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 /**
  53  * kdb_handle_escape() - validity check on an accumulated escape sequence.
  54  * @buf:        Accumulated escape characters to be examined. Note that buf
  55  *              is not a string, it is an array of characters and need not be
  56  *              nil terminated.
  57  * @sz:         Number of accumulated escape characters.
  58  *
  59  * Return: -1 if the escape sequence is unwanted, 0 if it is incomplete,
  60  * otherwise it returns a mapped key value to pass to the upper layers.
  61  */
  62 static int kdb_handle_escape(char *buf, size_t sz)
  63 {
  64         char *lastkey = buf + sz - 1;
  65
  66         switch (sz) {
  67         case 1:
  68                 if (*lastkey == '\e')
  69                         return 0;
  70                 break;
  71
  72         case 2: /* \e<something> */
  73                 if (*lastkey == '[')
  74                         return 0;
  75                 break;
  76
  77         case 3:
  78                 switch (*lastkey) {
  79                 case 'A': /* \e[A, up arrow */
  80                         return 16;
  81                 case 'B': /* \e[B, down arrow */
  82                         return 14;
  83                 case 'C': /* \e[C, right arrow */
  84                         return 6;
  85                 case 'D': /* \e[D, left arrow */
  86                         return 2;
  87                 case '1': /* \e[<1,3,4>], may be home, del, end */
  88                 case '3':
  89                 case '4':
  90                         return 0;
  91                 }
  92                 break;
  93
  94         case 4:
  95                 if (*lastkey == '~') {
  96                         switch (buf[2]) {
  97                         case '1': /* \e[1~, home */
  98                                 return 1;
  99                         case '3': /* \e[3~, del */
 100                                 return 4;
 101                         case '4': /* \e[4~, end */
 102                                 return 5;
 103                         }
 104                 }
 105                 break;
 106         }
 107
 108         return -1;
 109 }
 110
 111 static int kdb_read_get_key(char *buffer, size_t bufsize)
 112 {
 113 #define ESCAPE_UDELAY 1000
 114 #define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
 115         char escape_data[5];    /* longest vt100 escape sequence is 4 bytes */
 116         char *ped = escape_data;
 117         int escape_delay = 0;
 118         get_char_func *f, *f_escape = NULL;
 119         int key;
 120
 121         for (f = &kdb_poll_funcs[0]; ; ++f) {
 122                 if (*f == NULL) {
 123                         /* Reset NMI watchdog once per poll loop */
 124                         touch_nmi_watchdog();
 125                         f = &kdb_poll_funcs[0];
 126                 }
 127
 128                 key = (*f)();
 129
 130                 if (key == -1) {
 131                         if (escape_delay) {
 132                                 udelay(ESCAPE_UDELAY);
 133                                 if (--escape_delay == 0)
 134                                         return '\e';
 135                         }
 136                         continue;
 137                 }
 138
 139                 if (bufsize <= 2) {
 140                         if (key == '\r')
 141                                 key = '\n';
 142                         *buffer++ = key;
 143                         *buffer = '\0';
 144                         return -1;
 145                 }
 146
 147                 if (escape_delay == 0 && key == '\e') {
 148                         escape_delay = ESCAPE_DELAY;
 149                         ped = escape_data;
 150                         f_escape = f;
 151                 }
 152                 if (escape_delay) {
 153                         if (f_escape != f)
 154                                 return '\e';
 155
 156                         *ped++ = key;
 157                         key = kdb_handle_escape(escape_data, ped - escape_data);
 158                         if (key < 0)
 159                                 return '\e';
 160                         if (key == 0)
 161                                 continue;
 162                 }
 163
 164                 break;  /* A key to process */
 165         }
 166         return key;
 167 }
 168
 169 /*
 170  * kdb_read
 171  *
 172  *      This function reads a string of characters, terminated by
 173  *      a newline, or by reaching the end of the supplied buffer,
 174  *      from the current kernel debugger console device.
 175  * Parameters:
 176  *      buffer  - Address of character buffer to receive input characters.
 177  *      bufsize - size, in bytes, of the character buffer
 178  * Returns:
 179  *      Returns a pointer to the buffer containing the received
 180  *      character string.  This string will be terminated by a
 181  *      newline character.
 182  * Locking:
 183  *      No locks are required to be held upon entry to this
 184  *      function.  It is not reentrant - it relies on the fact
 185  *      that while kdb is running on only one "master debug" cpu.
 186  * Remarks:
 187  *
 188  * The buffer size must be >= 2.  A buffer size of 2 means that the caller only
 189  * wants a single key.
 190  *
 191  * An escape key could be the start of a vt100 control sequence such as \e[D
 192  * (left arrow) or it could be a character in its own right.  The standard
 193  * method for detecting the difference is to wait for 2 seconds to see if there
 194  * are any other characters.  kdb is complicated by the lack of a timer service
 195  * (interrupts are off), by multiple input sources and by the need to sometimes
 196  * return after just one key.  Escape sequence processing has to be done as
 197  * states in the polling loop.
 198  */
 199
 200 static char *kdb_read(char *buffer, size_t bufsize)
 201 {
 202         char *cp = buffer;
 203         char *bufend = buffer+bufsize-2;        /* Reserve space for newline
 204                                                  * and null byte */
 205         char *lastchar;
 206         char *p_tmp;
 207         char tmp;
 208         static char tmpbuffer[CMD_BUFLEN];
 209         int len = strlen(buffer);
 210         int len_tmp;
 211         int tab = 0;
 212         int count;
 213         int i;
 214         int diag, dtab_count;
 215         int key, buf_size, ret;
 216
 217
 218         diag = kdbgetintenv("DTABCOUNT", &dtab_count);
 219         if (diag)
 220                 dtab_count = 30;
 221
 222         if (len > 0) {
 223                 cp += len;
 224                 if (*(buffer+len-1) == '\n')
 225                         cp--;
 226         }
 227
 228         lastchar = cp;
 229         *cp = '\0';
 230         kdb_printf("%s", buffer);
 231 poll_again:
 232         key = kdb_read_get_key(buffer, bufsize);
 233         if (key == -1)
 234                 return buffer;
 235         if (key != 9)
 236                 tab = 0;
 237         switch (key) {
 238         case 8: /* backspace */
 239                 if (cp > buffer) {
 240                         if (cp < lastchar) {
 241                                 memcpy(tmpbuffer, cp, lastchar - cp);
 242                                 memcpy(cp-1, tmpbuffer, lastchar - cp);
 243                         }
 244                         *(--lastchar) = '\0';
 245                         --cp;
 246                         kdb_printf("\b%s \r", cp);
 247                         tmp = *cp;
 248                         *cp = '\0';
 249                         kdb_printf(kdb_prompt_str);
 250                         kdb_printf("%s", buffer);
 251                         *cp = tmp;
 252                 }
 253                 break;
 254         case 13: /* enter */
 255                 *lastchar++ = '\n';
 256                 *lastchar++ = '\0';
 257                 if (!KDB_STATE(KGDB_TRANS)) {
 258                         KDB_STATE_SET(KGDB_TRANS);
 259                         kdb_printf("%s", buffer);
 260                 }
 261                 kdb_printf("\n");
 262                 return buffer;
 263         case 4: /* Del */
 264                 if (cp < lastchar) {
 265                         memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
 266                         memcpy(cp, tmpbuffer, lastchar - cp - 1);
 267                         *(--lastchar) = '\0';
 268                         kdb_printf("%s \r", cp);
 269                         tmp = *cp;
 270                         *cp = '\0';
 271                         kdb_printf(kdb_prompt_str);
 272                         kdb_printf("%s", buffer);
 273                         *cp = tmp;
 274                 }
 275                 break;
 276         case 1: /* Home */
 277                 if (cp > buffer) {
 278                         kdb_printf("\r");
 279                         kdb_printf(kdb_prompt_str);
 280                         cp = buffer;
 281                 }
 282                 break;
 283         case 5: /* End */
 284                 if (cp < lastchar) {
 285                         kdb_printf("%s", cp);
 286                         cp = lastchar;
 287                 }
 288                 break;
 289         case 2: /* Left */
 290                 if (cp > buffer) {
 291                         kdb_printf("\b");
 292                         --cp;
 293                 }
 294                 break;
 295         case 14: /* Down */
 296                 memset(tmpbuffer, ' ',
 297                        strlen(kdb_prompt_str) + (lastchar-buffer));
 298                 *(tmpbuffer+strlen(kdb_prompt_str) +
 299                   (lastchar-buffer)) = '\0';
 300                 kdb_printf("\r%s\r", tmpbuffer);
 301                 *lastchar = (char)key;
 302                 *(lastchar+1) = '\0';
 303                 return lastchar;
 304         case 6: /* Right */
 305                 if (cp < lastchar) {
 306                         kdb_printf("%c", *cp);
 307                         ++cp;
 308                 }
 309                 break;
 310         case 16: /* Up */
 311                 memset(tmpbuffer, ' ',
 312                        strlen(kdb_prompt_str) + (lastchar-buffer));
 313                 *(tmpbuffer+strlen(kdb_prompt_str) +
 314                   (lastchar-buffer)) = '\0';
 315                 kdb_printf("\r%s\r", tmpbuffer);
 316                 *lastchar = (char)key;
 317                 *(lastchar+1) = '\0';
 318                 return lastchar;
 319         case 9: /* Tab */
 320                 if (tab < 2)
 321                         ++tab;
 322                 p_tmp = buffer;
 323                 while (*p_tmp == ' ')
 324                         p_tmp++;
 325                 if (p_tmp > cp)
 326                         break;
 327                 memcpy(tmpbuffer, p_tmp, cp-p_tmp);
 328                 *(tmpbuffer + (cp-p_tmp)) = '\0';
 329                 p_tmp = strrchr(tmpbuffer, ' ');
 330                 if (p_tmp)
 331                         ++p_tmp;
 332                 else
 333                         p_tmp = tmpbuffer;
 334                 len = strlen(p_tmp);
 335                 buf_size = sizeof(tmpbuffer) - (p_tmp - tmpbuffer);
 336                 count = kallsyms_symbol_complete(p_tmp, buf_size);
 337                 if (tab == 2 && count > 0) {
 338                         kdb_printf("\n%d symbols are found.", count);
 339                         if (count > dtab_count) {
 340                                 count = dtab_count;
 341                                 kdb_printf(" But only first %d symbols will"
 342                                            " be printed.\nYou can change the"
 343                                            " environment variable DTABCOUNT.",
 344                                            count);
 345                         }
 346                         kdb_printf("\n");
 347                         for (i = 0; i < count; i++) {
 348                                 ret = kallsyms_symbol_next(p_tmp, i, buf_size);
 349                                 if (WARN_ON(!ret))
 350                                         break;
 351                                 if (ret != -E2BIG)
 352                                         kdb_printf("%s ", p_tmp);
 353                                 else
 354                                         kdb_printf("%s... ", p_tmp);
 355                                 *(p_tmp + len) = '\0';
 356                         }
 357                         if (i >= dtab_count)
 358                                 kdb_printf("...");
 359                         kdb_printf("\n");
 360                         kdb_printf(kdb_prompt_str);
 361                         kdb_printf("%s", buffer);
 362                 } else if (tab != 2 && count > 0) {
 363                         len_tmp = strlen(p_tmp);
 364                         strncpy(p_tmp+len_tmp, cp, lastchar-cp+1);
 365                         len_tmp = strlen(p_tmp);
 366                         strncpy(cp, p_tmp+len, len_tmp-len + 1);
 367                         len = len_tmp - len;
 368                         kdb_printf("%s", cp);
 369                         cp += len;
 370                         lastchar += len;
 371                 }
 372                 kdb_nextline = 1; /* reset output line number */
 373                 break;
 374         default:
 375                 if (key >= 32 && lastchar < bufend) {
 376                         if (cp < lastchar) {
 377                                 memcpy(tmpbuffer, cp, lastchar - cp);
 378                                 memcpy(cp+1, tmpbuffer, lastchar - cp);
 379                                 *++lastchar = '\0';
 380                                 *cp = key;
 381                                 kdb_printf("%s\r", cp);
 382                                 ++cp;
 383                                 tmp = *cp;
 384                                 *cp = '\0';
 385                                 kdb_printf(kdb_prompt_str);
 386                                 kdb_printf("%s", buffer);
 387                                 *cp = tmp;
 388                         } else {
 389                                 *++lastchar = '\0';
 390                                 *cp++ = key;
 391                                 /* The kgdb transition check will hide
 392                                  * printed characters if we think that
 393                                  * kgdb is connecting, until the check
 394                                  * fails */
 395                                 if (!KDB_STATE(KGDB_TRANS)) {
 396                                         if (kgdb_transition_check(buffer))
 397                                                 return buffer;
 398                                 } else {
 399                                         kdb_printf("%c", key);
 400                                 }
 401                         }
 402                         /* Special escape to kgdb */
 403                         if (lastchar - buffer >= 5 &&
 404                             strcmp(lastchar - 5, "$?#3f") == 0) {
 405                                 kdb_gdb_state_pass(lastchar - 5);
 406                                 strcpy(buffer, "kgdb");
 407                                 KDB_STATE_SET(DOING_KGDB);
 408                                 return buffer;
 409                         }
 410                         if (lastchar - buffer >= 11 &&
 411                             strcmp(lastchar - 11, "$qSupported") == 0) {
 412                                 kdb_gdb_state_pass(lastchar - 11);
 413                                 strcpy(buffer, "kgdb");
 414                                 KDB_STATE_SET(DOING_KGDB);
 415                                 return buffer;
 416                         }
 417                 }
 418                 break;
 419         }
 420         goto poll_again;
 421 }
 422
 423 /*
 424  * kdb_getstr
 425  *
 426  *      Print the prompt string and read a command from the
 427  *      input device.
 428  *
 429  * Parameters:
 430  *      buffer  Address of buffer to receive command
 431  *      bufsize Size of buffer in bytes
 432  *      prompt  Pointer to string to use as prompt string
 433  * Returns:
 434  *      Pointer to command buffer.
 435  * Locking:
 436  *      None.
 437  * Remarks:
 438  *      For SMP kernels, the processor number will be
 439  *      substituted for %d, %x or %o in the prompt.
 440  */
 441
 442 char *kdb_getstr(char *buffer, size_t bufsize, const char *prompt)
 443 {
 444         if (prompt && kdb_prompt_str != prompt)
 445                 strscpy(kdb_prompt_str, prompt, CMD_BUFLEN);
 446         kdb_printf(kdb_prompt_str);
 447         kdb_nextline = 1;       /* Prompt and input resets line number */
 448         return kdb_read(buffer, bufsize);
 449 }
 450
 451 /*
 452  * kdb_input_flush
 453  *
 454  *      Get rid of any buffered console input.
 455  *
 456  * Parameters:
 457  *      none
 458  * Returns:
 459  *      nothing
 460  * Locking:
 461  *      none
 462  * Remarks:
 463  *      Call this function whenever you want to flush input.  If there is any
 464  *      outstanding input, it ignores all characters until there has been no
 465  *      data for approximately 1ms.
 466  */
 467
 468 static void kdb_input_flush(void)
 469 {
 470         get_char_func *f;
 471         int res;
 472         int flush_delay = 1;
 473         while (flush_delay) {
 474                 flush_delay--;
 475 empty:
 476                 touch_nmi_watchdog();
 477                 for (f = &kdb_poll_funcs[0]; *f; ++f) {
 478                         res = (*f)();
 479                         if (res != -1) {
 480                                 flush_delay = 1;
 481                                 goto empty;
 482                         }
 483                 }
 484                 if (flush_delay)
 485                         mdelay(1);
 486         }
 487 }
 488
 489 /*
 490  * kdb_printf
 491  *
 492  *      Print a string to the output device(s).
 493  *
 494  * Parameters:
 495  *      printf-like format and optional args.
 496  * Returns:
 497  *      0
 498  * Locking:
 499  *      None.
 500  * Remarks:
 501  *      use 'kdbcons->write()' to avoid polluting 'log_buf' with
 502  *      kdb output.
 503  *
 504  *  If the user is doing a cmd args | grep srch
 505  *  then kdb_grepping_flag is set.
 506  *  In that case we need to accumulate full lines (ending in \n) before
 507  *  searching for the pattern.
 508  */
 509
 510 static char kdb_buffer[256];    /* A bit too big to go on stack */
 511 static char *next_avail = kdb_buffer;
 512 static int  size_avail;
 513 static int  suspend_grep;
 514
 515 /*
 516  * search arg1 to see if it contains arg2
 517  * (kdmain.c provides flags for ^pat and pat$)
 518  *
 519  * return 1 for found, 0 for not found
 520  */
 521 static int kdb_search_string(char *searched, char *searchfor)
 522 {
 523         char firstchar, *cp;
 524         int len1, len2;
 525
 526         /* not counting the newline at the end of "searched" */
 527         len1 = strlen(searched)-1;
 528         len2 = strlen(searchfor);
 529         if (len1 < len2)
 530                 return 0;
 531         if (kdb_grep_leading && kdb_grep_trailing && len1 != len2)
 532                 return 0;
 533         if (kdb_grep_leading) {
 534                 if (!strncmp(searched, searchfor, len2))
 535                         return 1;
 536         } else if (kdb_grep_trailing) {
 537                 if (!strncmp(searched+len1-len2, searchfor, len2))
 538                         return 1;
 539         } else {
 540                 firstchar = *searchfor;
 541                 cp = searched;
 542                 while ((cp = strchr(cp, firstchar))) {
 543                         if (!strncmp(cp, searchfor, len2))
 544                                 return 1;
 545                         cp++;
 546                 }
 547         }
 548         return 0;
 549 }
 550
 551 int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
 552 {
 553         int diag;
 554         int linecount;
 555         int colcount;
 556         int logging, saved_loglevel = 0;
 557         int retlen = 0;
 558         int fnd, len;
 559         int this_cpu, old_cpu;
 560         char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
 561         char *moreprompt = "more> ";
 562         struct console *c = console_drivers;
 563         unsigned long uninitialized_var(flags);
 564
 565         /* Serialize kdb_printf if multiple cpus try to write at once.
 566          * But if any cpu goes recursive in kdb, just print the output,
 567          * even if it is interleaved with any other text.
 568          */
 569         local_irq_save(flags);
 570         this_cpu = smp_processor_id();
 571         for (;;) {
 572                 old_cpu = cmpxchg(&kdb_printf_cpu, -1, this_cpu);
 573                 if (old_cpu == -1 || old_cpu == this_cpu)
 574                         break;
 575
 576                 cpu_relax();
 577         }
 578
 579         diag = kdbgetintenv("LINES", &linecount);
 580         if (diag || linecount <= 1)
 581                 linecount = 24;
 582
 583         diag = kdbgetintenv("COLUMNS", &colcount);
 584         if (diag || colcount <= 1)
 585                 colcount = 80;
 586
 587         diag = kdbgetintenv("LOGGING", &logging);
 588         if (diag)
 589                 logging = 0;
 590
 591         if (!kdb_grepping_flag || suspend_grep) {
 592                 /* normally, every vsnprintf starts a new buffer */
 593                 next_avail = kdb_buffer;
 594                 size_avail = sizeof(kdb_buffer);
 595         }
 596         vsnprintf(next_avail, size_avail, fmt, ap);
 597
 598         /*
 599          * If kdb_parse() found that the command was cmd xxx | grep yyy
 600          * then kdb_grepping_flag is set, and kdb_grep_string contains yyy
 601          *
 602          * Accumulate the print data up to a newline before searching it.
 603          * (vsnprintf does null-terminate the string that it generates)
 604          */
 605
 606         /* skip the search if prints are temporarily unconditional */
 607         if (!suspend_grep && kdb_grepping_flag) {
 608                 cp = strchr(kdb_buffer, '\n');
 609                 if (!cp) {
 610                         /*
 611                          * Special cases that don't end with newlines
 612                          * but should be written without one:
 613                          *   The "[nn]kdb> " prompt should
 614                          *   appear at the front of the buffer.
 615                          *
 616                          *   The "[nn]more " prompt should also be
 617                          *     (MOREPROMPT -> moreprompt)
 618                          *   written *   but we print that ourselves,
 619                          *   we set the suspend_grep flag to make
 620                          *   it unconditional.
 621                          *
 622                          */
 623                         if (next_avail == kdb_buffer) {
 624                                 /*
 625                                  * these should occur after a newline,
 626                                  * so they will be at the front of the
 627                                  * buffer
 628                                  */
 629                                 cp2 = kdb_buffer;
 630                                 len = strlen(kdb_prompt_str);
 631                                 if (!strncmp(cp2, kdb_prompt_str, len)) {
 632                                         /*
 633                                          * We're about to start a new
 634                                          * command, so we can go back
 635                                          * to normal mode.
 636                                          */
 637                                         kdb_grepping_flag = 0;
 638                                         goto kdb_printit;
 639                                 }
 640                         }
 641                         /* no newline; don't search/write the buffer
 642                            until one is there */
 643                         len = strlen(kdb_buffer);
 644                         next_avail = kdb_buffer + len;
 645                         size_avail = sizeof(kdb_buffer) - len;
 646                         goto kdb_print_out;
 647                 }
 648
 649                 /*
 650                  * The newline is present; print through it or discard
 651                  * it, depending on the results of the search.
 652                  */
 653                 cp++;                /* to byte after the newline */
 654                 replaced_byte = *cp; /* remember what/where it was */
 655                 cphold = cp;
 656                 *cp = '\0';          /* end the string for our search */
 657
 658                 /*
 659                  * We now have a newline at the end of the string
 660                  * Only continue with this output if it contains the
 661                  * search string.
 662                  */
 663                 fnd = kdb_search_string(kdb_buffer, kdb_grep_string);
 664                 if (!fnd) {
 665                         /*
 666                          * At this point the complete line at the start
 667                          * of kdb_buffer can be discarded, as it does
 668                          * not contain what the user is looking for.
 669                          * Shift the buffer left.
 670                          */
 671                         *cphold = replaced_byte;
 672                         strcpy(kdb_buffer, cphold);
 673                         len = strlen(kdb_buffer);
 674                         next_avail = kdb_buffer + len;
 675                         size_avail = sizeof(kdb_buffer) - len;
 676                         goto kdb_print_out;
 677                 }
 678                 if (kdb_grepping_flag >= KDB_GREPPING_FLAG_SEARCH)
 679                         /*
 680                          * This was a interactive search (using '/' at more
 681                          * prompt) and it has completed. Clear the flag.
 682                          */
 683                         kdb_grepping_flag = 0;
 684                 /*
 685                  * at this point the string is a full line and
 686                  * should be printed, up to the null.
 687                  */
 688         }
 689 kdb_printit:
 690
 691         /*
 692          * Write to all consoles.
 693          */
 694         retlen = strlen(kdb_buffer);
 695         cp = (char *) printk_skip_headers(kdb_buffer);
 696         if (!dbg_kdb_mode && kgdb_connected) {
 697                 gdbstub_msg_write(cp, retlen - (cp - kdb_buffer));
 698         } else {
 699                 if (dbg_io_ops && !dbg_io_ops->is_console) {
 700                         len = retlen - (cp - kdb_buffer);
 701                         cp2 = cp;
 702                         while (len--) {
 703                                 dbg_io_ops->write_char(*cp2);
 704                                 cp2++;
 705                         }
 706                 }
 707                 while (c) {
 708                         c->write(c, cp, retlen - (cp - kdb_buffer));
 709                         touch_nmi_watchdog();
 710                         c = c->next;
 711                 }
 712         }
 713         if (logging) {
 714                 saved_loglevel = console_loglevel;
 715                 console_loglevel = CONSOLE_LOGLEVEL_SILENT;
 716                 if (printk_get_level(kdb_buffer) || src == KDB_MSGSRC_PRINTK)
 717                         printk("%s", kdb_buffer);
 718                 else
 719                         pr_info("%s", kdb_buffer);
 720         }
 721
 722         if (KDB_STATE(PAGER)) {
 723                 /*
 724                  * Check printed string to decide how to bump the
 725                  * kdb_nextline to control when the more prompt should
 726                  * show up.
 727                  */
 728                 int got = 0;
 729                 len = retlen;
 730                 while (len--) {
 731                         if (kdb_buffer[len] == '\n') {
 732                                 kdb_nextline++;
 733                                 got = 0;
 734                         } else if (kdb_buffer[len] == '\r') {
 735                                 got = 0;
 736                         } else {
 737                                 got++;
 738                         }
 739                 }
 740                 kdb_nextline += got / (colcount + 1);
 741         }
 742
 743         /* check for having reached the LINES number of printed lines */
 744         if (kdb_nextline >= linecount) {
 745                 char buf1[16] = "";
 746
 747                 /* Watch out for recursion here.  Any routine that calls
 748                  * kdb_printf will come back through here.  And kdb_read
 749                  * uses kdb_printf to echo on serial consoles ...
 750                  */
 751                 kdb_nextline = 1;       /* In case of recursion */
 752
 753                 /*
 754                  * Pause until cr.
 755                  */
 756                 moreprompt = kdbgetenv("MOREPROMPT");
 757                 if (moreprompt == NULL)
 758                         moreprompt = "more> ";
 759
 760                 kdb_input_flush();
 761                 c = console_drivers;
 762
 763                 if (dbg_io_ops && !dbg_io_ops->is_console) {
 764                         len = strlen(moreprompt);
 765                         cp = moreprompt;
 766                         while (len--) {
 767                                 dbg_io_ops->write_char(*cp);
 768                                 cp++;
 769                         }
 770                 }
 771                 while (c) {
 772                         c->write(c, moreprompt, strlen(moreprompt));
 773                         touch_nmi_watchdog();
 774                         c = c->next;
 775                 }
 776
 777                 if (logging)
 778                         printk("%s", moreprompt);
 779
 780                 kdb_read(buf1, 2); /* '2' indicates to return
 781                                     * immediately after getting one key. */
 782                 kdb_nextline = 1;       /* Really set output line 1 */
 783
 784                 /* empty and reset the buffer: */
 785                 kdb_buffer[0] = '\0';
 786                 next_avail = kdb_buffer;
 787                 size_avail = sizeof(kdb_buffer);
 788                 if ((buf1[0] == 'q') || (buf1[0] == 'Q')) {
 789                         /* user hit q or Q */
 790                         KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
 791                         KDB_STATE_CLEAR(PAGER);
 792                         /* end of command output; back to normal mode */
 793                         kdb_grepping_flag = 0;
 794                         kdb_printf("\n");
 795                 } else if (buf1[0] == ' ') {
 796                         kdb_printf("\r");
 797                         suspend_grep = 1; /* for this recursion */
 798                 } else if (buf1[0] == '\n') {
 799                         kdb_nextline = linecount - 1;
 800                         kdb_printf("\r");
 801                         suspend_grep = 1; /* for this recursion */
 802                 } else if (buf1[0] == '/' && !kdb_grepping_flag) {
 803                         kdb_printf("\r");
 804                         kdb_getstr(kdb_grep_string, KDB_GREP_STRLEN,
 805                                    kdbgetenv("SEARCHPROMPT") ?: "search> ");
 806                         *strchrnul(kdb_grep_string, '\n') = '\0';
 807                         kdb_grepping_flag += KDB_GREPPING_FLAG_SEARCH;
 808                         suspend_grep = 1; /* for this recursion */
 809                 } else if (buf1[0] && buf1[0] != '\n') {
 810                         /* user hit something other than enter */
 811                         suspend_grep = 1; /* for this recursion */
 812                         if (buf1[0] != '/')
 813                                 kdb_printf(
 814                                     "\nOnly 'q', 'Q' or '/' are processed at "
 815                                     "more prompt, input ignored\n");
 816                         else
 817                                 kdb_printf("\n'/' cannot be used during | "
 818                                            "grep filtering, input ignored\n");
 819                 } else if (kdb_grepping_flag) {
 820                         /* user hit enter */
 821                         suspend_grep = 1; /* for this recursion */
 822                         kdb_printf("\n");
 823                 }
 824                 kdb_input_flush();
 825         }
 826
 827         /*
 828          * For grep searches, shift the printed string left.
 829          *  replaced_byte contains the character that was overwritten with
 830          *  the terminating null, and cphold points to the null.
 831          * Then adjust the notion of available space in the buffer.
 832          */
 833         if (kdb_grepping_flag && !suspend_grep) {
 834                 *cphold = replaced_byte;
 835                 strcpy(kdb_buffer, cphold);
 836                 len = strlen(kdb_buffer);
 837                 next_avail = kdb_buffer + len;
 838                 size_avail = sizeof(kdb_buffer) - len;
 839         }
 840
 841 kdb_print_out:
 842         suspend_grep = 0; /* end of what may have been a recursive call */
 843         if (logging)
 844                 console_loglevel = saved_loglevel;
 845         /* kdb_printf_cpu locked the code above. */
 846         smp_store_release(&kdb_printf_cpu, old_cpu);
 847         local_irq_restore(flags);
 848         return retlen;
 849 }
 850
 851 int kdb_printf(const char *fmt, ...)
 852 {
 853         va_list ap;
 854         int r;
 855
 856         va_start(ap, fmt);
 857         r = vkdb_printf(KDB_MSGSRC_INTERNAL, fmt, ap);
 858         va_end(ap);
 859
 860         return r;
 861 }
 862 EXPORT_SYMBOL_GPL(kdb_printf);