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
  39typedef 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
  55typedef 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[0];
  64} debug_sprintf_entry_t;
  65
  66/* internal function prototyes */
  67
  68static int debug_init(void);
  69static ssize_t debug_output(struct file *file, char __user *user_buf,
  70			    size_t user_len, loff_t *offset);
  71static ssize_t debug_input(struct file *file, const char __user *user_buf,
  72			   size_t user_len, loff_t *offset);
  73static int debug_open(struct inode *inode, struct file *file);
  74static int debug_close(struct inode *inode, struct file *file);
  75static debug_info_t *debug_info_create(const char *name, int pages_per_area,
  76				       int nr_areas, int buf_size, umode_t mode);
  77static void debug_info_get(debug_info_t *);
  78static void debug_info_put(debug_info_t *);
  79static int debug_prolog_level_fn(debug_info_t *id,
  80				 struct debug_view *view, char *out_buf);
  81static 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);
  84static int debug_prolog_pages_fn(debug_info_t *id,
  85				 struct debug_view *view, char *out_buf);
  86static 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);
  89static 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);
  92static int debug_hex_ascii_format_fn(debug_info_t *id, struct debug_view *view,
  93				     char *out_buf, const char *in_buf);
  94static int debug_sprintf_format_fn(debug_info_t *id, struct debug_view *view,
  95				   char *out_buf, const char *inbuf);
  96static void debug_areas_swap(debug_info_t *a, debug_info_t *b);
  97static void debug_events_append(debug_info_t *dest, debug_info_t *src);
  98
  99/* globals */
 100
 101struct 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};
 109EXPORT_SYMBOL(debug_hex_ascii_view);
 110
 111static 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
 120static 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
 129static struct debug_view debug_flush_view = {
 130	"flush",
 131	NULL,
 132	NULL,
 133	NULL,
 134	&debug_input_flush_fn,
 135	NULL
 136};
 137
 138struct debug_view debug_sprintf_view = {
 139	"sprintf",
 140	NULL,
 141	&debug_dflt_header_fn,
 142	&debug_sprintf_format_fn,
 143	NULL,
 144	NULL
 145};
 146EXPORT_SYMBOL(debug_sprintf_view);
 147
 148/* used by dump analysis tools to determine version of debug feature */
 149static unsigned int __used debug_feature_version = __DEBUG_FEATURE_VERSION;
 150
 151/* static globals */
 152
 153static debug_info_t *debug_area_first;
 154static debug_info_t *debug_area_last;
 155static DEFINE_MUTEX(debug_mutex);
 156
 157static int initialized;
 158static int debug_critical;
 159
 160static 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	.llseek  = no_llseek,
 167};
 168
 169static struct dentry *debug_debugfs_root_entry;
 170
 171/* functions */
 172
 173/*
 174 * debug_areas_alloc
 175 * - Debug areas are implemented as a threedimensonal array:
 176 *   areas[areanumber][pagenumber][pageoffset]
 177 */
 178
 179static debug_entry_t ***debug_areas_alloc(int pages_per_area, int nr_areas)
 180{
 181	debug_entry_t ***areas;
 182	int i, j;
 183
 184	areas = kmalloc_array(nr_areas, sizeof(debug_entry_t **), GFP_KERNEL);
 185	if (!areas)
 186		goto fail_malloc_areas;
 187	for (i = 0; i < nr_areas; i++) {
 188		/* GFP_NOWARN to avoid user triggerable WARN, we handle fails */
 189		areas[i] = kmalloc_array(pages_per_area,
 190					 sizeof(debug_entry_t *),
 191					 GFP_KERNEL | __GFP_NOWARN);
 192		if (!areas[i])
 193			goto fail_malloc_areas2;
 194		for (j = 0; j < pages_per_area; j++) {
 195			areas[i][j] = kzalloc(PAGE_SIZE, GFP_KERNEL);
 196			if (!areas[i][j]) {
 197				for (j--; j >= 0 ; j--)
 198					kfree(areas[i][j]);
 199				kfree(areas[i]);
 200				goto fail_malloc_areas2;
 201			}
 202		}
 203	}
 204	return areas;
 205
 206fail_malloc_areas2:
 207	for (i--; i >= 0; i--) {
 208		for (j = 0; j < pages_per_area; j++)
 209			kfree(areas[i][j]);
 210		kfree(areas[i]);
 211	}
 212	kfree(areas);
 213fail_malloc_areas:
 214	return NULL;
 215}
 216
 217/*
 218 * debug_info_alloc
 219 * - alloc new debug-info
 220 */
 221static debug_info_t *debug_info_alloc(const char *name, int pages_per_area,
 222				      int nr_areas, int buf_size, int level,
 223				      int mode)
 224{
 225	debug_info_t *rc;
 226
 227	/* alloc everything */
 228	rc = kmalloc(sizeof(debug_info_t), GFP_KERNEL);
 229	if (!rc)
 230		goto fail_malloc_rc;
 231	rc->active_entries = kcalloc(nr_areas, sizeof(int), GFP_KERNEL);
 232	if (!rc->active_entries)
 233		goto fail_malloc_active_entries;
 234	rc->active_pages = kcalloc(nr_areas, sizeof(int), GFP_KERNEL);
 235	if (!rc->active_pages)
 236		goto fail_malloc_active_pages;
 237	if ((mode == ALL_AREAS) && (pages_per_area != 0)) {
 238		rc->areas = debug_areas_alloc(pages_per_area, nr_areas);
 239		if (!rc->areas)
 240			goto fail_malloc_areas;
 241	} else {
 242		rc->areas = NULL;
 243	}
 244
 245	/* initialize members */
 246	spin_lock_init(&rc->lock);
 247	rc->pages_per_area = pages_per_area;
 248	rc->nr_areas	   = nr_areas;
 249	rc->active_area    = 0;
 250	rc->level	   = level;
 251	rc->buf_size	   = buf_size;
 252	rc->entry_size	   = sizeof(debug_entry_t) + buf_size;
 253	strscpy(rc->name, name, sizeof(rc->name));
 254	memset(rc->views, 0, DEBUG_MAX_VIEWS * sizeof(struct debug_view *));
 255	memset(rc->debugfs_entries, 0, DEBUG_MAX_VIEWS * sizeof(struct dentry *));
 256	refcount_set(&(rc->ref_count), 0);
 257
 258	return rc;
 259
 260fail_malloc_areas:
 261	kfree(rc->active_pages);
 262fail_malloc_active_pages:
 263	kfree(rc->active_entries);
 264fail_malloc_active_entries:
 265	kfree(rc);
 266fail_malloc_rc:
 267	return NULL;
 268}
 269
 270/*
 271 * debug_areas_free
 272 * - free all debug areas
 273 */
 274static void debug_areas_free(debug_info_t *db_info)
 275{
 276	int i, j;
 277
 278	if (!db_info->areas)
 279		return;
 280	for (i = 0; i < db_info->nr_areas; i++) {
 281		for (j = 0; j < db_info->pages_per_area; j++)
 282			kfree(db_info->areas[i][j]);
 283		kfree(db_info->areas[i]);
 284	}
 285	kfree(db_info->areas);
 286	db_info->areas = NULL;
 287}
 288
 289/*
 290 * debug_info_free
 291 * - free memory debug-info
 292 */
 293static void debug_info_free(debug_info_t *db_info)
 294{
 295	debug_areas_free(db_info);
 296	kfree(db_info->active_entries);
 297	kfree(db_info->active_pages);
 298	kfree(db_info);
 299}
 300
 301/*
 302 * debug_info_create
 303 * - create new debug-info
 304 */
 305
 306static debug_info_t *debug_info_create(const char *name, int pages_per_area,
 307				       int nr_areas, int buf_size, umode_t mode)
 308{
 309	debug_info_t *rc;
 310
 311	rc = debug_info_alloc(name, pages_per_area, nr_areas, buf_size,
 312			      DEBUG_DEFAULT_LEVEL, ALL_AREAS);
 313	if (!rc)
 314		goto out;
 315
 316	rc->mode = mode & ~S_IFMT;
 317	refcount_set(&rc->ref_count, 1);
 318out:
 319	return rc;
 320}
 321
 322/*
 323 * debug_info_copy
 324 * - copy debug-info
 325 */
 326static debug_info_t *debug_info_copy(debug_info_t *in, int mode)
 327{
 328	unsigned long flags;
 329	debug_info_t *rc;
 330	int i, j;
 331
 332	/* get a consistent copy of the debug areas */
 333	do {
 334		rc = debug_info_alloc(in->name, in->pages_per_area,
 335			in->nr_areas, in->buf_size, in->level, mode);
 336		spin_lock_irqsave(&in->lock, flags);
 337		if (!rc)
 338			goto out;
 339		/* has something changed in the meantime ? */
 340		if ((rc->pages_per_area == in->pages_per_area) &&
 341		    (rc->nr_areas == in->nr_areas)) {
 342			break;
 343		}
 344		spin_unlock_irqrestore(&in->lock, flags);
 345		debug_info_free(rc);
 346	} while (1);
 347
 348	if (mode == NO_AREAS)
 349		goto out;
 350
 351	for (i = 0; i < in->nr_areas; i++) {
 352		for (j = 0; j < in->pages_per_area; j++)
 353			memcpy(rc->areas[i][j], in->areas[i][j], PAGE_SIZE);
 354	}
 355out:
 356	spin_unlock_irqrestore(&in->lock, flags);
 357	return rc;
 358}
 359
 360/*
 361 * debug_info_get
 362 * - increments reference count for debug-info
 363 */
 364static void debug_info_get(debug_info_t *db_info)
 365{
 366	if (db_info)
 367		refcount_inc(&db_info->ref_count);
 368}
 369
 370/*
 371 * debug_info_put:
 372 * - decreases reference count for debug-info and frees it if necessary
 373 */
 374static void debug_info_put(debug_info_t *db_info)
 375{
 376	if (!db_info)
 377		return;
 378	if (refcount_dec_and_test(&db_info->ref_count))
 379		debug_info_free(db_info);
 380}
 381
 382/*
 383 * debug_format_entry:
 384 * - format one debug entry and return size of formated data
 385 */
 386static int debug_format_entry(file_private_info_t *p_info)
 387{
 388	debug_info_t *id_snap	= p_info->debug_info_snap;
 389	struct debug_view *view = p_info->view;
 390	debug_entry_t *act_entry;
 391	size_t len = 0;
 392
 393	if (p_info->act_entry == DEBUG_PROLOG_ENTRY) {
 394		/* print prolog */
 395		if (view->prolog_proc)
 396			len += view->prolog_proc(id_snap, view, p_info->temp_buf);
 397		goto out;
 398	}
 399	if (!id_snap->areas) /* this is true, if we have a prolog only view */
 400		goto out;    /* or if 'pages_per_area' is 0 */
 401	act_entry = (debug_entry_t *) ((char *)id_snap->areas[p_info->act_area]
 402				       [p_info->act_page] + p_info->act_entry);
 403
 404	if (act_entry->clock == 0LL)
 405		goto out; /* empty entry */
 406	if (view->header_proc)
 407		len += view->header_proc(id_snap, view, p_info->act_area,
 408					 act_entry, p_info->temp_buf + len);
 409	if (view->format_proc)
 410		len += view->format_proc(id_snap, view, p_info->temp_buf + len,
 411					 DEBUG_DATA(act_entry));
 412out:
 413	return len;
 414}
 415
 416/*
 417 * debug_next_entry:
 418 * - goto next entry in p_info
 419 */
 420static inline int debug_next_entry(file_private_info_t *p_info)
 421{
 422	debug_info_t *id;
 423
 424	id = p_info->debug_info_snap;
 425	if (p_info->act_entry == DEBUG_PROLOG_ENTRY) {
 426		p_info->act_entry = 0;
 427		p_info->act_page  = 0;
 428		goto out;
 429	}
 430	if (!id->areas)
 431		return 1;
 432	p_info->act_entry += id->entry_size;
 433	/* switch to next page, if we reached the end of the page  */
 434	if (p_info->act_entry > (PAGE_SIZE - id->entry_size)) {
 435		/* next page */
 436		p_info->act_entry = 0;
 437		p_info->act_page += 1;
 438		if ((p_info->act_page % id->pages_per_area) == 0) {
 439			/* next area */
 440			p_info->act_area++;
 441			p_info->act_page = 0;
 442		}
 443		if (p_info->act_area >= id->nr_areas)
 444			return 1;
 445	}
 446out:
 447	return 0;
 448}
 449
 450/*
 451 * debug_output:
 452 * - called for user read()
 453 * - copies formated debug entries to the user buffer
 454 */
 455static ssize_t debug_output(struct file *file,		/* file descriptor */
 456			    char __user *user_buf,	/* user buffer */
 457			    size_t len,			/* length of buffer */
 458			    loff_t *offset)		/* offset in the file */
 459{
 460	size_t count = 0;
 461	size_t entry_offset;
 462	file_private_info_t *p_info;
 463
 464	p_info = (file_private_info_t *) file->private_data;
 465	if (*offset != p_info->offset)
 466		return -EPIPE;
 467	if (p_info->act_area >= p_info->debug_info_snap->nr_areas)
 468		return 0;
 469	entry_offset = p_info->act_entry_offset;
 470	while (count < len) {
 471		int formatted_line_residue;
 472		int formatted_line_size;
 473		int user_buf_residue;
 474		size_t copy_size;
 475
 476		formatted_line_size = debug_format_entry(p_info);
 477		formatted_line_residue = formatted_line_size - entry_offset;
 478		user_buf_residue = len-count;
 479		copy_size = min(user_buf_residue, formatted_line_residue);
 480		if (copy_size) {
 481			if (copy_to_user(user_buf + count, p_info->temp_buf
 482					 + entry_offset, copy_size))
 483				return -EFAULT;
 484			count += copy_size;
 485			entry_offset += copy_size;
 486		}
 487		if (copy_size == formatted_line_residue) {
 488			entry_offset = 0;
 489			if (debug_next_entry(p_info))
 490				goto out;
 491		}
 492	}
 493out:
 494	p_info->offset		 = *offset + count;
 495	p_info->act_entry_offset = entry_offset;
 496	*offset = p_info->offset;
 497	return count;
 498}
 499
 500/*
 501 * debug_input:
 502 * - called for user write()
 503 * - calls input function of view
 504 */
 505static ssize_t debug_input(struct file *file, const char __user *user_buf,
 506			   size_t length, loff_t *offset)
 507{
 508	file_private_info_t *p_info;
 509	int rc = 0;
 510
 511	mutex_lock(&debug_mutex);
 512	p_info = ((file_private_info_t *) file->private_data);
 513	if (p_info->view->input_proc) {
 514		rc = p_info->view->input_proc(p_info->debug_info_org,
 515					      p_info->view, file, user_buf,
 516					      length, offset);
 517	} else {
 518		rc = -EPERM;
 519	}
 520	mutex_unlock(&debug_mutex);
 521	return rc; /* number of input characters */
 522}
 523
 524/*
 525 * debug_open:
 526 * - called for user open()
 527 * - copies formated output to private_data area of the file
 528 *   handle
 529 */
 530static int debug_open(struct inode *inode, struct file *file)
 531{
 532	debug_info_t *debug_info, *debug_info_snapshot;
 533	file_private_info_t *p_info;
 534	int i, rc = 0;
 535
 536	mutex_lock(&debug_mutex);
 537	debug_info = file_inode(file)->i_private;
 538	/* find debug view */
 539	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
 540		if (!debug_info->views[i])
 541			continue;
 542		else if (debug_info->debugfs_entries[i] == file->f_path.dentry)
 543			goto found; /* found view ! */
 544	}
 545	/* no entry found */
 546	rc = -EINVAL;
 547	goto out;
 548
 549found:
 550
 551	/* Make snapshot of current debug areas to get it consistent.	  */
 552	/* To copy all the areas is only needed, if we have a view which  */
 553	/* formats the debug areas. */
 554
 555	if (!debug_info->views[i]->format_proc && !debug_info->views[i]->header_proc)
 556		debug_info_snapshot = debug_info_copy(debug_info, NO_AREAS);
 557	else
 558		debug_info_snapshot = debug_info_copy(debug_info, ALL_AREAS);
 559
 560	if (!debug_info_snapshot) {
 561		rc = -ENOMEM;
 562		goto out;
 563	}
 564	p_info = kmalloc(sizeof(file_private_info_t), GFP_KERNEL);
 565	if (!p_info) {
 566		debug_info_free(debug_info_snapshot);
 567		rc = -ENOMEM;
 568		goto out;
 569	}
 570	p_info->offset = 0;
 571	p_info->debug_info_snap = debug_info_snapshot;
 572	p_info->debug_info_org	= debug_info;
 573	p_info->view = debug_info->views[i];
 574	p_info->act_area = 0;
 575	p_info->act_page = 0;
 576	p_info->act_entry = DEBUG_PROLOG_ENTRY;
 577	p_info->act_entry_offset = 0;
 578	file->private_data = p_info;
 579	debug_info_get(debug_info);
 580	nonseekable_open(inode, file);
 581out:
 582	mutex_unlock(&debug_mutex);
 583	return rc;
 584}
 585
 586/*
 587 * debug_close:
 588 * - called for user close()
 589 * - deletes  private_data area of the file handle
 590 */
 591static int debug_close(struct inode *inode, struct file *file)
 592{
 593	file_private_info_t *p_info;
 594
 595	p_info = (file_private_info_t *) file->private_data;
 596	if (p_info->debug_info_snap)
 597		debug_info_free(p_info->debug_info_snap);
 598	debug_info_put(p_info->debug_info_org);
 599	kfree(file->private_data);
 600	return 0; /* success */
 601}
 602
 603/* Create debugfs entries and add to internal list. */
 604static void _debug_register(debug_info_t *id)
 605{
 606	/* create root directory */
 607	id->debugfs_root_entry = debugfs_create_dir(id->name,
 608						    debug_debugfs_root_entry);
 609
 610	/* append new element to linked list */
 611	if (!debug_area_first) {
 612		/* first element in list */
 613		debug_area_first = id;
 614		id->prev = NULL;
 615	} else {
 616		/* append element to end of list */
 617		debug_area_last->next = id;
 618		id->prev = debug_area_last;
 619	}
 620	debug_area_last = id;
 621	id->next = NULL;
 622
 623	debug_register_view(id, &debug_level_view);
 624	debug_register_view(id, &debug_flush_view);
 625	debug_register_view(id, &debug_pages_view);
 626}
 627
 628/**
 629 * debug_register_mode() - creates and initializes debug area.
 630 *
 631 * @name:	Name of debug log (e.g. used for debugfs entry)
 632 * @pages_per_area:	Number of pages, which will be allocated per area
 633 * @nr_areas:	Number of debug areas
 634 * @buf_size:	Size of data area in each debug entry
 635 * @mode:	File mode for debugfs files. E.g. S_IRWXUGO
 636 * @uid:	User ID for debugfs files. Currently only 0 is supported.
 637 * @gid:	Group ID for debugfs files. Currently only 0 is supported.
 638 *
 639 * Return:
 640 * - Handle for generated debug area
 641 * - %NULL if register failed
 642 *
 643 * Allocates memory for a debug log.
 644 * Must not be called within an interrupt handler.
 645 */
 646debug_info_t *debug_register_mode(const char *name, int pages_per_area,
 647				  int nr_areas, int buf_size, umode_t mode,
 648				  uid_t uid, gid_t gid)
 649{
 650	debug_info_t *rc = NULL;
 651
 652	/* Since debugfs currently does not support uid/gid other than root, */
 653	/* we do not allow gid/uid != 0 until we get support for that. */
 654	if ((uid != 0) || (gid != 0))
 655		pr_warn("Root becomes the owner of all s390dbf files in sysfs\n");
 656	BUG_ON(!initialized);
 657
 658	/* create new debug_info */
 659	rc = debug_info_create(name, pages_per_area, nr_areas, buf_size, mode);
 660	if (rc) {
 661		mutex_lock(&debug_mutex);
 662		_debug_register(rc);
 663		mutex_unlock(&debug_mutex);
 664	} else {
 665		pr_err("Registering debug feature %s failed\n", name);
 666	}
 667	return rc;
 668}
 669EXPORT_SYMBOL(debug_register_mode);
 670
 671/**
 672 * debug_register() - creates and initializes debug area with default file mode.
 673 *
 674 * @name:	Name of debug log (e.g. used for debugfs entry)
 675 * @pages_per_area:	Number of pages, which will be allocated per area
 676 * @nr_areas:	Number of debug areas
 677 * @buf_size:	Size of data area in each debug entry
 678 *
 679 * Return:
 680 * - Handle for generated debug area
 681 * - %NULL if register failed
 682 *
 683 * Allocates memory for a debug log.
 684 * The debugfs file mode access permissions are read and write for user.
 685 * Must not be called within an interrupt handler.
 686 */
 687debug_info_t *debug_register(const char *name, int pages_per_area,
 688			     int nr_areas, int buf_size)
 689{
 690	return debug_register_mode(name, pages_per_area, nr_areas, buf_size,
 691				   S_IRUSR | S_IWUSR, 0, 0);
 692}
 693EXPORT_SYMBOL(debug_register);
 694
 695/**
 696 * debug_register_static() - registers a static debug area
 697 *
 698 * @id: Handle for static debug area
 699 * @pages_per_area: Number of pages per area
 700 * @nr_areas: Number of debug areas
 701 *
 702 * Register debug_info_t defined using DEFINE_STATIC_DEBUG_INFO.
 703 *
 704 * Note: This function is called automatically via an initcall generated by
 705 *	 DEFINE_STATIC_DEBUG_INFO.
 706 */
 707void debug_register_static(debug_info_t *id, int pages_per_area, int nr_areas)
 708{
 709	unsigned long flags;
 710	debug_info_t *copy;
 711
 712	if (!initialized) {
 713		pr_err("Tried to register debug feature %s too early\n",
 714		       id->name);
 715		return;
 716	}
 717
 718	copy = debug_info_alloc("", pages_per_area, nr_areas, id->buf_size,
 719				id->level, ALL_AREAS);
 720	if (!copy) {
 721		pr_err("Registering debug feature %s failed\n", id->name);
 722
 723		/* Clear pointers to prevent tracing into released initdata. */
 724		spin_lock_irqsave(&id->lock, flags);
 725		id->areas = NULL;
 726		id->active_pages = NULL;
 727		id->active_entries = NULL;
 728		spin_unlock_irqrestore(&id->lock, flags);
 729
 730		return;
 731	}
 732
 733	/* Replace static trace area with dynamic copy. */
 734	spin_lock_irqsave(&id->lock, flags);
 735	debug_events_append(copy, id);
 736	debug_areas_swap(id, copy);
 737	spin_unlock_irqrestore(&id->lock, flags);
 738
 739	/* Clear pointers to initdata and discard copy. */
 740	copy->areas = NULL;
 741	copy->active_pages = NULL;
 742	copy->active_entries = NULL;
 743	debug_info_free(copy);
 744
 745	mutex_lock(&debug_mutex);
 746	_debug_register(id);
 747	mutex_unlock(&debug_mutex);
 748}
 749
 750/* Remove debugfs entries and remove from internal list. */
 751static void _debug_unregister(debug_info_t *id)
 752{
 753	int i;
 754
 755	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
 756		if (!id->views[i])
 757			continue;
 758		debugfs_remove(id->debugfs_entries[i]);
 759	}
 760	debugfs_remove(id->debugfs_root_entry);
 761	if (id == debug_area_first)
 762		debug_area_first = id->next;
 763	if (id == debug_area_last)
 764		debug_area_last = id->prev;
 765	if (id->prev)
 766		id->prev->next = id->next;
 767	if (id->next)
 768		id->next->prev = id->prev;
 769}
 770
 771/**
 772 * debug_unregister() - give back debug area.
 773 *
 774 * @id:		handle for debug log
 775 *
 776 * Return:
 777 *    none
 778 */
 779void debug_unregister(debug_info_t *id)
 780{
 781	if (!id)
 782		return;
 783	mutex_lock(&debug_mutex);
 784	_debug_unregister(id);
 785	mutex_unlock(&debug_mutex);
 786
 787	debug_info_put(id);
 788}
 789EXPORT_SYMBOL(debug_unregister);
 790
 791/*
 792 * debug_set_size:
 793 * - set area size (number of pages) and number of areas
 794 */
 795static int debug_set_size(debug_info_t *id, int nr_areas, int pages_per_area)
 796{
 797	debug_info_t *new_id;
 798	unsigned long flags;
 799
 800	if (!id || (nr_areas <= 0) || (pages_per_area < 0))
 801		return -EINVAL;
 802
 803	new_id = debug_info_alloc("", pages_per_area, nr_areas, id->buf_size,
 804				  id->level, ALL_AREAS);
 805	if (!new_id) {
 806		pr_info("Allocating memory for %i pages failed\n",
 807			pages_per_area);
 808		return -ENOMEM;
 809	}
 810
 811	spin_lock_irqsave(&id->lock, flags);
 812	debug_events_append(new_id, id);
 813	debug_areas_swap(new_id, id);
 814	debug_info_free(new_id);
 815	spin_unlock_irqrestore(&id->lock, flags);
 816	pr_info("%s: set new size (%i pages)\n", id->name, pages_per_area);
 817
 818	return 0;
 819}
 820
 821/**
 822 * debug_set_level() - Sets new actual debug level if new_level is valid.
 823 *
 824 * @id:		handle for debug log
 825 * @new_level:	new debug level
 826 *
 827 * Return:
 828 *    none
 829 */
 830void debug_set_level(debug_info_t *id, int new_level)
 831{
 832	unsigned long flags;
 833
 834	if (!id)
 835		return;
 836
 837	if (new_level == DEBUG_OFF_LEVEL) {
 
 838		pr_info("%s: switched off\n", id->name);
 839	} else if ((new_level > DEBUG_MAX_LEVEL) || (new_level < 0)) {
 840		pr_info("%s: level %i is out of range (%i - %i)\n",
 841			id->name, new_level, 0, DEBUG_MAX_LEVEL);
 842		return;
 
 843	}
 844
 845	spin_lock_irqsave(&id->lock, flags);
 846	id->level = new_level;
 847	spin_unlock_irqrestore(&id->lock, flags);
 848}
 849EXPORT_SYMBOL(debug_set_level);
 850
 851/*
 852 * proceed_active_entry:
 853 * - set active entry to next in the ring buffer
 854 */
 855static inline void proceed_active_entry(debug_info_t *id)
 856{
 857	if ((id->active_entries[id->active_area] += id->entry_size)
 858	    > (PAGE_SIZE - id->entry_size)) {
 859		id->active_entries[id->active_area] = 0;
 860		id->active_pages[id->active_area] =
 861			(id->active_pages[id->active_area] + 1) %
 862			id->pages_per_area;
 863	}
 864}
 865
 866/*
 867 * proceed_active_area:
 868 * - set active area to next in the ring buffer
 869 */
 870static inline void proceed_active_area(debug_info_t *id)
 871{
 872	id->active_area++;
 873	id->active_area = id->active_area % id->nr_areas;
 874}
 875
 876/*
 877 * get_active_entry:
 878 */
 879static inline debug_entry_t *get_active_entry(debug_info_t *id)
 880{
 881	return (debug_entry_t *) (((char *) id->areas[id->active_area]
 882				   [id->active_pages[id->active_area]]) +
 883				  id->active_entries[id->active_area]);
 884}
 885
 886/* Swap debug areas of a and b. */
 887static void debug_areas_swap(debug_info_t *a, debug_info_t *b)
 888{
 889	swap(a->nr_areas, b->nr_areas);
 890	swap(a->pages_per_area, b->pages_per_area);
 891	swap(a->areas, b->areas);
 892	swap(a->active_area, b->active_area);
 893	swap(a->active_pages, b->active_pages);
 894	swap(a->active_entries, b->active_entries);
 895}
 896
 897/* Append all debug events in active area from source to destination log. */
 898static void debug_events_append(debug_info_t *dest, debug_info_t *src)
 899{
 900	debug_entry_t *from, *to, *last;
 901
 902	if (!src->areas || !dest->areas)
 903		return;
 904
 905	/* Loop over all entries in src, starting with oldest. */
 906	from = get_active_entry(src);
 907	last = from;
 908	do {
 909		if (from->clock != 0LL) {
 910			to = get_active_entry(dest);
 911			memset(to, 0, dest->entry_size);
 912			memcpy(to, from, min(src->entry_size,
 913					     dest->entry_size));
 914			proceed_active_entry(dest);
 915		}
 916
 917		proceed_active_entry(src);
 918		from = get_active_entry(src);
 919	} while (from != last);
 920}
 921
 922/*
 923 * debug_finish_entry:
 924 * - set timestamp, caller address, cpu number etc.
 925 */
 926
 927static inline void debug_finish_entry(debug_info_t *id, debug_entry_t *active,
 928				      int level, int exception)
 929{
 930	unsigned long timestamp;
 931	union tod_clock clk;
 932
 933	store_tod_clock_ext(&clk);
 934	timestamp = clk.us;
 935	timestamp -= TOD_UNIX_EPOCH >> 12;
 936	active->clock = timestamp;
 937	active->cpu = smp_processor_id();
 938	active->caller = __builtin_return_address(0);
 939	active->exception = exception;
 940	active->level = level;
 941	proceed_active_entry(id);
 942	if (exception)
 943		proceed_active_area(id);
 944}
 945
 946static int debug_stoppable = 1;
 947static int debug_active = 1;
 948
 949#define CTL_S390DBF_STOPPABLE 5678
 950#define CTL_S390DBF_ACTIVE 5679
 951
 952/*
 953 * proc handler for the running debug_active sysctl
 954 * always allow read, allow write only if debug_stoppable is set or
 955 * if debug_active is already off
 956 */
 957static int s390dbf_procactive(struct ctl_table *table, int write,
 958			      void *buffer, size_t *lenp, loff_t *ppos)
 959{
 960	if (!write || debug_stoppable || !debug_active)
 961		return proc_dointvec(table, write, buffer, lenp, ppos);
 962	else
 963		return 0;
 964}
 965
 966static struct ctl_table s390dbf_table[] = {
 967	{
 968		.procname	= "debug_stoppable",
 969		.data		= &debug_stoppable,
 970		.maxlen		= sizeof(int),
 971		.mode		= S_IRUGO | S_IWUSR,
 972		.proc_handler	= proc_dointvec,
 973	},
 974	{
 975		.procname	= "debug_active",
 976		.data		= &debug_active,
 977		.maxlen		= sizeof(int),
 978		.mode		= S_IRUGO | S_IWUSR,
 979		.proc_handler	= s390dbf_procactive,
 980	},
 981	{ }
 982};
 983
 984static struct ctl_table s390dbf_dir_table[] = {
 985	{
 986		.procname	= "s390dbf",
 987		.maxlen		= 0,
 988		.mode		= S_IRUGO | S_IXUGO,
 989		.child		= s390dbf_table,
 990	},
 991	{ }
 992};
 993
 994static struct ctl_table_header *s390dbf_sysctl_header;
 995
 996/**
 997 * debug_stop_all() - stops the debug feature if stopping is allowed.
 998 *
 999 * Return:
1000 * -   none
1001 *
1002 * Currently used in case of a kernel oops.
1003 */
1004void debug_stop_all(void)
1005{
1006	if (debug_stoppable)
1007		debug_active = 0;
1008}
1009EXPORT_SYMBOL(debug_stop_all);
1010
1011/**
1012 * debug_set_critical() - event/exception functions try lock instead of spin.
1013 *
1014 * Return:
1015 * -   none
1016 *
1017 * Currently used in case of stopping all CPUs but the current one.
1018 * Once in this state, functions to write a debug entry for an
1019 * event or exception no longer spin on the debug area lock,
1020 * but only try to get it and fail if they do not get the lock.
1021 */
1022void debug_set_critical(void)
1023{
1024	debug_critical = 1;
1025}
1026
1027/*
1028 * debug_event_common:
1029 * - write debug entry with given size
1030 */
1031debug_entry_t *debug_event_common(debug_info_t *id, int level, const void *buf,
1032				  int len)
1033{
1034	debug_entry_t *active;
1035	unsigned long flags;
1036
1037	if (!debug_active || !id->areas)
1038		return NULL;
1039	if (debug_critical) {
1040		if (!spin_trylock_irqsave(&id->lock, flags))
1041			return NULL;
1042	} else {
1043		spin_lock_irqsave(&id->lock, flags);
1044	}
1045	do {
1046		active = get_active_entry(id);
1047		memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
1048		if (len < id->buf_size)
1049			memset((DEBUG_DATA(active)) + len, 0, id->buf_size - len);
1050		debug_finish_entry(id, active, level, 0);
1051		len -= id->buf_size;
1052		buf += id->buf_size;
1053	} while (len > 0);
1054
1055	spin_unlock_irqrestore(&id->lock, flags);
1056	return active;
1057}
1058EXPORT_SYMBOL(debug_event_common);
1059
1060/*
1061 * debug_exception_common:
1062 * - write debug entry with given size and switch to next debug area
1063 */
1064debug_entry_t *debug_exception_common(debug_info_t *id, int level,
1065				      const void *buf, int len)
1066{
1067	debug_entry_t *active;
1068	unsigned long flags;
1069
1070	if (!debug_active || !id->areas)
1071		return NULL;
1072	if (debug_critical) {
1073		if (!spin_trylock_irqsave(&id->lock, flags))
1074			return NULL;
1075	} else {
1076		spin_lock_irqsave(&id->lock, flags);
1077	}
1078	do {
1079		active = get_active_entry(id);
1080		memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
1081		if (len < id->buf_size)
1082			memset((DEBUG_DATA(active)) + len, 0, id->buf_size - len);
1083		debug_finish_entry(id, active, level, len <= id->buf_size);
1084		len -= id->buf_size;
1085		buf += id->buf_size;
1086	} while (len > 0);
1087
1088	spin_unlock_irqrestore(&id->lock, flags);
1089	return active;
1090}
1091EXPORT_SYMBOL(debug_exception_common);
1092
1093/*
1094 * counts arguments in format string for sprintf view
1095 */
1096static inline int debug_count_numargs(char *string)
1097{
1098	int numargs = 0;
1099
1100	while (*string) {
1101		if (*string++ == '%')
1102			numargs++;
1103	}
1104	return numargs;
1105}
1106
1107/*
1108 * debug_sprintf_event:
1109 */
1110debug_entry_t *__debug_sprintf_event(debug_info_t *id, int level, char *string, ...)
1111{
1112	debug_sprintf_entry_t *curr_event;
1113	debug_entry_t *active;
1114	unsigned long flags;
1115	int numargs, idx;
1116	va_list ap;
1117
1118	if (!debug_active || !id->areas)
1119		return NULL;
1120	numargs = debug_count_numargs(string);
1121
1122	if (debug_critical) {
1123		if (!spin_trylock_irqsave(&id->lock, flags))
1124			return NULL;
1125	} else {
1126		spin_lock_irqsave(&id->lock, flags);
1127	}
1128	active = get_active_entry(id);
1129	curr_event = (debug_sprintf_entry_t *) DEBUG_DATA(active);
1130	va_start(ap, string);
1131	curr_event->string = string;
1132	for (idx = 0; idx < min(numargs, (int)(id->buf_size / sizeof(long)) - 1); idx++)
1133		curr_event->args[idx] = va_arg(ap, long);
1134	va_end(ap);
1135	debug_finish_entry(id, active, level, 0);
1136	spin_unlock_irqrestore(&id->lock, flags);
1137
1138	return active;
1139}
1140EXPORT_SYMBOL(__debug_sprintf_event);
1141
1142/*
1143 * debug_sprintf_exception:
1144 */
1145debug_entry_t *__debug_sprintf_exception(debug_info_t *id, int level, char *string, ...)
1146{
1147	debug_sprintf_entry_t *curr_event;
1148	debug_entry_t *active;
1149	unsigned long flags;
1150	int numargs, idx;
1151	va_list ap;
1152
1153	if (!debug_active || !id->areas)
1154		return NULL;
1155
1156	numargs = debug_count_numargs(string);
1157
1158	if (debug_critical) {
1159		if (!spin_trylock_irqsave(&id->lock, flags))
1160			return NULL;
1161	} else {
1162		spin_lock_irqsave(&id->lock, flags);
1163	}
1164	active = get_active_entry(id);
1165	curr_event = (debug_sprintf_entry_t *)DEBUG_DATA(active);
1166	va_start(ap, string);
1167	curr_event->string = string;
1168	for (idx = 0; idx < min(numargs, (int)(id->buf_size / sizeof(long)) - 1); idx++)
1169		curr_event->args[idx] = va_arg(ap, long);
1170	va_end(ap);
1171	debug_finish_entry(id, active, level, 1);
1172	spin_unlock_irqrestore(&id->lock, flags);
1173
1174	return active;
1175}
1176EXPORT_SYMBOL(__debug_sprintf_exception);
1177
1178/**
1179 * debug_register_view() - registers new debug view and creates debugfs
1180 *			   dir entry
1181 *
1182 * @id:		handle for debug log
1183 * @view:	pointer to debug view struct
1184 *
1185 * Return:
1186 * -   0  : ok
1187 * -   < 0: Error
1188 */
1189int debug_register_view(debug_info_t *id, struct debug_view *view)
1190{
1191	unsigned long flags;
1192	struct dentry *pde;
1193	umode_t mode;
1194	int rc = 0;
1195	int i;
1196
1197	if (!id)
1198		goto out;
1199	mode = (id->mode | S_IFREG) & ~S_IXUGO;
1200	if (!(view->prolog_proc || view->format_proc || view->header_proc))
1201		mode &= ~(S_IRUSR | S_IRGRP | S_IROTH);
1202	if (!view->input_proc)
1203		mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
1204	pde = debugfs_create_file(view->name, mode, id->debugfs_root_entry,
1205				  id, &debug_file_ops);
1206	spin_lock_irqsave(&id->lock, flags);
1207	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
1208		if (!id->views[i])
1209			break;
1210	}
1211	if (i == DEBUG_MAX_VIEWS) {
 
 
1212		rc = -1;
1213	} else {
1214		id->views[i] = view;
1215		id->debugfs_entries[i] = pde;
1216	}
1217	spin_unlock_irqrestore(&id->lock, flags);
1218	if (rc) {
1219		pr_err("Registering view %s/%s would exceed the maximum "
1220		       "number of views %i\n", id->name, view->name, i);
1221		debugfs_remove(pde);
1222	}
1223out:
1224	return rc;
1225}
1226EXPORT_SYMBOL(debug_register_view);
1227
1228/**
1229 * debug_unregister_view() - unregisters debug view and removes debugfs
1230 *			     dir entry
1231 *
1232 * @id:		handle for debug log
1233 * @view:	pointer to debug view struct
1234 *
1235 * Return:
1236 * -   0  : ok
1237 * -   < 0: Error
1238 */
1239int debug_unregister_view(debug_info_t *id, struct debug_view *view)
1240{
1241	struct dentry *dentry = NULL;
1242	unsigned long flags;
1243	int i, rc = 0;
1244
1245	if (!id)
1246		goto out;
1247	spin_lock_irqsave(&id->lock, flags);
1248	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
1249		if (id->views[i] == view)
1250			break;
1251	}
1252	if (i == DEBUG_MAX_VIEWS) {
1253		rc = -1;
1254	} else {
1255		dentry = id->debugfs_entries[i];
1256		id->views[i] = NULL;
1257		id->debugfs_entries[i] = NULL;
1258	}
1259	spin_unlock_irqrestore(&id->lock, flags);
1260	debugfs_remove(dentry);
1261out:
1262	return rc;
1263}
1264EXPORT_SYMBOL(debug_unregister_view);
1265
1266static inline char *debug_get_user_string(const char __user *user_buf,
1267					  size_t user_len)
1268{
1269	char *buffer;
1270
1271	buffer = kmalloc(user_len + 1, GFP_KERNEL);
1272	if (!buffer)
1273		return ERR_PTR(-ENOMEM);
1274	if (copy_from_user(buffer, user_buf, user_len) != 0) {
1275		kfree(buffer);
1276		return ERR_PTR(-EFAULT);
1277	}
1278	/* got the string, now strip linefeed. */
1279	if (buffer[user_len - 1] == '\n')
1280		buffer[user_len - 1] = 0;
1281	else
1282		buffer[user_len] = 0;
1283	return buffer;
1284}
1285
1286static inline int debug_get_uint(char *buf)
1287{
1288	int rc;
1289
1290	buf = skip_spaces(buf);
1291	rc = simple_strtoul(buf, &buf, 10);
1292	if (*buf)
1293		rc = -EINVAL;
1294	return rc;
1295}
1296
1297/*
1298 * functions for debug-views
1299 ***********************************
1300*/
1301
1302/*
1303 * prints out actual debug level
1304 */
1305
1306static int debug_prolog_pages_fn(debug_info_t *id, struct debug_view *view,
1307				 char *out_buf)
1308{
1309	return sprintf(out_buf, "%i\n", id->pages_per_area);
1310}
1311
1312/*
1313 * reads new size (number of pages per debug area)
1314 */
1315
1316static int debug_input_pages_fn(debug_info_t *id, struct debug_view *view,
1317				struct file *file, const char __user *user_buf,
1318				size_t user_len, loff_t *offset)
1319{
1320	int rc, new_pages;
1321	char *str;
1322
1323	if (user_len > 0x10000)
1324		user_len = 0x10000;
1325	if (*offset != 0) {
1326		rc = -EPIPE;
1327		goto out;
1328	}
1329	str = debug_get_user_string(user_buf, user_len);
1330	if (IS_ERR(str)) {
1331		rc = PTR_ERR(str);
1332		goto out;
1333	}
1334	new_pages = debug_get_uint(str);
1335	if (new_pages < 0) {
1336		rc = -EINVAL;
1337		goto free_str;
1338	}
1339	rc = debug_set_size(id, id->nr_areas, new_pages);
1340	if (rc != 0) {
1341		rc = -EINVAL;
1342		goto free_str;
1343	}
1344	rc = user_len;
1345free_str:
1346	kfree(str);
1347out:
1348	*offset += user_len;
1349	return rc;		/* number of input characters */
1350}
1351
1352/*
1353 * prints out actual debug level
1354 */
1355static int debug_prolog_level_fn(debug_info_t *id, struct debug_view *view,
1356				 char *out_buf)
1357{
1358	int rc = 0;
1359
1360	if (id->level == DEBUG_OFF_LEVEL)
1361		rc = sprintf(out_buf, "-\n");
1362	else
1363		rc = sprintf(out_buf, "%i\n", id->level);
1364	return rc;
1365}
1366
1367/*
1368 * reads new debug level
1369 */
1370static int debug_input_level_fn(debug_info_t *id, struct debug_view *view,
1371				struct file *file, const char __user *user_buf,
1372				size_t user_len, loff_t *offset)
1373{
1374	int rc, new_level;
1375	char *str;
1376
1377	if (user_len > 0x10000)
1378		user_len = 0x10000;
1379	if (*offset != 0) {
1380		rc = -EPIPE;
1381		goto out;
1382	}
1383	str = debug_get_user_string(user_buf, user_len);
1384	if (IS_ERR(str)) {
1385		rc = PTR_ERR(str);
1386		goto out;
1387	}
1388	if (str[0] == '-') {
1389		debug_set_level(id, DEBUG_OFF_LEVEL);
1390		rc = user_len;
1391		goto free_str;
1392	} else {
1393		new_level = debug_get_uint(str);
1394	}
1395	if (new_level < 0) {
1396		pr_warn("%s is not a valid level for a debug feature\n", str);
1397		rc = -EINVAL;
1398	} else {
1399		debug_set_level(id, new_level);
1400		rc = user_len;
1401	}
1402free_str:
1403	kfree(str);
1404out:
1405	*offset += user_len;
1406	return rc;		/* number of input characters */
1407}
1408
1409/*
1410 * flushes debug areas
1411 */
1412static void debug_flush(debug_info_t *id, int area)
1413{
1414	unsigned long flags;
1415	int i, j;
1416
1417	if (!id || !id->areas)
1418		return;
1419	spin_lock_irqsave(&id->lock, flags);
1420	if (area == DEBUG_FLUSH_ALL) {
1421		id->active_area = 0;
1422		memset(id->active_entries, 0, id->nr_areas * sizeof(int));
1423		for (i = 0; i < id->nr_areas; i++) {
1424			id->active_pages[i] = 0;
1425			for (j = 0; j < id->pages_per_area; j++)
1426				memset(id->areas[i][j], 0, PAGE_SIZE);
1427		}
1428	} else if (area >= 0 && area < id->nr_areas) {
1429		id->active_entries[area] = 0;
1430		id->active_pages[area] = 0;
1431		for (i = 0; i < id->pages_per_area; i++)
1432			memset(id->areas[area][i], 0, PAGE_SIZE);
1433	}
1434	spin_unlock_irqrestore(&id->lock, flags);
1435}
1436
1437/*
1438 * view function: flushes debug areas
1439 */
1440static int debug_input_flush_fn(debug_info_t *id, struct debug_view *view,
1441				struct file *file, const char __user *user_buf,
1442				size_t user_len, loff_t *offset)
1443{
1444	char input_buf[1];
1445	int rc = user_len;
1446
1447	if (user_len > 0x10000)
1448		user_len = 0x10000;
1449	if (*offset != 0) {
1450		rc = -EPIPE;
1451		goto out;
1452	}
1453	if (copy_from_user(input_buf, user_buf, 1)) {
1454		rc = -EFAULT;
1455		goto out;
1456	}
1457	if (input_buf[0] == '-') {
1458		debug_flush(id, DEBUG_FLUSH_ALL);
1459		goto out;
1460	}
1461	if (isdigit(input_buf[0])) {
1462		int area = ((int) input_buf[0] - (int) '0');
1463
1464		debug_flush(id, area);
1465		goto out;
1466	}
1467
1468	pr_info("Flushing debug data failed because %c is not a valid "
1469		 "area\n", input_buf[0]);
1470
1471out:
1472	*offset += user_len;
1473	return rc;		/* number of input characters */
1474}
1475
1476/*
1477 * prints debug data in hex/ascii format
1478 */
1479static int debug_hex_ascii_format_fn(debug_info_t *id, struct debug_view *view,
1480				     char *out_buf, const char *in_buf)
1481{
1482	int i, rc = 0;
1483
1484	for (i = 0; i < id->buf_size; i++)
1485		rc += sprintf(out_buf + rc, "%02x ", ((unsigned char *) in_buf)[i]);
1486	rc += sprintf(out_buf + rc, "| ");
1487	for (i = 0; i < id->buf_size; i++) {
1488		unsigned char c = in_buf[i];
1489
1490		if (isascii(c) && isprint(c))
1491			rc += sprintf(out_buf + rc, "%c", c);
1492		else
1493			rc += sprintf(out_buf + rc, ".");
1494	}
1495	rc += sprintf(out_buf + rc, "\n");
1496	return rc;
1497}
1498
1499/*
1500 * prints header for debug entry
1501 */
1502int debug_dflt_header_fn(debug_info_t *id, struct debug_view *view,
1503			 int area, debug_entry_t *entry, char *out_buf)
1504{
1505	unsigned long sec, usec;
1506	unsigned long caller;
1507	unsigned int level;
1508	char *except_str;
1509	int rc = 0;
1510
1511	level = entry->level;
1512	sec = entry->clock;
1513	usec = do_div(sec, USEC_PER_SEC);
1514
1515	if (entry->exception)
1516		except_str = "*";
1517	else
1518		except_str = "-";
1519	caller = (unsigned long) entry->caller;
1520	rc += sprintf(out_buf, "%02i %011ld:%06lu %1u %1s %04u %px  ",
1521		      area, sec, usec, level, except_str,
1522		      entry->cpu, (void *)caller);
1523	return rc;
1524}
1525EXPORT_SYMBOL(debug_dflt_header_fn);
1526
1527/*
1528 * prints debug data sprintf-formated:
1529 * debug_sprinf_event/exception calls must be used together with this view
1530 */
1531
1532#define DEBUG_SPRINTF_MAX_ARGS 10
1533
1534static int debug_sprintf_format_fn(debug_info_t *id, struct debug_view *view,
1535				   char *out_buf, const char *inbuf)
1536{
1537	debug_sprintf_entry_t *curr_event = (debug_sprintf_entry_t *)inbuf;
1538	int num_longs, num_used_args = 0, i, rc = 0;
1539	int index[DEBUG_SPRINTF_MAX_ARGS];
1540
1541	/* count of longs fit into one entry */
1542	num_longs = id->buf_size / sizeof(long);
1543
1544	if (num_longs < 1)
1545		goto out; /* bufsize of entry too small */
1546	if (num_longs == 1) {
1547		/* no args, we use only the string */
1548		strcpy(out_buf, curr_event->string);
1549		rc = strlen(curr_event->string);
1550		goto out;
1551	}
1552
1553	/* number of arguments used for sprintf (without the format string) */
1554	num_used_args = min(DEBUG_SPRINTF_MAX_ARGS, (num_longs - 1));
1555
1556	memset(index, 0, DEBUG_SPRINTF_MAX_ARGS * sizeof(int));
1557
1558	for (i = 0; i < num_used_args; i++)
1559		index[i] = i;
1560
1561	rc = sprintf(out_buf, curr_event->string, curr_event->args[index[0]],
1562		     curr_event->args[index[1]], curr_event->args[index[2]],
1563		     curr_event->args[index[3]], curr_event->args[index[4]],
1564		     curr_event->args[index[5]], curr_event->args[index[6]],
1565		     curr_event->args[index[7]], curr_event->args[index[8]],
1566		     curr_event->args[index[9]]);
1567out:
1568	return rc;
1569}
1570
1571/*
1572 * debug_init:
1573 * - is called exactly once to initialize the debug feature
1574 */
1575static int __init debug_init(void)
1576{
1577	s390dbf_sysctl_header = register_sysctl_table(s390dbf_dir_table);
1578	mutex_lock(&debug_mutex);
1579	debug_debugfs_root_entry = debugfs_create_dir(DEBUG_DIR_ROOT, NULL);
1580	initialized = 1;
1581	mutex_unlock(&debug_mutex);
1582	return 0;
1583}
1584postcore_initcall(debug_init);