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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/kdb.h>
  25 #include <linux/kallsyms.h>
  26 #include "kdb_private.h"
  27
  28 #define CMD_BUFLEN 256
  29 char kdb_prompt_str[CMD_BUFLEN];
  30
  31
  32 static void kgdb_transition_check(char *buffer)
  33 {
  34         int slen = strlen(buffer);
  35         if (strncmp(buffer, "$?#3f", slen) != 0 &&
  36             strncmp(buffer, "$qSupported#37", slen) != 0 &&
  37             strncmp(buffer, "+$qSupported#37", slen) != 0) {
  38                 KDB_STATE_SET(KGDB_TRANS);
  39                 kdb_printf("%s", buffer);
  40         }
  41 }
  42
  43 static int kdb_read_get_key(char *buffer, size_t bufsize)
  44 {
  45 #define ESCAPE_UDELAY 1000
  46 #define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
  47         char escape_data[5];    /* longest vt100 escape sequence is 4 bytes */
  48         char *ped = escape_data;
  49         int escape_delay = 0;
  50         get_char_func *f, *f_escape = NULL;
  51         int key;
  52
  53         for (f = &kdb_poll_funcs[0]; ; ++f) {
  54                 if (*f == NULL) {
  55                         /* Reset NMI watchdog once per poll loop */
  56                         touch_nmi_watchdog();
  57                         f = &kdb_poll_funcs[0];
  58                 }
  59                 if (escape_delay == 2) {
  60                         *ped = '\0';
  61                         ped = escape_data;
  62                         --escape_delay;
  63                 }
  64                 if (escape_delay == 1) {
  65                         key = *ped++;
  66                         if (!*ped)
  67                                 --escape_delay;
  68                         break;
  69                 }
  70                 key = (*f)();
  71                 if (key == -1) {
  72                         if (escape_delay) {
  73                                 udelay(ESCAPE_UDELAY);
  74                                 --escape_delay;
  75                         }
  76                         continue;
  77                 }
  78                 if (bufsize <= 2) {
  79                         if (key == '\r')
  80                                 key = '\n';
  81                         *buffer++ = key;
  82                         *buffer = '\0';
  83                         return -1;
  84                 }
  85                 if (escape_delay == 0 && key == '\e') {
  86                         escape_delay = ESCAPE_DELAY;
  87                         ped = escape_data;
  88                         f_escape = f;
  89                 }
  90                 if (escape_delay) {
  91                         *ped++ = key;
  92                         if (f_escape != f) {
  93                                 escape_delay = 2;
  94                                 continue;
  95                         }
  96                         if (ped - escape_data == 1) {
  97                                 /* \e */
  98                                 continue;
  99                         } else if (ped - escape_data == 2) {
 100                                 /* \e<something> */
 101                                 if (key != '[')
 102                                         escape_delay = 2;
 103                                 continue;
 104                         } else if (ped - escape_data == 3) {
 105                                 /* \e[<something> */
 106                                 int mapkey = 0;
 107                                 switch (key) {
 108                                 case 'A': /* \e[A, up arrow */
 109                                         mapkey = 16;
 110                                         break;
 111                                 case 'B': /* \e[B, down arrow */
 112                                         mapkey = 14;
 113                                         break;
 114                                 case 'C': /* \e[C, right arrow */
 115                                         mapkey = 6;
 116                                         break;
 117                                 case 'D': /* \e[D, left arrow */
 118                                         mapkey = 2;
 119                                         break;
 120                                 case '1': /* dropthrough */
 121                                 case '3': /* dropthrough */
 122                                 /* \e[<1,3,4>], may be home, del, end */
 123                                 case '4':
 124                                         mapkey = -1;
 125                                         break;
 126                                 }
 127                                 if (mapkey != -1) {
 128                                         if (mapkey > 0) {
 129                                                 escape_data[0] = mapkey;
 130                                                 escape_data[1] = '\0';
 131                                         }
 132                                         escape_delay = 2;
 133                                 }
 134                                 continue;
 135                         } else if (ped - escape_data == 4) {
 136                                 /* \e[<1,3,4><something> */
 137                                 int mapkey = 0;
 138                                 if (key == '~') {
 139                                         switch (escape_data[2]) {
 140                                         case '1': /* \e[1~, home */
 141                                                 mapkey = 1;
 142                                                 break;
 143                                         case '3': /* \e[3~, del */
 144                                                 mapkey = 4;
 145                                                 break;
 146                                         case '4': /* \e[4~, end */
 147                                                 mapkey = 5;
 148                                                 break;
 149                                         }
 150                                 }
 151                                 if (mapkey > 0) {
 152                                         escape_data[0] = mapkey;
 153                                         escape_data[1] = '\0';
 154                                 }
 155                                 escape_delay = 2;
 156                                 continue;
 157                         }
 158                 }
 159                 break;  /* A key to process */
 160         }
 161         return key;
 162 }
 163
 164 /*
 165  * kdb_read
 166  *
 167  *      This function reads a string of characters, terminated by
 168  *      a newline, or by reaching the end of the supplied buffer,
 169  *      from the current kernel debugger console device.
 170  * Parameters:
 171  *      buffer  - Address of character buffer to receive input characters.
 172  *      bufsize - size, in bytes, of the character buffer
 173  * Returns:
 174  *      Returns a pointer to the buffer containing the received
 175  *      character string.  This string will be terminated by a
 176  *      newline character.
 177  * Locking:
 178  *      No locks are required to be held upon entry to this
 179  *      function.  It is not reentrant - it relies on the fact
 180  *      that while kdb is running on only one "master debug" cpu.
 181  * Remarks:
 182  *
 183  * The buffer size must be >= 2.  A buffer size of 2 means that the caller only
 184  * wants a single key.
 185  *
 186  * An escape key could be the start of a vt100 control sequence such as \e[D
 187  * (left arrow) or it could be a character in its own right.  The standard
 188  * method for detecting the difference is to wait for 2 seconds to see if there
 189  * are any other characters.  kdb is complicated by the lack of a timer service
 190  * (interrupts are off), by multiple input sources and by the need to sometimes
 191  * return after just one key.  Escape sequence processing has to be done as
 192  * states in the polling loop.
 193  */
 194
 195 static char *kdb_read(char *buffer, size_t bufsize)
 196 {
 197         char *cp = buffer;
 198         char *bufend = buffer+bufsize-2;        /* Reserve space for newline
 199                                                  * and null byte */
 200         char *lastchar;
 201         char *p_tmp;
 202         char tmp;
 203         static char tmpbuffer[CMD_BUFLEN];
 204         int len = strlen(buffer);
 205         int len_tmp;
 206         int tab = 0;
 207         int count;
 208         int i;
 209         int diag, dtab_count;
 210         int key;
 211
 212
 213         diag = kdbgetintenv("DTABCOUNT", &dtab_count);
 214         if (diag)
 215                 dtab_count = 30;
 216
 217         if (len > 0) {
 218                 cp += len;
 219                 if (*(buffer+len-1) == '\n')
 220                         cp--;
 221         }
 222
 223         lastchar = cp;
 224         *cp = '\0';
 225         kdb_printf("%s", buffer);
 226 poll_again:
 227         key = kdb_read_get_key(buffer, bufsize);
 228         if (key == -1)
 229                 return buffer;
 230         if (key != 9)
 231                 tab = 0;
 232         switch (key) {
 233         case 8: /* backspace */
 234                 if (cp > buffer) {
 235                         if (cp < lastchar) {
 236                                 memcpy(tmpbuffer, cp, lastchar - cp);
 237                                 memcpy(cp-1, tmpbuffer, lastchar - cp);
 238                         }
 239                         *(--lastchar) = '\0';
 240                         --cp;
 241                         kdb_printf("\b%s \r", cp);
 242                         tmp = *cp;
 243                         *cp = '\0';
 244                         kdb_printf(kdb_prompt_str);
 245                         kdb_printf("%s", buffer);
 246                         *cp = tmp;
 247                 }
 248                 break;
 249         case 13: /* enter */
 250                 *lastchar++ = '\n';
 251                 *lastchar++ = '\0';
 252                 kdb_printf("\n");
 253                 return buffer;
 254         case 4: /* Del */
 255                 if (cp < lastchar) {
 256                         memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
 257                         memcpy(cp, tmpbuffer, lastchar - cp - 1);
 258                         *(--lastchar) = '\0';
 259                         kdb_printf("%s \r", cp);
 260                         tmp = *cp;
 261                         *cp = '\0';
 262                         kdb_printf(kdb_prompt_str);
 263                         kdb_printf("%s", buffer);
 264                         *cp = tmp;
 265                 }
 266                 break;
 267         case 1: /* Home */
 268                 if (cp > buffer) {
 269                         kdb_printf("\r");
 270                         kdb_printf(kdb_prompt_str);
 271                         cp = buffer;
 272                 }
 273                 break;
 274         case 5: /* End */
 275                 if (cp < lastchar) {
 276                         kdb_printf("%s", cp);
 277                         cp = lastchar;
 278                 }
 279                 break;
 280         case 2: /* Left */
 281                 if (cp > buffer) {
 282                         kdb_printf("\b");
 283                         --cp;
 284                 }
 285                 break;
 286         case 14: /* Down */
 287                 memset(tmpbuffer, ' ',
 288                        strlen(kdb_prompt_str) + (lastchar-buffer));
 289                 *(tmpbuffer+strlen(kdb_prompt_str) +
 290                   (lastchar-buffer)) = '\0';
 291                 kdb_printf("\r%s\r", tmpbuffer);
 292                 *lastchar = (char)key;
 293                 *(lastchar+1) = '\0';
 294                 return lastchar;
 295         case 6: /* Right */
 296                 if (cp < lastchar) {
 297                         kdb_printf("%c", *cp);
 298                         ++cp;
 299                 }
 300                 break;
 301         case 16: /* Up */
 302                 memset(tmpbuffer, ' ',
 303                        strlen(kdb_prompt_str) + (lastchar-buffer));
 304                 *(tmpbuffer+strlen(kdb_prompt_str) +
 305                   (lastchar-buffer)) = '\0';
 306                 kdb_printf("\r%s\r", tmpbuffer);
 307                 *lastchar = (char)key;
 308                 *(lastchar+1) = '\0';
 309                 return lastchar;
 310         case 9: /* Tab */
 311                 if (tab < 2)
 312                         ++tab;
 313                 p_tmp = buffer;
 314                 while (*p_tmp == ' ')
 315                         p_tmp++;
 316                 if (p_tmp > cp)
 317                         break;
 318                 memcpy(tmpbuffer, p_tmp, cp-p_tmp);
 319                 *(tmpbuffer + (cp-p_tmp)) = '\0';
 320                 p_tmp = strrchr(tmpbuffer, ' ');
 321                 if (p_tmp)
 322                         ++p_tmp;
 323                 else
 324                         p_tmp = tmpbuffer;
 325                 len = strlen(p_tmp);
 326                 count = kallsyms_symbol_complete(p_tmp,
 327                                                  sizeof(tmpbuffer) -
 328                                                  (p_tmp - tmpbuffer));
 329                 if (tab == 2 && count > 0) {
 330                         kdb_printf("\n%d symbols are found.", count);
 331                         if (count > dtab_count) {
 332                                 count = dtab_count;
 333                                 kdb_printf(" But only first %d symbols will"
 334                                            " be printed.\nYou can change the"
 335                                            " environment variable DTABCOUNT.",
 336                                            count);
 337                         }
 338                         kdb_printf("\n");
 339                         for (i = 0; i < count; i++) {
 340                                 if (kallsyms_symbol_next(p_tmp, i) < 0)
 341                                         break;
 342                                 kdb_printf("%s ", p_tmp);
 343                                 *(p_tmp + len) = '\0';
 344                         }
 345                         if (i >= dtab_count)
 346                                 kdb_printf("...");
 347                         kdb_printf("\n");
 348                         kdb_printf(kdb_prompt_str);
 349                         kdb_printf("%s", buffer);
 350                 } else if (tab != 2 && count > 0) {
 351                         len_tmp = strlen(p_tmp);
 352                         strncpy(p_tmp+len_tmp, cp, lastchar-cp+1);
 353                         len_tmp = strlen(p_tmp);
 354                         strncpy(cp, p_tmp+len, len_tmp-len + 1);
 355                         len = len_tmp - len;
 356                         kdb_printf("%s", cp);
 357                         cp += len;
 358                         lastchar += len;
 359                 }
 360                 kdb_nextline = 1; /* reset output line number */
 361                 break;
 362         default:
 363                 if (key >= 32 && lastchar < bufend) {
 364                         if (cp < lastchar) {
 365                                 memcpy(tmpbuffer, cp, lastchar - cp);
 366                                 memcpy(cp+1, tmpbuffer, lastchar - cp);
 367                                 *++lastchar = '\0';
 368                                 *cp = key;
 369                                 kdb_printf("%s\r", cp);
 370                                 ++cp;
 371                                 tmp = *cp;
 372                                 *cp = '\0';
 373                                 kdb_printf(kdb_prompt_str);
 374                                 kdb_printf("%s", buffer);
 375                                 *cp = tmp;
 376                         } else {
 377                                 *++lastchar = '\0';
 378                                 *cp++ = key;
 379                                 /* The kgdb transition check will hide
 380                                  * printed characters if we think that
 381                                  * kgdb is connecting, until the check
 382                                  * fails */
 383                                 if (!KDB_STATE(KGDB_TRANS))
 384                                         kgdb_transition_check(buffer);
 385                                 else
 386                                         kdb_printf("%c", key);
 387                         }
 388                         /* Special escape to kgdb */
 389                         if (lastchar - buffer >= 5 &&
 390                             strcmp(lastchar - 5, "$?#3f") == 0) {
 391                                 strcpy(buffer, "kgdb");
 392                                 KDB_STATE_SET(DOING_KGDB);
 393                                 return buffer;
 394                         }
 395                         if (lastchar - buffer >= 14 &&
 396                             strcmp(lastchar - 14, "$qSupported#37") == 0) {
 397                                 strcpy(buffer, "kgdb");
 398                                 KDB_STATE_SET(DOING_KGDB2);
 399                                 return buffer;
 400                         }
 401                 }
 402                 break;
 403         }
 404         goto poll_again;
 405 }
 406
 407 /*
 408  * kdb_getstr
 409  *
 410  *      Print the prompt string and read a command from the
 411  *      input device.
 412  *
 413  * Parameters:
 414  *      buffer  Address of buffer to receive command
 415  *      bufsize Size of buffer in bytes
 416  *      prompt  Pointer to string to use as prompt string
 417  * Returns:
 418  *      Pointer to command buffer.
 419  * Locking:
 420  *      None.
 421  * Remarks:
 422  *      For SMP kernels, the processor number will be
 423  *      substituted for %d, %x or %o in the prompt.
 424  */
 425
 426 char *kdb_getstr(char *buffer, size_t bufsize, char *prompt)
 427 {
 428         if (prompt && kdb_prompt_str != prompt)
 429                 strncpy(kdb_prompt_str, prompt, CMD_BUFLEN);
 430         kdb_printf(kdb_prompt_str);
 431         kdb_nextline = 1;       /* Prompt and input resets line number */
 432         return kdb_read(buffer, bufsize);
 433 }
 434
 435 /*
 436  * kdb_input_flush
 437  *
 438  *      Get rid of any buffered console input.
 439  *
 440  * Parameters:
 441  *      none
 442  * Returns:
 443  *      nothing
 444  * Locking:
 445  *      none
 446  * Remarks:
 447  *      Call this function whenever you want to flush input.  If there is any
 448  *      outstanding input, it ignores all characters until there has been no
 449  *      data for approximately 1ms.
 450  */
 451
 452 static void kdb_input_flush(void)
 453 {
 454         get_char_func *f;
 455         int res;
 456         int flush_delay = 1;
 457         while (flush_delay) {
 458                 flush_delay--;
 459 empty:
 460                 touch_nmi_watchdog();
 461                 for (f = &kdb_poll_funcs[0]; *f; ++f) {
 462                         res = (*f)();
 463                         if (res != -1) {
 464                                 flush_delay = 1;
 465                                 goto empty;
 466                         }
 467                 }
 468                 if (flush_delay)
 469                         mdelay(1);
 470         }
 471 }
 472
 473 /*
 474  * kdb_printf
 475  *
 476  *      Print a string to the output device(s).
 477  *
 478  * Parameters:
 479  *      printf-like format and optional args.
 480  * Returns:
 481  *      0
 482  * Locking:
 483  *      None.
 484  * Remarks:
 485  *      use 'kdbcons->write()' to avoid polluting 'log_buf' with
 486  *      kdb output.
 487  *
 488  *  If the user is doing a cmd args | grep srch
 489  *  then kdb_grepping_flag is set.
 490  *  In that case we need to accumulate full lines (ending in \n) before
 491  *  searching for the pattern.
 492  */
 493
 494 static char kdb_buffer[256];    /* A bit too big to go on stack */
 495 static char *next_avail = kdb_buffer;
 496 static int  size_avail;
 497 static int  suspend_grep;
 498
 499 /*
 500  * search arg1 to see if it contains arg2
 501  * (kdmain.c provides flags for ^pat and pat$)
 502  *
 503  * return 1 for found, 0 for not found
 504  */
 505 static int kdb_search_string(char *searched, char *searchfor)
 506 {
 507         char firstchar, *cp;
 508         int len1, len2;
 509
 510         /* not counting the newline at the end of "searched" */
 511         len1 = strlen(searched)-1;
 512         len2 = strlen(searchfor);
 513         if (len1 < len2)
 514                 return 0;
 515         if (kdb_grep_leading && kdb_grep_trailing && len1 != len2)
 516                 return 0;
 517         if (kdb_grep_leading) {
 518                 if (!strncmp(searched, searchfor, len2))
 519                         return 1;
 520         } else if (kdb_grep_trailing) {
 521                 if (!strncmp(searched+len1-len2, searchfor, len2))
 522                         return 1;
 523         } else {
 524                 firstchar = *searchfor;
 525                 cp = searched;
 526                 while ((cp = strchr(cp, firstchar))) {
 527                         if (!strncmp(cp, searchfor, len2))
 528                                 return 1;
 529                         cp++;
 530                 }
 531         }
 532         return 0;
 533 }
 534
 535 int kdb_printf(const char *fmt, ...)
 536 {
 537         va_list ap;
 538         int diag;
 539         int linecount;
 540         int logging, saved_loglevel = 0;
 541         int got_printf_lock = 0;
 542         int retlen = 0;
 543         int fnd, len;
 544         char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
 545         char *moreprompt = "more> ";
 546         struct console *c = console_drivers;
 547         static DEFINE_SPINLOCK(kdb_printf_lock);
 548         unsigned long uninitialized_var(flags);
 549
 550         preempt_disable();
 551         /* Serialize kdb_printf if multiple cpus try to write at once.
 552          * But if any cpu goes recursive in kdb, just print the output,
 553          * even if it is interleaved with any other text.
 554          */
 555         if (!KDB_STATE(PRINTF_LOCK)) {
 556                 KDB_STATE_SET(PRINTF_LOCK);
 557                 spin_lock_irqsave(&kdb_printf_lock, flags);
 558                 got_printf_lock = 1;
 559                 atomic_inc(&kdb_event);
 560         } else {
 561                 __acquire(kdb_printf_lock);
 562         }
 563
 564         diag = kdbgetintenv("LINES", &linecount);
 565         if (diag || linecount <= 1)
 566                 linecount = 24;
 567
 568         diag = kdbgetintenv("LOGGING", &logging);
 569         if (diag)
 570                 logging = 0;
 571
 572         if (!kdb_grepping_flag || suspend_grep) {
 573                 /* normally, every vsnprintf starts a new buffer */
 574                 next_avail = kdb_buffer;
 575                 size_avail = sizeof(kdb_buffer);
 576         }
 577         va_start(ap, fmt);
 578         vsnprintf(next_avail, size_avail, fmt, ap);
 579         va_end(ap);
 580
 581         /*
 582          * If kdb_parse() found that the command was cmd xxx | grep yyy
 583          * then kdb_grepping_flag is set, and kdb_grep_string contains yyy
 584          *
 585          * Accumulate the print data up to a newline before searching it.
 586          * (vsnprintf does null-terminate the string that it generates)
 587          */
 588
 589         /* skip the search if prints are temporarily unconditional */
 590         if (!suspend_grep && kdb_grepping_flag) {
 591                 cp = strchr(kdb_buffer, '\n');
 592                 if (!cp) {
 593                         /*
 594                          * Special cases that don't end with newlines
 595                          * but should be written without one:
 596                          *   The "[nn]kdb> " prompt should
 597                          *   appear at the front of the buffer.
 598                          *
 599                          *   The "[nn]more " prompt should also be
 600                          *     (MOREPROMPT -> moreprompt)
 601                          *   written *   but we print that ourselves,
 602                          *   we set the suspend_grep flag to make
 603                          *   it unconditional.
 604                          *
 605                          */
 606                         if (next_avail == kdb_buffer) {
 607                                 /*
 608                                  * these should occur after a newline,
 609                                  * so they will be at the front of the
 610                                  * buffer
 611                                  */
 612                                 cp2 = kdb_buffer;
 613                                 len = strlen(kdb_prompt_str);
 614                                 if (!strncmp(cp2, kdb_prompt_str, len)) {
 615                                         /*
 616                                          * We're about to start a new
 617                                          * command, so we can go back
 618                                          * to normal mode.
 619                                          */
 620                                         kdb_grepping_flag = 0;
 621                                         goto kdb_printit;
 622                                 }
 623                         }
 624                         /* no newline; don't search/write the buffer
 625                            until one is there */
 626                         len = strlen(kdb_buffer);
 627                         next_avail = kdb_buffer + len;
 628                         size_avail = sizeof(kdb_buffer) - len;
 629                         goto kdb_print_out;
 630                 }
 631
 632                 /*
 633                  * The newline is present; print through it or discard
 634                  * it, depending on the results of the search.
 635                  */
 636                 cp++;                /* to byte after the newline */
 637                 replaced_byte = *cp; /* remember what/where it was */
 638                 cphold = cp;
 639                 *cp = '\0';          /* end the string for our search */
 640
 641                 /*
 642                  * We now have a newline at the end of the string
 643                  * Only continue with this output if it contains the
 644                  * search string.
 645                  */
 646                 fnd = kdb_search_string(kdb_buffer, kdb_grep_string);
 647                 if (!fnd) {
 648                         /*
 649                          * At this point the complete line at the start
 650                          * of kdb_buffer can be discarded, as it does
 651                          * not contain what the user is looking for.
 652                          * Shift the buffer left.
 653                          */
 654                         *cphold = replaced_byte;
 655                         strcpy(kdb_buffer, cphold);
 656                         len = strlen(kdb_buffer);
 657                         next_avail = kdb_buffer + len;
 658                         size_avail = sizeof(kdb_buffer) - len;
 659                         goto kdb_print_out;
 660                 }
 661                 /*
 662                  * at this point the string is a full line and
 663                  * should be printed, up to the null.
 664                  */
 665         }
 666 kdb_printit:
 667
 668         /*
 669          * Write to all consoles.
 670          */
 671         retlen = strlen(kdb_buffer);
 672         while (c) {
 673                 c->write(c, kdb_buffer, retlen);
 674                 touch_nmi_watchdog();
 675                 c = c->next;
 676         }
 677         if (logging) {
 678                 saved_loglevel = console_loglevel;
 679                 console_loglevel = 0;
 680                 printk(KERN_INFO "%s", kdb_buffer);
 681         }
 682
 683         if (KDB_STATE(PAGER) && strchr(kdb_buffer, '\n'))
 684                 kdb_nextline++;
 685
 686         /* check for having reached the LINES number of printed lines */
 687         if (kdb_nextline == linecount) {
 688                 char buf1[16] = "";
 689 #if defined(CONFIG_SMP)
 690                 char buf2[32];
 691 #endif
 692
 693                 /* Watch out for recursion here.  Any routine that calls
 694                  * kdb_printf will come back through here.  And kdb_read
 695                  * uses kdb_printf to echo on serial consoles ...
 696                  */
 697                 kdb_nextline = 1;       /* In case of recursion */
 698
 699                 /*
 700                  * Pause until cr.
 701                  */
 702                 moreprompt = kdbgetenv("MOREPROMPT");
 703                 if (moreprompt == NULL)
 704                         moreprompt = "more> ";
 705
 706 #if defined(CONFIG_SMP)
 707                 if (strchr(moreprompt, '%')) {
 708                         sprintf(buf2, moreprompt, get_cpu());
 709                         put_cpu();
 710                         moreprompt = buf2;
 711                 }
 712 #endif
 713
 714                 kdb_input_flush();
 715                 c = console_drivers;
 716
 717                 while (c) {
 718                         c->write(c, moreprompt, strlen(moreprompt));
 719                         touch_nmi_watchdog();
 720                         c = c->next;
 721                 }
 722
 723                 if (logging)
 724                         printk("%s", moreprompt);
 725
 726                 kdb_read(buf1, 2); /* '2' indicates to return
 727                                     * immediately after getting one key. */
 728                 kdb_nextline = 1;       /* Really set output line 1 */
 729
 730                 /* empty and reset the buffer: */
 731                 kdb_buffer[0] = '\0';
 732                 next_avail = kdb_buffer;
 733                 size_avail = sizeof(kdb_buffer);
 734                 if ((buf1[0] == 'q') || (buf1[0] == 'Q')) {
 735                         /* user hit q or Q */
 736                         KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
 737                         KDB_STATE_CLEAR(PAGER);
 738                         /* end of command output; back to normal mode */
 739                         kdb_grepping_flag = 0;
 740                         kdb_printf("\n");
 741                 } else if (buf1[0] == ' ') {
 742                         kdb_printf("\n");
 743                         suspend_grep = 1; /* for this recursion */
 744                 } else if (buf1[0] == '\n') {
 745                         kdb_nextline = linecount - 1;
 746                         kdb_printf("\r");
 747                         suspend_grep = 1; /* for this recursion */
 748                 } else if (buf1[0] && buf1[0] != '\n') {
 749                         /* user hit something other than enter */
 750                         suspend_grep = 1; /* for this recursion */
 751                         kdb_printf("\nOnly 'q' or 'Q' are processed at more "
 752                                    "prompt, input ignored\n");
 753                 } else if (kdb_grepping_flag) {
 754                         /* user hit enter */
 755                         suspend_grep = 1; /* for this recursion */
 756                         kdb_printf("\n");
 757                 }
 758                 kdb_input_flush();
 759         }
 760
 761         /*
 762          * For grep searches, shift the printed string left.
 763          *  replaced_byte contains the character that was overwritten with
 764          *  the terminating null, and cphold points to the null.
 765          * Then adjust the notion of available space in the buffer.
 766          */
 767         if (kdb_grepping_flag && !suspend_grep) {
 768                 *cphold = replaced_byte;
 769                 strcpy(kdb_buffer, cphold);
 770                 len = strlen(kdb_buffer);
 771                 next_avail = kdb_buffer + len;
 772                 size_avail = sizeof(kdb_buffer) - len;
 773         }
 774
 775 kdb_print_out:
 776         suspend_grep = 0; /* end of what may have been a recursive call */
 777         if (logging)
 778                 console_loglevel = saved_loglevel;
 779         if (KDB_STATE(PRINTF_LOCK) && got_printf_lock) {
 780                 got_printf_lock = 0;
 781                 spin_unlock_irqrestore(&kdb_printf_lock, flags);
 782                 KDB_STATE_CLEAR(PRINTF_LOCK);
 783                 atomic_dec(&kdb_event);
 784         } else {
 785                 __release(kdb_printf_lock);
 786         }
 787         preempt_enable();
 788         return retlen;
 789 }