpriv->msg_array[monpriv->read_index];
384 	}
385 
386 	if (!monmsg->pos)
387 		monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
388 	if (mon_check_mca(monmsg))
389 		goto reply;
390 
391 	/* read monitor control element (12 bytes) first */
392 	mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
393 	if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
394 		count = min(count, (size_t) mce_start + 12 - monmsg->pos);
395 		ret = copy_to_user(data, __va(monmsg->pos), count);
396 		if (ret)
397 			return -EFAULT;
398 		monmsg->pos += count;
399 		if (monmsg->pos == mce_start + 12)
400 			monmsg->pos = mon_rec_start(monmsg);
401 		goto out_copy;
402 	}
403 
404 	/* read records */
405 	if (monmsg->pos <= mon_rec_end(monmsg)) {
406 		count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
407 					    + 1);
408 		ret = copy_to_user(data, __va(monmsg->pos), count);
409 		if (ret)
410 			return -EFAULT;
411 		monmsg->pos += count;
412 		if (monmsg->pos > mon_rec_end(monmsg))
413 			mon_next_mca(monmsg);
414 		goto out_copy;
415 	}
416 reply:
417 	ret = mon_send_reply(monmsg, monpriv);
418 	return ret;
419 
420 out_copy:
421 	*ppos += count;
422 	return count;
423 }
424 
mon_poll(struct file * filp,struct poll_table_struct * p)425 static __poll_t mon_poll(struct file *filp, struct poll_table_struct *p)
426 {
427 	struct mon_private *monpriv = filp->private_data;
428 
429 	poll_wait(filp, &mon_read_wait_queue, p);
430 	if (unlikely(atomic_read(&monpriv->iucv_severed)))
431 		return EPOLLERR;
432 	if (atomic_read(&monpriv->read_ready))
433 		return EPOLLIN | EPOLLRDNORM;
434 	return 0;
435 }
436 
437 static const struct file_operations mon_fops = {
438 	.owner   = THIS_MODULE,
439 	.open    = &mon_open,
440 	.release = &mon_close,
441 	.read    = &mon_read,
442 	.poll    = &mon_poll,
443 	.llseek  = noop_llseek,
444 };
445 
446 static struct miscdevice mon_dev = {
447 	.name       = "monreader",
448 	.fops       = &mon_fops,
449 	.minor      = MISC_DYNAMIC_MINOR,
450 };
451 
452 /******************************************************************************
453  *                              module init/exit                              *
454  *****************************************************************************/
mon_init(void)455 static int __init mon_init(void)
456 {
457 	int rc;
458 
459 	if (!MACHINE_IS_VM) {
460 		pr_err("The z/VM *MONITOR record device driver cannot be "
461 		       "loaded without z/VM\n");
462 		return -ENODEV;
463 	}
464 
465 	/*
466 	 * Register with IUCV and connect to *MONITOR service
467 	 */
468 	rc = iucv_register(&monreader_iucv_handler, 1);
469 	if (rc) {
470 		pr_err("The z/VM *MONITOR record device driver failed to "
471 		       "register with IUCV\n");
472 		return rc;
473 	}
474 
475 	rc = segment_type(mon_dcss_name);
476 	if (rc < 0) {
477 		segment_warning(rc, mon_dcss_name);
478 		goto out_iucv;
479 	}
480 	if (rc != SEG_TYPE_SC) {
481 		pr_err("The specified *MONITOR DCSS %s does not have the "
482 		       "required type SC\n", mon_dcss_name);
483 		rc = -EINVAL;
484 		goto out_iucv;
485 	}
486 
487 	rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
488 			  &mon_dcss_start, &mon_dcss_end);
489 	if (rc < 0) {
490 		segment_warning(rc, mon_dcss_name);
491 		rc = -EINVAL;
492 		goto out_iucv;
493 	}
494 	dcss_mkname(mon_dcss_name, &user_data_connect[8]);
495 
496 	/*
497 	 * misc_register() has to be the last action in module_init(), because
498 	 * file operations will be available right after this.
499 	 */
500 	rc = misc_register(&mon_dev);
501 	if (rc < 0 )
502 		goto out;
503 	return 0;
504 
505 out:
506 	segment_unload(mon_dcss_name);
507 out_iucv:
508 	iucv_unregister(&monreader_iucv_handler, 1);
509 	return rc;
510 }
511 
mon_exit(void)512 static void __exit mon_exit(void)
513 {
514 	segment_unload(mon_dcss_name);
515 	misc_deregister(&mon_dev);
516 	iucv_unregister(&monreader_iucv_handler, 1);
517 	return;
518 }
519 
520 
521 module_init(mon_init);
522 module_exit(mon_exit);
523 
524 module_param_string(mondcss, mon_dcss_name, 9, 0444);
525 MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
526 		 "service, max. 8 chars. Default is MONDCSS");
527 
528 MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>");
529 MODULE_DESCRIPTION("Character device driver for reading z/VM "
530 		   "monitor service records.");
531 MODULE_LICENSE("GPL");
532