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Linux/arch/s390/kernel/debug.c

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  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:
652  * - Creates and initializes debug area for the caller
653  *   The mode parameter allows to specify access rights for the s390dbf files
654  * - Returns handle for debug area
655  */
656 debug_info_t *debug_register_mode(const char *name, int pages_per_area,
657                                   int nr_areas, int buf_size, umode_t mode,
658                                   uid_t uid, gid_t gid)
659 {
660         debug_info_t *rc = NULL;
661 
662         /* Since debugfs currently does not support uid/gid other than root, */
663         /* we do not allow gid/uid != 0 until we get support for that. */
664         if ((uid != 0) || (gid != 0))
665                 pr_warn("Root becomes the owner of all s390dbf files in sysfs\n");
666         BUG_ON(!initialized);
667         mutex_lock(&debug_mutex);
668 
669         /* create new debug_info */
670         rc = debug_info_create(name, pages_per_area, nr_areas, buf_size, mode);
671         if (!rc)
672                 goto out;
673         debug_register_view(rc, &debug_level_view);
674         debug_register_view(rc, &debug_flush_view);
675         debug_register_view(rc, &debug_pages_view);
676 out:
677         if (!rc)
678                 pr_err("Registering debug feature %s failed\n", name);
679         mutex_unlock(&debug_mutex);
680         return rc;
681 }
682 EXPORT_SYMBOL(debug_register_mode);
683 
684 /*
685  * debug_register:
686  * - creates and initializes debug area for the caller
687  * - returns handle for debug area
688  */
689 debug_info_t *debug_register(const char *name, int pages_per_area,
690                              int nr_areas, int buf_size)
691 {
692         return debug_register_mode(name, pages_per_area, nr_areas, buf_size,
693                                    S_IRUSR | S_IWUSR, 0, 0);
694 }
695 EXPORT_SYMBOL(debug_register);
696 
697 /*
698  * debug_unregister:
699  * - give back debug area
700  */
701 void debug_unregister(debug_info_t *id)
702 {
703         if (!id)
704                 return;
705         mutex_lock(&debug_mutex);
706         debug_info_put(id);
707         mutex_unlock(&debug_mutex);
708 }
709 EXPORT_SYMBOL(debug_unregister);
710 
711 /*
712  * debug_set_size:
713  * - set area size (number of pages) and number of areas
714  */
715 static int debug_set_size(debug_info_t *id, int nr_areas, int pages_per_area)
716 {
717         debug_entry_t ***new_areas;
718         unsigned long flags;
719         int rc = 0;
720 
721         if (!id || (nr_areas <= 0) || (pages_per_area < 0))
722                 return -EINVAL;
723         if (pages_per_area > 0) {
724                 new_areas = debug_areas_alloc(pages_per_area, nr_areas);
725                 if (!new_areas) {
726                         pr_info("Allocating memory for %i pages failed\n",
727                                 pages_per_area);
728                         rc = -ENOMEM;
729                         goto out;
730                 }
731         } else {
732                 new_areas = NULL;
733         }
734         spin_lock_irqsave(&id->lock, flags);
735         debug_areas_free(id);
736         id->areas = new_areas;
737         id->nr_areas = nr_areas;
738         id->pages_per_area = pages_per_area;
739         id->active_area = 0;
740         memset(id->active_entries, 0, sizeof(int)*id->nr_areas);
741         memset(id->active_pages, 0, sizeof(int)*id->nr_areas);
742         spin_unlock_irqrestore(&id->lock, flags);
743         pr_info("%s: set new size (%i pages)\n", id->name, pages_per_area);
744 out:
745         return rc;
746 }
747 
748 /*
749  * debug_set_level:
750  * - set actual debug level
751  */
752 void debug_set_level(debug_info_t *id, int new_level)
753 {
754         unsigned long flags;
755 
756         if (!id)
757                 return;
758         spin_lock_irqsave(&id->lock, flags);
759         if (new_level == DEBUG_OFF_LEVEL) {
760                 id->level = DEBUG_OFF_LEVEL;
761                 pr_info("%s: switched off\n", id->name);
762         } else if ((new_level > DEBUG_MAX_LEVEL) || (new_level < 0)) {
763                 pr_info("%s: level %i is out of range (%i - %i)\n",
764                         id->name, new_level, 0, DEBUG_MAX_LEVEL);
765         } else {
766                 id->level = new_level;
767         }
768         spin_unlock_irqrestore(&id->lock, flags);
769 }
770 EXPORT_SYMBOL(debug_set_level);
771 
772 /*
773  * proceed_active_entry:
774  * - set active entry to next in the ring buffer
775  */
776 static inline void proceed_active_entry(debug_info_t *id)
777 {
778         if ((id->active_entries[id->active_area] += id->entry_size)
779             > (PAGE_SIZE - id->entry_size)) {
780                 id->active_entries[id->active_area] = 0;
781                 id->active_pages[id->active_area] =
782                         (id->active_pages[id->active_area] + 1) %
783                         id->pages_per_area;
784         }
785 }
786 
787 /*
788  * proceed_active_area:
789  * - set active area to next in the ring buffer
790  */
791 static inline void proceed_active_area(debug_info_t *id)
792 {
793         id->active_area++;
794         id->active_area = id->active_area % id->nr_areas;
795 }
796 
797 /*
798  * get_active_entry:
799  */
800 static inline debug_entry_t *get_active_entry(debug_info_t *id)
801 {
802         return (debug_entry_t *) (((char *) id->areas[id->active_area]
803                                    [id->active_pages[id->active_area]]) +
804                                   id->active_entries[id->active_area]);
805 }
806 
807 /*
808  * debug_finish_entry:
809  * - set timestamp, caller address, cpu number etc.
810  */
811 
812 static inline void debug_finish_entry(debug_info_t *id, debug_entry_t *active,
813                                       int level, int exception)
814 {
815         active->id.stck = get_tod_clock_fast() -
816                 *(unsigned long long *) &tod_clock_base[1];
817         active->id.fields.cpuid = smp_processor_id();
818         active->caller = __builtin_return_address(0);
819         active->id.fields.exception = exception;
820         active->id.fields.level = level;
821         proceed_active_entry(id);
822         if (exception)
823                 proceed_active_area(id);
824 }
825 
826 static int debug_stoppable = 1;
827 static int debug_active = 1;
828 
829 #define CTL_S390DBF_STOPPABLE 5678
830 #define CTL_S390DBF_ACTIVE 5679
831 
832 /*
833  * proc handler for the running debug_active sysctl
834  * always allow read, allow write only if debug_stoppable is set or
835  * if debug_active is already off
836  */
837 static int s390dbf_procactive(struct ctl_table *table, int write,
838                               void __user *buffer, size_t *lenp, loff_t *ppos)
839 {
840         if (!write || debug_stoppable || !debug_active)
841                 return proc_dointvec(table, write, buffer, lenp, ppos);
842         else
843                 return 0;
844 }
845 
846 static struct ctl_table s390dbf_table[] = {
847         {
848                 .procname       = "debug_stoppable",
849                 .data           = &debug_stoppable,
850                 .maxlen         = sizeof(int),
851                 .mode           = S_IRUGO | S_IWUSR,
852                 .proc_handler   = proc_dointvec,
853         },
854         {
855                 .procname       = "debug_active",
856                 .data           = &debug_active,
857                 .maxlen         = sizeof(int),
858                 .mode           = S_IRUGO | S_IWUSR,
859                 .proc_handler   = s390dbf_procactive,
860         },
861         { }
862 };
863 
864 static struct ctl_table s390dbf_dir_table[] = {
865         {
866                 .procname       = "s390dbf",
867                 .maxlen         = 0,
868                 .mode           = S_IRUGO | S_IXUGO,
869                 .child          = s390dbf_table,
870         },
871         { }
872 };
873 
874 static struct ctl_table_header *s390dbf_sysctl_header;
875 
876 void debug_stop_all(void)
877 {
878         if (debug_stoppable)
879                 debug_active = 0;
880 }
881 EXPORT_SYMBOL(debug_stop_all);
882 
883 void debug_set_critical(void)
884 {
885         debug_critical = 1;
886 }
887 
888 /*
889  * debug_event_common:
890  * - write debug entry with given size
891  */
892 debug_entry_t *debug_event_common(debug_info_t *id, int level, const void *buf,
893                                   int len)
894 {
895         debug_entry_t *active;
896         unsigned long flags;
897 
898         if (!debug_active || !id->areas)
899                 return NULL;
900         if (debug_critical) {
901                 if (!spin_trylock_irqsave(&id->lock, flags))
902                         return NULL;
903         } else {
904                 spin_lock_irqsave(&id->lock, flags);
905         }
906         do {
907                 active = get_active_entry(id);
908                 memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
909                 if (len < id->buf_size)
910                         memset((DEBUG_DATA(active)) + len, 0, id->buf_size - len);
911                 debug_finish_entry(id, active, level, 0);
912                 len -= id->buf_size;
913                 buf += id->buf_size;
914         } while (len > 0);
915 
916         spin_unlock_irqrestore(&id->lock, flags);
917         return active;
918 }
919 EXPORT_SYMBOL(debug_event_common);
920 
921 /*
922  * debug_exception_common:
923  * - write debug entry with given size and switch to next debug area
924  */
925 debug_entry_t *debug_exception_common(debug_info_t *id, int level,
926                                       const void *buf, int len)
927 {
928         debug_entry_t *active;
929         unsigned long flags;
930 
931         if (!debug_active || !id->areas)
932                 return NULL;
933         if (debug_critical) {
934                 if (!spin_trylock_irqsave(&id->lock, flags))
935                         return NULL;
936         } else {
937                 spin_lock_irqsave(&id->lock, flags);
938         }
939         do {
940                 active = get_active_entry(id);
941                 memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
942                 if (len < id->buf_size)
943                         memset((DEBUG_DATA(active)) + len, 0, id->buf_size - len);
944                 debug_finish_entry(id, active, level, len <= id->buf_size);
945                 len -= id->buf_size;
946                 buf += id->buf_size;
947         } while (len > 0);
948 
949         spin_unlock_irqrestore(&id->lock, flags);
950         return active;
951 }
952 EXPORT_SYMBOL(debug_exception_common);
953 
954 /*
955  * counts arguments in format string for sprintf view
956  */
957 static inline int debug_count_numargs(char *string)
958 {
959         int numargs = 0;
960 
961         while (*string) {
962                 if (*string++ == '%')
963                         numargs++;
964         }
965         return numargs;
966 }
967 
968 /*
969  * debug_sprintf_event:
970  */
971 debug_entry_t *__debug_sprintf_event(debug_info_t *id, int level, char *string, ...)
972 {
973         debug_sprintf_entry_t *curr_event;
974         debug_entry_t *active;
975         unsigned long flags;
976         int numargs, idx;
977         va_list ap;
978 
979         if (!debug_active || !id->areas)
980                 return NULL;
981         numargs = debug_count_numargs(string);
982 
983         if (debug_critical) {
984                 if (!spin_trylock_irqsave(&id->lock, flags))
985                         return NULL;
986         } else {
987                 spin_lock_irqsave(&id->lock, flags);
988         }
989         active = get_active_entry(id);
990         curr_event = (debug_sprintf_entry_t *) DEBUG_DATA(active);
991         va_start(ap, string);
992         curr_event->string = string;
993         for (idx = 0; idx < min(numargs, (int)(id->buf_size / sizeof(long)) - 1); idx++)
994                 curr_event->args[idx] = va_arg(ap, long);
995         va_end(ap);
996         debug_finish_entry(id, active, level, 0);
997         spin_unlock_irqrestore(&id->lock, flags);
998 
999         return active;
1000 }
1001 EXPORT_SYMBOL(__debug_sprintf_event);
1002 
1003 /*
1004  * debug_sprintf_exception:
1005  */
1006 debug_entry_t *__debug_sprintf_exception(debug_info_t *id, int level, char *string, ...)
1007 {
1008         debug_sprintf_entry_t *curr_event;
1009         debug_entry_t *active;
1010         unsigned long flags;
1011         int numargs, idx;
1012         va_list ap;
1013 
1014         if (!debug_active || !id->areas)
1015                 return NULL;
1016 
1017         numargs = debug_count_numargs(string);
1018 
1019         if (debug_critical) {
1020                 if (!spin_trylock_irqsave(&id->lock, flags))
1021                         return NULL;
1022         } else {
1023                 spin_lock_irqsave(&id->lock, flags);
1024         }
1025         active = get_active_entry(id);
1026         curr_event = (debug_sprintf_entry_t *)DEBUG_DATA(active);
1027         va_start(ap, string);
1028         curr_event->string = string;
1029         for (idx = 0; idx < min(numargs, (int)(id->buf_size / sizeof(long)) - 1); idx++)
1030                 curr_event->args[idx] = va_arg(ap, long);
1031         va_end(ap);
1032         debug_finish_entry(id, active, level, 1);
1033         spin_unlock_irqrestore(&id->lock, flags);
1034 
1035         return active;
1036 }
1037 EXPORT_SYMBOL(__debug_sprintf_exception);
1038 
1039 /*
1040  * debug_register_view:
1041  */
1042 int debug_register_view(debug_info_t *id, struct debug_view *view)
1043 {
1044         unsigned long flags;
1045         struct dentry *pde;
1046         umode_t mode;
1047         int rc = 0;
1048         int i;
1049 
1050         if (!id)
1051                 goto out;
1052         mode = (id->mode | S_IFREG) & ~S_IXUGO;
1053         if (!(view->prolog_proc || view->format_proc || view->header_proc))
1054                 mode &= ~(S_IRUSR | S_IRGRP | S_IROTH);
1055         if (!view->input_proc)
1056                 mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
1057         pde = debugfs_create_file(view->name, mode, id->debugfs_root_entry,
1058                                   id, &debug_file_ops);
1059         if (!pde) {
1060                 pr_err("Registering view %s/%s failed due to out of "
1061                        "memory\n", id->name, view->name);
1062                 rc = -1;
1063                 goto out;
1064         }
1065         spin_lock_irqsave(&id->lock, flags);
1066         for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
1067                 if (!id->views[i])
1068                         break;
1069         }
1070         if (i == DEBUG_MAX_VIEWS) {
1071                 pr_err("Registering view %s/%s would exceed the maximum "
1072                        "number of views %i\n", id->name, view->name, i);
1073                 rc = -1;
1074         } else {
1075                 id->views[i] = view;
1076                 id->debugfs_entries[i] = pde;
1077         }
1078         spin_unlock_irqrestore(&id->lock, flags);
1079         if (rc)
1080                 debugfs_remove(pde);
1081 out:
1082         return rc;
1083 }
1084 EXPORT_SYMBOL(debug_register_view);
1085 
1086 /*
1087  * debug_unregister_view:
1088  */
1089 int debug_unregister_view(debug_info_t *id, struct debug_view *view)
1090 {
1091         struct dentry *dentry = NULL;
1092         unsigned long flags;
1093         int i, rc = 0;
1094 
1095         if (!id)
1096                 goto out;
1097         spin_lock_irqsave(&id->lock, flags);
1098         for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
1099                 if (id->views[i] == view)
1100                         break;
1101         }
1102         if (i == DEBUG_MAX_VIEWS) {
1103                 rc = -1;
1104         } else {
1105                 dentry = id->debugfs_entries[i];
1106                 id->views[i] = NULL;
1107                 id->debugfs_entries[i] = NULL;
1108         }
1109         spin_unlock_irqrestore(&id->lock, flags);
1110         debugfs_remove(dentry);
1111 out:
1112         return rc;
1113 }
1114 EXPORT_SYMBOL(debug_unregister_view);
1115 
1116 static inline char *debug_get_user_string(const char __user *user_buf,
1117                                           size_t user_len)
1118 {
1119         char *buffer;
1120 
1121         buffer = kmalloc(user_len + 1, GFP_KERNEL);
1122         if (!buffer)
1123                 return ERR_PTR(-ENOMEM);
1124         if (copy_from_user(buffer, user_buf, user_len) != 0) {
1125                 kfree(buffer);
1126                 return ERR_PTR(-EFAULT);
1127         }
1128         /* got the string, now strip linefeed. */
1129         if (buffer[user_len - 1] == '\n')
1130                 buffer[user_len - 1] = 0;
1131         else
1132                 buffer[user_len] = 0;
1133         return buffer;
1134 }
1135 
1136 static inline int debug_get_uint(char *buf)
1137 {
1138         int rc;
1139 
1140         buf = skip_spaces(buf);
1141         rc = simple_strtoul(buf, &buf, 10);
1142         if (*buf)
1143                 rc = -EINVAL;
1144         return rc;
1145 }
1146 
1147 /*
1148  * functions for debug-views
1149  ***********************************
1150 */
1151 
1152 /*
1153  * prints out actual debug level
1154  */
1155 
1156 static int debug_prolog_pages_fn(debug_info_t *id, struct debug_view *view,
1157                                  char *out_buf)
1158 {
1159         return sprintf(out_buf, "%i\n", id->pages_per_area);
1160 }
1161 
1162 /*
1163  * reads new size (number of pages per debug area)
1164  */
1165 
1166 static int debug_input_pages_fn(debug_info_t *id, struct debug_view *view,
1167                                 struct file *file, const char __user *user_buf,
1168                                 size_t user_len, loff_t *offset)
1169 {
1170         int rc, new_pages;
1171         char *str;
1172 
1173         if (user_len > 0x10000)
1174                 user_len = 0x10000;
1175         if (*offset != 0) {
1176                 rc = -EPIPE;
1177                 goto out;
1178         }
1179         str = debug_get_user_string(user_buf, user_len);
1180         if (IS_ERR(str)) {
1181                 rc = PTR_ERR(str);
1182                 goto out;
1183         }
1184         new_pages = debug_get_uint(str);
1185         if (new_pages < 0) {
1186                 rc = -EINVAL;
1187                 goto free_str;
1188         }
1189         rc = debug_set_size(id, id->nr_areas, new_pages);
1190         if (rc != 0) {
1191                 rc = -EINVAL;
1192                 goto free_str;
1193         }
1194         rc = user_len;
1195 free_str:
1196         kfree(str);
1197 out:
1198         *offset += user_len;
1199         return rc;              /* number of input characters */
1200 }
1201 
1202 /*
1203  * prints out actual debug level
1204  */
1205 static int debug_prolog_level_fn(debug_info_t *id, struct debug_view *view,
1206                                  char *out_buf)
1207 {
1208         int rc = 0;
1209 
1210         if (id->level == DEBUG_OFF_LEVEL)
1211                 rc = sprintf(out_buf, "-\n");
1212         else
1213                 rc = sprintf(out_buf, "%i\n", id->level);
1214         return rc;
1215 }
1216 
1217 /*
1218  * reads new debug level
1219  */
1220 static int debug_input_level_fn(debug_info_t *id, struct debug_view *view,
1221                                 struct file *file, const char __user *user_buf,
1222                                 size_t user_len, loff_t *offset)
1223 {
1224         int rc, new_level;
1225         char *str;
1226 
1227         if (user_len > 0x10000)
1228                 user_len = 0x10000;
1229         if (*offset != 0) {
1230                 rc = -EPIPE;
1231                 goto out;
1232         }
1233         str = debug_get_user_string(user_buf, user_len);
1234         if (IS_ERR(str)) {
1235                 rc = PTR_ERR(str);
1236                 goto out;
1237         }
1238         if (str[0] == '-') {
1239                 debug_set_level(id, DEBUG_OFF_LEVEL);
1240                 rc = user_len;
1241                 goto free_str;
1242         } else {
1243                 new_level = debug_get_uint(str);
1244         }
1245         if (new_level < 0) {
1246                 pr_warn("%s is not a valid level for a debug feature\n", str);
1247                 rc = -EINVAL;
1248         } else {
1249                 debug_set_level(id, new_level);
1250                 rc = user_len;
1251         }
1252 free_str:
1253         kfree(str);
1254 out:
1255         *offset += user_len;
1256         return rc;              /* number of input characters */
1257 }
1258 
1259 /*
1260  * flushes debug areas
1261  */
1262 static void debug_flush(debug_info_t *id, int area)
1263 {
1264         unsigned long flags;
1265         int i, j;
1266 
1267         if (!id || !id->areas)
1268                 return;
1269         spin_lock_irqsave(&id->lock, flags);
1270         if (area == DEBUG_FLUSH_ALL) {
1271                 id->active_area = 0;
1272                 memset(id->active_entries, 0, id->nr_areas * sizeof(int));
1273                 for (i = 0; i < id->nr_areas; i++) {
1274                         id->active_pages[i] = 0;
1275                         for (j = 0; j < id->pages_per_area; j++)
1276                                 memset(id->areas[i][j], 0, PAGE_SIZE);
1277                 }
1278         } else if (area >= 0 && area < id->nr_areas) {
1279                 id->active_entries[area] = 0;
1280                 id->active_pages[area] = 0;
1281                 for (i = 0; i < id->pages_per_area; i++)
1282                         memset(id->areas[area][i], 0, PAGE_SIZE);
1283         }
1284         spin_unlock_irqrestore(&id->lock, flags);
1285 }
1286 
1287 /*
1288  * view function: flushes debug areas
1289  */
1290 static int debug_input_flush_fn(debug_info_t *id, struct debug_view *view,
1291                                 struct file *file, const char __user *user_buf,
1292                                 size_t user_len, loff_t *offset)
1293 {
1294         char input_buf[1];
1295         int rc = user_len;
1296 
1297         if (user_len > 0x10000)
1298                 user_len = 0x10000;
1299         if (*offset != 0) {
1300                 rc = -EPIPE;
1301                 goto out;
1302         }
1303         if (copy_from_user(input_buf, user_buf, 1)) {
1304                 rc = -EFAULT;
1305                 goto out;
1306         }
1307         if (input_buf[0] == '-') {
1308                 debug_flush(id, DEBUG_FLUSH_ALL);
1309                 goto out;
1310         }
1311         if (isdigit(input_buf[0])) {
1312                 int area = ((int) input_buf[0] - (int) '');
1313 
1314                 debug_flush(id, area);
1315                 goto out;
1316         }
1317 
1318         pr_info("Flushing debug data failed because %c is not a valid "
1319                  "area\n", input_buf[0]);
1320 
1321 out:
1322         *offset += user_len;
1323         return rc;              /* number of input characters */
1324 }
1325 
1326 /*
1327  * prints debug header in raw format
1328  */
1329 static int debug_raw_header_fn(debug_info_t *id, struct debug_view *view,
1330                                int area, debug_entry_t *entry, char *out_buf)
1331 {
1332         int rc;
1333 
1334         rc = sizeof(debug_entry_t);
1335         memcpy(out_buf, entry, sizeof(debug_entry_t));
1336         return rc;
1337 }
1338 
1339 /*
1340  * prints debug data in raw format
1341  */
1342 static int debug_raw_format_fn(debug_info_t *id, struct debug_view *view,
1343                                char *out_buf, const char *in_buf)
1344 {
1345         int rc;
1346 
1347         rc = id->buf_size;
1348         memcpy(out_buf, in_buf, id->buf_size);
1349         return rc;
1350 }
1351 
1352 /*
1353  * prints debug data in hex/ascii format
1354  */
1355 static int debug_hex_ascii_format_fn(debug_info_t *id, struct debug_view *view,
1356                                      char *out_buf, const char *in_buf)
1357 {
1358         int i, rc = 0;
1359 
1360         for (i = 0; i < id->buf_size; i++)
1361                 rc += sprintf(out_buf + rc, "%02x ", ((unsigned char *) in_buf)[i]);
1362         rc += sprintf(out_buf + rc, "| ");
1363         for (i = 0; i < id->buf_size; i++) {
1364                 unsigned char c = in_buf[i];
1365 
1366                 if (isascii(c) && isprint(c))
1367                         rc += sprintf(out_buf + rc, "%c", c);
1368                 else
1369                         rc += sprintf(out_buf + rc, ".");
1370         }
1371         rc += sprintf(out_buf + rc, "\n");
1372         return rc;
1373 }
1374 
1375 /*
1376  * prints header for debug entry
1377  */
1378 int debug_dflt_header_fn(debug_info_t *id, struct debug_view *view,
1379                          int area, debug_entry_t *entry, char *out_buf)
1380 {
1381         unsigned long base, sec, usec;
1382         unsigned long caller;
1383         unsigned int level;
1384         char *except_str;
1385         int rc = 0;
1386 
1387         level = entry->id.fields.level;
1388         base = (*(unsigned long *) &tod_clock_base[0]) >> 4;
1389         sec = (entry->id.stck >> 12) + base - (TOD_UNIX_EPOCH >> 12);
1390         usec = do_div(sec, USEC_PER_SEC);
1391 
1392         if (entry->id.fields.exception)
1393                 except_str = "*";
1394         else
1395                 except_str = "-";
1396         caller = (unsigned long) entry->caller;
1397         rc += sprintf(out_buf, "%02i %011ld:%06lu %1u %1s %02i %pK  ",
1398                       area, sec, usec, level, except_str,
1399                       entry->id.fields.cpuid, (void *)caller);
1400         return rc;
1401 }
1402 EXPORT_SYMBOL(debug_dflt_header_fn);
1403 
1404 /*
1405  * prints debug data sprintf-formated:
1406  * debug_sprinf_event/exception calls must be used together with this view
1407  */
1408 
1409 #define DEBUG_SPRINTF_MAX_ARGS 10
1410 
1411 static int debug_sprintf_format_fn(debug_info_t *id, struct debug_view *view,
1412                                    char *out_buf, debug_sprintf_entry_t *curr_event)
1413 {
1414         int num_longs, num_used_args = 0, i, rc = 0;
1415         int index[DEBUG_SPRINTF_MAX_ARGS];
1416 
1417         /* count of longs fit into one entry */
1418         num_longs = id->buf_size / sizeof(long);
1419 
1420         if (num_longs < 1)
1421                 goto out; /* bufsize of entry too small */
1422         if (num_longs == 1) {
1423                 /* no args, we use only the string */
1424                 strcpy(out_buf, curr_event->string);
1425                 rc = strlen(curr_event->string);
1426                 goto out;
1427         }
1428 
1429         /* number of arguments used for sprintf (without the format string) */
1430         num_used_args = min(DEBUG_SPRINTF_MAX_ARGS, (num_longs - 1));
1431 
1432         memset(index, 0, DEBUG_SPRINTF_MAX_ARGS * sizeof(int));
1433 
1434         for (i = 0; i < num_used_args; i++)
1435                 index[i] = i;
1436 
1437         rc = sprintf(out_buf, curr_event->string, curr_event->args[index[0]],
1438                      curr_event->args[index[1]], curr_event->args[index[2]],
1439                      curr_event->args[index[3]], curr_event->args[index[4]],
1440                      curr_event->args[index[5]], curr_event->args[index[6]],
1441                      curr_event->args[index[7]], curr_event->args[index[8]],
1442                      curr_event->args[index[9]]);
1443 out:
1444         return rc;
1445 }
1446 
1447 /*
1448  * debug_init:
1449  * - is called exactly once to initialize the debug feature
1450  */
1451 static int __init debug_init(void)
1452 {
1453         s390dbf_sysctl_header = register_sysctl_table(s390dbf_dir_table);
1454         mutex_lock(&debug_mutex);
1455         debug_debugfs_root_entry = debugfs_create_dir(DEBUG_DIR_ROOT, NULL);
1456         initialized = 1;
1457         mutex_unlock(&debug_mutex);
1458         return 0;
1459 }
1460 postcore_initcall(debug_init);
1461 

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