xref: /openbmc/linux/arch/s390/kernel/debug.c (revision 305c8388)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *   S/390 debug facility
4  *
5  *    Copyright IBM Corp. 1999, 2012
6  *
7  *    Author(s): Michael Holzheu (holzheu@de.ibm.com),
8  *		 Holger Smolinski (Holger.Smolinski@de.ibm.com)
9  *
10  *    Bugreports to: <Linux390@de.ibm.com>
11  */
12 
13 #define KMSG_COMPONENT "s390dbf"
14 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
15 
16 #include <linux/stddef.h>
17 #include <linux/kernel.h>
18 #include <linux/errno.h>
19 #include <linux/slab.h>
20 #include <linux/ctype.h>
21 #include <linux/string.h>
22 #include <linux/sysctl.h>
23 #include <linux/uaccess.h>
24 #include <linux/export.h>
25 #include <linux/init.h>
26 #include <linux/fs.h>
27 #include <linux/debugfs.h>
28 
29 #include <asm/debug.h>
30 
31 #define DEBUG_PROLOG_ENTRY -1
32 
33 #define ALL_AREAS 0 /* copy all debug areas */
34 #define NO_AREAS  1 /* copy no debug areas */
35 
36 /* typedefs */
37 
38 typedef struct file_private_info {
39 	loff_t offset;			/* offset of last read in file */
40 	int    act_area;		/* number of last formated area */
41 	int    act_page;		/* act page in given area */
42 	int    act_entry;		/* last formated entry (offset */
43 					/* relative to beginning of last */
44 					/* formated page) */
45 	size_t act_entry_offset;	/* up to this offset we copied */
46 					/* in last read the last formated */
47 					/* entry to userland */
48 	char   temp_buf[2048];		/* buffer for output */
49 	debug_info_t *debug_info_org;	/* original debug information */
50 	debug_info_t *debug_info_snap;	/* snapshot of debug information */
51 	struct debug_view *view;	/* used view of debug info */
52 } file_private_info_t;
53 
54 typedef struct {
55 	char *string;
56 	/*
57 	 * This assumes that all args are converted into longs
58 	 * on L/390 this is the case for all types of parameter
59 	 * except of floats, and long long (32 bit)
60 	 *
61 	 */
62 	long args[0];
63 } debug_sprintf_entry_t;
64 
65 /* internal function prototyes */
66 
67 static int debug_init(void);
68 static ssize_t debug_output(struct file *file, char __user *user_buf,
69 			    size_t user_len, loff_t *offset);
70 static ssize_t debug_input(struct file *file, const char __user *user_buf,
71 			   size_t user_len, loff_t *offset);
72 static int debug_open(struct inode *inode, struct file *file);
73 static int debug_close(struct inode *inode, struct file *file);
74 static debug_info_t *debug_info_create(const char *name, int pages_per_area,
75 				       int nr_areas, int buf_size, umode_t mode);
76 static void debug_info_get(debug_info_t *);
77 static void debug_info_put(debug_info_t *);
78 static int debug_prolog_level_fn(debug_info_t *id,
79 				 struct debug_view *view, char *out_buf);
80 static int debug_input_level_fn(debug_info_t *id, struct debug_view *view,
81 				struct file *file, const char __user *user_buf,
82 				size_t user_buf_size, loff_t *offset);
83 static int debug_prolog_pages_fn(debug_info_t *id,
84 				 struct debug_view *view, char *out_buf);
85 static int debug_input_pages_fn(debug_info_t *id, struct debug_view *view,
86 				struct file *file, const char __user *user_buf,
87 				size_t user_buf_size, loff_t *offset);
88 static int debug_input_flush_fn(debug_info_t *id, struct debug_view *view,
89 				struct file *file, const char __user *user_buf,
90 				size_t user_buf_size, loff_t *offset);
91 static int debug_hex_ascii_format_fn(debug_info_t *id, struct debug_view *view,
92 				     char *out_buf, const char *in_buf);
93 static int debug_raw_format_fn(debug_info_t *id,
94 			       struct debug_view *view, char *out_buf,
95 			       const char *in_buf);
96 static int debug_raw_header_fn(debug_info_t *id, struct debug_view *view,
97 			       int area, debug_entry_t *entry, char *out_buf);
98 
99 static int debug_sprintf_format_fn(debug_info_t *id, struct debug_view *view,
100 				   char *out_buf, debug_sprintf_entry_t *curr_event);
101 
102 /* globals */
103 
104 struct debug_view debug_raw_view = {
105 	"raw",
106 	NULL,
107 	&debug_raw_header_fn,
108 	&debug_raw_format_fn,
109 	NULL,
110 	NULL
111 };
112 EXPORT_SYMBOL(debug_raw_view);
113 
114 struct debug_view debug_hex_ascii_view = {
115 	"hex_ascii",
116 	NULL,
117 	&debug_dflt_header_fn,
118 	&debug_hex_ascii_format_fn,
119 	NULL,
120 	NULL
121 };
122 EXPORT_SYMBOL(debug_hex_ascii_view);
123 
124 static struct debug_view debug_level_view = {
125 	"level",
126 	&debug_prolog_level_fn,
127 	NULL,
128 	NULL,
129 	&debug_input_level_fn,
130 	NULL
131 };
132 
133 static struct debug_view debug_pages_view = {
134 	"pages",
135 	&debug_prolog_pages_fn,
136 	NULL,
137 	NULL,
138 	&debug_input_pages_fn,
139 	NULL
140 };
141 
142 static struct debug_view debug_flush_view = {
143 	"flush",
144 	NULL,
145 	NULL,
146 	NULL,
147 	&debug_input_flush_fn,
148 	NULL
149 };
150 
151 struct debug_view debug_sprintf_view = {
152 	"sprintf",
153 	NULL,
154 	&debug_dflt_header_fn,
155 	(debug_format_proc_t *)&debug_sprintf_format_fn,
156 	NULL,
157 	NULL
158 };
159 EXPORT_SYMBOL(debug_sprintf_view);
160 
161 /* used by dump analysis tools to determine version of debug feature */
162 static unsigned int __used debug_feature_version = __DEBUG_FEATURE_VERSION;
163 
164 /* static globals */
165 
166 static debug_info_t *debug_area_first;
167 static debug_info_t *debug_area_last;
168 static DEFINE_MUTEX(debug_mutex);
169 
170 static int initialized;
171 static int debug_critical;
172 
173 static const struct file_operations debug_file_ops = {
174 	.owner	 = THIS_MODULE,
175 	.read	 = debug_output,
176 	.write	 = debug_input,
177 	.open	 = debug_open,
178 	.release = debug_close,
179 	.llseek  = no_llseek,
180 };
181 
182 static struct dentry *debug_debugfs_root_entry;
183 
184 /* functions */
185 
186 /*
187  * debug_areas_alloc
188  * - Debug areas are implemented as a threedimensonal array:
189  *   areas[areanumber][pagenumber][pageoffset]
190  */
191 
192 static debug_entry_t ***debug_areas_alloc(int pages_per_area, int nr_areas)
193 {
194 	debug_entry_t ***areas;
195 	int i, j;
196 
197 	areas = kmalloc_array(nr_areas, sizeof(debug_entry_t **), GFP_KERNEL);
198 	if (!areas)
199 		goto fail_malloc_areas;
200 	for (i = 0; i < nr_areas; i++) {
201 		areas[i] = kmalloc_array(pages_per_area,
202 					 sizeof(debug_entry_t *),
203 					 GFP_KERNEL);
204 		if (!areas[i])
205 			goto fail_malloc_areas2;
206 		for (j = 0; j < pages_per_area; j++) {
207 			areas[i][j] = kzalloc(PAGE_SIZE, GFP_KERNEL);
208 			if (!areas[i][j]) {
209 				for (j--; j >= 0 ; j--)
210 					kfree(areas[i][j]);
211 				kfree(areas[i]);
212 				goto fail_malloc_areas2;
213 			}
214 		}
215 	}
216 	return areas;
217 
218 fail_malloc_areas2:
219 	for (i--; i >= 0; i--) {
220 		for (j = 0; j < pages_per_area; j++)
221 			kfree(areas[i][j]);
222 		kfree(areas[i]);
223 	}
224 	kfree(areas);
225 fail_malloc_areas:
226 	return NULL;
227 }
228 
229 /*
230  * debug_info_alloc
231  * - alloc new debug-info
232  */
233 static debug_info_t *debug_info_alloc(const char *name, int pages_per_area,
234 				      int nr_areas, int buf_size, int level,
235 				      int mode)
236 {
237 	debug_info_t *rc;
238 
239 	/* alloc everything */
240 	rc = kmalloc(sizeof(debug_info_t), GFP_KERNEL);
241 	if (!rc)
242 		goto fail_malloc_rc;
243 	rc->active_entries = kcalloc(nr_areas, sizeof(int), GFP_KERNEL);
244 	if (!rc->active_entries)
245 		goto fail_malloc_active_entries;
246 	rc->active_pages = kcalloc(nr_areas, sizeof(int), GFP_KERNEL);
247 	if (!rc->active_pages)
248 		goto fail_malloc_active_pages;
249 	if ((mode == ALL_AREAS) && (pages_per_area != 0)) {
250 		rc->areas = debug_areas_alloc(pages_per_area, nr_areas);
251 		if (!rc->areas)
252 			goto fail_malloc_areas;
253 	} else {
254 		rc->areas = NULL;
255 	}
256 
257 	/* initialize members */
258 	spin_lock_init(&rc->lock);
259 	rc->pages_per_area = pages_per_area;
260 	rc->nr_areas	   = nr_areas;
261 	rc->active_area    = 0;
262 	rc->level	   = level;
263 	rc->buf_size	   = buf_size;
264 	rc->entry_size	   = sizeof(debug_entry_t) + buf_size;
265 	strlcpy(rc->name, name, sizeof(rc->name));
266 	memset(rc->views, 0, DEBUG_MAX_VIEWS * sizeof(struct debug_view *));
267 	memset(rc->debugfs_entries, 0, DEBUG_MAX_VIEWS * sizeof(struct dentry *));
268 	refcount_set(&(rc->ref_count), 0);
269 
270 	return rc;
271 
272 fail_malloc_areas:
273 	kfree(rc->active_pages);
274 fail_malloc_active_pages:
275 	kfree(rc->active_entries);
276 fail_malloc_active_entries:
277 	kfree(rc);
278 fail_malloc_rc:
279 	return NULL;
280 }
281 
282 /*
283  * debug_areas_free
284  * - free all debug areas
285  */
286 static void debug_areas_free(debug_info_t *db_info)
287 {
288 	int i, j;
289 
290 	if (!db_info->areas)
291 		return;
292 	for (i = 0; i < db_info->nr_areas; i++) {
293 		for (j = 0; j < db_info->pages_per_area; j++)
294 			kfree(db_info->areas[i][j]);
295 		kfree(db_info->areas[i]);
296 	}
297 	kfree(db_info->areas);
298 	db_info->areas = NULL;
299 }
300 
301 /*
302  * debug_info_free
303  * - free memory debug-info
304  */
305 static void debug_info_free(debug_info_t *db_info)
306 {
307 	debug_areas_free(db_info);
308 	kfree(db_info->active_entries);
309 	kfree(db_info->active_pages);
310 	kfree(db_info);
311 }
312 
313 /*
314  * debug_info_create
315  * - create new debug-info
316  */
317 
318 static debug_info_t *debug_info_create(const char *name, int pages_per_area,
319 				       int nr_areas, int buf_size, umode_t mode)
320 {
321 	debug_info_t *rc;
322 
323 	rc = debug_info_alloc(name, pages_per_area, nr_areas, buf_size,
324 			      DEBUG_DEFAULT_LEVEL, ALL_AREAS);
325 	if (!rc)
326 		goto out;
327 
328 	rc->mode = mode & ~S_IFMT;
329 
330 	/* create root directory */
331 	rc->debugfs_root_entry = debugfs_create_dir(rc->name,
332 						    debug_debugfs_root_entry);
333 
334 	/* append new element to linked list */
335 	if (!debug_area_first) {
336 		/* first element in list */
337 		debug_area_first = rc;
338 		rc->prev = NULL;
339 	} else {
340 		/* append element to end of list */
341 		debug_area_last->next = rc;
342 		rc->prev = debug_area_last;
343 	}
344 	debug_area_last = rc;
345 	rc->next = NULL;
346 
347 	refcount_set(&rc->ref_count, 1);
348 out:
349 	return rc;
350 }
351 
352 /*
353  * debug_info_copy
354  * - copy debug-info
355  */
356 static debug_info_t *debug_info_copy(debug_info_t *in, int mode)
357 {
358 	unsigned long flags;
359 	debug_info_t *rc;
360 	int i, j;
361 
362 	/* get a consistent copy of the debug areas */
363 	do {
364 		rc = debug_info_alloc(in->name, in->pages_per_area,
365 			in->nr_areas, in->buf_size, in->level, mode);
366 		spin_lock_irqsave(&in->lock, flags);
367 		if (!rc)
368 			goto out;
369 		/* has something changed in the meantime ? */
370 		if ((rc->pages_per_area == in->pages_per_area) &&
371 		    (rc->nr_areas == in->nr_areas)) {
372 			break;
373 		}
374 		spin_unlock_irqrestore(&in->lock, flags);
375 		debug_info_free(rc);
376 	} while (1);
377 
378 	if (mode == NO_AREAS)
379 		goto out;
380 
381 	for (i = 0; i < in->nr_areas; i++) {
382 		for (j = 0; j < in->pages_per_area; j++)
383 			memcpy(rc->areas[i][j], in->areas[i][j], PAGE_SIZE);
384 	}
385 out:
386 	spin_unlock_irqrestore(&in->lock, flags);
387 	return rc;
388 }
389 
390 /*
391  * debug_info_get
392  * - increments reference count for debug-info
393  */
394 static void debug_info_get(debug_info_t *db_info)
395 {
396 	if (db_info)
397 		refcount_inc(&db_info->ref_count);
398 }
399 
400 /*
401  * debug_info_put:
402  * - decreases reference count for debug-info and frees it if necessary
403  */
404 static void debug_info_put(debug_info_t *db_info)
405 {
406 	int i;
407 
408 	if (!db_info)
409 		return;
410 	if (refcount_dec_and_test(&db_info->ref_count)) {
411 		for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
412 			if (!db_info->views[i])
413 				continue;
414 			debugfs_remove(db_info->debugfs_entries[i]);
415 		}
416 		debugfs_remove(db_info->debugfs_root_entry);
417 		if (db_info == debug_area_first)
418 			debug_area_first = db_info->next;
419 		if (db_info == debug_area_last)
420 			debug_area_last = db_info->prev;
421 		if (db_info->prev)
422 			db_info->prev->next = db_info->next;
423 		if (db_info->next)
424 			db_info->next->prev = db_info->prev;
425 		debug_info_free(db_info);
426 	}
427 }
428 
429 /*
430  * debug_format_entry:
431  * - format one debug entry and return size of formated data
432  */
433 static int debug_format_entry(file_private_info_t *p_info)
434 {
435 	debug_info_t *id_snap	= p_info->debug_info_snap;
436 	struct debug_view *view = p_info->view;
437 	debug_entry_t *act_entry;
438 	size_t len = 0;
439 
440 	if (p_info->act_entry == DEBUG_PROLOG_ENTRY) {
441 		/* print prolog */
442 		if (view->prolog_proc)
443 			len += view->prolog_proc(id_snap, view, p_info->temp_buf);
444 		goto out;
445 	}
446 	if (!id_snap->areas) /* this is true, if we have a prolog only view */
447 		goto out;    /* or if 'pages_per_area' is 0 */
448 	act_entry = (debug_entry_t *) ((char *)id_snap->areas[p_info->act_area]
449 				       [p_info->act_page] + p_info->act_entry);
450 
451 	if (act_entry->id.stck == 0LL)
452 		goto out; /* empty entry */
453 	if (view->header_proc)
454 		len += view->header_proc(id_snap, view, p_info->act_area,
455 					 act_entry, p_info->temp_buf + len);
456 	if (view->format_proc)
457 		len += view->format_proc(id_snap, view, p_info->temp_buf + len,
458 					 DEBUG_DATA(act_entry));
459 out:
460 	return len;
461 }
462 
463 /*
464  * debug_next_entry:
465  * - goto next entry in p_info
466  */
467 static inline int debug_next_entry(file_private_info_t *p_info)
468 {
469 	debug_info_t *id;
470 
471 	id = p_info->debug_info_snap;
472 	if (p_info->act_entry == DEBUG_PROLOG_ENTRY) {
473 		p_info->act_entry = 0;
474 		p_info->act_page  = 0;
475 		goto out;
476 	}
477 	if (!id->areas)
478 		return 1;
479 	p_info->act_entry += id->entry_size;
480 	/* switch to next page, if we reached the end of the page  */
481 	if (p_info->act_entry > (PAGE_SIZE - id->entry_size)) {
482 		/* next page */
483 		p_info->act_entry = 0;
484 		p_info->act_page += 1;
485 		if ((p_info->act_page % id->pages_per_area) == 0) {
486 			/* next area */
487 			p_info->act_area++;
488 			p_info->act_page = 0;
489 		}
490 		if (p_info->act_area >= id->nr_areas)
491 			return 1;
492 	}
493 out:
494 	return 0;
495 }
496 
497 /*
498  * debug_output:
499  * - called for user read()
500  * - copies formated debug entries to the user buffer
501  */
502 static ssize_t debug_output(struct file *file,		/* file descriptor */
503 			    char __user *user_buf,	/* user buffer */
504 			    size_t len,			/* length of buffer */
505 			    loff_t *offset)		/* offset in the file */
506 {
507 	size_t count = 0;
508 	size_t entry_offset;
509 	file_private_info_t *p_info;
510 
511 	p_info = (file_private_info_t *) file->private_data;
512 	if (*offset != p_info->offset)
513 		return -EPIPE;
514 	if (p_info->act_area >= p_info->debug_info_snap->nr_areas)
515 		return 0;
516 	entry_offset = p_info->act_entry_offset;
517 	while (count < len) {
518 		int formatted_line_residue;
519 		int formatted_line_size;
520 		int user_buf_residue;
521 		size_t copy_size;
522 
523 		formatted_line_size = debug_format_entry(p_info);
524 		formatted_line_residue = formatted_line_size - entry_offset;
525 		user_buf_residue = len-count;
526 		copy_size = min(user_buf_residue, formatted_line_residue);
527 		if (copy_size) {
528 			if (copy_to_user(user_buf + count, p_info->temp_buf
529 					 + entry_offset, copy_size))
530 				return -EFAULT;
531 			count += copy_size;
532 			entry_offset += copy_size;
533 		}
534 		if (copy_size == formatted_line_residue) {
535 			entry_offset = 0;
536 			if (debug_next_entry(p_info))
537 				goto out;
538 		}
539 	}
540 out:
541 	p_info->offset		 = *offset + count;
542 	p_info->act_entry_offset = entry_offset;
543 	*offset = p_info->offset;
544 	return count;
545 }
546 
547 /*
548  * debug_input:
549  * - called for user write()
550  * - calls input function of view
551  */
552 static ssize_t debug_input(struct file *file, const char __user *user_buf,
553 			   size_t length, loff_t *offset)
554 {
555 	file_private_info_t *p_info;
556 	int rc = 0;
557 
558 	mutex_lock(&debug_mutex);
559 	p_info = ((file_private_info_t *) file->private_data);
560 	if (p_info->view->input_proc) {
561 		rc = p_info->view->input_proc(p_info->debug_info_org,
562 					      p_info->view, file, user_buf,
563 					      length, offset);
564 	} else {
565 		rc = -EPERM;
566 	}
567 	mutex_unlock(&debug_mutex);
568 	return rc; /* number of input characters */
569 }
570 
571 /*
572  * debug_open:
573  * - called for user open()
574  * - copies formated output to private_data area of the file
575  *   handle
576  */
577 static int debug_open(struct inode *inode, struct file *file)
578 {
579 	debug_info_t *debug_info, *debug_info_snapshot;
580 	file_private_info_t *p_info;
581 	int i, rc = 0;
582 
583 	mutex_lock(&debug_mutex);
584 	debug_info = file_inode(file)->i_private;
585 	/* find debug view */
586 	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
587 		if (!debug_info->views[i])
588 			continue;
589 		else if (debug_info->debugfs_entries[i] == file->f_path.dentry)
590 			goto found; /* found view ! */
591 	}
592 	/* no entry found */
593 	rc = -EINVAL;
594 	goto out;
595 
596 found:
597 
598 	/* Make snapshot of current debug areas to get it consistent.	  */
599 	/* To copy all the areas is only needed, if we have a view which  */
600 	/* formats the debug areas. */
601 
602 	if (!debug_info->views[i]->format_proc && !debug_info->views[i]->header_proc)
603 		debug_info_snapshot = debug_info_copy(debug_info, NO_AREAS);
604 	else
605 		debug_info_snapshot = debug_info_copy(debug_info, ALL_AREAS);
606 
607 	if (!debug_info_snapshot) {
608 		rc = -ENOMEM;
609 		goto out;
610 	}
611 	p_info = kmalloc(sizeof(file_private_info_t), GFP_KERNEL);
612 	if (!p_info) {
613 		debug_info_free(debug_info_snapshot);
614 		rc = -ENOMEM;
615 		goto out;
616 	}
617 	p_info->offset = 0;
618 	p_info->debug_info_snap = debug_info_snapshot;
619 	p_info->debug_info_org	= debug_info;
620 	p_info->view = debug_info->views[i];
621 	p_info->act_area = 0;
622 	p_info->act_page = 0;
623 	p_info->act_entry = DEBUG_PROLOG_ENTRY;
624 	p_info->act_entry_offset = 0;
625 	file->private_data = p_info;
626 	debug_info_get(debug_info);
627 	nonseekable_open(inode, file);
628 out:
629 	mutex_unlock(&debug_mutex);
630 	return rc;
631 }
632 
633 /*
634  * debug_close:
635  * - called for user close()
636  * - deletes  private_data area of the file handle
637  */
638 static int debug_close(struct inode *inode, struct file *file)
639 {
640 	file_private_info_t *p_info;
641 
642 	p_info = (file_private_info_t *) file->private_data;
643 	if (p_info->debug_info_snap)
644 		debug_info_free(p_info->debug_info_snap);
645 	debug_info_put(p_info->debug_info_org);
646 	kfree(file->private_data);
647 	return 0; /* success */
648 }
649 
650 /**
651  * debug_register_mode() - creates and initializes debug area.
652  *
653  * @name:	Name of debug log (e.g. used for debugfs entry)
654  * @pages_per_area:	Number of pages, which will be allocated per area
655  * @nr_areas:	Number of debug areas
656  * @buf_size:	Size of data area in each debug entry
657  * @mode:	File mode for debugfs files. E.g. S_IRWXUGO
658  * @uid:	User ID for debugfs files. Currently only 0 is supported.
659  * @gid:	Group ID for debugfs files. Currently only 0 is supported.
660  *
661  * Return:
662  * - Handle for generated debug area
663  * - %NULL if register failed
664  *
665  * Allocates memory for a debug log.
666  * Must not be called within an interrupt handler.
667  */
668 debug_info_t *debug_register_mode(const char *name, int pages_per_area,
669 				  int nr_areas, int buf_size, umode_t mode,
670 				  uid_t uid, gid_t gid)
671 {
672 	debug_info_t *rc = NULL;
673 
674 	/* Since debugfs currently does not support uid/gid other than root, */
675 	/* we do not allow gid/uid != 0 until we get support for that. */
676 	if ((uid != 0) || (gid != 0))
677 		pr_warn("Root becomes the owner of all s390dbf files in sysfs\n");
678 	BUG_ON(!initialized);
679 	mutex_lock(&debug_mutex);
680 
681 	/* create new debug_info */
682 	rc = debug_info_create(name, pages_per_area, nr_areas, buf_size, mode);
683 	if (!rc)
684 		goto out;
685 	debug_register_view(rc, &debug_level_view);
686 	debug_register_view(rc, &debug_flush_view);
687 	debug_register_view(rc, &debug_pages_view);
688 out:
689 	if (!rc)
690 		pr_err("Registering debug feature %s failed\n", name);
691 	mutex_unlock(&debug_mutex);
692 	return rc;
693 }
694 EXPORT_SYMBOL(debug_register_mode);
695 
696 /**
697  * debug_register() - creates and initializes debug area with default file mode.
698  *
699  * @name:	Name of debug log (e.g. used for debugfs entry)
700  * @pages_per_area:	Number of pages, which will be allocated per area
701  * @nr_areas:	Number of debug areas
702  * @buf_size:	Size of data area in each debug entry
703  *
704  * Return:
705  * - Handle for generated debug area
706  * - %NULL if register failed
707  *
708  * Allocates memory for a debug log.
709  * The debugfs file mode access permissions are read and write for user.
710  * Must not be called within an interrupt handler.
711  */
712 debug_info_t *debug_register(const char *name, int pages_per_area,
713 			     int nr_areas, int buf_size)
714 {
715 	return debug_register_mode(name, pages_per_area, nr_areas, buf_size,
716 				   S_IRUSR | S_IWUSR, 0, 0);
717 }
718 EXPORT_SYMBOL(debug_register);
719 
720 /**
721  * debug_unregister() - give back debug area.
722  *
723  * @id:		handle for debug log
724  *
725  * Return:
726  *    none
727  */
728 void debug_unregister(debug_info_t *id)
729 {
730 	if (!id)
731 		return;
732 	mutex_lock(&debug_mutex);
733 	debug_info_put(id);
734 	mutex_unlock(&debug_mutex);
735 }
736 EXPORT_SYMBOL(debug_unregister);
737 
738 /*
739  * debug_set_size:
740  * - set area size (number of pages) and number of areas
741  */
742 static int debug_set_size(debug_info_t *id, int nr_areas, int pages_per_area)
743 {
744 	debug_entry_t ***new_areas;
745 	unsigned long flags;
746 	int rc = 0;
747 
748 	if (!id || (nr_areas <= 0) || (pages_per_area < 0))
749 		return -EINVAL;
750 	if (pages_per_area > 0) {
751 		new_areas = debug_areas_alloc(pages_per_area, nr_areas);
752 		if (!new_areas) {
753 			pr_info("Allocating memory for %i pages failed\n",
754 				pages_per_area);
755 			rc = -ENOMEM;
756 			goto out;
757 		}
758 	} else {
759 		new_areas = NULL;
760 	}
761 	spin_lock_irqsave(&id->lock, flags);
762 	debug_areas_free(id);
763 	id->areas = new_areas;
764 	id->nr_areas = nr_areas;
765 	id->pages_per_area = pages_per_area;
766 	id->active_area = 0;
767 	memset(id->active_entries, 0, sizeof(int)*id->nr_areas);
768 	memset(id->active_pages, 0, sizeof(int)*id->nr_areas);
769 	spin_unlock_irqrestore(&id->lock, flags);
770 	pr_info("%s: set new size (%i pages)\n", id->name, pages_per_area);
771 out:
772 	return rc;
773 }
774 
775 /**
776  * debug_set_level() - Sets new actual debug level if new_level is valid.
777  *
778  * @id:		handle for debug log
779  * @new_level:	new debug level
780  *
781  * Return:
782  *    none
783  */
784 void debug_set_level(debug_info_t *id, int new_level)
785 {
786 	unsigned long flags;
787 
788 	if (!id)
789 		return;
790 	spin_lock_irqsave(&id->lock, flags);
791 	if (new_level == DEBUG_OFF_LEVEL) {
792 		id->level = DEBUG_OFF_LEVEL;
793 		pr_info("%s: switched off\n", id->name);
794 	} else if ((new_level > DEBUG_MAX_LEVEL) || (new_level < 0)) {
795 		pr_info("%s: level %i is out of range (%i - %i)\n",
796 			id->name, new_level, 0, DEBUG_MAX_LEVEL);
797 	} else {
798 		id->level = new_level;
799 	}
800 	spin_unlock_irqrestore(&id->lock, flags);
801 }
802 EXPORT_SYMBOL(debug_set_level);
803 
804 /*
805  * proceed_active_entry:
806  * - set active entry to next in the ring buffer
807  */
808 static inline void proceed_active_entry(debug_info_t *id)
809 {
810 	if ((id->active_entries[id->active_area] += id->entry_size)
811 	    > (PAGE_SIZE - id->entry_size)) {
812 		id->active_entries[id->active_area] = 0;
813 		id->active_pages[id->active_area] =
814 			(id->active_pages[id->active_area] + 1) %
815 			id->pages_per_area;
816 	}
817 }
818 
819 /*
820  * proceed_active_area:
821  * - set active area to next in the ring buffer
822  */
823 static inline void proceed_active_area(debug_info_t *id)
824 {
825 	id->active_area++;
826 	id->active_area = id->active_area % id->nr_areas;
827 }
828 
829 /*
830  * get_active_entry:
831  */
832 static inline debug_entry_t *get_active_entry(debug_info_t *id)
833 {
834 	return (debug_entry_t *) (((char *) id->areas[id->active_area]
835 				   [id->active_pages[id->active_area]]) +
836 				  id->active_entries[id->active_area]);
837 }
838 
839 /*
840  * debug_finish_entry:
841  * - set timestamp, caller address, cpu number etc.
842  */
843 
844 static inline void debug_finish_entry(debug_info_t *id, debug_entry_t *active,
845 				      int level, int exception)
846 {
847 	active->id.stck = get_tod_clock_fast() -
848 		*(unsigned long long *) &tod_clock_base[1];
849 	active->id.fields.cpuid = smp_processor_id();
850 	active->caller = __builtin_return_address(0);
851 	active->id.fields.exception = exception;
852 	active->id.fields.level = level;
853 	proceed_active_entry(id);
854 	if (exception)
855 		proceed_active_area(id);
856 }
857 
858 static int debug_stoppable = 1;
859 static int debug_active = 1;
860 
861 #define CTL_S390DBF_STOPPABLE 5678
862 #define CTL_S390DBF_ACTIVE 5679
863 
864 /*
865  * proc handler for the running debug_active sysctl
866  * always allow read, allow write only if debug_stoppable is set or
867  * if debug_active is already off
868  */
869 static int s390dbf_procactive(struct ctl_table *table, int write,
870 			      void *buffer, size_t *lenp, loff_t *ppos)
871 {
872 	if (!write || debug_stoppable || !debug_active)
873 		return proc_dointvec(table, write, buffer, lenp, ppos);
874 	else
875 		return 0;
876 }
877 
878 static struct ctl_table s390dbf_table[] = {
879 	{
880 		.procname	= "debug_stoppable",
881 		.data		= &debug_stoppable,
882 		.maxlen		= sizeof(int),
883 		.mode		= S_IRUGO | S_IWUSR,
884 		.proc_handler	= proc_dointvec,
885 	},
886 	{
887 		.procname	= "debug_active",
888 		.data		= &debug_active,
889 		.maxlen		= sizeof(int),
890 		.mode		= S_IRUGO | S_IWUSR,
891 		.proc_handler	= s390dbf_procactive,
892 	},
893 	{ }
894 };
895 
896 static struct ctl_table s390dbf_dir_table[] = {
897 	{
898 		.procname	= "s390dbf",
899 		.maxlen		= 0,
900 		.mode		= S_IRUGO | S_IXUGO,
901 		.child		= s390dbf_table,
902 	},
903 	{ }
904 };
905 
906 static struct ctl_table_header *s390dbf_sysctl_header;
907 
908 /**
909  * debug_stop_all() - stops the debug feature if stopping is allowed.
910  *
911  * Return:
912  * -   none
913  *
914  * Currently used in case of a kernel oops.
915  */
916 void debug_stop_all(void)
917 {
918 	if (debug_stoppable)
919 		debug_active = 0;
920 }
921 EXPORT_SYMBOL(debug_stop_all);
922 
923 /**
924  * debug_set_critical() - event/exception functions try lock instead of spin.
925  *
926  * Return:
927  * -   none
928  *
929  * Currently used in case of stopping all CPUs but the current one.
930  * Once in this state, functions to write a debug entry for an
931  * event or exception no longer spin on the debug area lock,
932  * but only try to get it and fail if they do not get the lock.
933  */
934 void debug_set_critical(void)
935 {
936 	debug_critical = 1;
937 }
938 
939 /*
940  * debug_event_common:
941  * - write debug entry with given size
942  */
943 debug_entry_t *debug_event_common(debug_info_t *id, int level, const void *buf,
944 				  int len)
945 {
946 	debug_entry_t *active;
947 	unsigned long flags;
948 
949 	if (!debug_active || !id->areas)
950 		return NULL;
951 	if (debug_critical) {
952 		if (!spin_trylock_irqsave(&id->lock, flags))
953 			return NULL;
954 	} else {
955 		spin_lock_irqsave(&id->lock, flags);
956 	}
957 	do {
958 		active = get_active_entry(id);
959 		memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
960 		if (len < id->buf_size)
961 			memset((DEBUG_DATA(active)) + len, 0, id->buf_size - len);
962 		debug_finish_entry(id, active, level, 0);
963 		len -= id->buf_size;
964 		buf += id->buf_size;
965 	} while (len > 0);
966 
967 	spin_unlock_irqrestore(&id->lock, flags);
968 	return active;
969 }
970 EXPORT_SYMBOL(debug_event_common);
971 
972 /*
973  * debug_exception_common:
974  * - write debug entry with given size and switch to next debug area
975  */
976 debug_entry_t *debug_exception_common(debug_info_t *id, int level,
977 				      const void *buf, int len)
978 {
979 	debug_entry_t *active;
980 	unsigned long flags;
981 
982 	if (!debug_active || !id->areas)
983 		return NULL;
984 	if (debug_critical) {
985 		if (!spin_trylock_irqsave(&id->lock, flags))
986 			return NULL;
987 	} else {
988 		spin_lock_irqsave(&id->lock, flags);
989 	}
990 	do {
991 		active = get_active_entry(id);
992 		memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
993 		if (len < id->buf_size)
994 			memset((DEBUG_DATA(active)) + len, 0, id->buf_size - len);
995 		debug_finish_entry(id, active, level, len <= id->buf_size);
996 		len -= id->buf_size;
997 		buf += id->buf_size;
998 	} while (len > 0);
999 
1000 	spin_unlock_irqrestore(&id->lock, flags);
1001 	return active;
1002 }
1003 EXPORT_SYMBOL(debug_exception_common);
1004 
1005 /*
1006  * counts arguments in format string for sprintf view
1007  */
1008 static inline int debug_count_numargs(char *string)
1009 {
1010 	int numargs = 0;
1011 
1012 	while (*string) {
1013 		if (*string++ == '%')
1014 			numargs++;
1015 	}
1016 	return numargs;
1017 }
1018 
1019 /*
1020  * debug_sprintf_event:
1021  */
1022 debug_entry_t *__debug_sprintf_event(debug_info_t *id, int level, char *string, ...)
1023 {
1024 	debug_sprintf_entry_t *curr_event;
1025 	debug_entry_t *active;
1026 	unsigned long flags;
1027 	int numargs, idx;
1028 	va_list ap;
1029 
1030 	if (!debug_active || !id->areas)
1031 		return NULL;
1032 	numargs = debug_count_numargs(string);
1033 
1034 	if (debug_critical) {
1035 		if (!spin_trylock_irqsave(&id->lock, flags))
1036 			return NULL;
1037 	} else {
1038 		spin_lock_irqsave(&id->lock, flags);
1039 	}
1040 	active = get_active_entry(id);
1041 	curr_event = (debug_sprintf_entry_t *) DEBUG_DATA(active);
1042 	va_start(ap, string);
1043 	curr_event->string = string;
1044 	for (idx = 0; idx < min(numargs, (int)(id->buf_size / sizeof(long)) - 1); idx++)
1045 		curr_event->args[idx] = va_arg(ap, long);
1046 	va_end(ap);
1047 	debug_finish_entry(id, active, level, 0);
1048 	spin_unlock_irqrestore(&id->lock, flags);
1049 
1050 	return active;
1051 }
1052 EXPORT_SYMBOL(__debug_sprintf_event);
1053 
1054 /*
1055  * debug_sprintf_exception:
1056  */
1057 debug_entry_t *__debug_sprintf_exception(debug_info_t *id, int level, char *string, ...)
1058 {
1059 	debug_sprintf_entry_t *curr_event;
1060 	debug_entry_t *active;
1061 	unsigned long flags;
1062 	int numargs, idx;
1063 	va_list ap;
1064 
1065 	if (!debug_active || !id->areas)
1066 		return NULL;
1067 
1068 	numargs = debug_count_numargs(string);
1069 
1070 	if (debug_critical) {
1071 		if (!spin_trylock_irqsave(&id->lock, flags))
1072 			return NULL;
1073 	} else {
1074 		spin_lock_irqsave(&id->lock, flags);
1075 	}
1076 	active = get_active_entry(id);
1077 	curr_event = (debug_sprintf_entry_t *)DEBUG_DATA(active);
1078 	va_start(ap, string);
1079 	curr_event->string = string;
1080 	for (idx = 0; idx < min(numargs, (int)(id->buf_size / sizeof(long)) - 1); idx++)
1081 		curr_event->args[idx] = va_arg(ap, long);
1082 	va_end(ap);
1083 	debug_finish_entry(id, active, level, 1);
1084 	spin_unlock_irqrestore(&id->lock, flags);
1085 
1086 	return active;
1087 }
1088 EXPORT_SYMBOL(__debug_sprintf_exception);
1089 
1090 /**
1091  * debug_register_view() - registers new debug view and creates debugfs
1092  *			   dir entry
1093  *
1094  * @id:		handle for debug log
1095  * @view:	pointer to debug view struct
1096  *
1097  * Return:
1098  * -   0  : ok
1099  * -   < 0: Error
1100  */
1101 int debug_register_view(debug_info_t *id, struct debug_view *view)
1102 {
1103 	unsigned long flags;
1104 	struct dentry *pde;
1105 	umode_t mode;
1106 	int rc = 0;
1107 	int i;
1108 
1109 	if (!id)
1110 		goto out;
1111 	mode = (id->mode | S_IFREG) & ~S_IXUGO;
1112 	if (!(view->prolog_proc || view->format_proc || view->header_proc))
1113 		mode &= ~(S_IRUSR | S_IRGRP | S_IROTH);
1114 	if (!view->input_proc)
1115 		mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
1116 	pde = debugfs_create_file(view->name, mode, id->debugfs_root_entry,
1117 				  id, &debug_file_ops);
1118 	spin_lock_irqsave(&id->lock, flags);
1119 	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
1120 		if (!id->views[i])
1121 			break;
1122 	}
1123 	if (i == DEBUG_MAX_VIEWS) {
1124 		pr_err("Registering view %s/%s would exceed the maximum "
1125 		       "number of views %i\n", id->name, view->name, i);
1126 		rc = -1;
1127 	} else {
1128 		id->views[i] = view;
1129 		id->debugfs_entries[i] = pde;
1130 	}
1131 	spin_unlock_irqrestore(&id->lock, flags);
1132 	if (rc)
1133 		debugfs_remove(pde);
1134 out:
1135 	return rc;
1136 }
1137 EXPORT_SYMBOL(debug_register_view);
1138 
1139 /**
1140  * debug_unregister_view() - unregisters debug view and removes debugfs
1141  *			     dir entry
1142  *
1143  * @id:		handle for debug log
1144  * @view:	pointer to debug view struct
1145  *
1146  * Return:
1147  * -   0  : ok
1148  * -   < 0: Error
1149  */
1150 int debug_unregister_view(debug_info_t *id, struct debug_view *view)
1151 {
1152 	struct dentry *dentry = NULL;
1153 	unsigned long flags;
1154 	int i, rc = 0;
1155 
1156 	if (!id)
1157 		goto out;
1158 	spin_lock_irqsave(&id->lock, flags);
1159 	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
1160 		if (id->views[i] == view)
1161 			break;
1162 	}
1163 	if (i == DEBUG_MAX_VIEWS) {
1164 		rc = -1;
1165 	} else {
1166 		dentry = id->debugfs_entries[i];
1167 		id->views[i] = NULL;
1168 		id->debugfs_entries[i] = NULL;
1169 	}
1170 	spin_unlock_irqrestore(&id->lock, flags);
1171 	debugfs_remove(dentry);
1172 out:
1173 	return rc;
1174 }
1175 EXPORT_SYMBOL(debug_unregister_view);
1176 
1177 static inline char *debug_get_user_string(const char __user *user_buf,
1178 					  size_t user_len)
1179 {
1180 	char *buffer;
1181 
1182 	buffer = kmalloc(user_len + 1, GFP_KERNEL);
1183 	if (!buffer)
1184 		return ERR_PTR(-ENOMEM);
1185 	if (copy_from_user(buffer, user_buf, user_len) != 0) {
1186 		kfree(buffer);
1187 		return ERR_PTR(-EFAULT);
1188 	}
1189 	/* got the string, now strip linefeed. */
1190 	if (buffer[user_len - 1] == '\n')
1191 		buffer[user_len - 1] = 0;
1192 	else
1193 		buffer[user_len] = 0;
1194 	return buffer;
1195 }
1196 
1197 static inline int debug_get_uint(char *buf)
1198 {
1199 	int rc;
1200 
1201 	buf = skip_spaces(buf);
1202 	rc = simple_strtoul(buf, &buf, 10);
1203 	if (*buf)
1204 		rc = -EINVAL;
1205 	return rc;
1206 }
1207 
1208 /*
1209  * functions for debug-views
1210  ***********************************
1211 */
1212 
1213 /*
1214  * prints out actual debug level
1215  */
1216 
1217 static int debug_prolog_pages_fn(debug_info_t *id, struct debug_view *view,
1218 				 char *out_buf)
1219 {
1220 	return sprintf(out_buf, "%i\n", id->pages_per_area);
1221 }
1222 
1223 /*
1224  * reads new size (number of pages per debug area)
1225  */
1226 
1227 static int debug_input_pages_fn(debug_info_t *id, struct debug_view *view,
1228 				struct file *file, const char __user *user_buf,
1229 				size_t user_len, loff_t *offset)
1230 {
1231 	int rc, new_pages;
1232 	char *str;
1233 
1234 	if (user_len > 0x10000)
1235 		user_len = 0x10000;
1236 	if (*offset != 0) {
1237 		rc = -EPIPE;
1238 		goto out;
1239 	}
1240 	str = debug_get_user_string(user_buf, user_len);
1241 	if (IS_ERR(str)) {
1242 		rc = PTR_ERR(str);
1243 		goto out;
1244 	}
1245 	new_pages = debug_get_uint(str);
1246 	if (new_pages < 0) {
1247 		rc = -EINVAL;
1248 		goto free_str;
1249 	}
1250 	rc = debug_set_size(id, id->nr_areas, new_pages);
1251 	if (rc != 0) {
1252 		rc = -EINVAL;
1253 		goto free_str;
1254 	}
1255 	rc = user_len;
1256 free_str:
1257 	kfree(str);
1258 out:
1259 	*offset += user_len;
1260 	return rc;		/* number of input characters */
1261 }
1262 
1263 /*
1264  * prints out actual debug level
1265  */
1266 static int debug_prolog_level_fn(debug_info_t *id, struct debug_view *view,
1267 				 char *out_buf)
1268 {
1269 	int rc = 0;
1270 
1271 	if (id->level == DEBUG_OFF_LEVEL)
1272 		rc = sprintf(out_buf, "-\n");
1273 	else
1274 		rc = sprintf(out_buf, "%i\n", id->level);
1275 	return rc;
1276 }
1277 
1278 /*
1279  * reads new debug level
1280  */
1281 static int debug_input_level_fn(debug_info_t *id, struct debug_view *view,
1282 				struct file *file, const char __user *user_buf,
1283 				size_t user_len, loff_t *offset)
1284 {
1285 	int rc, new_level;
1286 	char *str;
1287 
1288 	if (user_len > 0x10000)
1289 		user_len = 0x10000;
1290 	if (*offset != 0) {
1291 		rc = -EPIPE;
1292 		goto out;
1293 	}
1294 	str = debug_get_user_string(user_buf, user_len);
1295 	if (IS_ERR(str)) {
1296 		rc = PTR_ERR(str);
1297 		goto out;
1298 	}
1299 	if (str[0] == '-') {
1300 		debug_set_level(id, DEBUG_OFF_LEVEL);
1301 		rc = user_len;
1302 		goto free_str;
1303 	} else {
1304 		new_level = debug_get_uint(str);
1305 	}
1306 	if (new_level < 0) {
1307 		pr_warn("%s is not a valid level for a debug feature\n", str);
1308 		rc = -EINVAL;
1309 	} else {
1310 		debug_set_level(id, new_level);
1311 		rc = user_len;
1312 	}
1313 free_str:
1314 	kfree(str);
1315 out:
1316 	*offset += user_len;
1317 	return rc;		/* number of input characters */
1318 }
1319 
1320 /*
1321  * flushes debug areas
1322  */
1323 static void debug_flush(debug_info_t *id, int area)
1324 {
1325 	unsigned long flags;
1326 	int i, j;
1327 
1328 	if (!id || !id->areas)
1329 		return;
1330 	spin_lock_irqsave(&id->lock, flags);
1331 	if (area == DEBUG_FLUSH_ALL) {
1332 		id->active_area = 0;
1333 		memset(id->active_entries, 0, id->nr_areas * sizeof(int));
1334 		for (i = 0; i < id->nr_areas; i++) {
1335 			id->active_pages[i] = 0;
1336 			for (j = 0; j < id->pages_per_area; j++)
1337 				memset(id->areas[i][j], 0, PAGE_SIZE);
1338 		}
1339 	} else if (area >= 0 && area < id->nr_areas) {
1340 		id->active_entries[area] = 0;
1341 		id->active_pages[area] = 0;
1342 		for (i = 0; i < id->pages_per_area; i++)
1343 			memset(id->areas[area][i], 0, PAGE_SIZE);
1344 	}
1345 	spin_unlock_irqrestore(&id->lock, flags);
1346 }
1347 
1348 /*
1349  * view function: flushes debug areas
1350  */
1351 static int debug_input_flush_fn(debug_info_t *id, struct debug_view *view,
1352 				struct file *file, const char __user *user_buf,
1353 				size_t user_len, loff_t *offset)
1354 {
1355 	char input_buf[1];
1356 	int rc = user_len;
1357 
1358 	if (user_len > 0x10000)
1359 		user_len = 0x10000;
1360 	if (*offset != 0) {
1361 		rc = -EPIPE;
1362 		goto out;
1363 	}
1364 	if (copy_from_user(input_buf, user_buf, 1)) {
1365 		rc = -EFAULT;
1366 		goto out;
1367 	}
1368 	if (input_buf[0] == '-') {
1369 		debug_flush(id, DEBUG_FLUSH_ALL);
1370 		goto out;
1371 	}
1372 	if (isdigit(input_buf[0])) {
1373 		int area = ((int) input_buf[0] - (int) '0');
1374 
1375 		debug_flush(id, area);
1376 		goto out;
1377 	}
1378 
1379 	pr_info("Flushing debug data failed because %c is not a valid "
1380 		 "area\n", input_buf[0]);
1381 
1382 out:
1383 	*offset += user_len;
1384 	return rc;		/* number of input characters */
1385 }
1386 
1387 /*
1388  * prints debug header in raw format
1389  */
1390 static int debug_raw_header_fn(debug_info_t *id, struct debug_view *view,
1391 			       int area, debug_entry_t *entry, char *out_buf)
1392 {
1393 	int rc;
1394 
1395 	rc = sizeof(debug_entry_t);
1396 	memcpy(out_buf, entry, sizeof(debug_entry_t));
1397 	return rc;
1398 }
1399 
1400 /*
1401  * prints debug data in raw format
1402  */
1403 static int debug_raw_format_fn(debug_info_t *id, struct debug_view *view,
1404 			       char *out_buf, const char *in_buf)
1405 {
1406 	int rc;
1407 
1408 	rc = id->buf_size;
1409 	memcpy(out_buf, in_buf, id->buf_size);
1410 	return rc;
1411 }
1412 
1413 /*
1414  * prints debug data in hex/ascii format
1415  */
1416 static int debug_hex_ascii_format_fn(debug_info_t *id, struct debug_view *view,
1417 				     char *out_buf, const char *in_buf)
1418 {
1419 	int i, rc = 0;
1420 
1421 	for (i = 0; i < id->buf_size; i++)
1422 		rc += sprintf(out_buf + rc, "%02x ", ((unsigned char *) in_buf)[i]);
1423 	rc += sprintf(out_buf + rc, "| ");
1424 	for (i = 0; i < id->buf_size; i++) {
1425 		unsigned char c = in_buf[i];
1426 
1427 		if (isascii(c) && isprint(c))
1428 			rc += sprintf(out_buf + rc, "%c", c);
1429 		else
1430 			rc += sprintf(out_buf + rc, ".");
1431 	}
1432 	rc += sprintf(out_buf + rc, "\n");
1433 	return rc;
1434 }
1435 
1436 /*
1437  * prints header for debug entry
1438  */
1439 int debug_dflt_header_fn(debug_info_t *id, struct debug_view *view,
1440 			 int area, debug_entry_t *entry, char *out_buf)
1441 {
1442 	unsigned long base, sec, usec;
1443 	unsigned long caller;
1444 	unsigned int level;
1445 	char *except_str;
1446 	int rc = 0;
1447 
1448 	level = entry->id.fields.level;
1449 	base = (*(unsigned long *) &tod_clock_base[0]) >> 4;
1450 	sec = (entry->id.stck >> 12) + base - (TOD_UNIX_EPOCH >> 12);
1451 	usec = do_div(sec, USEC_PER_SEC);
1452 
1453 	if (entry->id.fields.exception)
1454 		except_str = "*";
1455 	else
1456 		except_str = "-";
1457 	caller = (unsigned long) entry->caller;
1458 	rc += sprintf(out_buf, "%02i %011ld:%06lu %1u %1s %02i %pK  ",
1459 		      area, sec, usec, level, except_str,
1460 		      entry->id.fields.cpuid, (void *)caller);
1461 	return rc;
1462 }
1463 EXPORT_SYMBOL(debug_dflt_header_fn);
1464 
1465 /*
1466  * prints debug data sprintf-formated:
1467  * debug_sprinf_event/exception calls must be used together with this view
1468  */
1469 
1470 #define DEBUG_SPRINTF_MAX_ARGS 10
1471 
1472 static int debug_sprintf_format_fn(debug_info_t *id, struct debug_view *view,
1473 				   char *out_buf, debug_sprintf_entry_t *curr_event)
1474 {
1475 	int num_longs, num_used_args = 0, i, rc = 0;
1476 	int index[DEBUG_SPRINTF_MAX_ARGS];
1477 
1478 	/* count of longs fit into one entry */
1479 	num_longs = id->buf_size / sizeof(long);
1480 
1481 	if (num_longs < 1)
1482 		goto out; /* bufsize of entry too small */
1483 	if (num_longs == 1) {
1484 		/* no args, we use only the string */
1485 		strcpy(out_buf, curr_event->string);
1486 		rc = strlen(curr_event->string);
1487 		goto out;
1488 	}
1489 
1490 	/* number of arguments used for sprintf (without the format string) */
1491 	num_used_args = min(DEBUG_SPRINTF_MAX_ARGS, (num_longs - 1));
1492 
1493 	memset(index, 0, DEBUG_SPRINTF_MAX_ARGS * sizeof(int));
1494 
1495 	for (i = 0; i < num_used_args; i++)
1496 		index[i] = i;
1497 
1498 	rc = sprintf(out_buf, curr_event->string, curr_event->args[index[0]],
1499 		     curr_event->args[index[1]], curr_event->args[index[2]],
1500 		     curr_event->args[index[3]], curr_event->args[index[4]],
1501 		     curr_event->args[index[5]], curr_event->args[index[6]],
1502 		     curr_event->args[index[7]], curr_event->args[index[8]],
1503 		     curr_event->args[index[9]]);
1504 out:
1505 	return rc;
1506 }
1507 
1508 /*
1509  * debug_init:
1510  * - is called exactly once to initialize the debug feature
1511  */
1512 static int __init debug_init(void)
1513 {
1514 	s390dbf_sysctl_header = register_sysctl_table(s390dbf_dir_table);
1515 	mutex_lock(&debug_mutex);
1516 	debug_debugfs_root_entry = debugfs_create_dir(DEBUG_DIR_ROOT, NULL);
1517 	initialized = 1;
1518 	mutex_unlock(&debug_mutex);
1519 	return 0;
1520 }
1521 postcore_initcall(debug_init);
1522