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