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 int kdb_printf_cpu = -1;
  34
  35 static int kgdb_transition_check(char *buffer)
  36 {
  37         if (buffer[0] != '+' && buffer[0] != '$') {
  38                 KDB_STATE_SET(KGDB_TRANS);
  39                 kdb_printf("%s", buffer);
  40         } else {
  41                 int slen = strlen(buffer);
  42                 if (slen > 3 && buffer[slen - 3] == '#') {
  43                         kdb_gdb_state_pass(buffer);
  44                         strcpy(buffer, "kgdb");
  45                         KDB_STATE_SET(DOING_KGDB);
  46                         return 1;
  47                 }
  48         }
  49         return 0;
  50 }
  51
  52 static int kdb_read_get_key(char *buffer, size_t bufsize)
  53 {
  54 #define ESCAPE_UDELAY 1000
  55 #define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
  56         char escape_data[5];    /* longest vt100 escape sequence is 4 bytes */
  57         char *ped = escape_data;
  58         int escape_delay = 0;
  59         get_char_func *f, *f_escape = NULL;
  60         int key;
  61
  62         for (f = &kdb_poll_funcs[0]; ; ++f) {
  63                 if (*f == NULL) {
  64                         /* Reset NMI watchdog once per poll loop */
  65                         touch_nmi_watchdog();
  66                         f = &kdb_poll_funcs[0];
  67                 }
  68                 if (escape_delay == 2) {
  69                         *ped = '\0';
  70                         ped = escape_data;
  71                         --escape_delay;
  72                 }
  73                 if (escape_delay == 1) {
  74                         key = *ped++;
  75                         if (!*ped)
  76                                 --escape_delay;
  77                         break;
  78                 }
  79                 key = (*f)();
  80                 if (key == -1) {
  81                         if (escape_delay) {
  82                                 udelay(ESCAPE_UDELAY);
  83                                 --escape_delay;
  84                         }
  85                         continue;
  86                 }
  87                 if (bufsize <= 2) {
  88                         if (key == '\r')
  89                                 key = '\n';
  90                         *buffer++ = key;
  91                         *buffer = '\0';
  92                         return -1;
  93                 }
  94                 if (escape_delay == 0 && key == '\e') {
  95                         escape_delay = ESCAPE_DELAY;
  96                         ped = escape_data;
  97                         f_escape = f;
  98                 }
  99                 if (escape_delay) {
 100                         *ped++ = key;
 101                         if (f_escape != f) {
 102                                 escape_delay = 2;
 103                                 continue;
 104                         }
 105                         if (ped - escape_data == 1) {
 106                                 /* \e */
 107                                 continue;
 108                         } else if (ped - escape_data == 2) {
 109                                 /* \e<something> */
 110                                 if (key != '[')
 111                                         escape_delay = 2;
 112                                 continue;
 113                         } else if (ped - escape_data == 3) {
 114                                 /* \e[<something> */
 115                                 int mapkey = 0;
 116                                 switch (key) {
 117                                 case 'A': /* \e[A, up arrow */
 118                                         mapkey = 16;
 119                                         break;
 120                                 case 'B': /* \e[B, down arrow */
 121                                         mapkey = 14;
 122                                         break;
 123                                 case 'C': /* \e[C, right arrow */
 124                                         mapkey = 6;
 125                                         break;
 126                                 case 'D': /* \e[D, left arrow */
 127                                         mapkey = 2;
 128                                         break;
 129                                 case '1': /* dropthrough */
 130                                 case '3': /* dropthrough */
 131                                 /* \e[<1,3,4>], may be home, del, end */
 132                                 case '4':
 133                                         mapkey = -1;
 134                                         break;
 135                                 }
 136                                 if (mapkey != -1) {
 137                                         if (mapkey > 0) {
 138                                                 escape_data[0] = mapkey;
 139                                                 escape_data[1] = '\0';
 140                                         }
 141                                         escape_delay = 2;
 142                                 }
 143                                 continue;
 144                         } else if (ped - escape_data == 4) {
 145                                 /* \e[<1,3,4><something> */
 146                                 int mapkey = 0;
 147                                 if (key == '~') {
 148                                         switch (escape_data[2]) {
 149                                         case '1': /* \e[1~, home */
 150                                                 mapkey = 1;
 151                                                 break;
 152                                         case '3': /* \e[3~, del */
 153                                                 mapkey = 4;
 154                                                 break;
 155                                         case '4': /* \e[4~, end */
 156                                                 mapkey = 5;
 157                                                 break;
 158                                         }
 159                                 }
 160                                 if (mapkey > 0) {
 161                                         escape_data[0] = mapkey;
 162                                         escape_data[1] = '\0';
 163                                 }
 164                                 escape_delay = 2;
 165                                 continue;
 166                         }
 167                 }
 168                 break;  /* A key to process */
 169         }
 170         return key;
 171 }
 172
 173 /*
 174  * kdb_read
 175  *
 176  *      This function reads a string of characters, terminated by
 177  *      a newline, or by reaching the end of the supplied buffer,
 178  *      from the current kernel debugger console device.
 179  * Parameters:
 180  *      buffer  - Address of character buffer to receive input characters.
 181  *      bufsize - size, in bytes, of the character buffer
 182  * Returns:
 183  *      Returns a pointer to the buffer containing the received
 184  *      character string.  This string will be terminated by a
 185  *      newline character.
 186  * Locking:
 187  *      No locks are required to be held upon entry to this
 188  *      function.  It is not reentrant - it relies on the fact
 189  *      that while kdb is running on only one "master debug" cpu.
 190  * Remarks:
 191  *
 192  * The buffer size must be >= 2.  A buffer size of 2 means that the caller only
 193  * wants a single key.
 194  *
 195  * An escape key could be the start of a vt100 control sequence such as \e[D
 196  * (left arrow) or it could be a character in its own right.  The standard
 197  * method for detecting the difference is to wait for 2 seconds to see if there
 198  * are any other characters.  kdb is complicated by the lack of a timer service
 199  * (interrupts are off), by multiple input sources and by the need to sometimes
 200  * return after just one key.  Escape sequence processing has to be done as
 201  * states in the polling loop.
 202  */
 203
 204 static char *kdb_read(char *buffer, size_t bufsize)
 205 {
 206         char *cp = buffer;
 207         char *bufend = buffer+bufsize-2;        /* Reserve space for newline
 208                                                  * and null byte */
 209         char *lastchar;
 210         char *p_tmp;
 211         char tmp;
 212         static char tmpbuffer[CMD_BUFLEN];
 213         int len = strlen(buffer);
 214         int len_tmp;
 215         int tab = 0;
 216         int count;
 217         int i;
 218         int diag, dtab_count;
 219         int key, buf_size, ret;
 220
 221
 222         diag = kdbgetintenv("DTABCOUNT", &dtab_count);
 223         if (diag)
 224                 dtab_count = 30;
 225
 226         if (len > 0) {
 227                 cp += len;
 228                 if (*(buffer+len-1) == '\n')
 229                         cp--;
 230         }
 231
 232         lastchar = cp;
 233         *cp = '\0';
 234         kdb_printf("%s", buffer);
 235 poll_again:
 236         key = kdb_read_get_key(buffer, bufsize);
 237         if (key == -1)
 238                 return buffer;
 239         if (key != 9)
 240                 tab = 0;
 241         switch (key) {
 242         case 8: /* backspace */
 243                 if (cp > buffer) {
 244                         if (cp < lastchar) {
 245                                 memcpy(tmpbuffer, cp, lastchar - cp);
 246                                 memcpy(cp-1, tmpbuffer, lastchar - cp);
 247                         }
 248                         *(--lastchar) = '\0';
 249                         --cp;
 250                         kdb_printf("\b%s \r", cp);
 251                         tmp = *cp;
 252                         *cp = '\0';
 253                         kdb_printf(kdb_prompt_str);
 254                         kdb_printf("%s", buffer);
 255                         *cp = tmp;
 256                 }
 257                 break;
 258         case 13: /* enter */
 259                 *lastchar++ = '\n';
 260                 *lastchar++ = '\0';
 261                 if (!KDB_STATE(KGDB_TRANS)) {
 262                         KDB_STATE_SET(KGDB_TRANS);
 263                         kdb_printf("%s", buffer);
 264                 }
 265                 kdb_printf("\n");
 266                 return buffer;
 267         case 4: /* Del */
 268                 if (cp < lastchar) {
 269                         memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
 270                         memcpy(cp, tmpbuffer, lastchar - cp - 1);
 271                         *(--lastchar) = '\0';
 272                         kdb_printf("%s \r", cp);
 273                         tmp = *cp;
 274                         *cp = '\0';
 275                         kdb_printf(kdb_prompt_str);
 276                         kdb_printf("%s", buffer);
 277                         *cp = tmp;
 278                 }
 279                 break;
 280         case 1: /* Home */
 281                 if (cp > buffer) {
 282                         kdb_printf("\r");
 283                         kdb_printf(kdb_prompt_str);
 284                         cp = buffer;
 285                 }
 286                 break;
 287         case 5: /* End */
 288                 if (cp < lastchar) {
 289                         kdb_printf("%s", cp);
 290                         cp = lastchar;
 291                 }
 292                 break;
 293         case 2: /* Left */
 294                 if (cp > buffer) {
 295                         kdb_printf("\b");
 296                         --cp;
 297                 }
 298                 break;
 299         case 14: /* Down */
 300                 memset(tmpbuffer, ' ',
 301                        strlen(kdb_prompt_str) + (lastchar-buffer));
 302                 *(tmpbuffer+strlen(kdb_prompt_str) +
 303                   (lastchar-buffer)) = '\0';
 304                 kdb_printf("\r%s\r", tmpbuffer);
 305                 *lastchar = (char)key;
 306                 *(lastchar+1) = '\0';
 307                 return lastchar;
 308         case 6: /* Right */
 309                 if (cp < lastchar) {
 310                         kdb_printf("%c", *cp);
 311                         ++cp;
 312                 }
 313                 break;
 314         case 16: /* Up */
 315                 memset(tmpbuffer, ' ',
 316                        strlen(kdb_prompt_str) + (lastchar-buffer));
 317                 *(tmpbuffer+strlen(kdb_prompt_str) +
 318                   (lastchar-buffer)) = '\0';
 319                 kdb_printf("\r%s\r", tmpbuffer);
 320                 *lastchar = (char)key;
 321                 *(lastchar+1) = '\0';
 322                 return lastchar;
 323         case 9: /* Tab */
 324                 if (tab < 2)
 325                         ++tab;
 326                 p_tmp = buffer;
 327                 while (*p_tmp == ' ')
 328                         p_tmp++;
 329                 if (p_tmp > cp)
 330                         break;
 331                 memcpy(tmpbuffer, p_tmp, cp-p_tmp);
 332                 *(tmpbuffer + (cp-p_tmp)) = '\0';
 333                 p_tmp = strrchr(tmpbuffer, ' ');
 334                 if (p_tmp)
 335                         ++p_tmp;
 336                 else
 337                         p_tmp = tmpbuffer;
 338                 len = strlen(p_tmp);
 339                 buf_size = sizeof(tmpbuffer) - (p_tmp - tmpbuffer);
 340                 count = kallsyms_symbol_complete(p_tmp, buf_size);
 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                                 ret = kallsyms_symbol_next(p_tmp, i, buf_size);
 353                                 if (WARN_ON(!ret))
 354                                         break;
 355                                 if (ret != -E2BIG)
 356                                         kdb_printf("%s ", p_tmp);
 357                                 else
 358                                         kdb_printf("%s... ", p_tmp);
 359                                 *(p_tmp + len) = '\0';
 360                         }
 361                         if (i >= dtab_count)
 362                                 kdb_printf("...");
 363                         kdb_printf("\n");
 364                         kdb_printf(kdb_prompt_str);
 365                         kdb_printf("%s", buffer);
 366                 } else if (tab != 2 && count > 0) {
 367                         len_tmp = strlen(p_tmp);
 368                         strncpy(p_tmp+len_tmp, cp, lastchar-cp+1);
 369                         len_tmp = strlen(p_tmp);
 370                         strncpy(cp, p_tmp+len, len_tmp-len + 1);
 371                         len = len_tmp - len;
 372                         kdb_printf("%s", cp);
 373                         cp += len;
 374                         lastchar += len;
 375                 }
 376                 kdb_nextline = 1; /* reset output line number */
 377                 break;
 378         default:
 379                 if (key >= 32 && lastchar < bufend) {
 380                         if (cp < lastchar) {
 381                                 memcpy(tmpbuffer, cp, lastchar - cp);
 382                                 memcpy(cp+1, tmpbuffer, lastchar - cp);
 383                                 *++lastchar = '\0';
 384                                 *cp = key;
 385                                 kdb_printf("%s\r", cp);
 386                                 ++cp;
 387                                 tmp = *cp;
 388                                 *cp = '\0';
 389                                 kdb_printf(kdb_prompt_str);
 390                                 kdb_printf("%s", buffer);
 391                                 *cp = tmp;
 392                         } else {
 393                                 *++lastchar = '\0';
 394                                 *cp++ = key;
 395                                 /* The kgdb transition check will hide
 396                                  * printed characters if we think that
 397                                  * kgdb is connecting, until the check
 398                                  * fails */
 399                                 if (!KDB_STATE(KGDB_TRANS)) {
 400                                         if (kgdb_transition_check(buffer))
 401                                                 return buffer;
 402                                 } else {
 403                                         kdb_printf("%c", key);
 404                                 }
 405                         }
 406                         /* Special escape to kgdb */
 407                         if (lastchar - buffer >= 5 &&
 408                             strcmp(lastchar - 5, "$?#3f") == 0) {
 409                                 kdb_gdb_state_pass(lastchar - 5);
 410                                 strcpy(buffer, "kgdb");
 411                                 KDB_STATE_SET(DOING_KGDB);
 412                                 return buffer;
 413                         }
 414                         if (lastchar - buffer >= 11 &&
 415                             strcmp(lastchar - 11, "$qSupported") == 0) {
 416                                 kdb_gdb_state_pass(lastchar - 11);
 417                                 strcpy(buffer, "kgdb");
 418                                 KDB_STATE_SET(DOING_KGDB);
 419                                 return buffer;
 420                         }
 421                 }
 422                 break;
 423         }
 424         goto poll_again;
 425 }
 426
 427 /*
 428  * kdb_getstr
 429  *
 430  *      Print the prompt string and read a command from the
 431  *      input device.
 432  *
 433  * Parameters:
 434  *      buffer  Address of buffer to receive command
 435  *      bufsize Size of buffer in bytes
 436  *      prompt  Pointer to string to use as prompt string
 437  * Returns:
 438  *      Pointer to command buffer.
 439  * Locking:
 440  *      None.
 441  * Remarks:
 442  *      For SMP kernels, the processor number will be
 443  *      substituted for %d, %x or %o in the prompt.
 444  */
 445
 446 char *kdb_getstr(char *buffer, size_t bufsize, const char *prompt)
 447 {
 448         if (prompt && kdb_prompt_str != prompt)
 449                 strncpy(kdb_prompt_str, prompt, CMD_BUFLEN);
 450         kdb_printf(kdb_prompt_str);
 451         kdb_nextline = 1;       /* Prompt and input resets line number */
 452         return kdb_read(buffer, bufsize);
 453 }
 454
 455 /*
 456  * kdb_input_flush
 457  *
 458  *      Get rid of any buffered console input.
 459  *
 460  * Parameters:
 461  *      none
 462  * Returns:
 463  *      nothing
 464  * Locking:
 465  *      none
 466  * Remarks:
 467  *      Call this function whenever you want to flush input.  If there is any
 468  *      outstanding input, it ignores all characters until there has been no
 469  *      data for approximately 1ms.
 470  */
 471
 472 static void kdb_input_flush(void)
 473 {
 474         get_char_func *f;
 475         int res;
 476         int flush_delay = 1;
 477         while (flush_delay) {
 478                 flush_delay--;
 479 empty:
 480                 touch_nmi_watchdog();
 481                 for (f = &kdb_poll_funcs[0]; *f; ++f) {
 482                         res = (*f)();
 483                         if (res != -1) {
 484                                 flush_delay = 1;
 485                                 goto empty;
 486                         }
 487                 }
 488                 if (flush_delay)
 489                         mdelay(1);
 490         }
 491 }
 492
 493 /*
 494  * kdb_printf
 495  *
 496  *      Print a string to the output device(s).
 497  *
 498  * Parameters:
 499  *      printf-like format and optional args.
 500  * Returns:
 501  *      0
 502  * Locking:
 503  *      None.
 504  * Remarks:
 505  *      use 'kdbcons->write()' to avoid polluting 'log_buf' with
 506  *      kdb output.
 507  *
 508  *  If the user is doing a cmd args | grep srch
 509  *  then kdb_grepping_flag is set.
 510  *  In that case we need to accumulate full lines (ending in \n) before
 511  *  searching for the pattern.
 512  */
 513
 514 static char kdb_buffer[256];    /* A bit too big to go on stack */
 515 static char *next_avail = kdb_buffer;
 516 static int  size_avail;
 517 static int  suspend_grep;
 518
 519 /*
 520  * search arg1 to see if it contains arg2
 521  * (kdmain.c provides flags for ^pat and pat$)
 522  *
 523  * return 1 for found, 0 for not found
 524  */
 525 static int kdb_search_string(char *searched, char *searchfor)
 526 {
 527         char firstchar, *cp;
 528         int len1, len2;
 529
 530         /* not counting the newline at the end of "searched" */
 531         len1 = strlen(searched)-1;
 532         len2 = strlen(searchfor);
 533         if (len1 < len2)
 534                 return 0;
 535         if (kdb_grep_leading && kdb_grep_trailing && len1 != len2)
 536                 return 0;
 537         if (kdb_grep_leading) {
 538                 if (!strncmp(searched, searchfor, len2))
 539                         return 1;
 540         } else if (kdb_grep_trailing) {
 541                 if (!strncmp(searched+len1-len2, searchfor, len2))
 542                         return 1;
 543         } else {
 544                 firstchar = *searchfor;
 545                 cp = searched;
 546                 while ((cp = strchr(cp, firstchar))) {
 547                         if (!strncmp(cp, searchfor, len2))
 548                                 return 1;
 549                         cp++;
 550                 }
 551         }
 552         return 0;
 553 }
 554
 555 int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
 556 {
 557         int diag;
 558         int linecount;
 559         int colcount;
 560         int logging, saved_loglevel = 0;
 561         int retlen = 0;
 562         int fnd, len;
 563         int this_cpu, old_cpu;
 564         char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
 565         char *moreprompt = "more> ";
 566         struct console *c = console_drivers;
 567         unsigned long uninitialized_var(flags);
 568
 569         /* Serialize kdb_printf if multiple cpus try to write at once.
 570          * But if any cpu goes recursive in kdb, just print the output,
 571          * even if it is interleaved with any other text.
 572          */
 573         local_irq_save(flags);
 574         this_cpu = smp_processor_id();
 575         for (;;) {
 576                 old_cpu = cmpxchg(&kdb_printf_cpu, -1, this_cpu);
 577                 if (old_cpu == -1 || old_cpu == this_cpu)
 578                         break;
 579
 580                 cpu_relax();
 581         }
 582
 583         diag = kdbgetintenv("LINES", &linecount);
 584         if (diag || linecount <= 1)
 585                 linecount = 24;
 586
 587         diag = kdbgetintenv("COLUMNS", &colcount);
 588         if (diag || colcount <= 1)
 589                 colcount = 80;
 590
 591         diag = kdbgetintenv("LOGGING", &logging);
 592         if (diag)
 593                 logging = 0;
 594
 595         if (!kdb_grepping_flag || suspend_grep) {
 596                 /* normally, every vsnprintf starts a new buffer */
 597                 next_avail = kdb_buffer;
 598                 size_avail = sizeof(kdb_buffer);
 599         }
 600         vsnprintf(next_avail, size_avail, fmt, ap);
 601
 602         /*
 603          * If kdb_parse() found that the command was cmd xxx | grep yyy
 604          * then kdb_grepping_flag is set, and kdb_grep_string contains yyy
 605          *
 606          * Accumulate the print data up to a newline before searching it.
 607          * (vsnprintf does null-terminate the string that it generates)
 608          */
 609
 610         /* skip the search if prints are temporarily unconditional */
 611         if (!suspend_grep && kdb_grepping_flag) {
 612                 cp = strchr(kdb_buffer, '\n');
 613                 if (!cp) {
 614                         /*
 615                          * Special cases that don't end with newlines
 616                          * but should be written without one:
 617                          *   The "[nn]kdb> " prompt should
 618                          *   appear at the front of the buffer.
 619                          *
 620                          *   The "[nn]more " prompt should also be
 621                          *     (MOREPROMPT -> moreprompt)
 622                          *   written *   but we print that ourselves,
 623                          *   we set the suspend_grep flag to make
 624                          *   it unconditional.
 625                          *
 626                          */
 627                         if (next_avail == kdb_buffer) {
 628                                 /*
 629                                  * these should occur after a newline,
 630                                  * so they will be at the front of the
 631                                  * buffer
 632                                  */
 633                                 cp2 = kdb_buffer;
 634                                 len = strlen(kdb_prompt_str);
 635                                 if (!strncmp(cp2, kdb_prompt_str, len)) {
 636                                         /*
 637                                          * We're about to start a new
 638                                          * command, so we can go back
 639                                          * to normal mode.
 640                                          */
 641                                         kdb_grepping_flag = 0;
 642                                         goto kdb_printit;
 643                                 }
 644                         }
 645                         /* no newline; don't search/write the buffer
 646                            until one is there */
 647                         len = strlen(kdb_buffer);
 648                         next_avail = kdb_buffer + len;
 649                         size_avail = sizeof(kdb_buffer) - len;
 650                         goto kdb_print_out;
 651                 }
 652
 653                 /*
 654                  * The newline is present; print through it or discard
 655                  * it, depending on the results of the search.
 656                  */
 657                 cp++;                /* to byte after the newline */
 658                 replaced_byte = *cp; /* remember what/where it was */
 659                 cphold = cp;
 660                 *cp = '\0';          /* end the string for our search */
 661
 662                 /*
 663                  * We now have a newline at the end of the string
 664                  * Only continue with this output if it contains the
 665                  * search string.
 666                  */
 667                 fnd = kdb_search_string(kdb_buffer, kdb_grep_string);
 668                 if (!fnd) {
 669                         /*
 670                          * At this point the complete line at the start
 671                          * of kdb_buffer can be discarded, as it does
 672                          * not contain what the user is looking for.
 673                          * Shift the buffer left.
 674                          */
 675                         *cphold = replaced_byte;
 676                         strcpy(kdb_buffer, cphold);
 677                         len = strlen(kdb_buffer);
 678                         next_avail = kdb_buffer + len;
 679                         size_avail = sizeof(kdb_buffer) - len;
 680                         goto kdb_print_out;
 681                 }
 682                 if (kdb_grepping_flag >= KDB_GREPPING_FLAG_SEARCH) {
 683                         /*
 684                          * This was a interactive search (using '/' at more
 685                          * prompt) and it has completed. Replace the \0 with
 686                          * its original value to ensure multi-line strings
 687                          * are handled properly, and return to normal mode.
 688                          */
 689                         *cphold = replaced_byte;
 690                         kdb_grepping_flag = 0;
 691                 }
 692                 /*
 693                  * at this point the string is a full line and
 694                  * should be printed, up to the null.
 695                  */
 696         }
 697 kdb_printit:
 698
 699         /*
 700          * Write to all consoles.
 701          */
 702         retlen = strlen(kdb_buffer);
 703         cp = (char *) printk_skip_headers(kdb_buffer);
 704         if (!dbg_kdb_mode && kgdb_connected) {
 705                 gdbstub_msg_write(cp, retlen - (cp - kdb_buffer));
 706         } else {
 707                 if (dbg_io_ops && !dbg_io_ops->is_console) {
 708                         len = retlen - (cp - kdb_buffer);
 709                         cp2 = cp;
 710                         while (len--) {
 711                                 dbg_io_ops->write_char(*cp2);
 712                                 cp2++;
 713                         }
 714                 }
 715                 while (c) {
 716                         c->write(c, cp, retlen - (cp - kdb_buffer));
 717                         touch_nmi_watchdog();
 718                         c = c->next;
 719                 }
 720         }
 721         if (logging) {
 722                 saved_loglevel = console_loglevel;
 723                 console_loglevel = CONSOLE_LOGLEVEL_SILENT;
 724                 if (printk_get_level(kdb_buffer) || src == KDB_MSGSRC_PRINTK)
 725                         printk("%s", kdb_buffer);
 726                 else
 727                         pr_info("%s", kdb_buffer);
 728         }
 729
 730         if (KDB_STATE(PAGER)) {
 731                 /*
 732                  * Check printed string to decide how to bump the
 733                  * kdb_nextline to control when the more prompt should
 734                  * show up.
 735                  */
 736                 int got = 0;
 737                 len = retlen;
 738                 while (len--) {
 739                         if (kdb_buffer[len] == '\n') {
 740                                 kdb_nextline++;
 741                                 got = 0;
 742                         } else if (kdb_buffer[len] == '\r') {
 743                                 got = 0;
 744                         } else {
 745                                 got++;
 746                         }
 747                 }
 748                 kdb_nextline += got / (colcount + 1);
 749         }
 750
 751         /* check for having reached the LINES number of printed lines */
 752         if (kdb_nextline >= linecount) {
 753                 char buf1[16] = "";
 754
 755                 /* Watch out for recursion here.  Any routine that calls
 756                  * kdb_printf will come back through here.  And kdb_read
 757                  * uses kdb_printf to echo on serial consoles ...
 758                  */
 759                 kdb_nextline = 1;       /* In case of recursion */
 760
 761                 /*
 762                  * Pause until cr.
 763                  */
 764                 moreprompt = kdbgetenv("MOREPROMPT");
 765                 if (moreprompt == NULL)
 766                         moreprompt = "more> ";
 767
 768                 kdb_input_flush();
 769                 c = console_drivers;
 770
 771                 if (dbg_io_ops && !dbg_io_ops->is_console) {
 772                         len = strlen(moreprompt);
 773                         cp = moreprompt;
 774                         while (len--) {
 775                                 dbg_io_ops->write_char(*cp);
 776                                 cp++;
 777                         }
 778                 }
 779                 while (c) {
 780                         c->write(c, moreprompt, strlen(moreprompt));
 781                         touch_nmi_watchdog();
 782                         c = c->next;
 783                 }
 784
 785                 if (logging)
 786                         printk("%s", moreprompt);
 787
 788                 kdb_read(buf1, 2); /* '2' indicates to return
 789                                     * immediately after getting one key. */
 790                 kdb_nextline = 1;       /* Really set output line 1 */
 791
 792                 /* empty and reset the buffer: */
 793                 kdb_buffer[0] = '\0';
 794                 next_avail = kdb_buffer;
 795                 size_avail = sizeof(kdb_buffer);
 796                 if ((buf1[0] == 'q') || (buf1[0] == 'Q')) {
 797                         /* user hit q or Q */
 798                         KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
 799                         KDB_STATE_CLEAR(PAGER);
 800                         /* end of command output; back to normal mode */
 801                         kdb_grepping_flag = 0;
 802                         kdb_printf("\n");
 803                 } else if (buf1[0] == ' ') {
 804                         kdb_printf("\r");
 805                         suspend_grep = 1; /* for this recursion */
 806                 } else if (buf1[0] == '\n') {
 807                         kdb_nextline = linecount - 1;
 808                         kdb_printf("\r");
 809                         suspend_grep = 1; /* for this recursion */
 810                 } else if (buf1[0] == '/' && !kdb_grepping_flag) {
 811                         kdb_printf("\r");
 812                         kdb_getstr(kdb_grep_string, KDB_GREP_STRLEN,
 813                                    kdbgetenv("SEARCHPROMPT") ?: "search> ");
 814                         *strchrnul(kdb_grep_string, '\n') = '\0';
 815                         kdb_grepping_flag += KDB_GREPPING_FLAG_SEARCH;
 816                         suspend_grep = 1; /* for this recursion */
 817                 } else if (buf1[0] && buf1[0] != '\n') {
 818                         /* user hit something other than enter */
 819                         suspend_grep = 1; /* for this recursion */
 820                         if (buf1[0] != '/')
 821                                 kdb_printf(
 822                                     "\nOnly 'q', 'Q' or '/' are processed at "
 823                                     "more prompt, input ignored\n");
 824                         else
 825                                 kdb_printf("\n'/' cannot be used during | "
 826                                            "grep filtering, input ignored\n");
 827                 } else if (kdb_grepping_flag) {
 828                         /* user hit enter */
 829                         suspend_grep = 1; /* for this recursion */
 830                         kdb_printf("\n");
 831                 }
 832                 kdb_input_flush();
 833         }
 834
 835         /*
 836          * For grep searches, shift the printed string left.
 837          *  replaced_byte contains the character that was overwritten with
 838          *  the terminating null, and cphold points to the null.
 839          * Then adjust the notion of available space in the buffer.
 840          */
 841         if (kdb_grepping_flag && !suspend_grep) {
 842                 *cphold = replaced_byte;
 843                 strcpy(kdb_buffer, cphold);
 844                 len = strlen(kdb_buffer);
 845                 next_avail = kdb_buffer + len;
 846                 size_avail = sizeof(kdb_buffer) - len;
 847         }
 848
 849 kdb_print_out:
 850         suspend_grep = 0; /* end of what may have been a recursive call */
 851         if (logging)
 852                 console_loglevel = saved_loglevel;
 853         /* kdb_printf_cpu locked the code above. */
 854         smp_store_release(&kdb_printf_cpu, old_cpu);
 855         local_irq_restore(flags);
 856         return retlen;
 857 }
 858
 859 int kdb_printf(const char *fmt, ...)
 860 {
 861         va_list ap;
 862         int r;
 863
 864         va_start(ap, fmt);
 865         r = vkdb_printf(KDB_MSGSRC_INTERNAL, fmt, ap);
 866         va_end(ap);
 867
 868         return r;
 869 }
 870 EXPORT_SYMBOL_GPL(kdb_printf);