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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 <[email protected]>
8 */
9
10#define pr_fmt(fmt) "monreader: " fmt
11
12#include <linux/module.h>
13#include <linux/moduleparam.h>
14#include <linux/init.h>
15#include <linux/errno.h>
16#include <linux/types.h>
17#include <linux/kernel.h>
18#include <linux/miscdevice.h>
19#include <linux/ctype.h>
20#include <linux/spinlock.h>
21#include <linux/interrupt.h>
22#include <linux/poll.h>
23#include <linux/slab.h>
24#include <net/iucv/iucv.h>
25#include <linux/uaccess.h>
26#include <asm/machine.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
37static char mon_dcss_name[9] = "MONDCSS\0";
38
39struct mon_msg {
40 u32 pos;
41 u32 mca_offset;
42 struct iucv_message msg;
43 char msglim_reached;
44 char replied_msglim;
45};
46
47struct 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
58static unsigned long mon_in_use = 0;
59
60static unsigned long mon_dcss_start;
61static unsigned long mon_dcss_end;
62
63static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue);
64static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue);
65
66static 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
76static 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 */
88static 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
102static inline unsigned long mon_mca_start(struct mon_msg *monmsg)
103{
104 return *(u32 *) &monmsg->msg.rmmsg;
105}
106
107static inline unsigned long mon_mca_end(struct mon_msg *monmsg)
108{
109 return *(u32 *) &monmsg->msg.rmmsg[4];
110}
111
112static 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
117static inline u32 mon_mca_size(struct mon_msg *monmsg)
118{
119 return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
120}
121
122static inline u32 mon_rec_start(struct mon_msg *monmsg)
123{
124 return *((u32 *)(__va(mon_mca_start(monmsg)) + monmsg->mca_offset + 4));
125}
126
127static inline u32 mon_rec_end(struct mon_msg *monmsg)
128{
129 return *((u32 *)(__va(mon_mca_start(monmsg)) + monmsg->mca_offset + 8));
130}
131
132static 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
147static 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
170static 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
179static struct mon_private *mon_alloc_mem(void)
180{
181 int i;
182 struct mon_private *monpriv;
183
184 monpriv = kzalloc_obj(struct mon_private);
185 if (!monpriv)
186 return NULL;
187 for (i = 0; i < MON_MSGLIM; i++) {
188 monpriv->msg_array[i] = kzalloc_obj(struct mon_msg);
189 if (!monpriv->msg_array[i]) {
190 mon_free_mem(monpriv);
191 return NULL;
192 }
193 }
194 return monpriv;
195}
196
197static inline void mon_next_mca(struct mon_msg *monmsg)
198{
199 if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12))
200 return;
201 monmsg->mca_offset += 12;
202 monmsg->pos = 0;
203}
204
205static struct mon_msg *mon_next_message(struct mon_private *monpriv)
206{
207 struct mon_msg *monmsg;
208
209 if (!atomic_read(&monpriv->read_ready))
210 return NULL;
211 monmsg = monpriv->msg_array[monpriv->read_index];
212 if (unlikely(monmsg->replied_msglim)) {
213 monmsg->replied_msglim = 0;
214 monmsg->msglim_reached = 0;
215 monmsg->pos = 0;
216 monmsg->mca_offset = 0;
217 monpriv->read_index = (monpriv->read_index + 1) %
218 MON_MSGLIM;
219 atomic_dec(&monpriv->read_ready);
220 return ERR_PTR(-EOVERFLOW);
221 }
222 return monmsg;
223}
224
225
226/******************************************************************************
227 * IUCV handler *
228 *****************************************************************************/
229static void mon_iucv_path_complete(struct iucv_path *path, u8 *ipuser)
230{
231 struct mon_private *monpriv = path->private;
232
233 atomic_set(&monpriv->iucv_connected, 1);
234 wake_up(&mon_conn_wait_queue);
235}
236
237static void mon_iucv_path_severed(struct iucv_path *path, u8 *ipuser)
238{
239 struct mon_private *monpriv = path->private;
240
241 pr_err("z/VM *MONITOR system service disconnected with rc=%i\n",
242 ipuser[0]);
243 iucv_path_sever(path, NULL);
244 atomic_set(&monpriv->iucv_severed, 1);
245 wake_up(&mon_conn_wait_queue);
246 wake_up_interruptible(&mon_read_wait_queue);
247}
248
249static void mon_iucv_message_pending(struct iucv_path *path,
250 struct iucv_message *msg)
251{
252 struct mon_private *monpriv = path->private;
253
254 memcpy(&monpriv->msg_array[monpriv->write_index]->msg,
255 msg, sizeof(*msg));
256 if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) {
257 pr_warn("The read queue for monitor data is full\n");
258 monpriv->msg_array[monpriv->write_index]->msglim_reached = 1;
259 }
260 monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM;
261 atomic_inc(&monpriv->read_ready);
262 wake_up_interruptible(&mon_read_wait_queue);
263}
264
265static struct iucv_handler monreader_iucv_handler = {
266 .path_complete = mon_iucv_path_complete,
267 .path_severed = mon_iucv_path_severed,
268 .message_pending = mon_iucv_message_pending,
269};
270
271/******************************************************************************
272 * file operations *
273 *****************************************************************************/
274static int mon_open(struct inode *inode, struct file *filp)
275{
276 struct mon_private *monpriv;
277 int rc;
278
279 /*
280 * only one user allowed
281 */
282 rc = -EBUSY;
283 if (test_and_set_bit(MON_IN_USE, &mon_in_use))
284 goto out;
285
286 rc = -ENOMEM;
287 monpriv = mon_alloc_mem();
288 if (!monpriv)
289 goto out_use;
290
291 /*
292 * Connect to *MONITOR service
293 */
294 monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
295 if (!monpriv->path)
296 goto out_priv;
297 rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
298 MON_SERVICE, NULL, user_data_connect, monpriv);
299 if (rc) {
300 pr_err("Connecting to the z/VM *MONITOR system service "
301 "failed with rc=%i\n", rc);
302 rc = -EIO;
303 goto out_path;
304 }
305 /*
306 * Wait for connection confirmation
307 */
308 wait_event(mon_conn_wait_queue,
309 atomic_read(&monpriv->iucv_connected) ||
310 atomic_read(&monpriv->iucv_severed));
311 if (atomic_read(&monpriv->iucv_severed)) {
312 atomic_set(&monpriv->iucv_severed, 0);
313 atomic_set(&monpriv->iucv_connected, 0);
314 rc = -EIO;
315 goto out_path;
316 }
317 filp->private_data = monpriv;
318 return nonseekable_open(inode, filp);
319
320out_path:
321 iucv_path_free(monpriv->path);
322out_priv:
323 mon_free_mem(monpriv);
324out_use:
325 clear_bit(MON_IN_USE, &mon_in_use);
326out:
327 return rc;
328}
329
330static int mon_close(struct inode *inode, struct file *filp)
331{
332 int rc, i;
333 struct mon_private *monpriv = filp->private_data;
334
335 /*
336 * Close IUCV connection and unregister
337 */
338 if (monpriv->path) {
339 rc = iucv_path_sever(monpriv->path, user_data_sever);
340 if (rc)
341 pr_warn("Disconnecting the z/VM *MONITOR system service failed with rc=%i\n",
342 rc);
343 iucv_path_free(monpriv->path);
344 }
345
346 atomic_set(&monpriv->iucv_severed, 0);
347 atomic_set(&monpriv->iucv_connected, 0);
348 atomic_set(&monpriv->read_ready, 0);
349 atomic_set(&monpriv->msglim_count, 0);
350 monpriv->write_index = 0;
351 monpriv->read_index = 0;
352
353 for (i = 0; i < MON_MSGLIM; i++)
354 kfree(monpriv->msg_array[i]);
355 kfree(monpriv);
356 clear_bit(MON_IN_USE, &mon_in_use);
357 return 0;
358}
359
360static ssize_t mon_read(struct file *filp, char __user *data,
361 size_t count, loff_t *ppos)
362{
363 struct mon_private *monpriv = filp->private_data;
364 struct mon_msg *monmsg;
365 int ret;
366 u32 mce_start;
367
368 monmsg = mon_next_message(monpriv);
369 if (IS_ERR(monmsg))
370 return PTR_ERR(monmsg);
371
372 if (!monmsg) {
373 if (filp->f_flags & O_NONBLOCK)
374 return -EAGAIN;
375 ret = wait_event_interruptible(mon_read_wait_queue,
376 atomic_read(&monpriv->read_ready) ||
377 atomic_read(&monpriv->iucv_severed));
378 if (ret)
379 return ret;
380 if (unlikely(atomic_read(&monpriv->iucv_severed)))
381 return -EIO;
382 monmsg = monpriv->msg_array[monpriv->read_index];
383 }
384
385 if (!monmsg->pos)
386 monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
387 if (mon_check_mca(monmsg))
388 goto reply;
389
390 /* read monitor control element (12 bytes) first */
391 mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
392 if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
393 count = min(count, (size_t) mce_start + 12 - monmsg->pos);
394 ret = copy_to_user(data, __va(monmsg->pos), count);
395 if (ret)
396 return -EFAULT;
397 monmsg->pos += count;
398 if (monmsg->pos == mce_start + 12)
399 monmsg->pos = mon_rec_start(monmsg);
400 goto out_copy;
401 }
402
403 /* read records */
404 if (monmsg->pos <= mon_rec_end(monmsg)) {
405 count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
406 + 1);
407 ret = copy_to_user(data, __va(monmsg->pos), count);
408 if (ret)
409 return -EFAULT;
410 monmsg->pos += count;
411 if (monmsg->pos > mon_rec_end(monmsg))
412 mon_next_mca(monmsg);
413 goto out_copy;
414 }
415reply:
416 ret = mon_send_reply(monmsg, monpriv);
417 return ret;
418
419out_copy:
420 *ppos += count;
421 return count;
422}
423
424static __poll_t mon_poll(struct file *filp, struct poll_table_struct *p)
425{
426 struct mon_private *monpriv = filp->private_data;
427
428 poll_wait(filp, &mon_read_wait_queue, p);
429 if (unlikely(atomic_read(&monpriv->iucv_severed)))
430 return EPOLLERR;
431 if (atomic_read(&monpriv->read_ready))
432 return EPOLLIN | EPOLLRDNORM;
433 return 0;
434}
435
436static const struct file_operations mon_fops = {
437 .owner = THIS_MODULE,
438 .open = &mon_open,
439 .release = &mon_close,
440 .read = &mon_read,
441 .poll = &mon_poll,
442 .llseek = noop_llseek,
443};
444
445static struct miscdevice mon_dev = {
446 .name = "monreader",
447 .fops = &mon_fops,
448 .minor = MISC_DYNAMIC_MINOR,
449};
450
451/******************************************************************************
452 * module init/exit *
453 *****************************************************************************/
454static int __init mon_init(void)
455{
456 int rc;
457
458 if (!machine_is_vm()) {
459 pr_err("The z/VM *MONITOR record device driver cannot be "
460 "loaded without z/VM\n");
461 return -ENODEV;
462 }
463
464 /*
465 * Register with IUCV and connect to *MONITOR service
466 */
467 rc = iucv_register(&monreader_iucv_handler, 1);
468 if (rc) {
469 pr_err("The z/VM *MONITOR record device driver failed to "
470 "register with IUCV\n");
471 return rc;
472 }
473
474 rc = segment_type(mon_dcss_name);
475 if (rc < 0) {
476 segment_warning(rc, mon_dcss_name);
477 goto out_iucv;
478 }
479 if (rc != SEG_TYPE_SC) {
480 pr_err("The specified *MONITOR DCSS %s does not have the "
481 "required type SC\n", mon_dcss_name);
482 rc = -EINVAL;
483 goto out_iucv;
484 }
485
486 rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
487 &mon_dcss_start, &mon_dcss_end);
488 if (rc < 0) {
489 segment_warning(rc, mon_dcss_name);
490 rc = -EINVAL;
491 goto out_iucv;
492 }
493 dcss_mkname(mon_dcss_name, &user_data_connect[8]);
494
495 /*
496 * misc_register() has to be the last action in module_init(), because
497 * file operations will be available right after this.
498 */
499 rc = misc_register(&mon_dev);
500 if (rc < 0 )
501 goto out;
502 return 0;
503
504out:
505 segment_unload(mon_dcss_name);
506out_iucv:
507 iucv_unregister(&monreader_iucv_handler, 1);
508 return rc;
509}
510
511static void __exit mon_exit(void)
512{
513 segment_unload(mon_dcss_name);
514 misc_deregister(&mon_dev);
515 iucv_unregister(&monreader_iucv_handler, 1);
516 return;
517}
518
519
520module_init(mon_init);
521module_exit(mon_exit);
522
523module_param_string(mondcss, mon_dcss_name, 9, 0444);
524MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
525 "service, max. 8 chars. Default is MONDCSS");
526
527MODULE_AUTHOR("Gerald Schaefer <[email protected]>");
528MODULE_DESCRIPTION("Character device driver for reading z/VM "
529 "monitor service records.");
530MODULE_LICENSE("GPL");