1  // SPDX-License-Identifier: GPL-2.0
2  /*
3   *   S/390 debug facility
4   *
5   *    Copyright IBM Corp. 1999, 2020
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/minmax.h>
28  #include <linux/debugfs.h>
29  
30  #include <asm/debug.h>
31  
32  #define DEBUG_PROLOG_ENTRY -1
33  
34  #define ALL_AREAS 0 /* copy all debug areas */
35  #define NO_AREAS  1 /* copy no debug areas */
36  
37  /* typedefs */
38  
39  typedef struct file_private_info {
40  	loff_t offset;			/* offset of last read in file */
41  	int    act_area;		/* number of last formated area */
42  	int    act_page;		/* act page in given area */
43  	int    act_entry;		/* last formated entry (offset */
44  					/* relative to beginning of last */
45  					/* formated page) */
46  	size_t act_entry_offset;	/* up to this offset we copied */
47  					/* in last read the last formated */
48  					/* entry to userland */
49  	char   temp_buf[2048];		/* buffer for output */
50  	debug_info_t *debug_info_org;	/* original debug information */
51  	debug_info_t *debug_info_snap;	/* snapshot of debug information */
52  	struct debug_view *view;	/* used view of debug info */
53  } file_private_info_t;
54  
55  typedef struct {
56  	char *string;
57  	/*
58  	 * This assumes that all args are converted into longs
59  	 * on L/390 this is the case for all types of parameter
60  	 * except of floats, and long long (32 bit)
61  	 *
62  	 */
63  	long args[];
64  } debug_sprintf_entry_t;
65  
66  /* internal function prototyes */
67  
68  static int debug_init(void);
69  static ssize_t debug_output(struct file *file, char __user *user_buf,
70  			    size_t user_len, loff_t *offset);
71  static ssize_t debug_input(struct file *file, const char __user *user_buf,
72  			   size_t user_len, loff_t *offset);
73  static int debug_open(struct inode *inode, struct file *file);
74  static int debug_close(struct inode *inode, struct file *file);
75  static debug_info_t *debug_info_create(const char *name, int pages_per_area,
76  				       int nr_areas, int buf_size, umode_t mode);
77  static void debug_info_get(debug_info_t *);
78  static void debug_info_put(debug_info_t *);
79  static int debug_prolog_level_fn(debug_info_t *id,
80  				 struct debug_view *view, char *out_buf);
81  static int debug_input_level_fn(debug_info_t *id, struct debug_view *view,
82  				struct file *file, const char __user *user_buf,
83  				size_t user_buf_size, loff_t *offset);
84  static int debug_prolog_pages_fn(debug_info_t *id,
85  				 struct debug_view *view, char *out_buf);
86  static int debug_input_pages_fn(debug_info_t *id, struct debug_view *view,
87  				struct file *file, const char __user *user_buf,
88  				size_t user_buf_size, loff_t *offset);
89  static int debug_input_flush_fn(debug_info_t *id, struct debug_view *view,
90  				struct file *file, const char __user *user_buf,
91  				size_t user_buf_size, loff_t *offset);
92  static int debug_hex_ascii_format_fn(debug_info_t *id, struct debug_view *view,
93  				     char *out_buf, const char *in_buf);
94  static int debug_sprintf_format_fn(debug_info_t *id, struct debug_view *view,
95  				   char *out_buf, const char *inbuf);
96  static void debug_areas_swap(debug_info_t *a, debug_info_t *b);
97  static void debug_events_append(debug_info_t *dest, debug_info_t *src);
98  
99  /* globals */
100  
101  struct debug_view debug_hex_ascii_view = {
102  	"hex_ascii",
103  	NULL,
104  	&debug_dflt_header_fn,
105  	&debug_hex_ascii_format_fn,
106  	NULL,
107  	NULL
108  };
109  EXPORT_SYMBOL(debug_hex_ascii_view);
110  
111  static struct debug_view debug_level_view = {
112  	"level",
113  	&debug_prolog_level_fn,
114  	NULL,
115  	NULL,
116  	&debug_input_level_fn,
117  	NULL
118  };
119  
120  static struct debug_view debug_pages_view = {
121  	"pages",
122  	&debug_prolog_pages_fn,
123  	NULL,
124  	NULL,
125  	&debug_input_pages_fn,
126  	NULL
127  };
128  
129  static struct debug_view debug_flush_view = {
130  	"flush",
131  	NULL,
132  	NULL,
133  	NULL,
134  	&debug_input_flush_fn,
135  	NULL
136  };
137  
138  struct debug_view debug_sprintf_view = {
139  	"sprintf",
140  	NULL,
141  	&debug_dflt_header_fn,
142  	&debug_sprintf_format_fn,
143  	NULL,
144  	NULL
145  };
146  EXPORT_SYMBOL(debug_sprintf_view);
147  
148  /* used by dump analysis tools to determine version of debug feature */
149  static unsigned int __used debug_feature_version = __DEBUG_FEATURE_VERSION;
150  
151  /* static globals */
152  
153  static debug_info_t *debug_area_first;
154  static debug_info_t *debug_area_last;
155  static DEFINE_MUTEX(debug_mutex);
156  
157  static int initialized;
158  static int debug_critical;
159  
160  static const struct file_operations debug_file_ops = {
161  	.owner	 = THIS_MODULE,
162  	.read	 = debug_output,
163  	.write	 = debug_input,
164  	.open	 = debug_open,
165  	.release = debug_close,
166  };
167  
168  static struct dentry *debug_debugfs_root_entry;
169  
170  /* functions */
171  
172  /*
173   * debug_areas_alloc
174   * - Debug areas are implemented as a threedimensonal array:
175   *   areas[areanumber][pagenumber][pageoffset]
176   */
177  
debug_areas_alloc(int pages_per_area,int nr_areas)178  static debug_entry_t ***debug_areas_alloc(int pages_per_area, int nr_areas)
179  {
180  	debug_entry_t ***areas;
181  	int i, j;
182  
183  	areas = kmalloc_array(nr_areas, sizeof(debug_entry_t **), GFP_KERNEL);
184  	if (!areas)
185  		goto fail_malloc_areas;
186  	for (i = 0; i < nr_areas; i++) {
187  		/* GFP_NOWARN to avoid user triggerable WARN, we handle fails */
188  		areas[i] = kmalloc_array(pages_per_area,
189  					 sizeof(debug_entry_t *),
190  					 GFP_KERNEL | __GFP_NOWARN);
191  		if (!areas[i])
192  			goto fail_malloc_areas2;
193  		for (j = 0; j < pages_per_area; j++) {
194  			areas[i][j] = kzalloc(PAGE_SIZE, GFP_KERNEL);
195  			if (!areas[i][j]) {
196  				for (j--; j >= 0 ; j--)
197  					kfree(areas[i][j]);
198  				kfree(areas[i]);
199  				goto fail_malloc_areas2;
200  			}
201  		}
202  	}
203  	return areas;
204  
205  fail_malloc_areas2:
206  	for (i--; i >= 0; i--) {
207  		for (j = 0; j < pages_per_area; j++)
208  			kfree(areas[i][j]);
209  		kfree(areas[i]);
210  	}
211  	kfree(areas);
212  fail_malloc_areas:
213  	return NULL;
214  }
215  
216  /*
217   * debug_info_alloc
218   * - alloc new debug-info
219   */
debug_info_alloc(const char * name,int pages_per_area,int nr_areas,int buf_size,int level,int mode)220  static debug_info_t *debug_info_alloc(const char *name, int pages_per_area,
221  				      int nr_areas, int buf_size, int level,
222  				      int mode)
223  {
224  	debug_info_t *rc;
225  
226  	/* alloc everything */
227  	rc = kmalloc(sizeof(debug_info_t), GFP_KERNEL);
228  	if (!rc)
229  		goto fail_malloc_rc;
230  	rc->active_entries = kcalloc(nr_areas, sizeof(int), GFP_KERNEL);
231  	if (!rc->active_entries)
232  		goto fail_malloc_active_entries;
233  	rc->active_pages = kcalloc(nr_areas, sizeof(int), GFP_KERNEL);
234  	if (!rc->active_pages)
235  		goto fail_malloc_active_pages;
236  	if ((mode == ALL_AREAS) && (pages_per_area != 0)) {
237  		rc->areas = debug_areas_alloc(pages_per_area, nr_areas);
238  		if (!rc->areas)
239  			goto fail_malloc_areas;
240  	} else {
241  		rc->areas = NULL;
242  	}
243  
244  	/* initialize members */
245  	spin_lock_init(&rc->lock);
246  	rc->pages_per_area = pages_per_area;
247  	rc->nr_areas	   = nr_areas;
248  	rc->active_area    = 0;
249  	rc->level	   = level;
250  	rc->buf_size	   = buf_size;
251  	rc->entry_size	   = sizeof(debug_entry_t) + buf_size;
252  	strscpy(rc->name, name, sizeof(rc->name));
253  	memset(rc->views, 0, DEBUG_MAX_VIEWS * sizeof(struct debug_view *));
254  	memset(rc->debugfs_entries, 0, DEBUG_MAX_VIEWS * sizeof(struct dentry *));
255  	refcount_set(&(rc->ref_count), 0);
256  
257  	return rc;
258  
259  fail_malloc_areas:
260  	kfree(rc->active_pages);
261  fail_malloc_active_pages:
262  	kfree(rc->active_entries);
263  fail_malloc_active_entries:
264  	kfree(rc);
265  fail_malloc_rc:
266  	return NULL;
267  }
268  
269  /*
270   * debug_areas_free
271   * - free all debug areas
272   */
debug_areas_free(debug_info_t * db_info)273  static void debug_areas_free(debug_info_t *db_info)
274  {
275  	int i, j;
276  
277  	if (!db_info->areas)
278  		return;
279  	for (i = 0; i < db_info->nr_areas; i++) {
280  		for (j = 0; j < db_info->pages_per_area; j++)
281  			kfree(db_info->areas[i][j]);
282  		kfree(db_info->areas[i]);
283  	}
284  	kfree(db_info->areas);
285  	db_info->areas = NULL;
286  }
287  
288  /*
289   * debug_info_free
290   * - free memory debug-info
291   */
debug_info_free(debug_info_t * db_info)292  static void debug_info_free(debug_info_t *db_info)
293  {
294  	debug_areas_free(db_info);
295  	kfree(db_info->active_entries);
296  	kfree(db_info->active_pages);
297  	kfree(db_info);
298  }
299  
300  /*
301   * debug_info_create
302   * - create new debug-info
303   */
304  
debug_info_create(const char * name,int pages_per_area,int nr_areas,int buf_size,umode_t mode)305  static debug_info_t *debug_info_create(const char *name, int pages_per_area,
306  				       int nr_areas, int buf_size, umode_t mode)
307  {
308  	debug_info_t *rc;
309  
310  	rc = debug_info_alloc(name, pages_per_area, nr_areas, buf_size,
311  			      DEBUG_DEFAULT_LEVEL, ALL_AREAS);
312  	if (!rc)
313  		goto out;
314  
315  	rc->mode = mode & ~S_IFMT;
316  	refcount_set(&rc->ref_count, 1);
317  out:
318  	return rc;
319  }
320  
321  /*
322   * debug_info_copy
323   * - copy debug-info
324   */
debug_info_copy(debug_info_t * in,int mode)325  static debug_info_t *debug_info_copy(debug_info_t *in, int mode)
326  {
327  	unsigned long flags;
328  	debug_info_t *rc;
329  	int i, j;
330  
331  	/* get a consistent copy of the debug areas */
332  	do {
333  		rc = debug_info_alloc(in->name, in->pages_per_area,
334  			in->nr_areas, in->buf_size, in->level, mode);
335  		spin_lock_irqsave(&in->lock, flags);
336  		if (!rc)
337  			goto out;
338  		/* has something changed in the meantime ? */
339  		if ((rc->pages_per_area == in->pages_per_area) &&
340  		    (rc->nr_areas == in->nr_areas)) {
341  			break;
342  		}
343  		spin_unlock_irqrestore(&in->lock, flags);
344  		debug_info_free(rc);
345  	} while (1);
346  
347  	if (mode == NO_AREAS)
348  		goto out;
349  
350  	for (i = 0; i < in->nr_areas; i++) {
351  		for (j = 0; j < in->pages_per_area; j++)
352  			memcpy(rc->areas[i][j], in->areas[i][j], PAGE_SIZE);
353  	}
354  out:
355  	spin_unlock_irqrestore(&in->lock, flags);
356  	return rc;
357  }
358  
359  /*
360   * debug_info_get
361   * - increments reference count for debug-info
362   */
debug_info_get(debug_info_t * db_info)363  static void debug_info_get(debug_info_t *db_info)
364  {
365  	if (db_info)
366  		refcount_inc(&db_info->ref_count);
367  }
368  
369  /*
370   * debug_info_put:
371   * - decreases reference count for debug-info and frees it if necessary
372   */
debug_info_put(debug_info_t * db_info)373  static void debug_info_put(debug_info_t *db_info)
374  {
375  	if (!db_info)
376  		return;
377  	if (refcount_dec_and_test(&db_info->ref_count))
378  		debug_info_free(db_info);
379  }
380  
381  /*
382   * debug_format_entry:
383   * - format one debug entry and return size of formated data
384   */
debug_format_entry(file_private_info_t * p_info)385  static int debug_format_entry(file_private_info_t *p_info)
386  {
387  	debug_info_t *id_snap	= p_info->debug_info_snap;
388  	struct debug_view *view = p_info->view;
389  	debug_entry_t *act_entry;
390  	size_t len = 0;
391  
392  	if (p_info->act_entry == DEBUG_PROLOG_ENTRY) {
393  		/* print prolog */
394  		if (view->prolog_proc)
395  			len += view->prolog_proc(id_snap, view, p_info->temp_buf);
396  		goto out;
397  	}
398  	if (!id_snap->areas) /* this is true, if we have a prolog only view */
399  		goto out;    /* or if 'pages_per_area' is 0 */
400  	act_entry = (debug_entry_t *) ((char *)id_snap->areas[p_info->act_area]
401  				       [p_info->act_page] + p_info->act_entry);
402  
403  	if (act_entry->clock == 0LL)
404  		goto out; /* empty entry */
405  	if (view->header_proc)
406  		len += view->header_proc(id_snap, view, p_info->act_area,
407  					 act_entry, p_info->temp_buf + len);
408  	if (view->format_proc)
409  		len += view->format_proc(id_snap, view, p_info->temp_buf + len,
410  					 DEBUG_DATA(act_entry));
411  out:
412  	return len;
413  }
414  
415  /*
416   * debug_next_entry:
417   * - goto next entry in p_info
418   */
debug_next_entry(file_private_info_t * p_info)419  static inline int debug_next_entry(file_private_info_t *p_info)
420  {
421  	debug_info_t *id;
422  
423  	id = p_info->debug_info_snap;
424  	if (p_info->act_entry == DEBUG_PROLOG_ENTRY) {
425  		p_info->act_entry = 0;
426  		p_info->act_page  = 0;
427  		goto out;
428  	}
429  	if (!id->areas)
430  		return 1;
431  	p_info->act_entry += id->entry_size;
432  	/* switch to next page, if we reached the end of the page  */
433  	if (p_info->act_entry > (PAGE_SIZE - id->entry_size)) {
434  		/* next page */
435  		p_info->act_entry = 0;
436  		p_info->act_page += 1;
437  		if ((p_info->act_page % id->pages_per_area) == 0) {
438  			/* next area */
439  			p_info->act_area++;
440  			p_info->act_page = 0;
441  		}
442  		if (p_info->act_area >= id->nr_areas)
443  			return 1;
444  	}
445  out:
446  	return 0;
447  }
448  
449  /*
450   * debug_output:
451   * - called for user read()
452   * - copies formated debug entries to the user buffer
453   */
debug_output(struct file * file,char __user * user_buf,size_t len,loff_t * offset)454  static ssize_t debug_output(struct file *file,		/* file descriptor */
455  			    char __user *user_buf,	/* user buffer */
456  			    size_t len,			/* length of buffer */
457  			    loff_t *offset)		/* offset in the file */
458  {
459  	size_t count = 0;
460  	size_t entry_offset;
461  	file_private_info_t *p_info;
462  
463  	p_info = (file_private_info_t *) file->private_data;
464  	if (*offset != p_info->offset)
465  		return -EPIPE;
466  	if (p_info->act_area >= p_info->debug_info_snap->nr_areas)
467  		return 0;
468  	entry_offset = p_info->act_entry_offset;
469  	while (count < len) {
470  		int formatted_line_residue;
471  		int formatted_line_size;
472  		int user_buf_residue;
473  		size_t copy_size;
474  
475  		formatted_line_size = debug_format_entry(p_info);
476  		formatted_line_residue = formatted_line_size - entry_offset;
477  		user_buf_residue = len-count;
478  		copy_size = min(user_buf_residue, formatted_line_residue);
479  		if (copy_size) {
480  			if (copy_to_user(user_buf + count, p_info->temp_buf
481  					 + entry_offset, copy_size))
482  				return -EFAULT;
483  			count += copy_size;
484  			entry_offset += copy_size;
485  		}
486  		if (copy_size == formatted_line_residue) {
487  			entry_offset = 0;
488  			if (debug_next_entry(p_info))
489  				goto out;
490  		}
491  	}
492  out:
493  	p_info->offset		 = *offset + count;
494  	p_info->act_entry_offset = entry_offset;
495  	*offset = p_info->offset;
496  	return count;
497  }
498  
499  /*
500   * debug_input:
501   * - called for user write()
502   * - calls input function of view
503   */
debug_input(struct file * file,const char __user * user_buf,size_t length,loff_t * offset)504  static ssize_t debug_input(struct file *file, const char __user *user_buf,
505  			   size_t length, loff_t *offset)
506  {
507  	file_private_info_t *p_info;
508  	int rc = 0;
509  
510  	mutex_lock(&debug_mutex);
511  	p_info = ((file_private_info_t *) file->private_data);
512  	if (p_info->view->input_proc) {
513  		rc = p_info->view->input_proc(p_info->debug_info_org,
514  					      p_info->view, file, user_buf,
515  					      length, offset);
516  	} else {
517  		rc = -EPERM;
518  	}
519  	mutex_unlock(&debug_mutex);
520  	return rc; /* number of input characters */
521  }
522  
523  /*
524   * debug_open:
525   * - called for user open()
526   * - copies formated output to private_data area of the file
527   *   handle
528   */
debug_open(struct inode * inode,struct file * file)529  static int debug_open(struct inode *inode, struct file *file)
530  {
531  	debug_info_t *debug_info, *debug_info_snapshot;
532  	file_private_info_t *p_info;
533  	int i, rc = 0;
534  
535  	mutex_lock(&debug_mutex);
536  	debug_info = file_inode(file)->i_private;
537  	/* find debug view */
538  	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
539  		if (!debug_info->views[i])
540  			continue;
541  		else if (debug_info->debugfs_entries[i] == file->f_path.dentry)
542  			goto found; /* found view ! */
543  	}
544  	/* no entry found */
545  	rc = -EINVAL;
546  	goto out;
547  
548  found:
549  
550  	/* Make snapshot of current debug areas to get it consistent.	  */
551  	/* To copy all the areas is only needed, if we have a view which  */
552  	/* formats the debug areas. */
553  
554  	if (!debug_info->views[i]->format_proc && !debug_info->views[i]->header_proc)
555  		debug_info_snapshot = debug_info_copy(debug_info, NO_AREAS);
556  	else
557  		debug_info_snapshot = debug_info_copy(debug_info, ALL_AREAS);
558  
559  	if (!debug_info_snapshot) {
560  		rc = -ENOMEM;
561  		goto out;
562  	}
563  	p_info = kmalloc(sizeof(file_private_info_t), GFP_KERNEL);
564  	if (!p_info) {
565  		debug_info_free(debug_info_snapshot);
566  		rc = -ENOMEM;
567  		goto out;
568  	}
569  	p_info->offset = 0;
570  	p_info->debug_info_snap = debug_info_snapshot;
571  	p_info->debug_info_org	= debug_info;
572  	p_info->view = debug_info->views[i];
573  	p_info->act_area = 0;
574  	p_info->act_page = 0;
575  	p_info->act_entry = DEBUG_PROLOG_ENTRY;
576  	p_info->act_entry_offset = 0;
577  	file->private_data = p_info;
578  	debug_info_get(debug_info);
579  	nonseekable_open(inode, file);
580  out:
581  	mutex_unlock(&debug_mutex);
582  	return rc;
583  }
584  
585  /*
586   * debug_close:
587   * - called for user close()
588   * - deletes  private_data area of the file handle
589   */
debug_close(struct inode * inode,struct file * file)590  static int debug_close(struct inode *inode, struct file *file)
591  {
592  	file_private_info_t *p_info;
593  
594  	p_info = (file_private_info_t *) file->private_data;
595  	if (p_info->debug_info_snap)
596  		debug_info_free(p_info->debug_info_snap);
597  	debug_info_put(p_info->debug_info_org);
598  	kfree(file->private_data);
599  	return 0; /* success */
600  }
601  
602  /* Create debugfs entries and add to internal list. */
_debug_register(debug_info_t * id)603  static void _debug_register(debug_info_t *id)
604  {
605  	/* create root directory */
606  	id->debugfs_root_entry = debugfs_create_dir(id->name,
607  						    debug_debugfs_root_entry);
608  
609  	/* append new element to linked list */
610  	if (!debug_area_first) {
611  		/* first element in list */
612  		debug_area_first = id;
613  		id->prev = NULL;
614  	} else {
615  		/* append element to end of list */
616  		debug_area_last->next = id;
617  		id->prev = debug_area_last;
618  	}
619  	debug_area_last = id;
620  	id->next = NULL;
621  
622  	debug_register_view(id, &debug_level_view);
623  	debug_register_view(id, &debug_flush_view);
624  	debug_register_view(id, &debug_pages_view);
625  }
626  
627  /**
628   * debug_register_mode() - creates and initializes debug area.
629   *
630   * @name:	Name of debug log (e.g. used for debugfs entry)
631   * @pages_per_area:	Number of pages, which will be allocated per area
632   * @nr_areas:	Number of debug areas
633   * @buf_size:	Size of data area in each debug entry
634   * @mode:	File mode for debugfs files. E.g. S_IRWXUGO
635   * @uid:	User ID for debugfs files. Currently only 0 is supported.
636   * @gid:	Group ID for debugfs files. Currently only 0 is supported.
637   *
638   * Return:
639   * - Handle for generated debug area
640   * - %NULL if register failed
641   *
642   * Allocates memory for a debug log.
643   * Must not be called within an interrupt handler.
644   */
debug_register_mode(const char * name,int pages_per_area,int nr_areas,int buf_size,umode_t mode,uid_t uid,gid_t gid)645  debug_info_t *debug_register_mode(const char *name, int pages_per_area,
646  				  int nr_areas, int buf_size, umode_t mode,
647  				  uid_t uid, gid_t gid)
648  {
649  	debug_info_t *rc = NULL;
650  
651  	/* Since debugfs currently does not support uid/gid other than root, */
652  	/* we do not allow gid/uid != 0 until we get support for that. */
653  	if ((uid != 0) || (gid != 0))
654  		pr_warn("Root becomes the owner of all s390dbf files in sysfs\n");
655  	BUG_ON(!initialized);
656  
657  	/* create new debug_info */
658  	rc = debug_info_create(name, pages_per_area, nr_areas, buf_size, mode);
659  	if (rc) {
660  		mutex_lock(&debug_mutex);
661  		_debug_register(rc);
662  		mutex_unlock(&debug_mutex);
663  	} else {
664  		pr_err("Registering debug feature %s failed\n", name);
665  	}
666  	return rc;
667  }
668  EXPORT_SYMBOL(debug_register_mode);
669  
670  /**
671   * debug_register() - creates and initializes debug area with default file mode.
672   *
673   * @name:	Name of debug log (e.g. used for debugfs entry)
674   * @pages_per_area:	Number of pages, which will be allocated per area
675   * @nr_areas:	Number of debug areas
676   * @buf_size:	Size of data area in each debug entry
677   *
678   * Return:
679   * - Handle for generated debug area
680   * - %NULL if register failed
681   *
682   * Allocates memory for a debug log.
683   * The debugfs file mode access permissions are read and write for user.
684   * Must not be called within an interrupt handler.
685   */
debug_register(const char * name,int pages_per_area,int nr_areas,int buf_size)686  debug_info_t *debug_register(const char *name, int pages_per_area,
687  			     int nr_areas, int buf_size)
688  {
689  	return debug_register_mode(name, pages_per_area, nr_areas, buf_size,
690  				   S_IRUSR | S_IWUSR, 0, 0);
691  }
692  EXPORT_SYMBOL(debug_register);
693  
694  /**
695   * debug_register_static() - registers a static debug area
696   *
697   * @id: Handle for static debug area
698   * @pages_per_area: Number of pages per area
699   * @nr_areas: Number of debug areas
700   *
701   * Register debug_info_t defined using DEFINE_STATIC_DEBUG_INFO.
702   *
703   * Note: This function is called automatically via an initcall generated by
704   *	 DEFINE_STATIC_DEBUG_INFO.
705   */
debug_register_static(debug_info_t * id,int pages_per_area,int nr_areas)706  void debug_register_static(debug_info_t *id, int pages_per_area, int nr_areas)
707  {
708  	unsigned long flags;
709  	debug_info_t *copy;
710  
711  	if (!initialized) {
712  		pr_err("Tried to register debug feature %s too early\n",
713  		       id->name);
714  		return;
715  	}
716  
717  	copy = debug_info_alloc("", pages_per_area, nr_areas, id->buf_size,
718  				id->level, ALL_AREAS);
719  	if (!copy) {
720  		pr_err("Registering debug feature %s failed\n", id->name);
721  
722  		/* Clear pointers to prevent tracing into released initdata. */
723  		spin_lock_irqsave(&id->lock, flags);
724  		id->areas = NULL;
725  		id->active_pages = NULL;
726  		id->active_entries = NULL;
727  		spin_unlock_irqrestore(&id->lock, flags);
728  
729  		return;
730  	}
731  
732  	/* Replace static trace area with dynamic copy. */
733  	spin_lock_irqsave(&id->lock, flags);
734  	debug_events_append(copy, id);
735  	debug_areas_swap(id, copy);
736  	spin_unlock_irqrestore(&id->lock, flags);
737  
738  	/* Clear pointers to initdata and discard copy. */
739  	copy->areas = NULL;
740  	copy->active_pages = NULL;
741  	copy->active_entries = NULL;
742  	debug_info_free(copy);
743  
744  	mutex_lock(&debug_mutex);
745  	_debug_register(id);
746  	mutex_unlock(&debug_mutex);
747  }
748  
749  /* Remove debugfs entries and remove from internal list. */
_debug_unregister(debug_info_t * id)750  static void _debug_unregister(debug_info_t *id)
751  {
752  	int i;
753  
754  	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
755  		if (!id->views[i])
756  			continue;
757  		debugfs_remove(id->debugfs_entries[i]);
758  	}
759  	debugfs_remove(id->debugfs_root_entry);
760  	if (id == debug_area_first)
761  		debug_area_first = id->next;
762  	if (id == debug_area_last)
763  		debug_area_last = id->prev;
764  	if (id->prev)
765  		id->prev->next = id->next;
766  	if (id->next)
767  		id->next->prev = id->prev;
768  }
769  
770  /**
771   * debug_unregister() - give back debug area.
772   *
773   * @id:		handle for debug log
774   *
775   * Return:
776   *    none
777   */
debug_unregister(debug_info_t * id)778  void debug_unregister(debug_info_t *id)
779  {
780  	if (!id)
781  		return;
782  	mutex_lock(&debug_mutex);
783  	_debug_unregister(id);
784  	mutex_unlock(&debug_mutex);
785  
786  	debug_info_put(id);
787  }
788  EXPORT_SYMBOL(debug_unregister);
789  
790  /*
791   * debug_set_size:
792   * - set area size (number of pages) and number of areas
793   */
debug_set_size(debug_info_t * id,int nr_areas,int pages_per_area)794  static int debug_set_size(debug_info_t *id, int nr_areas, int pages_per_area)
795  {
796  	debug_info_t *new_id;
797  	unsigned long flags;
798  
799  	if (!id || (nr_areas <= 0) || (pages_per_area < 0))
800  		return -EINVAL;
801  
802  	new_id = debug_info_alloc("", pages_per_area, nr_areas, id->buf_size,
803  				  id->level, ALL_AREAS);
804  	if (!new_id) {
805  		pr_info("Allocating memory for %i pages failed\n",
806  			pages_per_area);
807  		return -ENOMEM;
808  	}
809  
810  	spin_lock_irqsave(&id->lock, flags);
811  	debug_events_append(new_id, id);
812  	debug_areas_swap(new_id, id);
813  	debug_info_free(new_id);
814  	spin_unlock_irqrestore(&id->lock, flags);
815  	pr_info("%s: set new size (%i pages)\n", id->name, pages_per_area);
816  
817  	return 0;
818  }
819  
820  /**
821   * debug_set_level() - Sets new actual debug level if new_level is valid.
822   *
823   * @id:		handle for debug log
824   * @new_level:	new debug level
825   *
826   * Return:
827   *    none
828   */
debug_set_level(debug_info_t * id,int new_level)829  void debug_set_level(debug_info_t *id, int new_level)
830  {
831  	unsigned long flags;
832  
833  	if (!id)
834  		return;
835  
836  	if (new_level == DEBUG_OFF_LEVEL) {
837  		pr_info("%s: switched off\n", id->name);
838  	} else if ((new_level > DEBUG_MAX_LEVEL) || (new_level < 0)) {
839  		pr_info("%s: level %i is out of range (%i - %i)\n",
840  			id->name, new_level, 0, DEBUG_MAX_LEVEL);
841  		return;
842  	}
843  
844  	spin_lock_irqsave(&id->lock, flags);
845  	id->level = new_level;
846  	spin_unlock_irqrestore(&id->lock, flags);
847  }
848  EXPORT_SYMBOL(debug_set_level);
849  
850  /*
851   * proceed_active_entry:
852   * - set active entry to next in the ring buffer
853   */
proceed_active_entry(debug_info_t * id)854  static inline void proceed_active_entry(debug_info_t *id)
855  {
856  	if ((id->active_entries[id->active_area] += id->entry_size)
857  	    > (PAGE_SIZE - id->entry_size)) {
858  		id->active_entries[id->active_area] = 0;
859  		id->active_pages[id->active_area] =
860  			(id->active_pages[id->active_area] + 1) %
861  			id->pages_per_area;
862  	}
863  }
864  
865  /*
866   * proceed_active_area:
867   * - set active area to next in the ring buffer
868   */
proceed_active_area(debug_info_t * id)869  static inline void proceed_active_area(debug_info_t *id)
870  {
871  	id->active_area++;
872  	id->active_area = id->active_area % id->nr_areas;
873  }
874  
875  /*
876   * get_active_entry:
877   */
get_active_entry(debug_info_t * id)878  static inline debug_entry_t *get_active_entry(debug_info_t *id)
879  {
880  	return (debug_entry_t *) (((char *) id->areas[id->active_area]
881  				   [id->active_pages[id->active_area]]) +
882  				  id->active_entries[id->active_area]);
883  }
884  
885  /* Swap debug areas of a and b. */
debug_areas_swap(debug_info_t * a,debug_info_t * b)886  static void debug_areas_swap(debug_info_t *a, debug_info_t *b)
887  {
888  	swap(a->nr_areas, b->nr_areas);
889  	swap(a->pages_per_area, b->pages_per_area);
890  	swap(a->areas, b->areas);
891  	swap(a->active_area, b->active_area);
892  	swap(a->active_pages, b->active_pages);
893  	swap(a->active_entries, b->active_entries);
894  }
895  
896  /* Append all debug events in active area from source to destination log. */
debug_events_append(debug_info_t * dest,debug_info_t * src)897  static void debug_events_append(debug_info_t *dest, debug_info_t *src)
898  {
899  	debug_entry_t *from, *to, *last;
900  
901  	if (!src->areas || !dest->areas)
902  		return;
903  
904  	/* Loop over all entries in src, starting with oldest. */
905  	from = get_active_entry(src);
906  	last = from;
907  	do {
908  		if (from->clock != 0LL) {
909  			to = get_active_entry(dest);
910  			memset(to, 0, dest->entry_size);
911  			memcpy(to, from, min(src->entry_size,
912  					     dest->entry_size));
913  			proceed_active_entry(dest);
914  		}
915  
916  		proceed_active_entry(src);
917  		from = get_active_entry(src);
918  	} while (from != last);
919  }
920  
921  /*
922   * debug_finish_entry:
923   * - set timestamp, caller address, cpu number etc.
924   */
925  
debug_finish_entry(debug_info_t * id,debug_entry_t * active,int level,int exception)926  static inline void debug_finish_entry(debug_info_t *id, debug_entry_t *active,
927  				      int level, int exception)
928  {
929  	unsigned long timestamp;
930  	union tod_clock clk;
931  
932  	store_tod_clock_ext(&clk);
933  	timestamp = clk.us;
934  	timestamp -= TOD_UNIX_EPOCH >> 12;
935  	active->clock = timestamp;
936  	active->cpu = smp_processor_id();
937  	active->caller = __builtin_return_address(0);
938  	active->exception = exception;
939  	active->level = level;
940  	proceed_active_entry(id);
941  	if (exception)
942  		proceed_active_area(id);
943  }
944  
945  static int debug_stoppable = 1;
946  static int debug_active = 1;
947  
948  #define CTL_S390DBF_STOPPABLE 5678
949  #define CTL_S390DBF_ACTIVE 5679
950  
951  /*
952   * proc handler for the running debug_active sysctl
953   * always allow read, allow write only if debug_stoppable is set or
954   * if debug_active is already off
955   */
s390dbf_procactive(const struct ctl_table * table,int write,void * buffer,size_t * lenp,loff_t * ppos)956  static int s390dbf_procactive(const struct ctl_table *table, int write,
957  			      void *buffer, size_t *lenp, loff_t *ppos)
958  {
959  	if (!write || debug_stoppable || !debug_active)
960  		return proc_dointvec(table, write, buffer, lenp, ppos);
961  	else
962  		return 0;
963  }
964  
965  static struct ctl_table s390dbf_table[] = {
966  	{
967  		.procname	= "debug_stoppable",
968  		.data		= &debug_stoppable,
969  		.maxlen		= sizeof(int),
970  		.mode		= S_IRUGO | S_IWUSR,
971  		.proc_handler	= proc_dointvec,
972  	},
973  	{
974  		.procname	= "debug_active",
975  		.data		= &debug_active,
976  		.maxlen		= sizeof(int),
977  		.mode		= S_IRUGO | S_IWUSR,
978  		.proc_handler	= s390dbf_procactive,
979  	},
980  };
981  
982  static struct ctl_table_header *s390dbf_sysctl_header;
983  
984  /**
985   * debug_stop_all() - stops the debug feature if stopping is allowed.
986   *
987   * Return:
988   * -   none
989   *
990   * Currently used in case of a kernel oops.
991   */
debug_stop_all(void)992  void debug_stop_all(void)
993  {
994  	if (debug_stoppable)
995  		debug_active = 0;
996  }
997  EXPORT_SYMBOL(debug_stop_all);
998  
999  /**
1000   * debug_set_critical() - event/exception functions try lock instead of spin.
1001   *
1002   * Return:
1003   * -   none
1004   *
1005   * Currently used in case of stopping all CPUs but the current one.
1006   * Once in this state, functions to write a debug entry for an
1007   * event or exception no longer spin on the debug area lock,
1008   * but only try to get it and fail if they do not get the lock.
1009   */
debug_set_critical(void)1010  void debug_set_critical(void)
1011  {
1012  	debug_critical = 1;
1013  }
1014  
1015  /*
1016   * debug_event_common:
1017   * - write debug entry with given size
1018   */
debug_event_common(debug_info_t * id,int level,const void * buf,int len)1019  debug_entry_t *debug_event_common(debug_info_t *id, int level, const void *buf,
1020  				  int len)
1021  {
1022  	debug_entry_t *active;
1023  	unsigned long flags;
1024  
1025  	if (!debug_active || !id->areas)
1026  		return NULL;
1027  	if (debug_critical) {
1028  		if (!spin_trylock_irqsave(&id->lock, flags))
1029  			return NULL;
1030  	} else {
1031  		spin_lock_irqsave(&id->lock, flags);
1032  	}
1033  	do {
1034  		active = get_active_entry(id);
1035  		memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
1036  		if (len < id->buf_size)
1037  			memset((DEBUG_DATA(active)) + len, 0, id->buf_size - len);
1038  		debug_finish_entry(id, active, level, 0);
1039  		len -= id->buf_size;
1040  		buf += id->buf_size;
1041  	} while (len > 0);
1042  
1043  	spin_unlock_irqrestore(&id->lock, flags);
1044  	return active;
1045  }
1046  EXPORT_SYMBOL(debug_event_common);
1047  
1048  /*
1049   * debug_exception_common:
1050   * - write debug entry with given size and switch to next debug area
1051   */
debug_exception_common(debug_info_t * id,int level,const void * buf,int len)1052  debug_entry_t *debug_exception_common(debug_info_t *id, int level,
1053  				      const void *buf, int len)
1054  {
1055  	debug_entry_t *active;
1056  	unsigned long flags;
1057  
1058  	if (!debug_active || !id->areas)
1059  		return NULL;
1060  	if (debug_critical) {
1061  		if (!spin_trylock_irqsave(&id->lock, flags))
1062  			return NULL;
1063  	} else {
1064  		spin_lock_irqsave(&id->lock, flags);
1065  	}
1066  	do {
1067  		active = get_active_entry(id);
1068  		memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
1069  		if (len < id->buf_size)
1070  			memset((DEBUG_DATA(active)) + len, 0, id->buf_size - len);
1071  		debug_finish_entry(id, active, level, len <= id->buf_size);
1072  		len -= id->buf_size;
1073  		buf += id->buf_size;
1074  	} while (len > 0);
1075  
1076  	spin_unlock_irqrestore(&id->lock, flags);
1077  	return active;
1078  }
1079  EXPORT_SYMBOL(debug_exception_common);
1080  
1081  /*
1082   * counts arguments in format string for sprintf view
1083   */
debug_count_numargs(char * string)1084  static inline int debug_count_numargs(char *string)
1085  {
1086  	int numargs = 0;
1087  
1088  	while (*string) {
1089  		if (*string++ == '%')
1090  			numargs++;
1091  	}
1092  	return numargs;
1093  }
1094  
1095  /*
1096   * debug_sprintf_event:
1097   */
__debug_sprintf_event(debug_info_t * id,int level,char * string,...)1098  debug_entry_t *__debug_sprintf_event(debug_info_t *id, int level, char *string, ...)
1099  {
1100  	debug_sprintf_entry_t *curr_event;
1101  	debug_entry_t *active;
1102  	unsigned long flags;
1103  	int numargs, idx;
1104  	va_list ap;
1105  
1106  	if (!debug_active || !id->areas)
1107  		return NULL;
1108  	numargs = debug_count_numargs(string);
1109  
1110  	if (debug_critical) {
1111  		if (!spin_trylock_irqsave(&id->lock, flags))
1112  			return NULL;
1113  	} else {
1114  		spin_lock_irqsave(&id->lock, flags);
1115  	}
1116  	active = get_active_entry(id);
1117  	curr_event = (debug_sprintf_entry_t *) DEBUG_DATA(active);
1118  	va_start(ap, string);
1119  	curr_event->string = string;
1120  	for (idx = 0; idx < min(numargs, (int)(id->buf_size / sizeof(long)) - 1); idx++)
1121  		curr_event->args[idx] = va_arg(ap, long);
1122  	va_end(ap);
1123  	debug_finish_entry(id, active, level, 0);
1124  	spin_unlock_irqrestore(&id->lock, flags);
1125  
1126  	return active;
1127  }
1128  EXPORT_SYMBOL(__debug_sprintf_event);
1129  
1130  /*
1131   * debug_sprintf_exception:
1132   */
__debug_sprintf_exception(debug_info_t * id,int level,char * string,...)1133  debug_entry_t *__debug_sprintf_exception(debug_info_t *id, int level, char *string, ...)
1134  {
1135  	debug_sprintf_entry_t *curr_event;
1136  	debug_entry_t *active;
1137  	unsigned long flags;
1138  	int numargs, idx;
1139  	va_list ap;
1140  
1141  	if (!debug_active || !id->areas)
1142  		return NULL;
1143  
1144  	numargs = debug_count_numargs(string);
1145  
1146  	if (debug_critical) {
1147  		if (!spin_trylock_irqsave(&id->lock, flags))
1148  			return NULL;
1149  	} else {
1150  		spin_lock_irqsave(&id->lock, flags);
1151  	}
1152  	active = get_active_entry(id);
1153  	curr_event = (debug_sprintf_entry_t *)DEBUG_DATA(active);
1154  	va_start(ap, string);
1155  	curr_event->string = string;
1156  	for (idx = 0; idx < min(numargs, (int)(id->buf_size / sizeof(long)) - 1); idx++)
1157  		curr_event->args[idx] = va_arg(ap, long);
1158  	va_end(ap);
1159  	debug_finish_entry(id, active, level, 1);
1160  	spin_unlock_irqrestore(&id->lock, flags);
1161  
1162  	return active;
1163  }
1164  EXPORT_SYMBOL(__debug_sprintf_exception);
1165  
1166  /**
1167   * debug_register_view() - registers new debug view and creates debugfs
1168   *			   dir entry
1169   *
1170   * @id:		handle for debug log
1171   * @view:	pointer to debug view struct
1172   *
1173   * Return:
1174   * -   0  : ok
1175   * -   < 0: Error
1176   */
debug_register_view(debug_info_t * id,struct debug_view * view)1177  int debug_register_view(debug_info_t *id, struct debug_view *view)
1178  {
1179  	unsigned long flags;
1180  	struct dentry *pde;
1181  	umode_t mode;
1182  	int rc = 0;
1183  	int i;
1184  
1185  	if (!id)
1186  		goto out;
1187  	mode = (id->mode | S_IFREG) & ~S_IXUGO;
1188  	if (!(view->prolog_proc || view->format_proc || view->header_proc))
1189  		mode &= ~(S_IRUSR | S_IRGRP | S_IROTH);
1190  	if (!view->input_proc)
1191  		mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
1192  	pde = debugfs_create_file(view->name, mode, id->debugfs_root_entry,
1193  				  id, &debug_file_ops);
1194  	spin_lock_irqsave(&id->lock, flags);
1195  	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
1196  		if (!id->views[i])
1197  			break;
1198  	}
1199  	if (i == DEBUG_MAX_VIEWS) {
1200  		rc = -1;
1201  	} else {
1202  		id->views[i] = view;
1203  		id->debugfs_entries[i] = pde;
1204  	}
1205  	spin_unlock_irqrestore(&id->lock, flags);
1206  	if (rc) {
1207  		pr_err("Registering view %s/%s would exceed the maximum "
1208  		       "number of views %i\n", id->name, view->name, i);
1209  		debugfs_remove(pde);
1210  	}
1211  out:
1212  	return rc;
1213  }
1214  EXPORT_SYMBOL(debug_register_view);
1215  
1216  /**
1217   * debug_unregister_view() - unregisters debug view and removes debugfs
1218   *			     dir entry
1219   *
1220   * @id:		handle for debug log
1221   * @view:	pointer to debug view struct
1222   *
1223   * Return:
1224   * -   0  : ok
1225   * -   < 0: Error
1226   */
debug_unregister_view(debug_info_t * id,struct debug_view * view)1227  int debug_unregister_view(debug_info_t *id, struct debug_view *view)
1228  {
1229  	struct dentry *dentry = NULL;
1230  	unsigned long flags;
1231  	int i, rc = 0;
1232  
1233  	if (!id)
1234  		goto out;
1235  	spin_lock_irqsave(&id->lock, flags);
1236  	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
1237  		if (id->views[i] == view)
1238  			break;
1239  	}
1240  	if (i == DEBUG_MAX_VIEWS) {
1241  		rc = -1;
1242  	} else {
1243  		dentry = id->debugfs_entries[i];
1244  		id->views[i] = NULL;
1245  		id->debugfs_entries[i] = NULL;
1246  	}
1247  	spin_unlock_irqrestore(&id->lock, flags);
1248  	debugfs_remove(dentry);
1249  out:
1250  	return rc;
1251  }
1252  EXPORT_SYMBOL(debug_unregister_view);
1253  
debug_get_user_string(const char __user * user_buf,size_t user_len)1254  static inline char *debug_get_user_string(const char __user *user_buf,
1255  					  size_t user_len)
1256  {
1257  	char *buffer;
1258  
1259  	buffer = kmalloc(user_len + 1, GFP_KERNEL);
1260  	if (!buffer)
1261  		return ERR_PTR(-ENOMEM);
1262  	if (copy_from_user(buffer, user_buf, user_len) != 0) {
1263  		kfree(buffer);
1264  		return ERR_PTR(-EFAULT);
1265  	}
1266  	/* got the string, now strip linefeed. */
1267  	if (buffer[user_len - 1] == '\n')
1268  		buffer[user_len - 1] = 0;
1269  	else
1270  		buffer[user_len] = 0;
1271  	return buffer;
1272  }
1273  
debug_get_uint(char * buf)1274  static inline int debug_get_uint(char *buf)
1275  {
1276  	int rc;
1277  
1278  	buf = skip_spaces(buf);
1279  	rc = simple_strtoul(buf, &buf, 10);
1280  	if (*buf)
1281  		rc = -EINVAL;
1282  	return rc;
1283  }
1284  
1285  /*
1286   * functions for debug-views
1287   ***********************************
1288  */
1289  
1290  /*
1291   * prints out actual debug level
1292   */
1293  
debug_prolog_pages_fn(debug_info_t * id,struct debug_view * view,char * out_buf)1294  static int debug_prolog_pages_fn(debug_info_t *id, struct debug_view *view,
1295  				 char *out_buf)
1296  {
1297  	return sprintf(out_buf, "%i\n", id->pages_per_area);
1298  }
1299  
1300  /*
1301   * reads new size (number of pages per debug area)
1302   */
1303  
debug_input_pages_fn(debug_info_t * id,struct debug_view * view,struct file * file,const char __user * user_buf,size_t user_len,loff_t * offset)1304  static int debug_input_pages_fn(debug_info_t *id, struct debug_view *view,
1305  				struct file *file, const char __user *user_buf,
1306  				size_t user_len, loff_t *offset)
1307  {
1308  	int rc, new_pages;
1309  	char *str;
1310  
1311  	if (user_len > 0x10000)
1312  		user_len = 0x10000;
1313  	if (*offset != 0) {
1314  		rc = -EPIPE;
1315  		goto out;
1316  	}
1317  	str = debug_get_user_string(user_buf, user_len);
1318  	if (IS_ERR(str)) {
1319  		rc = PTR_ERR(str);
1320  		goto out;
1321  	}
1322  	new_pages = debug_get_uint(str);
1323  	if (new_pages < 0) {
1324  		rc = -EINVAL;
1325  		goto free_str;
1326  	}
1327  	rc = debug_set_size(id, id->nr_areas, new_pages);
1328  	if (rc != 0) {
1329  		rc = -EINVAL;
1330  		goto free_str;
1331  	}
1332  	rc = user_len;
1333  free_str:
1334  	kfree(str);
1335  out:
1336  	*offset += user_len;
1337  	return rc;		/* number of input characters */
1338  }
1339  
1340  /*
1341   * prints out actual debug level
1342   */
debug_prolog_level_fn(debug_info_t * id,struct debug_view * view,char * out_buf)1343  static int debug_prolog_level_fn(debug_info_t *id, struct debug_view *view,
1344  				 char *out_buf)
1345  {
1346  	int rc = 0;
1347  
1348  	if (id->level == DEBUG_OFF_LEVEL)
1349  		rc = sprintf(out_buf, "-\n");
1350  	else
1351  		rc = sprintf(out_buf, "%i\n", id->level);
1352  	return rc;
1353  }
1354  
1355  /*
1356   * reads new debug level
1357   */
debug_input_level_fn(debug_info_t * id,struct debug_view * view,struct file * file,const char __user * user_buf,size_t user_len,loff_t * offset)1358  static int debug_input_level_fn(debug_info_t *id, struct debug_view *view,
1359  				struct file *file, const char __user *user_buf,
1360  				size_t user_len, loff_t *offset)
1361  {
1362  	int rc, new_level;
1363  	char *str;
1364  
1365  	if (user_len > 0x10000)
1366  		user_len = 0x10000;
1367  	if (*offset != 0) {
1368  		rc = -EPIPE;
1369  		goto out;
1370  	}
1371  	str = debug_get_user_string(user_buf, user_len);
1372  	if (IS_ERR(str)) {
1373  		rc = PTR_ERR(str);
1374  		goto out;
1375  	}
1376  	if (str[0] == '-') {
1377  		debug_set_level(id, DEBUG_OFF_LEVEL);
1378  		rc = user_len;
1379  		goto free_str;
1380  	} else {
1381  		new_level = debug_get_uint(str);
1382  	}
1383  	if (new_level < 0) {
1384  		pr_warn("%s is not a valid level for a debug feature\n", str);
1385  		rc = -EINVAL;
1386  	} else {
1387  		debug_set_level(id, new_level);
1388  		rc = user_len;
1389  	}
1390  free_str:
1391  	kfree(str);
1392  out:
1393  	*offset += user_len;
1394  	return rc;		/* number of input characters */
1395  }
1396  
1397  /*
1398   * flushes debug areas
1399   */
debug_flush(debug_info_t * id,int area)1400  static void debug_flush(debug_info_t *id, int area)
1401  {
1402  	unsigned long flags;
1403  	int i, j;
1404  
1405  	if (!id || !id->areas)
1406  		return;
1407  	spin_lock_irqsave(&id->lock, flags);
1408  	if (area == DEBUG_FLUSH_ALL) {
1409  		id->active_area = 0;
1410  		memset(id->active_entries, 0, id->nr_areas * sizeof(int));
1411  		for (i = 0; i < id->nr_areas; i++) {
1412  			id->active_pages[i] = 0;
1413  			for (j = 0; j < id->pages_per_area; j++)
1414  				memset(id->areas[i][j], 0, PAGE_SIZE);
1415  		}
1416  	} else if (area >= 0 && area < id->nr_areas) {
1417  		id->active_entries[area] = 0;
1418  		id->active_pages[area] = 0;
1419  		for (i = 0; i < id->pages_per_area; i++)
1420  			memset(id->areas[area][i], 0, PAGE_SIZE);
1421  	}
1422  	spin_unlock_irqrestore(&id->lock, flags);
1423  }
1424  
1425  /*
1426   * view function: flushes debug areas
1427   */
debug_input_flush_fn(debug_info_t * id,struct debug_view * view,struct file * file,const char __user * user_buf,size_t user_len,loff_t * offset)1428  static int debug_input_flush_fn(debug_info_t *id, struct debug_view *view,
1429  				struct file *file, const char __user *user_buf,
1430  				size_t user_len, loff_t *offset)
1431  {
1432  	char input_buf[1];
1433  	int rc = user_len;
1434  
1435  	if (user_len > 0x10000)
1436  		user_len = 0x10000;
1437  	if (*offset != 0) {
1438  		rc = -EPIPE;
1439  		goto out;
1440  	}
1441  	if (copy_from_user(input_buf, user_buf, 1)) {
1442  		rc = -EFAULT;
1443  		goto out;
1444  	}
1445  	if (input_buf[0] == '-') {
1446  		debug_flush(id, DEBUG_FLUSH_ALL);
1447  		goto out;
1448  	}
1449  	if (isdigit(input_buf[0])) {
1450  		int area = ((int) input_buf[0] - (int) '0');
1451  
1452  		debug_flush(id, area);
1453  		goto out;
1454  	}
1455  
1456  	pr_info("Flushing debug data failed because %c is not a valid "
1457  		 "area\n", input_buf[0]);
1458  
1459  out:
1460  	*offset += user_len;
1461  	return rc;		/* number of input characters */
1462  }
1463  
1464  /*
1465   * prints debug data in hex/ascii format
1466   */
debug_hex_ascii_format_fn(debug_info_t * id,struct debug_view * view,char * out_buf,const char * in_buf)1467  static int debug_hex_ascii_format_fn(debug_info_t *id, struct debug_view *view,
1468  				     char *out_buf, const char *in_buf)
1469  {
1470  	int i, rc = 0;
1471  
1472  	for (i = 0; i < id->buf_size; i++)
1473  		rc += sprintf(out_buf + rc, "%02x ", ((unsigned char *) in_buf)[i]);
1474  	rc += sprintf(out_buf + rc, "| ");
1475  	for (i = 0; i < id->buf_size; i++) {
1476  		unsigned char c = in_buf[i];
1477  
1478  		if (isascii(c) && isprint(c))
1479  			rc += sprintf(out_buf + rc, "%c", c);
1480  		else
1481  			rc += sprintf(out_buf + rc, ".");
1482  	}
1483  	rc += sprintf(out_buf + rc, "\n");
1484  	return rc;
1485  }
1486  
1487  /*
1488   * prints header for debug entry
1489   */
debug_dflt_header_fn(debug_info_t * id,struct debug_view * view,int area,debug_entry_t * entry,char * out_buf)1490  int debug_dflt_header_fn(debug_info_t *id, struct debug_view *view,
1491  			 int area, debug_entry_t *entry, char *out_buf)
1492  {
1493  	unsigned long sec, usec;
1494  	unsigned long caller;
1495  	unsigned int level;
1496  	char *except_str;
1497  	int rc = 0;
1498  
1499  	level = entry->level;
1500  	sec = entry->clock;
1501  	usec = do_div(sec, USEC_PER_SEC);
1502  
1503  	if (entry->exception)
1504  		except_str = "*";
1505  	else
1506  		except_str = "-";
1507  	caller = (unsigned long) entry->caller;
1508  	rc += sprintf(out_buf, "%02i %011ld:%06lu %1u %1s %04u %px  ",
1509  		      area, sec, usec, level, except_str,
1510  		      entry->cpu, (void *)caller);
1511  	return rc;
1512  }
1513  EXPORT_SYMBOL(debug_dflt_header_fn);
1514  
1515  /*
1516   * prints debug data sprintf-formated:
1517   * debug_sprinf_event/exception calls must be used together with this view
1518   */
1519  
1520  #define DEBUG_SPRINTF_MAX_ARGS 10
1521  
debug_sprintf_format_fn(debug_info_t * id,struct debug_view * view,char * out_buf,const char * inbuf)1522  static int debug_sprintf_format_fn(debug_info_t *id, struct debug_view *view,
1523  				   char *out_buf, const char *inbuf)
1524  {
1525  	debug_sprintf_entry_t *curr_event = (debug_sprintf_entry_t *)inbuf;
1526  	int num_longs, num_used_args = 0, i, rc = 0;
1527  	int index[DEBUG_SPRINTF_MAX_ARGS];
1528  
1529  	/* count of longs fit into one entry */
1530  	num_longs = id->buf_size / sizeof(long);
1531  
1532  	if (num_longs < 1)
1533  		goto out; /* bufsize of entry too small */
1534  	if (num_longs == 1) {
1535  		/* no args, we use only the string */
1536  		strcpy(out_buf, curr_event->string);
1537  		rc = strlen(curr_event->string);
1538  		goto out;
1539  	}
1540  
1541  	/* number of arguments used for sprintf (without the format string) */
1542  	num_used_args = min(DEBUG_SPRINTF_MAX_ARGS, (num_longs - 1));
1543  
1544  	memset(index, 0, DEBUG_SPRINTF_MAX_ARGS * sizeof(int));
1545  
1546  	for (i = 0; i < num_used_args; i++)
1547  		index[i] = i;
1548  
1549  	rc = sprintf(out_buf, curr_event->string, curr_event->args[index[0]],
1550  		     curr_event->args[index[1]], curr_event->args[index[2]],
1551  		     curr_event->args[index[3]], curr_event->args[index[4]],
1552  		     curr_event->args[index[5]], curr_event->args[index[6]],
1553  		     curr_event->args[index[7]], curr_event->args[index[8]],
1554  		     curr_event->args[index[9]]);
1555  out:
1556  	return rc;
1557  }
1558  
1559  /*
1560   * debug_init:
1561   * - is called exactly once to initialize the debug feature
1562   */
debug_init(void)1563  static int __init debug_init(void)
1564  {
1565  	s390dbf_sysctl_header = register_sysctl("s390dbf", s390dbf_table);
1566  	mutex_lock(&debug_mutex);
1567  	debug_debugfs_root_entry = debugfs_create_dir(DEBUG_DIR_ROOT, NULL);
1568  	initialized = 1;
1569  	mutex_unlock(&debug_mutex);
1570  	return 0;
1571  }
1572  postcore_initcall(debug_init);
1573