s390/kernel/debug.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *   S/390 debug facility
   4  *
   5  *    Copyright IBM Corp. 1999, 2020
   6  *
   7  *    Author(s): Michael Holzheu (holzheu@de.ibm.com),
   8  *               Holger Smolinski (Holger.Smolinski@de.ibm.com)
   9  *
  10  *    Bugreports to: <Linux390@de.ibm.com>
  11  */
  12
  13 #define KMSG_COMPONENT "s390dbf"
  14 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  15
  16 #include <linux/stddef.h>
  17 #include <linux/kernel.h>
  18 #include <linux/errno.h>
  19 #include <linux/slab.h>
  20 #include <linux/ctype.h>
  21 #include <linux/string.h>
  22 #include <linux/sysctl.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/export.h>
  25 #include <linux/init.h>
  26 #include <linux/fs.h>
  27 #include <linux/minmax.h>
  28 #include <linux/debugfs.h>
  29
  30 #include <asm/debug.h>
  31
  32 #define DEBUG_PROLOG_ENTRY -1
  33
  34 #define ALL_AREAS 0 /* copy all debug areas */
  35 #define NO_AREAS  1 /* copy no debug areas */
  36
  37 /* typedefs */
  38
  39 typedef struct file_private_info {
  40         loff_t offset;                  /* offset of last read in file */
  41         int    act_area;                /* number of last formated area */
  42         int    act_page;                /* act page in given area */
  43         int    act_entry;               /* last formated entry (offset */
  44                                         /* relative to beginning of last */
  45                                         /* formated page) */
  46         size_t act_entry_offset;        /* up to this offset we copied */
  47                                         /* in last read the last formated */
  48                                         /* entry to userland */
  49         char   temp_buf[2048];          /* buffer for output */
  50         debug_info_t *debug_info_org;   /* original debug information */
  51         debug_info_t *debug_info_snap;  /* snapshot of debug information */
  52         struct debug_view *view;        /* used view of debug info */
  53 } file_private_info_t;
  54
  55 typedef struct {
  56         char *string;
  57         /*
  58          * This assumes that all args are converted into longs
  59          * on L/390 this is the case for all types of parameter
  60          * except of floats, and long long (32 bit)
  61          *
  62          */
  63         long args[0];
  64 } debug_sprintf_entry_t;
  65
  66 /* internal function prototyes */
  67
  68 static int debug_init(void);
  69 static ssize_t debug_output(struct file *file, char __user *user_buf,
  70                             size_t user_len, loff_t *offset);
  71 static ssize_t debug_input(struct file *file, const char __user *user_buf,
  72                            size_t user_len, loff_t *offset);
  73 static int debug_open(struct inode *inode, struct file *file);
  74 static int debug_close(struct inode *inode, struct file *file);
  75 static debug_info_t *debug_info_create(const char *name, int pages_per_area,
  76                                        int nr_areas, int buf_size, umode_t mode);
  77 static void debug_info_get(debug_info_t *);
  78 static void debug_info_put(debug_info_t *);
  79 static int debug_prolog_level_fn(debug_info_t *id,
  80                                  struct debug_view *view, char *out_buf);
  81 static int debug_input_level_fn(debug_info_t *id, struct debug_view *view,
  82                                 struct file *file, const char __user *user_buf,
  83                                 size_t user_buf_size, loff_t *offset);
  84 static int debug_prolog_pages_fn(debug_info_t *id,
  85                                  struct debug_view *view, char *out_buf);
  86 static int debug_input_pages_fn(debug_info_t *id, struct debug_view *view,
  87                                 struct file *file, const char __user *user_buf,
  88                                 size_t user_buf_size, loff_t *offset);
  89 static int debug_input_flush_fn(debug_info_t *id, struct debug_view *view,
  90                                 struct file *file, const char __user *user_buf,
  91                                 size_t user_buf_size, loff_t *offset);
  92 static int debug_hex_ascii_format_fn(debug_info_t *id, struct debug_view *view,
  93                                      char *out_buf, const char *in_buf);
  94 static int debug_sprintf_format_fn(debug_info_t *id, struct debug_view *view,
  95                                    char *out_buf, debug_sprintf_entry_t *curr_event);
  96 static void debug_areas_swap(debug_info_t *a, debug_info_t *b);
  97 static void debug_events_append(debug_info_t *dest, debug_info_t *src);
  98
  99 /* globals */
 100
 101 struct debug_view debug_hex_ascii_view = {
 102         "hex_ascii",
 103         NULL,
 104         &debug_dflt_header_fn,
 105         &debug_hex_ascii_format_fn,
 106         NULL,
 107         NULL
 108 };
 109 EXPORT_SYMBOL(debug_hex_ascii_view);
 110
 111 static struct debug_view debug_level_view = {
 112         "level",
 113         &debug_prolog_level_fn,
 114         NULL,
 115         NULL,
 116         &debug_input_level_fn,
 117         NULL
 118 };
 119
 120 static struct debug_view debug_pages_view = {
 121         "pages",
 122         &debug_prolog_pages_fn,
 123         NULL,
 124         NULL,
 125         &debug_input_pages_fn,
 126         NULL
 127 };
 128
 129 static struct debug_view debug_flush_view = {
 130         "flush",
 131         NULL,
 132         NULL,
 133         NULL,
 134         &debug_input_flush_fn,
 135         NULL
 136 };
 137
 138 struct debug_view debug_sprintf_view = {
 139         "sprintf",
 140         NULL,
 141         &debug_dflt_header_fn,
 142         (debug_format_proc_t *)&debug_sprintf_format_fn,
 143         NULL,
 144         NULL
 145 };
 146 EXPORT_SYMBOL(debug_sprintf_view);
 147
 148 /* used by dump analysis tools to determine version of debug feature */
 149 static unsigned int __used debug_feature_version = __DEBUG_FEATURE_VERSION;
 150
 151 /* static globals */
 152
 153 static debug_info_t *debug_area_first;
 154 static debug_info_t *debug_area_last;
 155 static DEFINE_MUTEX(debug_mutex);
 156
 157 static int initialized;
 158 static int debug_critical;
 159
 160 static const struct file_operations debug_file_ops = {
 161         .owner   = THIS_MODULE,
 162         .read    = debug_output,
 163         .write   = debug_input,
 164         .open    = debug_open,
 165         .release = debug_close,
 166         .llseek  = no_llseek,
 167 };
 168
 169 static struct dentry *debug_debugfs_root_entry;
 170
 171 /* functions */
 172
 173 /*
 174  * debug_areas_alloc
 175  * - Debug areas are implemented as a threedimensonal array:
 176  *   areas[areanumber][pagenumber][pageoffset]
 177  */
 178
 179 static debug_entry_t ***debug_areas_alloc(int pages_per_area, int nr_areas)
 180 {
 181         debug_entry_t ***areas;
 182         int i, j;
 183
 184         areas = kmalloc_array(nr_areas, sizeof(debug_entry_t **), GFP_KERNEL);
 185         if (!areas)
 186                 goto fail_malloc_areas;
 187         for (i = 0; i < nr_areas; i++) {
 188                 /* GFP_NOWARN to avoid user triggerable WARN, we handle fails */
 189                 areas[i] = kmalloc_array(pages_per_area,
 190                                          sizeof(debug_entry_t *),
 191                                          GFP_KERNEL | __GFP_NOWARN);
 192                 if (!areas[i])
 193                         goto fail_malloc_areas2;
 194                 for (j = 0; j < pages_per_area; j++) {
 195                         areas[i][j] = kzalloc(PAGE_SIZE, GFP_KERNEL);
 196                         if (!areas[i][j]) {
 197                                 for (j--; j >= 0 ; j--)
 198                                         kfree(areas[i][j]);
 199                                 kfree(areas[i]);
 200                                 goto fail_malloc_areas2;
 201                         }
 202                 }
 203         }
 204         return areas;
 205
 206 fail_malloc_areas2:
 207         for (i--; i >= 0; i--) {
 208                 for (j = 0; j < pages_per_area; j++)
 209                         kfree(areas[i][j]);
 210                 kfree(areas[i]);
 211         }
 212         kfree(areas);
 213 fail_malloc_areas:
 214         return NULL;
 215 }
 216
 217 /*
 218  * debug_info_alloc
 219  * - alloc new debug-info
 220  */
 221 static debug_info_t *debug_info_alloc(const char *name, int pages_per_area,
 222                                       int nr_areas, int buf_size, int level,
 223                                       int mode)
 224 {
 225         debug_info_t *rc;
 226
 227         /* alloc everything */
 228         rc = kmalloc(sizeof(debug_info_t), GFP_KERNEL);
 229         if (!rc)
 230                 goto fail_malloc_rc;
 231         rc->active_entries = kcalloc(nr_areas, sizeof(int), GFP_KERNEL);
 232         if (!rc->active_entries)
 233                 goto fail_malloc_active_entries;
 234         rc->active_pages = kcalloc(nr_areas, sizeof(int), GFP_KERNEL);
 235         if (!rc->active_pages)
 236                 goto fail_malloc_active_pages;
 237         if ((mode == ALL_AREAS) && (pages_per_area != 0)) {
 238                 rc->areas = debug_areas_alloc(pages_per_area, nr_areas);
 239                 if (!rc->areas)
 240                         goto fail_malloc_areas;
 241         } else {
 242                 rc->areas = NULL;
 243         }
 244
 245         /* initialize members */
 246         spin_lock_init(&rc->lock);
 247         rc->pages_per_area = pages_per_area;
 248         rc->nr_areas       = nr_areas;
 249         rc->active_area    = 0;
 250         rc->level          = level;
 251         rc->buf_size       = buf_size;
 252         rc->entry_size     = sizeof(debug_entry_t) + buf_size;
 253         strscpy(rc->name, name, sizeof(rc->name));
 254         memset(rc->views, 0, DEBUG_MAX_VIEWS * sizeof(struct debug_view *));
 255         memset(rc->debugfs_entries, 0, DEBUG_MAX_VIEWS * sizeof(struct dentry *));
 256         refcount_set(&(rc->ref_count), 0);
 257
 258         return rc;
 259
 260 fail_malloc_areas:
 261         kfree(rc->active_pages);
 262 fail_malloc_active_pages:
 263         kfree(rc->active_entries);
 264 fail_malloc_active_entries:
 265         kfree(rc);
 266 fail_malloc_rc:
 267         return NULL;
 268 }
 269
 270 /*
 271  * debug_areas_free
 272  * - free all debug areas
 273  */
 274 static void debug_areas_free(debug_info_t *db_info)
 275 {
 276         int i, j;
 277
 278         if (!db_info->areas)
 279                 return;
 280         for (i = 0; i < db_info->nr_areas; i++) {
 281                 for (j = 0; j < db_info->pages_per_area; j++)
 282                         kfree(db_info->areas[i][j]);
 283                 kfree(db_info->areas[i]);
 284         }
 285         kfree(db_info->areas);
 286         db_info->areas = NULL;
 287 }
 288
 289 /*
 290  * debug_info_free
 291  * - free memory debug-info
 292  */
 293 static void debug_info_free(debug_info_t *db_info)
 294 {
 295         debug_areas_free(db_info);
 296         kfree(db_info->active_entries);
 297         kfree(db_info->active_pages);
 298         kfree(db_info);
 299 }
 300
 301 /*
 302  * debug_info_create
 303  * - create new debug-info
 304  */
 305
 306 static debug_info_t *debug_info_create(const char *name, int pages_per_area,
 307                                        int nr_areas, int buf_size, umode_t mode)
 308 {
 309         debug_info_t *rc;
 310
 311         rc = debug_info_alloc(name, pages_per_area, nr_areas, buf_size,
 312                               DEBUG_DEFAULT_LEVEL, ALL_AREAS);
 313         if (!rc)
 314                 goto out;
 315
 316         rc->mode = mode & ~S_IFMT;
 317         refcount_set(&rc->ref_count, 1);
 318 out:
 319         return rc;
 320 }
 321
 322 /*
 323  * debug_info_copy
 324  * - copy debug-info
 325  */
 326 static debug_info_t *debug_info_copy(debug_info_t *in, int mode)
 327 {
 328         unsigned long flags;
 329         debug_info_t *rc;
 330         int i, j;
 331
 332         /* get a consistent copy of the debug areas */
 333         do {
 334                 rc = debug_info_alloc(in->name, in->pages_per_area,
 335                         in->nr_areas, in->buf_size, in->level, mode);
 336                 spin_lock_irqsave(&in->lock, flags);
 337                 if (!rc)
 338                         goto out;
 339                 /* has something changed in the meantime ? */
 340                 if ((rc->pages_per_area == in->pages_per_area) &&
 341                     (rc->nr_areas == in->nr_areas)) {
 342                         break;
 343                 }
 344                 spin_unlock_irqrestore(&in->lock, flags);
 345                 debug_info_free(rc);
 346         } while (1);
 347
 348         if (mode == NO_AREAS)
 349                 goto out;
 350
 351         for (i = 0; i < in->nr_areas; i++) {
 352                 for (j = 0; j < in->pages_per_area; j++)
 353                         memcpy(rc->areas[i][j], in->areas[i][j], PAGE_SIZE);
 354         }
 355 out:
 356         spin_unlock_irqrestore(&in->lock, flags);
 357         return rc;
 358 }
 359
 360 /*
 361  * debug_info_get
 362  * - increments reference count for debug-info
 363  */
 364 static void debug_info_get(debug_info_t *db_info)
 365 {
 366         if (db_info)
 367                 refcount_inc(&db_info->ref_count);
 368 }
 369
 370 /*
 371  * debug_info_put:
 372  * - decreases reference count for debug-info and frees it if necessary
 373  */
 374 static void debug_info_put(debug_info_t *db_info)
 375 {
 376         if (!db_info)
 377                 return;
 378         if (refcount_dec_and_test(&db_info->ref_count))
 379                 debug_info_free(db_info);
 380 }
 381
 382 /*
 383  * debug_format_entry:
 384  * - format one debug entry and return size of formated data
 385  */
 386 static int debug_format_entry(file_private_info_t *p_info)
 387 {
 388         debug_info_t *id_snap   = p_info->debug_info_snap;
 389         struct debug_view *view = p_info->view;
 390         debug_entry_t *act_entry;
 391         size_t len = 0;
 392
 393         if (p_info->act_entry == DEBUG_PROLOG_ENTRY) {
 394                 /* print prolog */
 395                 if (view->prolog_proc)
 396                         len += view->prolog_proc(id_snap, view, p_info->temp_buf);
 397                 goto out;
 398         }
 399         if (!id_snap->areas) /* this is true, if we have a prolog only view */
 400                 goto out;    /* or if 'pages_per_area' is 0 */
 401         act_entry = (debug_entry_t *) ((char *)id_snap->areas[p_info->act_area]
 402                                        [p_info->act_page] + p_info->act_entry);
 403
 404         if (act_entry->clock == 0LL)
 405                 goto out; /* empty entry */
 406         if (view->header_proc)
 407                 len += view->header_proc(id_snap, view, p_info->act_area,
 408                                          act_entry, p_info->temp_buf + len);
 409         if (view->format_proc)
 410                 len += view->format_proc(id_snap, view, p_info->temp_buf + len,
 411                                          DEBUG_DATA(act_entry));
 412 out:
 413         return len;
 414 }
 415
 416 /*
 417  * debug_next_entry:
 418  * - goto next entry in p_info
 419  */
 420 static inline int debug_next_entry(file_private_info_t *p_info)
 421 {
 422         debug_info_t *id;
 423
 424         id = p_info->debug_info_snap;
 425         if (p_info->act_entry == DEBUG_PROLOG_ENTRY) {
 426                 p_info->act_entry = 0;
 427                 p_info->act_page  = 0;
 428                 goto out;
 429         }
 430         if (!id->areas)
 431                 return 1;
 432         p_info->act_entry += id->entry_size;
 433         /* switch to next page, if we reached the end of the page  */
 434         if (p_info->act_entry > (PAGE_SIZE - id->entry_size)) {
 435                 /* next page */
 436                 p_info->act_entry = 0;
 437                 p_info->act_page += 1;
 438                 if ((p_info->act_page % id->pages_per_area) == 0) {
 439                         /* next area */
 440                         p_info->act_area++;
 441                         p_info->act_page = 0;
 442                 }
 443                 if (p_info->act_area >= id->nr_areas)
 444                         return 1;
 445         }
 446 out:
 447         return 0;
 448 }
 449
 450 /*
 451  * debug_output:
 452  * - called for user read()
 453  * - copies formated debug entries to the user buffer
 454  */
 455 static ssize_t debug_output(struct file *file,          /* file descriptor */
 456                             char __user *user_buf,      /* user buffer */
 457                             size_t len,                 /* length of buffer */
 458                             loff_t *offset)             /* offset in the file */
 459 {
 460         size_t count = 0;
 461         size_t entry_offset;
 462         file_private_info_t *p_info;
 463
 464         p_info = (file_private_info_t *) file->private_data;
 465         if (*offset != p_info->offset)
 466                 return -EPIPE;
 467         if (p_info->act_area >= p_info->debug_info_snap->nr_areas)
 468                 return 0;
 469         entry_offset = p_info->act_entry_offset;
 470         while (count < len) {
 471                 int formatted_line_residue;
 472                 int formatted_line_size;
 473                 int user_buf_residue;
 474                 size_t copy_size;
 475
 476                 formatted_line_size = debug_format_entry(p_info);
 477                 formatted_line_residue = formatted_line_size - entry_offset;
 478                 user_buf_residue = len-count;
 479                 copy_size = min(user_buf_residue, formatted_line_residue);
 480                 if (copy_size) {
 481                         if (copy_to_user(user_buf + count, p_info->temp_buf
 482                                          + entry_offset, copy_size))
 483                                 return -EFAULT;
 484                         count += copy_size;
 485                         entry_offset += copy_size;
 486                 }
 487                 if (copy_size == formatted_line_residue) {
 488                         entry_offset = 0;
 489                         if (debug_next_entry(p_info))
 490                                 goto out;
 491                 }
 492         }
 493 out:
 494         p_info->offset           = *offset + count;
 495         p_info->act_entry_offset = entry_offset;
 496         *offset = p_info->offset;
 497         return count;
 498 }
 499
 500 /*
 501  * debug_input:
 502  * - called for user write()
 503  * - calls input function of view
 504  */
 505 static ssize_t debug_input(struct file *file, const char __user *user_buf,
 506                            size_t length, loff_t *offset)
 507 {
 508         file_private_info_t *p_info;
 509         int rc = 0;
 510
 511         mutex_lock(&debug_mutex);
 512         p_info = ((file_private_info_t *) file->private_data);
 513         if (p_info->view->input_proc) {
 514                 rc = p_info->view->input_proc(p_info->debug_info_org,
 515                                               p_info->view, file, user_buf,
 516                                               length, offset);
 517         } else {
 518                 rc = -EPERM;
 519         }
 520         mutex_unlock(&debug_mutex);
 521         return rc; /* number of input characters */
 522 }
 523
 524 /*
 525  * debug_open:
 526  * - called for user open()
 527  * - copies formated output to private_data area of the file
 528  *   handle
 529  */
 530 static int debug_open(struct inode *inode, struct file *file)
 531 {
 532         debug_info_t *debug_info, *debug_info_snapshot;
 533         file_private_info_t *p_info;
 534         int i, rc = 0;
 535
 536         mutex_lock(&debug_mutex);
 537         debug_info = file_inode(file)->i_private;
 538         /* find debug view */
 539         for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
 540                 if (!debug_info->views[i])
 541                         continue;
 542                 else if (debug_info->debugfs_entries[i] == file->f_path.dentry)
 543                         goto found; /* found view ! */
 544         }
 545         /* no entry found */
 546         rc = -EINVAL;
 547         goto out;
 548
 549 found:
 550
 551         /* Make snapshot of current debug areas to get it consistent.     */
 552         /* To copy all the areas is only needed, if we have a view which  */
 553         /* formats the debug areas. */
 554
 555         if (!debug_info->views[i]->format_proc && !debug_info->views[i]->header_proc)
 556                 debug_info_snapshot = debug_info_copy(debug_info, NO_AREAS);
 557         else
 558                 debug_info_snapshot = debug_info_copy(debug_info, ALL_AREAS);
 559
 560         if (!debug_info_snapshot) {
 561                 rc = -ENOMEM;
 562                 goto out;
 563         }
 564         p_info = kmalloc(sizeof(file_private_info_t), GFP_KERNEL);
 565         if (!p_info) {
 566                 debug_info_free(debug_info_snapshot);
 567                 rc = -ENOMEM;
 568                 goto out;
 569         }
 570         p_info->offset = 0;
 571         p_info->debug_info_snap = debug_info_snapshot;
 572         p_info->debug_info_org  = debug_info;
 573         p_info->view = debug_info->views[i];
 574         p_info->act_area = 0;
 575         p_info->act_page = 0;
 576         p_info->act_entry = DEBUG_PROLOG_ENTRY;
 577         p_info->act_entry_offset = 0;
 578         file->private_data = p_info;
 579         debug_info_get(debug_info);
 580         nonseekable_open(inode, file);
 581 out:
 582         mutex_unlock(&debug_mutex);
 583         return rc;
 584 }
 585
 586 /*
 587  * debug_close:
 588  * - called for user close()
 589  * - deletes  private_data area of the file handle
 590  */
 591 static int debug_close(struct inode *inode, struct file *file)
 592 {
 593         file_private_info_t *p_info;
 594
 595         p_info = (file_private_info_t *) file->private_data;
 596         if (p_info->debug_info_snap)
 597                 debug_info_free(p_info->debug_info_snap);
 598         debug_info_put(p_info->debug_info_org);
 599         kfree(file->private_data);
 600         return 0; /* success */
 601 }
 602
 603 /* Create debugfs entries and add to internal list. */
 604 static void _debug_register(debug_info_t *id)
 605 {
 606         /* create root directory */
 607         id->debugfs_root_entry = debugfs_create_dir(id->name,
 608                                                     debug_debugfs_root_entry);
 609
 610         /* append new element to linked list */
 611         if (!debug_area_first) {
 612                 /* first element in list */
 613                 debug_area_first = id;
 614                 id->prev = NULL;
 615         } else {
 616                 /* append element to end of list */
 617                 debug_area_last->next = id;
 618                 id->prev = debug_area_last;
 619         }
 620         debug_area_last = id;
 621         id->next = NULL;
 622
 623         debug_register_view(id, &debug_level_view);
 624         debug_register_view(id, &debug_flush_view);
 625         debug_register_view(id, &debug_pages_view);
 626 }
 627
 628 /**
 629  * debug_register_mode() - creates and initializes debug area.
 630  *
 631  * @name:       Name of debug log (e.g. used for debugfs entry)
 632  * @pages_per_area:     Number of pages, which will be allocated per area
 633  * @nr_areas:   Number of debug areas
 634  * @buf_size:   Size of data area in each debug entry
 635  * @mode:       File mode for debugfs files. E.g. S_IRWXUGO
 636  * @uid:        User ID for debugfs files. Currently only 0 is supported.
 637  * @gid:        Group ID for debugfs files. Currently only 0 is supported.
 638  *
 639  * Return:
 640  * - Handle for generated debug area
 641  * - %NULL if register failed
 642  *
 643  * Allocates memory for a debug log.
 644  * Must not be called within an interrupt handler.
 645  */
 646 debug_info_t *debug_register_mode(const char *name, int pages_per_area,
 647                                   int nr_areas, int buf_size, umode_t mode,
 648                                   uid_t uid, gid_t gid)
 649 {
 650         debug_info_t *rc = NULL;
 651
 652         /* Since debugfs currently does not support uid/gid other than root, */
 653         /* we do not allow gid/uid != 0 until we get support for that. */
 654         if ((uid != 0) || (gid != 0))
 655                 pr_warn("Root becomes the owner of all s390dbf files in sysfs\n");
 656         BUG_ON(!initialized);
 657
 658         /* create new debug_info */
 659         rc = debug_info_create(name, pages_per_area, nr_areas, buf_size, mode);
 660         if (rc) {
 661                 mutex_lock(&debug_mutex);
 662                 _debug_register(rc);
 663                 mutex_unlock(&debug_mutex);
 664         } else {
 665                 pr_err("Registering debug feature %s failed\n", name);
 666         }
 667         return rc;
 668 }
 669 EXPORT_SYMBOL(debug_register_mode);
 670
 671 /**
 672  * debug_register() - creates and initializes debug area with default file mode.
 673  *
 674  * @name:       Name of debug log (e.g. used for debugfs entry)
 675  * @pages_per_area:     Number of pages, which will be allocated per area
 676  * @nr_areas:   Number of debug areas
 677  * @buf_size:   Size of data area in each debug entry
 678  *
 679  * Return:
 680  * - Handle for generated debug area
 681  * - %NULL if register failed
 682  *
 683  * Allocates memory for a debug log.
 684  * The debugfs file mode access permissions are read and write for user.
 685  * Must not be called within an interrupt handler.
 686  */
 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_register_static() - registers a static debug area
 697  *
 698  * @id: Handle for static debug area
 699  * @pages_per_area: Number of pages per area
 700  * @nr_areas: Number of debug areas
 701  *
 702  * Register debug_info_t defined using DEFINE_STATIC_DEBUG_INFO.
 703  *
 704  * Note: This function is called automatically via an initcall generated by
 705  *       DEFINE_STATIC_DEBUG_INFO.
 706  */
 707 void debug_register_static(debug_info_t *id, int pages_per_area, int nr_areas)
 708 {
 709         unsigned long flags;
 710         debug_info_t *copy;
 711
 712         if (!initialized) {
 713                 pr_err("Tried to register debug feature %s too early\n",
 714                        id->name);
 715                 return;
 716         }
 717
 718         copy = debug_info_alloc("", pages_per_area, nr_areas, id->buf_size,
 719                                 id->level, ALL_AREAS);
 720         if (!copy) {
 721                 pr_err("Registering debug feature %s failed\n", id->name);
 722
 723                 /* Clear pointers to prevent tracing into released initdata. */
 724                 spin_lock_irqsave(&id->lock, flags);
 725                 id->areas = NULL;
 726                 id->active_pages = NULL;
 727                 id->active_entries = NULL;
 728                 spin_unlock_irqrestore(&id->lock, flags);
 729
 730                 return;
 731         }
 732
 733         /* Replace static trace area with dynamic copy. */
 734         spin_lock_irqsave(&id->lock, flags);
 735         debug_events_append(copy, id);
 736         debug_areas_swap(id, copy);
 737         spin_unlock_irqrestore(&id->lock, flags);
 738
 739         /* Clear pointers to initdata and discard copy. */
 740         copy->areas = NULL;
 741         copy->active_pages = NULL;
 742         copy->active_entries = NULL;
 743         debug_info_free(copy);
 744
 745         mutex_lock(&debug_mutex);
 746         _debug_register(id);
 747         mutex_unlock(&debug_mutex);
 748 }
 749
 750 /* Remove debugfs entries and remove from internal list. */
 751 static void _debug_unregister(debug_info_t *id)
 752 {
 753         int i;
 754
 755         for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
 756                 if (!id->views[i])
 757                         continue;
 758                 debugfs_remove(id->debugfs_entries[i]);
 759         }
 760         debugfs_remove(id->debugfs_root_entry);
 761         if (id == debug_area_first)
 762                 debug_area_first = id->next;
 763         if (id == debug_area_last)
 764                 debug_area_last = id->prev;
 765         if (id->prev)
 766                 id->prev->next = id->next;
 767         if (id->next)
 768                 id->next->prev = id->prev;
 769 }
 770
 771 /**
 772  * debug_unregister() - give back debug area.
 773  *
 774  * @id:         handle for debug log
 775  *
 776  * Return:
 777  *    none
 778  */
 779 void debug_unregister(debug_info_t *id)
 780 {
 781         if (!id)
 782                 return;
 783         mutex_lock(&debug_mutex);
 784         _debug_unregister(id);
 785         mutex_unlock(&debug_mutex);
 786
 787         debug_info_put(id);
 788 }
 789 EXPORT_SYMBOL(debug_unregister);
 790
 791 /*
 792  * debug_set_size:
 793  * - set area size (number of pages) and number of areas
 794  */
 795 static int debug_set_size(debug_info_t *id, int nr_areas, int pages_per_area)
 796 {
 797         debug_info_t *new_id;
 798         unsigned long flags;
 799
 800         if (!id || (nr_areas <= 0) || (pages_per_area < 0))
 801                 return -EINVAL;
 802
 803         new_id = debug_info_alloc("", pages_per_area, nr_areas, id->buf_size,
 804                                   id->level, ALL_AREAS);
 805         if (!new_id) {
 806                 pr_info("Allocating memory for %i pages failed\n",
 807                         pages_per_area);
 808                 return -ENOMEM;
 809         }
 810
 811         spin_lock_irqsave(&id->lock, flags);
 812         debug_events_append(new_id, id);
 813         debug_areas_swap(new_id, id);
 814         debug_info_free(new_id);
 815         spin_unlock_irqrestore(&id->lock, flags);
 816         pr_info("%s: set new size (%i pages)\n", id->name, pages_per_area);
 817
 818         return 0;
 819 }
 820
 821 /**
 822  * debug_set_level() - Sets new actual debug level if new_level is valid.
 823  *
 824  * @id:         handle for debug log
 825  * @new_level:  new debug level
 826  *
 827  * Return:
 828  *    none
 829  */
 830 void debug_set_level(debug_info_t *id, int new_level)
 831 {
 832         unsigned long flags;
 833
 834         if (!id)
 835                 return;
 836
 837         if (new_level == DEBUG_OFF_LEVEL) {
 838                 pr_info("%s: switched off\n", id->name);
 839         } else if ((new_level > DEBUG_MAX_LEVEL) || (new_level < 0)) {
 840                 pr_info("%s: level %i is out of range (%i - %i)\n",
 841                         id->name, new_level, 0, DEBUG_MAX_LEVEL);
 842                 return;
 843         }
 844
 845         spin_lock_irqsave(&id->lock, flags);
 846         id->level = new_level;
 847         spin_unlock_irqrestore(&id->lock, flags);
 848 }
 849 EXPORT_SYMBOL(debug_set_level);
 850
 851 /*
 852  * proceed_active_entry:
 853  * - set active entry to next in the ring buffer
 854  */
 855 static inline void proceed_active_entry(debug_info_t *id)
 856 {
 857         if ((id->active_entries[id->active_area] += id->entry_size)
 858             > (PAGE_SIZE - id->entry_size)) {
 859                 id->active_entries[id->active_area] = 0;
 860                 id->active_pages[id->active_area] =
 861                         (id->active_pages[id->active_area] + 1) %
 862                         id->pages_per_area;
 863         }
 864 }
 865
 866 /*
 867  * proceed_active_area:
 868  * - set active area to next in the ring buffer
 869  */
 870 static inline void proceed_active_area(debug_info_t *id)
 871 {
 872         id->active_area++;
 873         id->active_area = id->active_area % id->nr_areas;
 874 }
 875
 876 /*
 877  * get_active_entry:
 878  */
 879 static inline debug_entry_t *get_active_entry(debug_info_t *id)
 880 {
 881         return (debug_entry_t *) (((char *) id->areas[id->active_area]
 882                                    [id->active_pages[id->active_area]]) +
 883                                   id->active_entries[id->active_area]);
 884 }
 885
 886 /* Swap debug areas of a and b. */
 887 static void debug_areas_swap(debug_info_t *a, debug_info_t *b)
 888 {
 889         swap(a->nr_areas, b->nr_areas);
 890         swap(a->pages_per_area, b->pages_per_area);
 891         swap(a->areas, b->areas);
 892         swap(a->active_area, b->active_area);
 893         swap(a->active_pages, b->active_pages);
 894         swap(a->active_entries, b->active_entries);
 895 }
 896
 897 /* Append all debug events in active area from source to destination log. */
 898 static void debug_events_append(debug_info_t *dest, debug_info_t *src)
 899 {
 900         debug_entry_t *from, *to, *last;
 901
 902         if (!src->areas || !dest->areas)
 903                 return;
 904
 905         /* Loop over all entries in src, starting with oldest. */
 906         from = get_active_entry(src);
 907         last = from;
 908         do {
 909                 if (from->clock != 0LL) {
 910                         to = get_active_entry(dest);
 911                         memset(to, 0, dest->entry_size);
 912                         memcpy(to, from, min(src->entry_size,
 913                                              dest->entry_size));
 914                         proceed_active_entry(dest);
 915                 }
 916
 917                 proceed_active_entry(src);
 918                 from = get_active_entry(src);
 919         } while (from != last);
 920 }
 921
 922 /*
 923  * debug_finish_entry:
 924  * - set timestamp, caller address, cpu number etc.
 925  */
 926
 927 static inline void debug_finish_entry(debug_info_t *id, debug_entry_t *active,
 928                                       int level, int exception)
 929 {
 930         unsigned long timestamp;
 931         union tod_clock clk;
 932
 933         store_tod_clock_ext(&clk);
 934         timestamp = clk.us;
 935         timestamp -= TOD_UNIX_EPOCH >> 12;
 936         active->clock = timestamp;
 937         active->cpu = smp_processor_id();
 938         active->caller = __builtin_return_address(0);
 939         active->exception = exception;
 940         active->level = level;
 941         proceed_active_entry(id);
 942         if (exception)
 943                 proceed_active_area(id);
 944 }
 945
 946 static int debug_stoppable = 1;
 947 static int debug_active = 1;
 948
 949 #define CTL_S390DBF_STOPPABLE 5678
 950 #define CTL_S390DBF_ACTIVE 5679
 951
 952 /*
 953  * proc handler for the running debug_active sysctl
 954  * always allow read, allow write only if debug_stoppable is set or
 955  * if debug_active is already off
 956  */
 957 static int s390dbf_procactive(struct ctl_table *table, int write,
 958                               void *buffer, size_t *lenp, loff_t *ppos)
 959 {
 960         if (!write || debug_stoppable || !debug_active)
 961                 return proc_dointvec(table, write, buffer, lenp, ppos);
 962         else
 963                 return 0;
 964 }
 965
 966 static struct ctl_table s390dbf_table[] = {
 967         {
 968                 .procname       = "debug_stoppable",
 969                 .data           = &debug_stoppable,
 970                 .maxlen         = sizeof(int),
 971                 .mode           = S_IRUGO | S_IWUSR,
 972                 .proc_handler   = proc_dointvec,
 973         },
 974         {
 975                 .procname       = "debug_active",
 976                 .data           = &debug_active,
 977                 .maxlen         = sizeof(int),
 978                 .mode           = S_IRUGO | S_IWUSR,
 979                 .proc_handler   = s390dbf_procactive,
 980         },
 981         { }
 982 };
 983
 984 static struct ctl_table s390dbf_dir_table[] = {
 985         {
 986                 .procname       = "s390dbf",
 987                 .maxlen         = 0,
 988                 .mode           = S_IRUGO | S_IXUGO,
 989                 .child          = s390dbf_table,
 990         },
 991         { }
 992 };
 993
 994 static struct ctl_table_header *s390dbf_sysctl_header;
 995
 996 /**
 997  * debug_stop_all() - stops the debug feature if stopping is allowed.
 998  *
 999  * Return:
1000  * -   none
1001  *
1002  * Currently used in case of a kernel oops.
1003  */
1004 void debug_stop_all(void)
1005 {
1006         if (debug_stoppable)
1007                 debug_active = 0;
1008 }
1009 EXPORT_SYMBOL(debug_stop_all);
1010
1011 /**
1012  * debug_set_critical() - event/exception functions try lock instead of spin.
1013  *
1014  * Return:
1015  * -   none
1016  *
1017  * Currently used in case of stopping all CPUs but the current one.
1018  * Once in this state, functions to write a debug entry for an
1019  * event or exception no longer spin on the debug area lock,
1020  * but only try to get it and fail if they do not get the lock.
1021  */
1022 void debug_set_critical(void)
1023 {
1024         debug_critical = 1;
1025 }
1026
1027 /*
1028  * debug_event_common:
1029  * - write debug entry with given size
1030  */
1031 debug_entry_t *debug_event_common(debug_info_t *id, int level, const void *buf,
1032                                   int len)
1033 {
1034         debug_entry_t *active;
1035         unsigned long flags;
1036
1037         if (!debug_active || !id->areas)
1038                 return NULL;
1039         if (debug_critical) {
1040                 if (!spin_trylock_irqsave(&id->lock, flags))
1041                         return NULL;
1042         } else {
1043                 spin_lock_irqsave(&id->lock, flags);
1044         }
1045         do {
1046                 active = get_active_entry(id);
1047                 memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
1048                 if (len < id->buf_size)
1049                         memset((DEBUG_DATA(active)) + len, 0, id->buf_size - len);
1050                 debug_finish_entry(id, active, level, 0);
1051                 len -= id->buf_size;
1052                 buf += id->buf_size;
1053         } while (len > 0);
1054
1055         spin_unlock_irqrestore(&id->lock, flags);
1056         return active;
1057 }
1058 EXPORT_SYMBOL(debug_event_common);
1059
1060 /*
1061  * debug_exception_common:
1062  * - write debug entry with given size and switch to next debug area
1063  */
1064 debug_entry_t *debug_exception_common(debug_info_t *id, int level,
1065                                       const void *buf, int len)
1066 {
1067         debug_entry_t *active;
1068         unsigned long flags;
1069
1070         if (!debug_active || !id->areas)
1071                 return NULL;
1072         if (debug_critical) {
1073                 if (!spin_trylock_irqsave(&id->lock, flags))
1074                         return NULL;
1075         } else {
1076                 spin_lock_irqsave(&id->lock, flags);
1077         }
1078         do {
1079                 active = get_active_entry(id);
1080                 memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
1081                 if (len < id->buf_size)
1082                         memset((DEBUG_DATA(active)) + len, 0, id->buf_size - len);
1083                 debug_finish_entry(id, active, level, len <= id->buf_size);
1084                 len -= id->buf_size;
1085                 buf += id->buf_size;
1086         } while (len > 0);
1087
1088         spin_unlock_irqrestore(&id->lock, flags);
1089         return active;
1090 }
1091 EXPORT_SYMBOL(debug_exception_common);
1092
1093 /*
1094  * counts arguments in format string for sprintf view
1095  */
1096 static inline int debug_count_numargs(char *string)
1097 {
1098         int numargs = 0;
1099
1100         while (*string) {
1101                 if (*string++ == '%')
1102                         numargs++;
1103         }
1104         return numargs;
1105 }
1106
1107 /*
1108  * debug_sprintf_event:
1109  */
1110 debug_entry_t *__debug_sprintf_event(debug_info_t *id, int level, char *string, ...)
1111 {
1112         debug_sprintf_entry_t *curr_event;
1113         debug_entry_t *active;
1114         unsigned long flags;
1115         int numargs, idx;
1116         va_list ap;
1117
1118         if (!debug_active || !id->areas)
1119                 return NULL;
1120         numargs = debug_count_numargs(string);
1121
1122         if (debug_critical) {
1123                 if (!spin_trylock_irqsave(&id->lock, flags))
1124                         return NULL;
1125         } else {
1126                 spin_lock_irqsave(&id->lock, flags);
1127         }
1128         active = get_active_entry(id);
1129         curr_event = (debug_sprintf_entry_t *) DEBUG_DATA(active);
1130         va_start(ap, string);
1131         curr_event->string = string;
1132         for (idx = 0; idx < min(numargs, (int)(id->buf_size / sizeof(long)) - 1); idx++)
1133                 curr_event->args[idx] = va_arg(ap, long);
1134         va_end(ap);
1135         debug_finish_entry(id, active, level, 0);
1136         spin_unlock_irqrestore(&id->lock, flags);
1137
1138         return active;
1139 }
1140 EXPORT_SYMBOL(__debug_sprintf_event);
1141
1142 /*
1143  * debug_sprintf_exception:
1144  */
1145 debug_entry_t *__debug_sprintf_exception(debug_info_t *id, int level, char *string, ...)
1146 {
1147         debug_sprintf_entry_t *curr_event;
1148         debug_entry_t *active;
1149         unsigned long flags;
1150         int numargs, idx;
1151         va_list ap;
1152
1153         if (!debug_active || !id->areas)
1154                 return NULL;
1155
1156         numargs = debug_count_numargs(string);
1157
1158         if (debug_critical) {
1159                 if (!spin_trylock_irqsave(&id->lock, flags))
1160                         return NULL;
1161         } else {
1162                 spin_lock_irqsave(&id->lock, flags);
1163         }
1164         active = get_active_entry(id);
1165         curr_event = (debug_sprintf_entry_t *)DEBUG_DATA(active);
1166         va_start(ap, string);
1167         curr_event->string = string;
1168         for (idx = 0; idx < min(numargs, (int)(id->buf_size / sizeof(long)) - 1); idx++)
1169                 curr_event->args[idx] = va_arg(ap, long);
1170         va_end(ap);
1171         debug_finish_entry(id, active, level, 1);
1172         spin_unlock_irqrestore(&id->lock, flags);
1173
1174         return active;
1175 }
1176 EXPORT_SYMBOL(__debug_sprintf_exception);
1177
1178 /**
1179  * debug_register_view() - registers new debug view and creates debugfs
1180  *                         dir entry
1181  *
1182  * @id:         handle for debug log
1183  * @view:       pointer to debug view struct
1184  *
1185  * Return:
1186  * -   0  : ok
1187  * -   < 0: Error
1188  */
1189 int debug_register_view(debug_info_t *id, struct debug_view *view)
1190 {
1191         unsigned long flags;
1192         struct dentry *pde;
1193         umode_t mode;
1194         int rc = 0;
1195         int i;
1196
1197         if (!id)
1198                 goto out;
1199         mode = (id->mode | S_IFREG) & ~S_IXUGO;
1200         if (!(view->prolog_proc || view->format_proc || view->header_proc))
1201                 mode &= ~(S_IRUSR | S_IRGRP | S_IROTH);
1202         if (!view->input_proc)
1203                 mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
1204         pde = debugfs_create_file(view->name, mode, id->debugfs_root_entry,
1205                                   id, &debug_file_ops);
1206         spin_lock_irqsave(&id->lock, flags);
1207         for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
1208                 if (!id->views[i])
1209                         break;
1210         }
1211         if (i == DEBUG_MAX_VIEWS) {
1212                 rc = -1;
1213         } else {
1214                 id->views[i] = view;
1215                 id->debugfs_entries[i] = pde;
1216         }
1217         spin_unlock_irqrestore(&id->lock, flags);
1218         if (rc) {
1219                 pr_err("Registering view %s/%s would exceed the maximum "
1220                        "number of views %i\n", id->name, view->name, i);
1221                 debugfs_remove(pde);
1222         }
1223 out:
1224         return rc;
1225 }
1226 EXPORT_SYMBOL(debug_register_view);
1227
1228 /**
1229  * debug_unregister_view() - unregisters debug view and removes debugfs
1230  *                           dir entry
1231  *
1232  * @id:         handle for debug log
1233  * @view:       pointer to debug view struct
1234  *
1235  * Return:
1236  * -   0  : ok
1237  * -   < 0: Error
1238  */
1239 int debug_unregister_view(debug_info_t *id, struct debug_view *view)
1240 {
1241         struct dentry *dentry = NULL;
1242         unsigned long flags;
1243         int i, rc = 0;
1244
1245         if (!id)
1246                 goto out;
1247         spin_lock_irqsave(&id->lock, flags);
1248         for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
1249                 if (id->views[i] == view)
1250                         break;
1251         }
1252         if (i == DEBUG_MAX_VIEWS) {
1253                 rc = -1;
1254         } else {
1255                 dentry = id->debugfs_entries[i];
1256                 id->views[i] = NULL;
1257                 id->debugfs_entries[i] = NULL;
1258         }
1259         spin_unlock_irqrestore(&id->lock, flags);
1260         debugfs_remove(dentry);
1261 out:
1262         return rc;
1263 }
1264 EXPORT_SYMBOL(debug_unregister_view);
1265
1266 static inline char *debug_get_user_string(const char __user *user_buf,
1267                                           size_t user_len)
1268 {
1269         char *buffer;
1270
1271         buffer = kmalloc(user_len + 1, GFP_KERNEL);
1272         if (!buffer)
1273                 return ERR_PTR(-ENOMEM);
1274         if (copy_from_user(buffer, user_buf, user_len) != 0) {
1275                 kfree(buffer);
1276                 return ERR_PTR(-EFAULT);
1277         }
1278         /* got the string, now strip linefeed. */
1279         if (buffer[user_len - 1] == '\n')
1280                 buffer[user_len - 1] = 0;
1281         else
1282                 buffer[user_len] = 0;
1283         return buffer;
1284 }
1285
1286 static inline int debug_get_uint(char *buf)
1287 {
1288         int rc;
1289
1290         buf = skip_spaces(buf);
1291         rc = simple_strtoul(buf, &buf, 10);
1292         if (*buf)
1293                 rc = -EINVAL;
1294         return rc;
1295 }
1296
1297 /*
1298  * functions for debug-views
1299  ***********************************
1300 */
1301
1302 /*
1303  * prints out actual debug level
1304  */
1305
1306 static int debug_prolog_pages_fn(debug_info_t *id, struct debug_view *view,
1307                                  char *out_buf)
1308 {
1309         return sprintf(out_buf, "%i\n", id->pages_per_area);
1310 }
1311
1312 /*
1313  * reads new size (number of pages per debug area)
1314  */
1315
1316 static int debug_input_pages_fn(debug_info_t *id, struct debug_view *view,
1317                                 struct file *file, const char __user *user_buf,
1318                                 size_t user_len, loff_t *offset)
1319 {
1320         int rc, new_pages;
1321         char *str;
1322
1323         if (user_len > 0x10000)
1324                 user_len = 0x10000;
1325         if (*offset != 0) {
1326                 rc = -EPIPE;
1327                 goto out;
1328         }
1329         str = debug_get_user_string(user_buf, user_len);
1330         if (IS_ERR(str)) {
1331                 rc = PTR_ERR(str);
1332                 goto out;
1333         }
1334         new_pages = debug_get_uint(str);
1335         if (new_pages < 0) {
1336                 rc = -EINVAL;
1337                 goto free_str;
1338         }
1339         rc = debug_set_size(id, id->nr_areas, new_pages);
1340         if (rc != 0) {
1341                 rc = -EINVAL;
1342                 goto free_str;
1343         }
1344         rc = user_len;
1345 free_str:
1346         kfree(str);
1347 out:
1348         *offset += user_len;
1349         return rc;              /* number of input characters */
1350 }
1351
1352 /*
1353  * prints out actual debug level
1354  */
1355 static int debug_prolog_level_fn(debug_info_t *id, struct debug_view *view,
1356                                  char *out_buf)
1357 {
1358         int rc = 0;
1359
1360         if (id->level == DEBUG_OFF_LEVEL)
1361                 rc = sprintf(out_buf, "-\n");
1362         else
1363                 rc = sprintf(out_buf, "%i\n", id->level);
1364         return rc;
1365 }
1366
1367 /*
1368  * reads new debug level
1369  */
1370 static int debug_input_level_fn(debug_info_t *id, struct debug_view *view,
1371                                 struct file *file, const char __user *user_buf,
1372                                 size_t user_len, loff_t *offset)
1373 {
1374         int rc, new_level;
1375         char *str;
1376
1377         if (user_len > 0x10000)
1378                 user_len = 0x10000;
1379         if (*offset != 0) {
1380                 rc = -EPIPE;
1381                 goto out;
1382         }
1383         str = debug_get_user_string(user_buf, user_len);
1384         if (IS_ERR(str)) {
1385                 rc = PTR_ERR(str);
1386                 goto out;
1387         }
1388         if (str[0] == '-') {
1389                 debug_set_level(id, DEBUG_OFF_LEVEL);
1390                 rc = user_len;
1391                 goto free_str;
1392         } else {
1393                 new_level = debug_get_uint(str);
1394         }
1395         if (new_level < 0) {
1396                 pr_warn("%s is not a valid level for a debug feature\n", str);
1397                 rc = -EINVAL;
1398         } else {
1399                 debug_set_level(id, new_level);
1400                 rc = user_len;
1401         }
1402 free_str:
1403         kfree(str);
1404 out:
1405         *offset += user_len;
1406         return rc;              /* number of input characters */
1407 }
1408
1409 /*
1410  * flushes debug areas
1411  */
1412 static void debug_flush(debug_info_t *id, int area)
1413 {
1414         unsigned long flags;
1415         int i, j;
1416
1417         if (!id || !id->areas)
1418                 return;
1419         spin_lock_irqsave(&id->lock, flags);
1420         if (area == DEBUG_FLUSH_ALL) {
1421                 id->active_area = 0;
1422                 memset(id->active_entries, 0, id->nr_areas * sizeof(int));
1423                 for (i = 0; i < id->nr_areas; i++) {
1424                         id->active_pages[i] = 0;
1425                         for (j = 0; j < id->pages_per_area; j++)
1426                                 memset(id->areas[i][j], 0, PAGE_SIZE);
1427                 }
1428         } else if (area >= 0 && area < id->nr_areas) {
1429                 id->active_entries[area] = 0;
1430                 id->active_pages[area] = 0;
1431                 for (i = 0; i < id->pages_per_area; i++)
1432                         memset(id->areas[area][i], 0, PAGE_SIZE);
1433         }
1434         spin_unlock_irqrestore(&id->lock, flags);
1435 }
1436
1437 /*
1438  * view function: flushes debug areas
1439  */
1440 static int debug_input_flush_fn(debug_info_t *id, struct debug_view *view,
1441                                 struct file *file, const char __user *user_buf,
1442                                 size_t user_len, loff_t *offset)
1443 {
1444         char input_buf[1];
1445         int rc = user_len;
1446
1447         if (user_len > 0x10000)
1448                 user_len = 0x10000;
1449         if (*offset != 0) {
1450                 rc = -EPIPE;
1451                 goto out;
1452         }
1453         if (copy_from_user(input_buf, user_buf, 1)) {
1454                 rc = -EFAULT;
1455                 goto out;
1456         }
1457         if (input_buf[0] == '-') {
1458                 debug_flush(id, DEBUG_FLUSH_ALL);
1459                 goto out;
1460         }
1461         if (isdigit(input_buf[0])) {
1462                 int area = ((int) input_buf[0] - (int) '0');
1463
1464                 debug_flush(id, area);
1465                 goto out;
1466         }
1467
1468         pr_info("Flushing debug data failed because %c is not a valid "
1469                  "area\n", input_buf[0]);
1470
1471 out:
1472         *offset += user_len;
1473         return rc;              /* number of input characters */
1474 }
1475
1476 /*
1477  * prints debug data in hex/ascii format
1478  */
1479 static int debug_hex_ascii_format_fn(debug_info_t *id, struct debug_view *view,
1480                                      char *out_buf, const char *in_buf)
1481 {
1482         int i, rc = 0;
1483
1484         for (i = 0; i < id->buf_size; i++)
1485                 rc += sprintf(out_buf + rc, "%02x ", ((unsigned char *) in_buf)[i]);
1486         rc += sprintf(out_buf + rc, "| ");
1487         for (i = 0; i < id->buf_size; i++) {
1488                 unsigned char c = in_buf[i];
1489
1490                 if (isascii(c) && isprint(c))
1491                         rc += sprintf(out_buf + rc, "%c", c);
1492                 else
1493                         rc += sprintf(out_buf + rc, ".");
1494         }
1495         rc += sprintf(out_buf + rc, "\n");
1496         return rc;
1497 }
1498
1499 /*
1500  * prints header for debug entry
1501  */
1502 int debug_dflt_header_fn(debug_info_t *id, struct debug_view *view,
1503                          int area, debug_entry_t *entry, char *out_buf)
1504 {
1505         unsigned long sec, usec;
1506         unsigned long caller;
1507         unsigned int level;
1508         char *except_str;
1509         int rc = 0;
1510
1511         level = entry->level;
1512         sec = entry->clock;
1513         usec = do_div(sec, USEC_PER_SEC);
1514
1515         if (entry->exception)
1516                 except_str = "*";
1517         else
1518                 except_str = "-";
1519         caller = (unsigned long) entry->caller;
1520         rc += sprintf(out_buf, "%02i %011ld:%06lu %1u %1s %04u %px  ",
1521                       area, sec, usec, level, except_str,
1522                       entry->cpu, (void *)caller);
1523         return rc;
1524 }
1525 EXPORT_SYMBOL(debug_dflt_header_fn);
1526
1527 /*
1528  * prints debug data sprintf-formated:
1529  * debug_sprinf_event/exception calls must be used together with this view
1530  */
1531
1532 #define DEBUG_SPRINTF_MAX_ARGS 10
1533
1534 static int debug_sprintf_format_fn(debug_info_t *id, struct debug_view *view,
1535                                    char *out_buf, debug_sprintf_entry_t *curr_event)
1536 {
1537         int num_longs, num_used_args = 0, i, rc = 0;
1538         int index[DEBUG_SPRINTF_MAX_ARGS];
1539
1540         /* count of longs fit into one entry */
1541         num_longs = id->buf_size / sizeof(long);
1542
1543         if (num_longs < 1)
1544                 goto out; /* bufsize of entry too small */
1545         if (num_longs == 1) {
1546                 /* no args, we use only the string */
1547                 strcpy(out_buf, curr_event->string);
1548                 rc = strlen(curr_event->string);
1549                 goto out;
1550         }
1551
1552         /* number of arguments used for sprintf (without the format string) */
1553         num_used_args = min(DEBUG_SPRINTF_MAX_ARGS, (num_longs - 1));
1554
1555         memset(index, 0, DEBUG_SPRINTF_MAX_ARGS * sizeof(int));
1556
1557         for (i = 0; i < num_used_args; i++)
1558                 index[i] = i;
1559
1560         rc = sprintf(out_buf, curr_event->string, curr_event->args[index[0]],
1561                      curr_event->args[index[1]], curr_event->args[index[2]],
1562                      curr_event->args[index[3]], curr_event->args[index[4]],
1563                      curr_event->args[index[5]], curr_event->args[index[6]],
1564                      curr_event->args[index[7]], curr_event->args[index[8]],
1565                      curr_event->args[index[9]]);
1566 out:
1567         return rc;
1568 }
1569
1570 /*
1571  * debug_init:
1572  * - is called exactly once to initialize the debug feature
1573  */
1574 static int __init debug_init(void)
1575 {
1576         s390dbf_sysctl_header = register_sysctl_table(s390dbf_dir_table);
1577         mutex_lock(&debug_mutex);
1578         debug_debugfs_root_entry = debugfs_create_dir(DEBUG_DIR_ROOT, NULL);
1579         initialized = 1;
1580         mutex_unlock(&debug_mutex);
1581         return 0;
1582 }
1583 postcore_initcall(debug_init);