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   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
  33 static void kgdb_transition_check(char *buffer)
  34 {
  35         int slen = strlen(buffer);
  36         if (strncmp(buffer, "$?#3f", slen) != 0 &&
  37             strncmp(buffer, "$qSupported#37", slen) != 0 &&
  38             strncmp(buffer, "+$qSupported#37", slen) != 0) {
  39                 KDB_STATE_SET(KGDB_TRANS);
  40                 kdb_printf("%s", buffer);
  41         }
  42 }
  43
  44 static int kdb_read_get_key(char *buffer, size_t bufsize)
  45 {
  46 #define ESCAPE_UDELAY 1000
  47 #define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
  48         char escape_data[5];    /* longest vt100 escape sequence is 4 bytes */
  49         char *ped = escape_data;
  50         int escape_delay = 0;
  51         get_char_func *f, *f_escape = NULL;
  52         int key;
  53
  54         for (f = &kdb_poll_funcs[0]; ; ++f) {
  55                 if (*f == NULL) {
  56                         /* Reset NMI watchdog once per poll loop */
  57                         touch_nmi_watchdog();
  58                         f = &kdb_poll_funcs[0];
  59                 }
  60                 if (escape_delay == 2) {
  61                         *ped = '\0';
  62                         ped = escape_data;
  63                         --escape_delay;
  64                 }
  65                 if (escape_delay == 1) {
  66                         key = *ped++;
  67                         if (!*ped)
  68                                 --escape_delay;
  69                         break;
  70                 }
  71                 key = (*f)();
  72                 if (key == -1) {
  73                         if (escape_delay) {
  74                                 udelay(ESCAPE_UDELAY);
  75                                 --escape_delay;
  76                         }
  77                         continue;
  78                 }
  79                 if (bufsize <= 2) {
  80                         if (key == '\r')
  81                                 key = '\n';
  82                         *buffer++ = key;
  83                         *buffer = '\0';
  84                         return -1;
  85                 }
  86                 if (escape_delay == 0 && key == '\e') {
  87                         escape_delay = ESCAPE_DELAY;
  88                         ped = escape_data;
  89                         f_escape = f;
  90                 }
  91                 if (escape_delay) {
  92                         *ped++ = key;
  93                         if (f_escape != f) {
  94                                 escape_delay = 2;
  95                                 continue;
  96                         }
  97                         if (ped - escape_data == 1) {
  98                                 /* \e */
  99                                 continue;
 100                         } else if (ped - escape_data == 2) {
 101                                 /* \e<something> */
 102                                 if (key != '[')
 103                                         escape_delay = 2;
 104                                 continue;
 105                         } else if (ped - escape_data == 3) {
 106                                 /* \e[<something> */
 107                                 int mapkey = 0;
 108                                 switch (key) {
 109                                 case 'A': /* \e[A, up arrow */
 110                                         mapkey = 16;
 111                                         break;
 112                                 case 'B': /* \e[B, down arrow */
 113                                         mapkey = 14;
 114                                         break;
 115                                 case 'C': /* \e[C, right arrow */
 116                                         mapkey = 6;
 117                                         break;
 118                                 case 'D': /* \e[D, left arrow */
 119                                         mapkey = 2;
 120                                         break;
 121                                 case '1': /* dropthrough */
 122                                 case '3': /* dropthrough */
 123                                 /* \e[<1,3,4>], may be home, del, end */
 124                                 case '4':
 125                                         mapkey = -1;
 126                                         break;
 127                                 }
 128                                 if (mapkey != -1) {
 129                                         if (mapkey > 0) {
 130                                                 escape_data[0] = mapkey;
 131                                                 escape_data[1] = '\0';
 132                                         }
 133                                         escape_delay = 2;
 134                                 }
 135                                 continue;
 136                         } else if (ped - escape_data == 4) {
 137                                 /* \e[<1,3,4><something> */
 138                                 int mapkey = 0;
 139                                 if (key == '~') {
 140                                         switch (escape_data[2]) {
 141                                         case '1': /* \e[1~, home */
 142                                                 mapkey = 1;
 143                                                 break;
 144                                         case '3': /* \e[3~, del */
 145                                                 mapkey = 4;
 146                                                 break;
 147                                         case '4': /* \e[4~, end */
 148                                                 mapkey = 5;
 149                                                 break;
 150                                         }
 151                                 }
 152                                 if (mapkey > 0) {
 153                                         escape_data[0] = mapkey;
 154                                         escape_data[1] = '\0';
 155                                 }
 156                                 escape_delay = 2;
 157                                 continue;
 158                         }
 159                 }
 160                 break;  /* A key to process */
 161         }
 162         return key;
 163 }
 164
 165 /*
 166  * kdb_read
 167  *
 168  *      This function reads a string of characters, terminated by
 169  *      a newline, or by reaching the end of the supplied buffer,
 170  *      from the current kernel debugger console device.
 171  * Parameters:
 172  *      buffer  - Address of character buffer to receive input characters.
 173  *      bufsize - size, in bytes, of the character buffer
 174  * Returns:
 175  *      Returns a pointer to the buffer containing the received
 176  *      character string.  This string will be terminated by a
 177  *      newline character.
 178  * Locking:
 179  *      No locks are required to be held upon entry to this
 180  *      function.  It is not reentrant - it relies on the fact
 181  *      that while kdb is running on only one "master debug" cpu.
 182  * Remarks:
 183  *
 184  * The buffer size must be >= 2.  A buffer size of 2 means that the caller only
 185  * wants a single key.
 186  *
 187  * An escape key could be the start of a vt100 control sequence such as \e[D
 188  * (left arrow) or it could be a character in its own right.  The standard
 189  * method for detecting the difference is to wait for 2 seconds to see if there
 190  * are any other characters.  kdb is complicated by the lack of a timer service
 191  * (interrupts are off), by multiple input sources and by the need to sometimes
 192  * return after just one key.  Escape sequence processing has to be done as
 193  * states in the polling loop.
 194  */
 195
 196 static char *kdb_read(char *buffer, size_t bufsize)
 197 {
 198         char *cp = buffer;
 199         char *bufend = buffer+bufsize-2;        /* Reserve space for newline
 200                                                  * and null byte */
 201         char *lastchar;
 202         char *p_tmp;
 203         char tmp;
 204         static char tmpbuffer[CMD_BUFLEN];
 205         int len = strlen(buffer);
 206         int len_tmp;
 207         int tab = 0;
 208         int count;
 209         int i;
 210         int diag, dtab_count;
 211         int key;
 212
 213
 214         diag = kdbgetintenv("DTABCOUNT", &dtab_count);
 215         if (diag)
 216                 dtab_count = 30;
 217
 218         if (len > 0) {
 219                 cp += len;
 220                 if (*(buffer+len-1) == '\n')
 221                         cp--;
 222         }
 223
 224         lastchar = cp;
 225         *cp = '\0';
 226         kdb_printf("%s", buffer);
 227 poll_again:
 228         key = kdb_read_get_key(buffer, bufsize);
 229         if (key == -1)
 230                 return buffer;
 231         if (key != 9)
 232                 tab = 0;
 233         switch (key) {
 234         case 8: /* backspace */
 235                 if (cp > buffer) {
 236                         if (cp < lastchar) {
 237                                 memcpy(tmpbuffer, cp, lastchar - cp);
 238                                 memcpy(cp-1, tmpbuffer, lastchar - cp);
 239                         }
 240                         *(--lastchar) = '\0';
 241                         --cp;
 242                         kdb_printf("\b%s \r", cp);
 243                         tmp = *cp;
 244                         *cp = '\0';
 245                         kdb_printf(kdb_prompt_str);
 246                         kdb_printf("%s", buffer);
 247                         *cp = tmp;
 248                 }
 249                 break;
 250         case 13: /* enter */
 251                 *lastchar++ = '\n';
 252                 *lastchar++ = '\0';
 253                 kdb_printf("\n");
 254                 return buffer;
 255         case 4: /* Del */
 256                 if (cp < lastchar) {
 257                         memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
 258                         memcpy(cp, tmpbuffer, lastchar - cp - 1);
 259                         *(--lastchar) = '\0';
 260                         kdb_printf("%s \r", cp);
 261                         tmp = *cp;
 262                         *cp = '\0';
 263                         kdb_printf(kdb_prompt_str);
 264                         kdb_printf("%s", buffer);
 265                         *cp = tmp;
 266                 }
 267                 break;
 268         case 1: /* Home */
 269                 if (cp > buffer) {
 270                         kdb_printf("\r");
 271                         kdb_printf(kdb_prompt_str);
 272                         cp = buffer;
 273                 }
 274                 break;
 275         case 5: /* End */
 276                 if (cp < lastchar) {
 277                         kdb_printf("%s", cp);
 278                         cp = lastchar;
 279                 }
 280                 break;
 281         case 2: /* Left */
 282                 if (cp > buffer) {
 283                         kdb_printf("\b");
 284                         --cp;
 285                 }
 286                 break;
 287         case 14: /* Down */
 288                 memset(tmpbuffer, ' ',
 289                        strlen(kdb_prompt_str) + (lastchar-buffer));
 290                 *(tmpbuffer+strlen(kdb_prompt_str) +
 291                   (lastchar-buffer)) = '\0';
 292                 kdb_printf("\r%s\r", tmpbuffer);
 293                 *lastchar = (char)key;
 294                 *(lastchar+1) = '\0';
 295                 return lastchar;
 296         case 6: /* Right */
 297                 if (cp < lastchar) {
 298                         kdb_printf("%c", *cp);
 299                         ++cp;
 300                 }
 301                 break;
 302         case 16: /* Up */
 303                 memset(tmpbuffer, ' ',
 304                        strlen(kdb_prompt_str) + (lastchar-buffer));
 305                 *(tmpbuffer+strlen(kdb_prompt_str) +
 306                   (lastchar-buffer)) = '\0';
 307                 kdb_printf("\r%s\r", tmpbuffer);
 308                 *lastchar = (char)key;
 309                 *(lastchar+1) = '\0';
 310                 return lastchar;
 311         case 9: /* Tab */
 312                 if (tab < 2)
 313                         ++tab;
 314                 p_tmp = buffer;
 315                 while (*p_tmp == ' ')
 316                         p_tmp++;
 317                 if (p_tmp > cp)
 318                         break;
 319                 memcpy(tmpbuffer, p_tmp, cp-p_tmp);
 320                 *(tmpbuffer + (cp-p_tmp)) = '\0';
 321                 p_tmp = strrchr(tmpbuffer, ' ');
 322                 if (p_tmp)
 323                         ++p_tmp;
 324                 else
 325                         p_tmp = tmpbuffer;
 326                 len = strlen(p_tmp);
 327                 count = kallsyms_symbol_complete(p_tmp,
 328                                                  sizeof(tmpbuffer) -
 329                                                  (p_tmp - tmpbuffer));
 330                 if (tab == 2 && count > 0) {
 331                         kdb_printf("\n%d symbols are found.", count);
 332                         if (count > dtab_count) {
 333                                 count = dtab_count;
 334                                 kdb_printf(" But only first %d symbols will"
 335                                            " be printed.\nYou can change the"
 336                                            " environment variable DTABCOUNT.",
 337                                            count);
 338                         }
 339                         kdb_printf("\n");
 340                         for (i = 0; i < count; i++) {
 341                                 if (kallsyms_symbol_next(p_tmp, i) < 0)
 342                                         break;
 343                                 kdb_printf("%s ", p_tmp);
 344                                 *(p_tmp + len) = '\0';
 345                         }
 346                         if (i >= dtab_count)
 347                                 kdb_printf("...");
 348                         kdb_printf("\n");
 349                         kdb_printf(kdb_prompt_str);
 350                         kdb_printf("%s", buffer);
 351                 } else if (tab != 2 && count > 0) {
 352                         len_tmp = strlen(p_tmp);
 353                         strncpy(p_tmp+len_tmp, cp, lastchar-cp+1);
 354                         len_tmp = strlen(p_tmp);
 355                         strncpy(cp, p_tmp+len, len_tmp-len + 1);
 356                         len = len_tmp - len;
 357                         kdb_printf("%s", cp);
 358                         cp += len;
 359                         lastchar += len;
 360                 }
 361                 kdb_nextline = 1; /* reset output line number */
 362                 break;
 363         default:
 364                 if (key >= 32 && lastchar < bufend) {
 365                         if (cp < lastchar) {
 366                                 memcpy(tmpbuffer, cp, lastchar - cp);
 367                                 memcpy(cp+1, tmpbuffer, lastchar - cp);
 368                                 *++lastchar = '\0';
 369                                 *cp = key;
 370                                 kdb_printf("%s\r", cp);
 371                                 ++cp;
 372                                 tmp = *cp;
 373                                 *cp = '\0';
 374                                 kdb_printf(kdb_prompt_str);
 375                                 kdb_printf("%s", buffer);
 376                                 *cp = tmp;
 377                         } else {
 378                                 *++lastchar = '\0';
 379                                 *cp++ = key;
 380                                 /* The kgdb transition check will hide
 381                                  * printed characters if we think that
 382                                  * kgdb is connecting, until the check
 383                                  * fails */
 384                                 if (!KDB_STATE(KGDB_TRANS))
 385                                         kgdb_transition_check(buffer);
 386                                 else
 387                                         kdb_printf("%c", key);
 388                         }
 389                         /* Special escape to kgdb */
 390                         if (lastchar - buffer >= 5 &&
 391                             strcmp(lastchar - 5, "$?#3f") == 0) {
 392                                 strcpy(buffer, "kgdb");
 393                                 KDB_STATE_SET(DOING_KGDB);
 394                                 return buffer;
 395                         }
 396                         if (lastchar - buffer >= 14 &&
 397                             strcmp(lastchar - 14, "$qSupported#37") == 0) {
 398                                 strcpy(buffer, "kgdb");
 399                                 KDB_STATE_SET(DOING_KGDB2);
 400                                 return buffer;
 401                         }
 402                 }
 403                 break;
 404         }
 405         goto poll_again;
 406 }
 407
 408 /*
 409  * kdb_getstr
 410  *
 411  *      Print the prompt string and read a command from the
 412  *      input device.
 413  *
 414  * Parameters:
 415  *      buffer  Address of buffer to receive command
 416  *      bufsize Size of buffer in bytes
 417  *      prompt  Pointer to string to use as prompt string
 418  * Returns:
 419  *      Pointer to command buffer.
 420  * Locking:
 421  *      None.
 422  * Remarks:
 423  *      For SMP kernels, the processor number will be
 424  *      substituted for %d, %x or %o in the prompt.
 425  */
 426
 427 char *kdb_getstr(char *buffer, size_t bufsize, char *prompt)
 428 {
 429         if (prompt && kdb_prompt_str != prompt)
 430                 strncpy(kdb_prompt_str, prompt, CMD_BUFLEN);
 431         kdb_printf(kdb_prompt_str);
 432         kdb_nextline = 1;       /* Prompt and input resets line number */
 433         return kdb_read(buffer, bufsize);
 434 }
 435
 436 /*
 437  * kdb_input_flush
 438  *
 439  *      Get rid of any buffered console input.
 440  *
 441  * Parameters:
 442  *      none
 443  * Returns:
 444  *      nothing
 445  * Locking:
 446  *      none
 447  * Remarks:
 448  *      Call this function whenever you want to flush input.  If there is any
 449  *      outstanding input, it ignores all characters until there has been no
 450  *      data for approximately 1ms.
 451  */
 452
 453 static void kdb_input_flush(void)
 454 {
 455         get_char_func *f;
 456         int res;
 457         int flush_delay = 1;
 458         while (flush_delay) {
 459                 flush_delay--;
 460 empty:
 461                 touch_nmi_watchdog();
 462                 for (f = &kdb_poll_funcs[0]; *f; ++f) {
 463                         res = (*f)();
 464                         if (res != -1) {
 465                                 flush_delay = 1;
 466                                 goto empty;
 467                         }
 468                 }
 469                 if (flush_delay)
 470                         mdelay(1);
 471         }
 472 }
 473
 474 /*
 475  * kdb_printf
 476  *
 477  *      Print a string to the output device(s).
 478  *
 479  * Parameters:
 480  *      printf-like format and optional args.
 481  * Returns:
 482  *      0
 483  * Locking:
 484  *      None.
 485  * Remarks:
 486  *      use 'kdbcons->write()' to avoid polluting 'log_buf' with
 487  *      kdb output.
 488  *
 489  *  If the user is doing a cmd args | grep srch
 490  *  then kdb_grepping_flag is set.
 491  *  In that case we need to accumulate full lines (ending in \n) before
 492  *  searching for the pattern.
 493  */
 494
 495 static char kdb_buffer[256];    /* A bit too big to go on stack */
 496 static char *next_avail = kdb_buffer;
 497 static int  size_avail;
 498 static int  suspend_grep;
 499
 500 /*
 501  * search arg1 to see if it contains arg2
 502  * (kdmain.c provides flags for ^pat and pat$)
 503  *
 504  * return 1 for found, 0 for not found
 505  */
 506 static int kdb_search_string(char *searched, char *searchfor)
 507 {
 508         char firstchar, *cp;
 509         int len1, len2;
 510
 511         /* not counting the newline at the end of "searched" */
 512         len1 = strlen(searched)-1;
 513         len2 = strlen(searchfor);
 514         if (len1 < len2)
 515                 return 0;
 516         if (kdb_grep_leading && kdb_grep_trailing && len1 != len2)
 517                 return 0;
 518         if (kdb_grep_leading) {
 519                 if (!strncmp(searched, searchfor, len2))
 520                         return 1;
 521         } else if (kdb_grep_trailing) {
 522                 if (!strncmp(searched+len1-len2, searchfor, len2))
 523                         return 1;
 524         } else {
 525                 firstchar = *searchfor;
 526                 cp = searched;
 527                 while ((cp = strchr(cp, firstchar))) {
 528                         if (!strncmp(cp, searchfor, len2))
 529                                 return 1;
 530                         cp++;
 531                 }
 532         }
 533         return 0;
 534 }
 535
 536 int kdb_printf(const char *fmt, ...)
 537 {
 538         va_list ap;
 539         int diag;
 540         int linecount;
 541         int logging, saved_loglevel = 0;
 542         int got_printf_lock = 0;
 543         int retlen = 0;
 544         int fnd, len;
 545         char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
 546         char *moreprompt = "more> ";
 547         struct console *c = console_drivers;
 548         static DEFINE_SPINLOCK(kdb_printf_lock);
 549         unsigned long uninitialized_var(flags);
 550
 551         preempt_disable();
 552         /* Serialize kdb_printf if multiple cpus try to write at once.
 553          * But if any cpu goes recursive in kdb, just print the output,
 554          * even if it is interleaved with any other text.
 555          */
 556         if (!KDB_STATE(PRINTF_LOCK)) {
 557                 KDB_STATE_SET(PRINTF_LOCK);
 558                 spin_lock_irqsave(&kdb_printf_lock, flags);
 559                 got_printf_lock = 1;
 560                 atomic_inc(&kdb_event);
 561         } else {
 562                 __acquire(kdb_printf_lock);
 563         }
 564
 565         diag = kdbgetintenv("LINES", &linecount);
 566         if (diag || linecount <= 1)
 567                 linecount = 24;
 568
 569         diag = kdbgetintenv("LOGGING", &logging);
 570         if (diag)
 571                 logging = 0;
 572
 573         if (!kdb_grepping_flag || suspend_grep) {
 574                 /* normally, every vsnprintf starts a new buffer */
 575                 next_avail = kdb_buffer;
 576                 size_avail = sizeof(kdb_buffer);
 577         }
 578         va_start(ap, fmt);
 579         vsnprintf(next_avail, size_avail, fmt, ap);
 580         va_end(ap);
 581
 582         /*
 583          * If kdb_parse() found that the command was cmd xxx | grep yyy
 584          * then kdb_grepping_flag is set, and kdb_grep_string contains yyy
 585          *
 586          * Accumulate the print data up to a newline before searching it.
 587          * (vsnprintf does null-terminate the string that it generates)
 588          */
 589
 590         /* skip the search if prints are temporarily unconditional */
 591         if (!suspend_grep && kdb_grepping_flag) {
 592                 cp = strchr(kdb_buffer, '\n');
 593                 if (!cp) {
 594                         /*
 595                          * Special cases that don't end with newlines
 596                          * but should be written without one:
 597                          *   The "[nn]kdb> " prompt should
 598                          *   appear at the front of the buffer.
 599                          *
 600                          *   The "[nn]more " prompt should also be
 601                          *     (MOREPROMPT -> moreprompt)
 602                          *   written *   but we print that ourselves,
 603                          *   we set the suspend_grep flag to make
 604                          *   it unconditional.
 605                          *
 606                          */
 607                         if (next_avail == kdb_buffer) {
 608                                 /*
 609                                  * these should occur after a newline,
 610                                  * so they will be at the front of the
 611                                  * buffer
 612                                  */
 613                                 cp2 = kdb_buffer;
 614                                 len = strlen(kdb_prompt_str);
 615                                 if (!strncmp(cp2, kdb_prompt_str, len)) {
 616                                         /*
 617                                          * We're about to start a new
 618                                          * command, so we can go back
 619                                          * to normal mode.
 620                                          */
 621                                         kdb_grepping_flag = 0;
 622                                         goto kdb_printit;
 623                                 }
 624                         }
 625                         /* no newline; don't search/write the buffer
 626                            until one is there */
 627                         len = strlen(kdb_buffer);
 628                         next_avail = kdb_buffer + len;
 629                         size_avail = sizeof(kdb_buffer) - len;
 630                         goto kdb_print_out;
 631                 }
 632
 633                 /*
 634                  * The newline is present; print through it or discard
 635                  * it, depending on the results of the search.
 636                  */
 637                 cp++;                /* to byte after the newline */
 638                 replaced_byte = *cp; /* remember what/where it was */
 639                 cphold = cp;
 640                 *cp = '\0';          /* end the string for our search */
 641
 642                 /*
 643                  * We now have a newline at the end of the string
 644                  * Only continue with this output if it contains the
 645                  * search string.
 646                  */
 647                 fnd = kdb_search_string(kdb_buffer, kdb_grep_string);
 648                 if (!fnd) {
 649                         /*
 650                          * At this point the complete line at the start
 651                          * of kdb_buffer can be discarded, as it does
 652                          * not contain what the user is looking for.
 653                          * Shift the buffer left.
 654                          */
 655                         *cphold = replaced_byte;
 656                         strcpy(kdb_buffer, cphold);
 657                         len = strlen(kdb_buffer);
 658                         next_avail = kdb_buffer + len;
 659                         size_avail = sizeof(kdb_buffer) - len;
 660                         goto kdb_print_out;
 661                 }
 662                 /*
 663                  * at this point the string is a full line and
 664                  * should be printed, up to the null.
 665                  */
 666         }
 667 kdb_printit:
 668
 669         /*
 670          * Write to all consoles.
 671          */
 672         retlen = strlen(kdb_buffer);
 673         if (!dbg_kdb_mode && kgdb_connected) {
 674                 gdbstub_msg_write(kdb_buffer, retlen);
 675         } else {
 676                 while (c) {
 677                         c->write(c, kdb_buffer, retlen);
 678                         touch_nmi_watchdog();
 679                         c = c->next;
 680                 }
 681         }
 682         if (logging) {
 683                 saved_loglevel = console_loglevel;
 684                 console_loglevel = 0;
 685                 printk(KERN_INFO "%s", kdb_buffer);
 686         }
 687
 688         if (KDB_STATE(PAGER) && strchr(kdb_buffer, '\n'))
 689                 kdb_nextline++;
 690
 691         /* check for having reached the LINES number of printed lines */
 692         if (kdb_nextline == linecount) {
 693                 char buf1[16] = "";
 694 #if defined(CONFIG_SMP)
 695                 char buf2[32];
 696 #endif
 697
 698                 /* Watch out for recursion here.  Any routine that calls
 699                  * kdb_printf will come back through here.  And kdb_read
 700                  * uses kdb_printf to echo on serial consoles ...
 701                  */
 702                 kdb_nextline = 1;       /* In case of recursion */
 703
 704                 /*
 705                  * Pause until cr.
 706                  */
 707                 moreprompt = kdbgetenv("MOREPROMPT");
 708                 if (moreprompt == NULL)
 709                         moreprompt = "more> ";
 710
 711 #if defined(CONFIG_SMP)
 712                 if (strchr(moreprompt, '%')) {
 713                         sprintf(buf2, moreprompt, get_cpu());
 714                         put_cpu();
 715                         moreprompt = buf2;
 716                 }
 717 #endif
 718
 719                 kdb_input_flush();
 720                 c = console_drivers;
 721
 722                 while (c) {
 723                         c->write(c, moreprompt, strlen(moreprompt));
 724                         touch_nmi_watchdog();
 725                         c = c->next;
 726                 }
 727
 728                 if (logging)
 729                         printk("%s", moreprompt);
 730
 731                 kdb_read(buf1, 2); /* '2' indicates to return
 732                                     * immediately after getting one key. */
 733                 kdb_nextline = 1;       /* Really set output line 1 */
 734
 735                 /* empty and reset the buffer: */
 736                 kdb_buffer[0] = '\0';
 737                 next_avail = kdb_buffer;
 738                 size_avail = sizeof(kdb_buffer);
 739                 if ((buf1[0] == 'q') || (buf1[0] == 'Q')) {
 740                         /* user hit q or Q */
 741                         KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
 742                         KDB_STATE_CLEAR(PAGER);
 743                         /* end of command output; back to normal mode */
 744                         kdb_grepping_flag = 0;
 745                         kdb_printf("\n");
 746                 } else if (buf1[0] == ' ') {
 747                         kdb_printf("\n");
 748                         suspend_grep = 1; /* for this recursion */
 749                 } else if (buf1[0] == '\n') {
 750                         kdb_nextline = linecount - 1;
 751                         kdb_printf("\r");
 752                         suspend_grep = 1; /* for this recursion */
 753                 } else if (buf1[0] && buf1[0] != '\n') {
 754                         /* user hit something other than enter */
 755                         suspend_grep = 1; /* for this recursion */
 756                         kdb_printf("\nOnly 'q' or 'Q' are processed at more "
 757                                    "prompt, input ignored\n");
 758                 } else if (kdb_grepping_flag) {
 759                         /* user hit enter */
 760                         suspend_grep = 1; /* for this recursion */
 761                         kdb_printf("\n");
 762                 }
 763                 kdb_input_flush();
 764         }
 765
 766         /*
 767          * For grep searches, shift the printed string left.
 768          *  replaced_byte contains the character that was overwritten with
 769          *  the terminating null, and cphold points to the null.
 770          * Then adjust the notion of available space in the buffer.
 771          */
 772         if (kdb_grepping_flag && !suspend_grep) {
 773                 *cphold = replaced_byte;
 774                 strcpy(kdb_buffer, cphold);
 775                 len = strlen(kdb_buffer);
 776                 next_avail = kdb_buffer + len;
 777                 size_avail = sizeof(kdb_buffer) - len;
 778         }
 779
 780 kdb_print_out:
 781         suspend_grep = 0; /* end of what may have been a recursive call */
 782         if (logging)
 783                 console_loglevel = saved_loglevel;
 784         if (KDB_STATE(PRINTF_LOCK) && got_printf_lock) {
 785                 got_printf_lock = 0;
 786                 spin_unlock_irqrestore(&kdb_printf_lock, flags);
 787                 KDB_STATE_CLEAR(PRINTF_LOCK);
 788                 atomic_dec(&kdb_event);
 789         } else {
 790                 __release(kdb_printf_lock);
 791         }
 792         preempt_enable();
 793         return retlen;
 794 }