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 *) 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 *) (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 *) (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, (void *) (unsigned long) monmsg->pos,
396 count);
397 if (ret)
398 return -EFAULT;
399 monmsg->pos += count;
400 if (monmsg->pos == mce_start + 12)
401 monmsg->pos = mon_rec_start(monmsg);
402 goto out_copy;
403 }
404
405 /* read records */
406 if (monmsg->pos <= mon_rec_end(monmsg)) {
407 count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
408 + 1);
409 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
410 count);
411 if (ret)
412 return -EFAULT;
413 monmsg->pos += count;
414 if (monmsg->pos > mon_rec_end(monmsg))
415 mon_next_mca(monmsg);
416 goto out_copy;
417 }
418 reply:
419 ret = mon_send_reply(monmsg, monpriv);
420 return ret;
421
422 out_copy:
423 *ppos += count;
424 return count;
425 }
426
mon_poll(struct file * filp,struct poll_table_struct * p)427 static __poll_t mon_poll(struct file *filp, struct poll_table_struct *p)
428 {
429 struct mon_private *monpriv = filp->private_data;
430
431 poll_wait(filp, &mon_read_wait_queue, p);
432 if (unlikely(atomic_read(&monpriv->iucv_severed)))
433 return EPOLLERR;
434 if (atomic_read(&monpriv->read_ready))
435 return EPOLLIN | EPOLLRDNORM;
436 return 0;
437 }
438
439 static const struct file_operations mon_fops = {
440 .owner = THIS_MODULE,
441 .open = &mon_open,
442 .release = &mon_close,
443 .read = &mon_read,
444 .poll = &mon_poll,
445 .llseek = noop_llseek,
446 };
447
448 static struct miscdevice mon_dev = {
449 .name = "monreader",
450 .fops = &mon_fops,
451 .minor = MISC_DYNAMIC_MINOR,
452 };
453
454 /******************************************************************************
455 * module init/exit *
456 *****************************************************************************/
mon_init(void)457 static int __init mon_init(void)
458 {
459 int rc;
460
461 if (!MACHINE_IS_VM) {
462 pr_err("The z/VM *MONITOR record device driver cannot be "
463 "loaded without z/VM\n");
464 return -ENODEV;
465 }
466
467 /*
468 * Register with IUCV and connect to *MONITOR service
469 */
470 rc = iucv_register(&monreader_iucv_handler, 1);
471 if (rc) {
472 pr_err("The z/VM *MONITOR record device driver failed to "
473 "register with IUCV\n");
474 return rc;
475 }
476
477 rc = segment_type(mon_dcss_name);
478 if (rc < 0) {
479 segment_warning(rc, mon_dcss_name);
480 goto out_iucv;
481 }
482 if (rc != SEG_TYPE_SC) {
483 pr_err("The specified *MONITOR DCSS %s does not have the "
484 "required type SC\n", mon_dcss_name);
485 rc = -EINVAL;
486 goto out_iucv;
487 }
488
489 rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
490 &mon_dcss_start, &mon_dcss_end);
491 if (rc < 0) {
492 segment_warning(rc, mon_dcss_name);
493 rc = -EINVAL;
494 goto out_iucv;
495 }
496 dcss_mkname(mon_dcss_name, &user_data_connect[8]);
497
498 /*
499 * misc_register() has to be the last action in module_init(), because
500 * file operations will be available right after this.
501 */
502 rc = misc_register(&mon_dev);
503 if (rc < 0 )
504 goto out;
505 return 0;
506
507 out:
508 segment_unload(mon_dcss_name);
509 out_iucv:
510 iucv_unregister(&monreader_iucv_handler, 1);
511 return rc;
512 }
513
mon_exit(void)514 static void __exit mon_exit(void)
515 {
516 segment_unload(mon_dcss_name);
517 misc_deregister(&mon_dev);
518 iucv_unregister(&monreader_iucv_handler, 1);
519 return;
520 }
521
522
523 module_init(mon_init);
524 module_exit(mon_exit);
525
526 module_param_string(mondcss, mon_dcss_name, 9, 0444);
527 MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
528 "service, max. 8 chars. Default is MONDCSS");
529
530 MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>");
531 MODULE_DESCRIPTION("Character device driver for reading z/VM "
532 "monitor service records.");
533 MODULE_LICENSE("GPL");
534