arch/s390/kernel/debug.c

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