kernel/debug/kdb/kdb_io.c

   1 /*
   2  * Kernel Debugger Architecture Independent Console I/O handler
   3  *
   4  * This file is subject to the terms and conditions of the GNU General Public
   5  * License.  See the file "COPYING" in the main directory of this archive
   6  * for more details.
   7  *
   8  * Copyright (c) 1999-2006 Silicon Graphics, Inc.  All Rights Reserved.
   9  * Copyright (c) 2009 Wind River Systems, Inc.  All Rights Reserved.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/types.h>
  14 #include <linux/ctype.h>
  15 #include <linux/kernel.h>
  16 #include <linux/init.h>
  17 #include <linux/kdev_t.h>
  18 #include <linux/console.h>
  19 #include <linux/string.h>
  20 #include <linux/sched.h>
  21 #include <linux/smp.h>
  22 #include <linux/nmi.h>
  23 #include <linux/delay.h>
  24 #include <linux/kgdb.h>
  25 #include <linux/kdb.h>
  26 #include <linux/kallsyms.h>
  27 #include "kdb_private.h"
  28
  29 #define CMD_BUFLEN 256
  30 char kdb_prompt_str[CMD_BUFLEN];
  31
  32 int kdb_trap_printk;
  33
  34 static int kgdb_transition_check(char *buffer)
  35 {
  36         if (buffer[0] != '+' && buffer[0] != '$') {
  37                 KDB_STATE_SET(KGDB_TRANS);
  38                 kdb_printf("%s", buffer);
  39         } else {
  40                 int slen = strlen(buffer);
  41                 if (slen > 3 && buffer[slen - 3] == '#') {
  42                         kdb_gdb_state_pass(buffer);
  43                         strcpy(buffer, "kgdb");
  44                         KDB_STATE_SET(DOING_KGDB);
  45                         return 1;
  46                 }
  47         }
  48         return 0;
  49 }
  50
  51 static int kdb_read_get_key(char *buffer, size_t bufsize)
  52 {
  53 #define ESCAPE_UDELAY 1000
  54 #define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
  55         char escape_data[5];    /* longest vt100 escape sequence is 4 bytes */
  56         char *ped = escape_data;
  57         int escape_delay = 0;
  58         get_char_func *f, *f_escape = NULL;
  59         int key;
  60
  61         for (f = &kdb_poll_funcs[0]; ; ++f) {
  62                 if (*f == NULL) {
  63                         /* Reset NMI watchdog once per poll loop */
  64                         touch_nmi_watchdog();
  65                         f = &kdb_poll_funcs[0];
  66                 }
  67                 if (escape_delay == 2) {
  68                         *ped = '\0';
  69                         ped = escape_data;
  70                         --escape_delay;
  71                 }
  72                 if (escape_delay == 1) {
  73                         key = *ped++;
  74                         if (!*ped)
  75                                 --escape_delay;
  76                         break;
  77                 }
  78                 key = (*f)();
  79                 if (key == -1) {
  80                         if (escape_delay) {
  81                                 udelay(ESCAPE_UDELAY);
  82                                 --escape_delay;
  83                         }
  84                         continue;
  85                 }
  86                 if (bufsize <= 2) {
  87                         if (key == '\r')
  88                                 key = '\n';
  89                         *buffer++ = key;
  90                         *buffer = '\0';
  91                         return -1;
  92                 }
  93                 if (escape_delay == 0 && key == '\e') {
  94                         escape_delay = ESCAPE_DELAY;
  95                         ped = escape_data;
  96                         f_escape = f;
  97                 }
  98                 if (escape_delay) {
  99                         *ped++ = key;
 100                         if (f_escape != f) {
 101                                 escape_delay = 2;
 102                                 continue;
 103                         }
 104                         if (ped - escape_data == 1) {
 105                                 /* \e */
 106                                 continue;
 107                         } else if (ped - escape_data == 2) {
 108                                 /* \e<something> */
 109                                 if (key != '[')
 110                                         escape_delay = 2;
 111                                 continue;
 112                         } else if (ped - escape_data == 3) {
 113                                 /* \e[<something> */
 114                                 int mapkey = 0;
 115                                 switch (key) {
 116                                 case 'A': /* \e[A, up arrow */
 117                                         mapkey = 16;
 118                                         break;
 119                                 case 'B': /* \e[B, down arrow */
 120                                         mapkey = 14;
 121                                         break;
 122                                 case 'C': /* \e[C, right arrow */
 123                                         mapkey = 6;
 124                                         break;
 125                                 case 'D': /* \e[D, left arrow */
 126                                         mapkey = 2;
 127                                         break;
 128                                 case '1': /* dropthrough */
 129                                 case '3': /* dropthrough */
 130                                 /* \e[<1,3,4>], may be home, del, end */
 131                                 case '4':
 132                                         mapkey = -1;
 133                                         break;
 134                                 }
 135                                 if (mapkey != -1) {
 136                                         if (mapkey > 0) {
 137                                                 escape_data[0] = mapkey;
 138                                                 escape_data[1] = '\0';
 139                                         }
 140                                         escape_delay = 2;
 141                                 }
 142                                 continue;
 143                         } else if (ped - escape_data == 4) {
 144                                 /* \e[<1,3,4><something> */
 145                                 int mapkey = 0;
 146                                 if (key == '~') {
 147                                         switch (escape_data[2]) {
 148                                         case '1': /* \e[1~, home */
 149                                                 mapkey = 1;
 150                                                 break;
 151                                         case '3': /* \e[3~, del */
 152                                                 mapkey = 4;
 153                                                 break;
 154                                         case '4': /* \e[4~, end */
 155                                                 mapkey = 5;
 156                                                 break;
 157                                         }
 158                                 }
 159                                 if (mapkey > 0) {
 160                                         escape_data[0] = mapkey;
 161                                         escape_data[1] = '\0';
 162                                 }
 163                                 escape_delay = 2;
 164                                 continue;
 165                         }
 166                 }
 167                 break;  /* A key to process */
 168         }
 169         return key;
 170 }
 171
 172 /*
 173  * kdb_read
 174  *
 175  *      This function reads a string of characters, terminated by
 176  *      a newline, or by reaching the end of the supplied buffer,
 177  *      from the current kernel debugger console device.
 178  * Parameters:
 179  *      buffer  - Address of character buffer to receive input characters.
 180  *      bufsize - size, in bytes, of the character buffer
 181  * Returns:
 182  *      Returns a pointer to the buffer containing the received
 183  *      character string.  This string will be terminated by a
 184  *      newline character.
 185  * Locking:
 186  *      No locks are required to be held upon entry to this
 187  *      function.  It is not reentrant - it relies on the fact
 188  *      that while kdb is running on only one "master debug" cpu.
 189  * Remarks:
 190  *
 191  * The buffer size must be >= 2.  A buffer size of 2 means that the caller only
 192  * wants a single key.
 193  *
 194  * An escape key could be the start of a vt100 control sequence such as \e[D
 195  * (left arrow) or it could be a character in its own right.  The standard
 196  * method for detecting the difference is to wait for 2 seconds to see if there
 197  * are any other characters.  kdb is complicated by the lack of a timer service
 198  * (interrupts are off), by multiple input sources and by the need to sometimes
 199  * return after just one key.  Escape sequence processing has to be done as
 200  * states in the polling loop.
 201  */
 202
 203 static char *kdb_read(char *buffer, size_t bufsize)
 204 {
 205         char *cp = buffer;
 206         char *bufend = buffer+bufsize-2;        /* Reserve space for newline
 207                                                  * and null byte */
 208         char *lastchar;
 209         char *p_tmp;
 210         char tmp;
 211         static char tmpbuffer[CMD_BUFLEN];
 212         int len = strlen(buffer);
 213         int len_tmp;
 214         int tab = 0;
 215         int count;
 216         int i;
 217         int diag, dtab_count;
 218         int key;
 219
 220
 221         diag = kdbgetintenv("DTABCOUNT", &dtab_count);
 222         if (diag)
 223                 dtab_count = 30;
 224
 225         if (len > 0) {
 226                 cp += len;
 227                 if (*(buffer+len-1) == '\n')
 228                         cp--;
 229         }
 230
 231         lastchar = cp;
 232         *cp = '\0';
 233         kdb_printf("%s", buffer);
 234 poll_again:
 235         key = kdb_read_get_key(buffer, bufsize);
 236         if (key == -1)
 237                 return buffer;
 238         if (key != 9)
 239                 tab = 0;
 240         switch (key) {
 241         case 8: /* backspace */
 242                 if (cp > buffer) {
 243                         if (cp < lastchar) {
 244                                 memcpy(tmpbuffer, cp, lastchar - cp);
 245                                 memcpy(cp-1, tmpbuffer, lastchar - cp);
 246                         }
 247                         *(--lastchar) = '\0';
 248                         --cp;
 249                         kdb_printf("\b%s \r", cp);
 250                         tmp = *cp;
 251                         *cp = '\0';
 252                         kdb_printf(kdb_prompt_str);
 253                         kdb_printf("%s", buffer);
 254                         *cp = tmp;
 255                 }
 256                 break;
 257         case 13: /* enter */
 258                 *lastchar++ = '\n';
 259                 *lastchar++ = '\0';
 260                 if (!KDB_STATE(KGDB_TRANS)) {
 261                         KDB_STATE_SET(KGDB_TRANS);
 262                         kdb_printf("%s", buffer);
 263                 }
 264                 kdb_printf("\n");
 265                 return buffer;
 266         case 4: /* Del */
 267                 if (cp < lastchar) {
 268                         memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
 269                         memcpy(cp, tmpbuffer, lastchar - cp - 1);
 270                         *(--lastchar) = '\0';
 271                         kdb_printf("%s \r", cp);
 272                         tmp = *cp;
 273                         *cp = '\0';
 274                         kdb_printf(kdb_prompt_str);
 275                         kdb_printf("%s", buffer);
 276                         *cp = tmp;
 277                 }
 278                 break;
 279         case 1: /* Home */
 280                 if (cp > buffer) {
 281                         kdb_printf("\r");
 282                         kdb_printf(kdb_prompt_str);
 283                         cp = buffer;
 284                 }
 285                 break;
 286         case 5: /* End */
 287                 if (cp < lastchar) {
 288                         kdb_printf("%s", cp);
 289                         cp = lastchar;
 290                 }
 291                 break;
 292         case 2: /* Left */
 293                 if (cp > buffer) {
 294                         kdb_printf("\b");
 295                         --cp;
 296                 }
 297                 break;
 298         case 14: /* Down */
 299                 memset(tmpbuffer, ' ',
 300                        strlen(kdb_prompt_str) + (lastchar-buffer));
 301                 *(tmpbuffer+strlen(kdb_prompt_str) +
 302                   (lastchar-buffer)) = '\0';
 303                 kdb_printf("\r%s\r", tmpbuffer);
 304                 *lastchar = (char)key;
 305                 *(lastchar+1) = '\0';
 306                 return lastchar;
 307         case 6: /* Right */
 308                 if (cp < lastchar) {
 309                         kdb_printf("%c", *cp);
 310                         ++cp;
 311                 }
 312                 break;
 313         case 16: /* Up */
 314                 memset(tmpbuffer, ' ',
 315                        strlen(kdb_prompt_str) + (lastchar-buffer));
 316                 *(tmpbuffer+strlen(kdb_prompt_str) +
 317                   (lastchar-buffer)) = '\0';
 318                 kdb_printf("\r%s\r", tmpbuffer);
 319                 *lastchar = (char)key;
 320                 *(lastchar+1) = '\0';
 321                 return lastchar;
 322         case 9: /* Tab */
 323                 if (tab < 2)
 324                         ++tab;
 325                 p_tmp = buffer;
 326                 while (*p_tmp == ' ')
 327                         p_tmp++;
 328                 if (p_tmp > cp)
 329                         break;
 330                 memcpy(tmpbuffer, p_tmp, cp-p_tmp);
 331                 *(tmpbuffer + (cp-p_tmp)) = '\0';
 332                 p_tmp = strrchr(tmpbuffer, ' ');
 333                 if (p_tmp)
 334                         ++p_tmp;
 335                 else
 336                         p_tmp = tmpbuffer;
 337                 len = strlen(p_tmp);
 338                 count = kallsyms_symbol_complete(p_tmp,
 339                                                  sizeof(tmpbuffer) -
 340                                                  (p_tmp - tmpbuffer));
 341                 if (tab == 2 && count > 0) {
 342                         kdb_printf("\n%d symbols are found.", count);
 343                         if (count > dtab_count) {
 344                                 count = dtab_count;
 345                                 kdb_printf(" But only first %d symbols will"
 346                                            " be printed.\nYou can change the"
 347                                            " environment variable DTABCOUNT.",
 348                                            count);
 349                         }
 350                         kdb_printf("\n");
 351                         for (i = 0; i < count; i++) {
 352                                 if (kallsyms_symbol_next(p_tmp, i) < 0)
 353                                         break;
 354                                 kdb_printf("%s ", p_tmp);
 355                                 *(p_tmp + len) = '\0';
 356                         }
 357                         if (i >= dtab_count)
 358                                 kdb_printf("...");
 359                         kdb_printf("\n");
 360                         kdb_printf(kdb_prompt_str);
 361                         kdb_printf("%s", buffer);
 362                 } else if (tab != 2 && count > 0) {
 363                         len_tmp = strlen(p_tmp);
 364                         strncpy(p_tmp+len_tmp, cp, lastchar-cp+1);
 365                         len_tmp = strlen(p_tmp);
 366                         strncpy(cp, p_tmp+len, len_tmp-len + 1);
 367                         len = len_tmp - len;
 368                         kdb_printf("%s", cp);
 369                         cp += len;
 370                         lastchar += len;
 371                 }
 372                 kdb_nextline = 1; /* reset output line number */
 373                 break;
 374         default:
 375                 if (key >= 32 && lastchar < bufend) {
 376                         if (cp < lastchar) {
 377                                 memcpy(tmpbuffer, cp, lastchar - cp);
 378                                 memcpy(cp+1, tmpbuffer, lastchar - cp);
 379                                 *++lastchar = '\0';
 380                                 *cp = key;
 381                                 kdb_printf("%s\r", cp);
 382                                 ++cp;
 383                                 tmp = *cp;
 384                                 *cp = '\0';
 385                                 kdb_printf(kdb_prompt_str);
 386                                 kdb_printf("%s", buffer);
 387                                 *cp = tmp;
 388                         } else {
 389                                 *++lastchar = '\0';
 390                                 *cp++ = key;
 391                                 /* The kgdb transition check will hide
 392                                  * printed characters if we think that
 393                                  * kgdb is connecting, until the check
 394                                  * fails */
 395                                 if (!KDB_STATE(KGDB_TRANS)) {
 396                                         if (kgdb_transition_check(buffer))
 397                                                 return buffer;
 398                                 } else {
 399                                         kdb_printf("%c", key);
 400                                 }
 401                         }
 402                         /* Special escape to kgdb */
 403                         if (lastchar - buffer >= 5 &&
 404                             strcmp(lastchar - 5, "$?#3f") == 0) {
 405                                 kdb_gdb_state_pass(lastchar - 5);
 406                                 strcpy(buffer, "kgdb");
 407                                 KDB_STATE_SET(DOING_KGDB);
 408                                 return buffer;
 409                         }
 410                         if (lastchar - buffer >= 11 &&
 411                             strcmp(lastchar - 11, "$qSupported") == 0) {
 412                                 kdb_gdb_state_pass(lastchar - 11);
 413                                 strcpy(buffer, "kgdb");
 414                                 KDB_STATE_SET(DOING_KGDB);
 415                                 return buffer;
 416                         }
 417                 }
 418                 break;
 419         }
 420         goto poll_again;
 421 }
 422
 423 /*
 424  * kdb_getstr
 425  *
 426  *      Print the prompt string and read a command from the
 427  *      input device.
 428  *
 429  * Parameters:
 430  *      buffer  Address of buffer to receive command
 431  *      bufsize Size of buffer in bytes
 432  *      prompt  Pointer to string to use as prompt string
 433  * Returns:
 434  *      Pointer to command buffer.
 435  * Locking:
 436  *      None.
 437  * Remarks:
 438  *      For SMP kernels, the processor number will be
 439  *      substituted for %d, %x or %o in the prompt.
 440  */
 441
 442 char *kdb_getstr(char *buffer, size_t bufsize, char *prompt)
 443 {
 444         if (prompt && kdb_prompt_str != prompt)
 445                 strncpy(kdb_prompt_str, prompt, CMD_BUFLEN);
 446         kdb_printf(kdb_prompt_str);
 447         kdb_nextline = 1;       /* Prompt and input resets line number */
 448         return kdb_read(buffer, bufsize);
 449 }
 450
 451 /*
 452  * kdb_input_flush
 453  *
 454  *      Get rid of any buffered console input.
 455  *
 456  * Parameters:
 457  *      none
 458  * Returns:
 459  *      nothing
 460  * Locking:
 461  *      none
 462  * Remarks:
 463  *      Call this function whenever you want to flush input.  If there is any
 464  *      outstanding input, it ignores all characters until there has been no
 465  *      data for approximately 1ms.
 466  */
 467
 468 static void kdb_input_flush(void)
 469 {
 470         get_char_func *f;
 471         int res;
 472         int flush_delay = 1;
 473         while (flush_delay) {
 474                 flush_delay--;
 475 empty:
 476                 touch_nmi_watchdog();
 477                 for (f = &kdb_poll_funcs[0]; *f; ++f) {
 478                         res = (*f)();
 479                         if (res != -1) {
 480                                 flush_delay = 1;
 481                                 goto empty;
 482                         }
 483                 }
 484                 if (flush_delay)
 485                         mdelay(1);
 486         }
 487 }
 488
 489 /*
 490  * kdb_printf
 491  *
 492  *      Print a string to the output device(s).
 493  *
 494  * Parameters:
 495  *      printf-like format and optional args.
 496  * Returns:
 497  *      0
 498  * Locking:
 499  *      None.
 500  * Remarks:
 501  *      use 'kdbcons->write()' to avoid polluting 'log_buf' with
 502  *      kdb output.
 503  *
 504  *  If the user is doing a cmd args | grep srch
 505  *  then kdb_grepping_flag is set.
 506  *  In that case we need to accumulate full lines (ending in \n) before
 507  *  searching for the pattern.
 508  */
 509
 510 static char kdb_buffer[256];    /* A bit too big to go on stack */
 511 static char *next_avail = kdb_buffer;
 512 static int  size_avail;
 513 static int  suspend_grep;
 514
 515 /*
 516  * search arg1 to see if it contains arg2
 517  * (kdmain.c provides flags for ^pat and pat$)
 518  *
 519  * return 1 for found, 0 for not found
 520  */
 521 static int kdb_search_string(char *searched, char *searchfor)
 522 {
 523         char firstchar, *cp;
 524         int len1, len2;
 525
 526         /* not counting the newline at the end of "searched" */
 527         len1 = strlen(searched)-1;
 528         len2 = strlen(searchfor);
 529         if (len1 < len2)
 530                 return 0;
 531         if (kdb_grep_leading && kdb_grep_trailing && len1 != len2)
 532                 return 0;
 533         if (kdb_grep_leading) {
 534                 if (!strncmp(searched, searchfor, len2))
 535                         return 1;
 536         } else if (kdb_grep_trailing) {
 537                 if (!strncmp(searched+len1-len2, searchfor, len2))
 538                         return 1;
 539         } else {
 540                 firstchar = *searchfor;
 541                 cp = searched;
 542                 while ((cp = strchr(cp, firstchar))) {
 543                         if (!strncmp(cp, searchfor, len2))
 544                                 return 1;
 545                         cp++;
 546                 }
 547         }
 548         return 0;
 549 }
 550
 551 int vkdb_printf(const char *fmt, va_list ap)
 552 {
 553         int diag;
 554         int linecount;
 555         int logging, saved_loglevel = 0;
 556         int saved_trap_printk;
 557         int got_printf_lock = 0;
 558         int retlen = 0;
 559         int fnd, len;
 560         char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
 561         char *moreprompt = "more> ";
 562         struct console *c = console_drivers;
 563         static DEFINE_SPINLOCK(kdb_printf_lock);
 564         unsigned long uninitialized_var(flags);
 565
 566         preempt_disable();
 567         saved_trap_printk = kdb_trap_printk;
 568         kdb_trap_printk = 0;
 569
 570         /* Serialize kdb_printf if multiple cpus try to write at once.
 571          * But if any cpu goes recursive in kdb, just print the output,
 572          * even if it is interleaved with any other text.
 573          */
 574         if (!KDB_STATE(PRINTF_LOCK)) {
 575                 KDB_STATE_SET(PRINTF_LOCK);
 576                 spin_lock_irqsave(&kdb_printf_lock, flags);
 577                 got_printf_lock = 1;
 578                 atomic_inc(&kdb_event);
 579         } else {
 580                 __acquire(kdb_printf_lock);
 581         }
 582
 583         diag = kdbgetintenv("LINES", &linecount);
 584         if (diag || linecount <= 1)
 585                 linecount = 24;
 586
 587         diag = kdbgetintenv("LOGGING", &logging);
 588         if (diag)
 589                 logging = 0;
 590
 591         if (!kdb_grepping_flag || suspend_grep) {
 592                 /* normally, every vsnprintf starts a new buffer */
 593                 next_avail = kdb_buffer;
 594                 size_avail = sizeof(kdb_buffer);
 595         }
 596         vsnprintf(next_avail, size_avail, fmt, ap);
 597
 598         /*
 599          * If kdb_parse() found that the command was cmd xxx | grep yyy
 600          * then kdb_grepping_flag is set, and kdb_grep_string contains yyy
 601          *
 602          * Accumulate the print data up to a newline before searching it.
 603          * (vsnprintf does null-terminate the string that it generates)
 604          */
 605
 606         /* skip the search if prints are temporarily unconditional */
 607         if (!suspend_grep && kdb_grepping_flag) {
 608                 cp = strchr(kdb_buffer, '\n');
 609                 if (!cp) {
 610                         /*
 611                          * Special cases that don't end with newlines
 612                          * but should be written without one:
 613                          *   The "[nn]kdb> " prompt should
 614                          *   appear at the front of the buffer.
 615                          *
 616                          *   The "[nn]more " prompt should also be
 617                          *     (MOREPROMPT -> moreprompt)
 618                          *   written *   but we print that ourselves,
 619                          *   we set the suspend_grep flag to make
 620                          *   it unconditional.
 621                          *
 622                          */
 623                         if (next_avail == kdb_buffer) {
 624                                 /*
 625                                  * these should occur after a newline,
 626                                  * so they will be at the front of the
 627                                  * buffer
 628                                  */
 629                                 cp2 = kdb_buffer;
 630                                 len = strlen(kdb_prompt_str);
 631                                 if (!strncmp(cp2, kdb_prompt_str, len)) {
 632                                         /*
 633                                          * We're about to start a new
 634                                          * command, so we can go back
 635                                          * to normal mode.
 636                                          */
 637                                         kdb_grepping_flag = 0;
 638                                         goto kdb_printit;
 639                                 }
 640                         }
 641                         /* no newline; don't search/write the buffer
 642                            until one is there */
 643                         len = strlen(kdb_buffer);
 644                         next_avail = kdb_buffer + len;
 645                         size_avail = sizeof(kdb_buffer) - len;
 646                         goto kdb_print_out;
 647                 }
 648
 649                 /*
 650                  * The newline is present; print through it or discard
 651                  * it, depending on the results of the search.
 652                  */
 653                 cp++;                /* to byte after the newline */
 654                 replaced_byte = *cp; /* remember what/where it was */
 655                 cphold = cp;
 656                 *cp = '\0';          /* end the string for our search */
 657
 658                 /*
 659                  * We now have a newline at the end of the string
 660                  * Only continue with this output if it contains the
 661                  * search string.
 662                  */
 663                 fnd = kdb_search_string(kdb_buffer, kdb_grep_string);
 664                 if (!fnd) {
 665                         /*
 666                          * At this point the complete line at the start
 667                          * of kdb_buffer can be discarded, as it does
 668                          * not contain what the user is looking for.
 669                          * Shift the buffer left.
 670                          */
 671                         *cphold = replaced_byte;
 672                         strcpy(kdb_buffer, cphold);
 673                         len = strlen(kdb_buffer);
 674                         next_avail = kdb_buffer + len;
 675                         size_avail = sizeof(kdb_buffer) - len;
 676                         goto kdb_print_out;
 677                 }
 678                 /*
 679                  * at this point the string is a full line and
 680                  * should be printed, up to the null.
 681                  */
 682         }
 683 kdb_printit:
 684
 685         /*
 686          * Write to all consoles.
 687          */
 688         retlen = strlen(kdb_buffer);
 689         if (!dbg_kdb_mode && kgdb_connected) {
 690                 gdbstub_msg_write(kdb_buffer, retlen);
 691         } else {
 692                 if (dbg_io_ops && !dbg_io_ops->is_console) {
 693                         len = strlen(kdb_buffer);
 694                         cp = kdb_buffer;
 695                         while (len--) {
 696                                 dbg_io_ops->write_char(*cp);
 697                                 cp++;
 698                         }
 699                 }
 700                 while (c) {
 701                         c->write(c, kdb_buffer, retlen);
 702                         touch_nmi_watchdog();
 703                         c = c->next;
 704                 }
 705         }
 706         if (logging) {
 707                 saved_loglevel = console_loglevel;
 708                 console_loglevel = 0;
 709                 printk(KERN_INFO "%s", kdb_buffer);
 710         }
 711
 712         if (KDB_STATE(PAGER) && strchr(kdb_buffer, '\n'))
 713                 kdb_nextline++;
 714
 715         /* check for having reached the LINES number of printed lines */
 716         if (kdb_nextline == linecount) {
 717                 char buf1[16] = "";
 718
 719                 /* Watch out for recursion here.  Any routine that calls
 720                  * kdb_printf will come back through here.  And kdb_read
 721                  * uses kdb_printf to echo on serial consoles ...
 722                  */
 723                 kdb_nextline = 1;       /* In case of recursion */
 724
 725                 /*
 726                  * Pause until cr.
 727                  */
 728                 moreprompt = kdbgetenv("MOREPROMPT");
 729                 if (moreprompt == NULL)
 730                         moreprompt = "more> ";
 731
 732                 kdb_input_flush();
 733                 c = console_drivers;
 734
 735                 if (dbg_io_ops && !dbg_io_ops->is_console) {
 736                         len = strlen(moreprompt);
 737                         cp = moreprompt;
 738                         while (len--) {
 739                                 dbg_io_ops->write_char(*cp);
 740                                 cp++;
 741                         }
 742                 }
 743                 while (c) {
 744                         c->write(c, moreprompt, strlen(moreprompt));
 745                         touch_nmi_watchdog();
 746                         c = c->next;
 747                 }
 748
 749                 if (logging)
 750                         printk("%s", moreprompt);
 751
 752                 kdb_read(buf1, 2); /* '2' indicates to return
 753                                     * immediately after getting one key. */
 754                 kdb_nextline = 1;       /* Really set output line 1 */
 755
 756                 /* empty and reset the buffer: */
 757                 kdb_buffer[0] = '\0';
 758                 next_avail = kdb_buffer;
 759                 size_avail = sizeof(kdb_buffer);
 760                 if ((buf1[0] == 'q') || (buf1[0] == 'Q')) {
 761                         /* user hit q or Q */
 762                         KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
 763                         KDB_STATE_CLEAR(PAGER);
 764                         /* end of command output; back to normal mode */
 765                         kdb_grepping_flag = 0;
 766                         kdb_printf("\n");
 767                 } else if (buf1[0] == ' ') {
 768                         kdb_printf("\n");
 769                         suspend_grep = 1; /* for this recursion */
 770                 } else if (buf1[0] == '\n') {
 771                         kdb_nextline = linecount - 1;
 772                         kdb_printf("\r");
 773                         suspend_grep = 1; /* for this recursion */
 774                 } else if (buf1[0] && buf1[0] != '\n') {
 775                         /* user hit something other than enter */
 776                         suspend_grep = 1; /* for this recursion */
 777                         kdb_printf("\nOnly 'q' or 'Q' are processed at more "
 778                                    "prompt, input ignored\n");
 779                 } else if (kdb_grepping_flag) {
 780                         /* user hit enter */
 781                         suspend_grep = 1; /* for this recursion */
 782                         kdb_printf("\n");
 783                 }
 784                 kdb_input_flush();
 785         }
 786
 787         /*
 788          * For grep searches, shift the printed string left.
 789          *  replaced_byte contains the character that was overwritten with
 790          *  the terminating null, and cphold points to the null.
 791          * Then adjust the notion of available space in the buffer.
 792          */
 793         if (kdb_grepping_flag && !suspend_grep) {
 794                 *cphold = replaced_byte;
 795                 strcpy(kdb_buffer, cphold);
 796                 len = strlen(kdb_buffer);
 797                 next_avail = kdb_buffer + len;
 798                 size_avail = sizeof(kdb_buffer) - len;
 799         }
 800
 801 kdb_print_out:
 802         suspend_grep = 0; /* end of what may have been a recursive call */
 803         if (logging)
 804                 console_loglevel = saved_loglevel;
 805         if (KDB_STATE(PRINTF_LOCK) && got_printf_lock) {
 806                 got_printf_lock = 0;
 807                 spin_unlock_irqrestore(&kdb_printf_lock, flags);
 808                 KDB_STATE_CLEAR(PRINTF_LOCK);
 809                 atomic_dec(&kdb_event);
 810         } else {
 811                 __release(kdb_printf_lock);
 812         }
 813         kdb_trap_printk = saved_trap_printk;
 814         preempt_enable();
 815         return retlen;
 816 }
 817
 818 int kdb_printf(const char *fmt, ...)
 819 {
 820         va_list ap;
 821         int r;
 822
 823         va_start(ap, fmt);
 824         r = vkdb_printf(fmt, ap);
 825         va_end(ap);
 826
 827         return r;
 828 }
 829 EXPORT_SYMBOL_GPL(kdb_printf);