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 | */ |
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 | |
102 | static inline unsigned long mon_mca_start(struct mon_msg *monmsg) |
103 | { |
104 | return *(u32 *) &monmsg->msg.rmmsg; |
105 | } |
106 | |
107 | static inline unsigned long mon_mca_end(struct mon_msg *monmsg) |
108 | { |
109 | return *(u32 *) &monmsg->msg.rmmsg[4]; |
110 | } |
111 | |
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 | |
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 | |
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 | |
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 | |
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, index: 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, index: 1) == 0) && (mon_mca_type(monmsg, index: 2) == 0))) |
143 | return -EINVAL; |
144 | return 0; |
145 | } |
146 | |
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(path: monpriv->path, msg: &monmsg->msg, |
153 | IUCV_IPRMDATA, NULL, size: 0); |
154 | atomic_dec(v: &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(v: &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 | |
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(objp: monpriv->msg_array[i]); |
176 | kfree(objp: monpriv); |
177 | } |
178 | |
179 | static struct mon_private *mon_alloc_mem(void) |
180 | { |
181 | int i; |
182 | struct mon_private *monpriv; |
183 | |
184 | monpriv = kzalloc(size: 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(size: 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 | |
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 | |
206 | static struct mon_msg *mon_next_message(struct mon_private *monpriv) |
207 | { |
208 | struct mon_msg *monmsg; |
209 | |
210 | if (!atomic_read(v: &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(v: &monpriv->read_ready); |
221 | return ERR_PTR(error: -EOVERFLOW); |
222 | } |
223 | return monmsg; |
224 | } |
225 | |
226 | |
227 | /****************************************************************************** |
228 | * IUCV handler * |
229 | *****************************************************************************/ |
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(v: &monpriv->iucv_connected, i: 1); |
235 | wake_up(&mon_conn_wait_queue); |
236 | } |
237 | |
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(v: &monpriv->iucv_severed, i: 1); |
246 | wake_up(&mon_conn_wait_queue); |
247 | wake_up_interruptible(&mon_read_wait_queue); |
248 | } |
249 | |
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(v: &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(v: &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 | *****************************************************************************/ |
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, addr: &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(path: monpriv->path, handler: &monreader_iucv_handler, |
299 | MON_SERVICE, NULL, userdata: user_data_connect, private: 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(v: &monpriv->iucv_severed)) { |
313 | atomic_set(v: &monpriv->iucv_severed, i: 0); |
314 | atomic_set(v: &monpriv->iucv_connected, i: 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(path: monpriv->path); |
323 | out_priv: |
324 | mon_free_mem(monpriv); |
325 | out_use: |
326 | clear_bit(MON_IN_USE, addr: &mon_in_use); |
327 | out: |
328 | return rc; |
329 | } |
330 | |
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(path: monpriv->path, userdata: 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(path: monpriv->path); |
345 | } |
346 | |
347 | atomic_set(v: &monpriv->iucv_severed, i: 0); |
348 | atomic_set(v: &monpriv->iucv_connected, i: 0); |
349 | atomic_set(v: &monpriv->read_ready, i: 0); |
350 | atomic_set(v: &monpriv->msglim_count, i: 0); |
351 | monpriv->write_index = 0; |
352 | monpriv->read_index = 0; |
353 | |
354 | for (i = 0; i < MON_MSGLIM; i++) |
355 | kfree(objp: monpriv->msg_array[i]); |
356 | kfree(objp: monpriv); |
357 | clear_bit(MON_IN_USE, addr: &mon_in_use); |
358 | return 0; |
359 | } |
360 | |
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(ptr: monmsg)) |
371 | return PTR_ERR(ptr: 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(to: data, __va(monmsg->pos), n: 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(to: data, __va(monmsg->pos), n: 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 | |
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, wait_address: &mon_read_wait_queue, p); |
430 | if (unlikely(atomic_read(&monpriv->iucv_severed))) |
431 | return EPOLLERR; |
432 | if (atomic_read(v: &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 | *****************************************************************************/ |
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(handler: &monreader_iucv_handler, smp: 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(ascii_name: mon_dcss_name, ebcdic_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(misc: &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(handle: &monreader_iucv_handler, smp: 1); |
509 | return rc; |
510 | } |
511 | |
512 | static void __exit mon_exit(void) |
513 | { |
514 | segment_unload(mon_dcss_name); |
515 | misc_deregister(misc: &mon_dev); |
516 | iucv_unregister(handle: &monreader_iucv_handler, smp: 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 | |