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 /**
 112  * kdb_getchar() - Read a single character from a kdb console (or consoles).
 113  *
 114  * Other than polling the various consoles that are currently enabled,
 115  * most of the work done in this function is dealing with escape sequences.
 116  *
 117  * An escape key could be the start of a vt100 control sequence such as \e[D
 118  * (left arrow) or it could be a character in its own right.  The standard
 119  * method for detecting the difference is to wait for 2 seconds to see if there
 120  * are any other characters.  kdb is complicated by the lack of a timer service
 121  * (interrupts are off), by multiple input sources. Escape sequence processing
 122  * has to be done as states in the polling loop.
 123  *
 124  * Return: The key pressed or a control code derived from an escape sequence.
 125  */
 126 char kdb_getchar(void)
 127 {
 128 #define ESCAPE_UDELAY 1000
 129 #define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
 130         char buf[4];    /* longest vt100 escape sequence is 4 bytes */
 131         char *pbuf = buf;
 132         int escape_delay = 0;
 133         get_char_func *f, *f_prev = NULL;
 134         int key;
 135
 136         for (f = &kdb_poll_funcs[0]; ; ++f) {
 137                 if (*f == NULL) {
 138                         /* Reset NMI watchdog once per poll loop */
 139                         touch_nmi_watchdog();
 140                         f = &kdb_poll_funcs[0];
 141                 }
 142
 143                 key = (*f)();
 144                 if (key == -1) {
 145                         if (escape_delay) {
 146                                 udelay(ESCAPE_UDELAY);
 147                                 if (--escape_delay == 0)
 148                                         return '\e';
 149                         }
 150                         continue;
 151                 }
 152
 153                 /*
 154                  * When the first character is received (or we get a change
 155                  * input source) we set ourselves up to handle an escape
 156                  * sequences (just in case).
 157                  */
 158                 if (f_prev != f) {
 159                         f_prev = f;
 160                         pbuf = buf;
 161                         escape_delay = ESCAPE_DELAY;
 162                 }
 163
 164                 *pbuf++ = key;
 165                 key = kdb_handle_escape(buf, pbuf - buf);
 166                 if (key < 0) /* no escape sequence; return best character */
 167                         return buf[pbuf - buf == 2 ? 1 : 0];
 168                 if (key > 0)
 169                         return key;
 170         }
 171
 172         unreachable();
 173 }
 174
 175 /*
 176  * kdb_read
 177  *
 178  *      This function reads a string of characters, terminated by
 179  *      a newline, or by reaching the end of the supplied buffer,
 180  *      from the current kernel debugger console device.
 181  * Parameters:
 182  *      buffer  - Address of character buffer to receive input characters.
 183  *      bufsize - size, in bytes, of the character buffer
 184  * Returns:
 185  *      Returns a pointer to the buffer containing the received
 186  *      character string.  This string will be terminated by a
 187  *      newline character.
 188  * Locking:
 189  *      No locks are required to be held upon entry to this
 190  *      function.  It is not reentrant - it relies on the fact
 191  *      that while kdb is running on only one "master debug" cpu.
 192  * Remarks:
 193  *      The buffer size must be >= 2.
 194  */
 195
 196 static char *kdb_read(char *buffer, size_t bufsize)
 197 {
 198         char *cp = buffer;
 199         char *bufend = buffer+bufsize-2;        /* Reserve space for newline
 200                                                  * and null byte */
 201         char *lastchar;
 202         char *p_tmp;
 203         char tmp;
 204         static char tmpbuffer[CMD_BUFLEN];
 205         int len = strlen(buffer);
 206         int len_tmp;
 207         int tab = 0;
 208         int count;
 209         int i;
 210         int diag, dtab_count;
 211         int key, buf_size, ret;
 212
 213
 214         diag = kdbgetintenv("DTABCOUNT", &dtab_count);
 215         if (diag)
 216                 dtab_count = 30;
 217
 218         if (len > 0) {
 219                 cp += len;
 220                 if (*(buffer+len-1) == '\n')
 221                         cp--;
 222         }
 223
 224         lastchar = cp;
 225         *cp = '\0';
 226         kdb_printf("%s", buffer);
 227 poll_again:
 228         key = kdb_getchar();
 229         if (key != 9)
 230                 tab = 0;
 231         switch (key) {
 232         case 8: /* backspace */
 233                 if (cp > buffer) {
 234                         if (cp < lastchar) {
 235                                 memcpy(tmpbuffer, cp, lastchar - cp);
 236                                 memcpy(cp-1, tmpbuffer, lastchar - cp);
 237                         }
 238                         *(--lastchar) = '\0';
 239                         --cp;
 240                         kdb_printf("\b%s \r", cp);
 241                         tmp = *cp;
 242                         *cp = '\0';
 243                         kdb_printf(kdb_prompt_str);
 244                         kdb_printf("%s", buffer);
 245                         *cp = tmp;
 246                 }
 247                 break;
 248         case 13: /* enter */
 249                 *lastchar++ = '\n';
 250                 *lastchar++ = '\0';
 251                 if (!KDB_STATE(KGDB_TRANS)) {
 252                         KDB_STATE_SET(KGDB_TRANS);
 253                         kdb_printf("%s", buffer);
 254                 }
 255                 kdb_printf("\n");
 256                 return buffer;
 257         case 4: /* Del */
 258                 if (cp < lastchar) {
 259                         memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
 260                         memcpy(cp, tmpbuffer, lastchar - cp - 1);
 261                         *(--lastchar) = '\0';
 262                         kdb_printf("%s \r", cp);
 263                         tmp = *cp;
 264                         *cp = '\0';
 265                         kdb_printf(kdb_prompt_str);
 266                         kdb_printf("%s", buffer);
 267                         *cp = tmp;
 268                 }
 269                 break;
 270         case 1: /* Home */
 271                 if (cp > buffer) {
 272                         kdb_printf("\r");
 273                         kdb_printf(kdb_prompt_str);
 274                         cp = buffer;
 275                 }
 276                 break;
 277         case 5: /* End */
 278                 if (cp < lastchar) {
 279                         kdb_printf("%s", cp);
 280                         cp = lastchar;
 281                 }
 282                 break;
 283         case 2: /* Left */
 284                 if (cp > buffer) {
 285                         kdb_printf("\b");
 286                         --cp;
 287                 }
 288                 break;
 289         case 14: /* Down */
 290                 memset(tmpbuffer, ' ',
 291                        strlen(kdb_prompt_str) + (lastchar-buffer));
 292                 *(tmpbuffer+strlen(kdb_prompt_str) +
 293                   (lastchar-buffer)) = '\0';
 294                 kdb_printf("\r%s\r", tmpbuffer);
 295                 *lastchar = (char)key;
 296                 *(lastchar+1) = '\0';
 297                 return lastchar;
 298         case 6: /* Right */
 299                 if (cp < lastchar) {
 300                         kdb_printf("%c", *cp);
 301                         ++cp;
 302                 }
 303                 break;
 304         case 16: /* Up */
 305                 memset(tmpbuffer, ' ',
 306                        strlen(kdb_prompt_str) + (lastchar-buffer));
 307                 *(tmpbuffer+strlen(kdb_prompt_str) +
 308                   (lastchar-buffer)) = '\0';
 309                 kdb_printf("\r%s\r", tmpbuffer);
 310                 *lastchar = (char)key;
 311                 *(lastchar+1) = '\0';
 312                 return lastchar;
 313         case 9: /* Tab */
 314                 if (tab < 2)
 315                         ++tab;
 316                 p_tmp = buffer;
 317                 while (*p_tmp == ' ')
 318                         p_tmp++;
 319                 if (p_tmp > cp)
 320                         break;
 321                 memcpy(tmpbuffer, p_tmp, cp-p_tmp);
 322                 *(tmpbuffer + (cp-p_tmp)) = '\0';
 323                 p_tmp = strrchr(tmpbuffer, ' ');
 324                 if (p_tmp)
 325                         ++p_tmp;
 326                 else
 327                         p_tmp = tmpbuffer;
 328                 len = strlen(p_tmp);
 329                 buf_size = sizeof(tmpbuffer) - (p_tmp - tmpbuffer);
 330                 count = kallsyms_symbol_complete(p_tmp, buf_size);
 331                 if (tab == 2 && count > 0) {
 332                         kdb_printf("\n%d symbols are found.", count);
 333                         if (count > dtab_count) {
 334                                 count = dtab_count;
 335                                 kdb_printf(" But only first %d symbols will"
 336                                            " be printed.\nYou can change the"
 337                                            " environment variable DTABCOUNT.",
 338                                            count);
 339                         }
 340                         kdb_printf("\n");
 341                         for (i = 0; i < count; i++) {
 342                                 ret = kallsyms_symbol_next(p_tmp, i, buf_size);
 343                                 if (WARN_ON(!ret))
 344                                         break;
 345                                 if (ret != -E2BIG)
 346                                         kdb_printf("%s ", p_tmp);
 347                                 else
 348                                         kdb_printf("%s... ", p_tmp);
 349                                 *(p_tmp + len) = '\0';
 350                         }
 351                         if (i >= dtab_count)
 352                                 kdb_printf("...");
 353                         kdb_printf("\n");
 354                         kdb_printf(kdb_prompt_str);
 355                         kdb_printf("%s", buffer);
 356                 } else if (tab != 2 && count > 0) {
 357                         len_tmp = strlen(p_tmp);
 358                         strncpy(p_tmp+len_tmp, cp, lastchar-cp+1);
 359                         len_tmp = strlen(p_tmp);
 360                         strncpy(cp, p_tmp+len, len_tmp-len + 1);
 361                         len = len_tmp - len;
 362                         kdb_printf("%s", cp);
 363                         cp += len;
 364                         lastchar += len;
 365                 }
 366                 kdb_nextline = 1; /* reset output line number */
 367                 break;
 368         default:
 369                 if (key >= 32 && lastchar < bufend) {
 370                         if (cp < lastchar) {
 371                                 memcpy(tmpbuffer, cp, lastchar - cp);
 372                                 memcpy(cp+1, tmpbuffer, lastchar - cp);
 373                                 *++lastchar = '\0';
 374                                 *cp = key;
 375                                 kdb_printf("%s\r", cp);
 376                                 ++cp;
 377                                 tmp = *cp;
 378                                 *cp = '\0';
 379                                 kdb_printf(kdb_prompt_str);
 380                                 kdb_printf("%s", buffer);
 381                                 *cp = tmp;
 382                         } else {
 383                                 *++lastchar = '\0';
 384                                 *cp++ = key;
 385                                 /* The kgdb transition check will hide
 386                                  * printed characters if we think that
 387                                  * kgdb is connecting, until the check
 388                                  * fails */
 389                                 if (!KDB_STATE(KGDB_TRANS)) {
 390                                         if (kgdb_transition_check(buffer))
 391                                                 return buffer;
 392                                 } else {
 393                                         kdb_printf("%c", key);
 394                                 }
 395                         }
 396                         /* Special escape to kgdb */
 397                         if (lastchar - buffer >= 5 &&
 398                             strcmp(lastchar - 5, "$?#3f") == 0) {
 399                                 kdb_gdb_state_pass(lastchar - 5);
 400                                 strcpy(buffer, "kgdb");
 401                                 KDB_STATE_SET(DOING_KGDB);
 402                                 return buffer;
 403                         }
 404                         if (lastchar - buffer >= 11 &&
 405                             strcmp(lastchar - 11, "$qSupported") == 0) {
 406                                 kdb_gdb_state_pass(lastchar - 11);
 407                                 strcpy(buffer, "kgdb");
 408                                 KDB_STATE_SET(DOING_KGDB);
 409                                 return buffer;
 410                         }
 411                 }
 412                 break;
 413         }
 414         goto poll_again;
 415 }
 416
 417 /*
 418  * kdb_getstr
 419  *
 420  *      Print the prompt string and read a command from the
 421  *      input device.
 422  *
 423  * Parameters:
 424  *      buffer  Address of buffer to receive command
 425  *      bufsize Size of buffer in bytes
 426  *      prompt  Pointer to string to use as prompt string
 427  * Returns:
 428  *      Pointer to command buffer.
 429  * Locking:
 430  *      None.
 431  * Remarks:
 432  *      For SMP kernels, the processor number will be
 433  *      substituted for %d, %x or %o in the prompt.
 434  */
 435
 436 char *kdb_getstr(char *buffer, size_t bufsize, const char *prompt)
 437 {
 438         if (prompt && kdb_prompt_str != prompt)
 439                 strscpy(kdb_prompt_str, prompt, CMD_BUFLEN);
 440         kdb_printf(kdb_prompt_str);
 441         kdb_nextline = 1;       /* Prompt and input resets line number */
 442         return kdb_read(buffer, bufsize);
 443 }
 444
 445 /*
 446  * kdb_input_flush
 447  *
 448  *      Get rid of any buffered console input.
 449  *
 450  * Parameters:
 451  *      none
 452  * Returns:
 453  *      nothing
 454  * Locking:
 455  *      none
 456  * Remarks:
 457  *      Call this function whenever you want to flush input.  If there is any
 458  *      outstanding input, it ignores all characters until there has been no
 459  *      data for approximately 1ms.
 460  */
 461
 462 static void kdb_input_flush(void)
 463 {
 464         get_char_func *f;
 465         int res;
 466         int flush_delay = 1;
 467         while (flush_delay) {
 468                 flush_delay--;
 469 empty:
 470                 touch_nmi_watchdog();
 471                 for (f = &kdb_poll_funcs[0]; *f; ++f) {
 472                         res = (*f)();
 473                         if (res != -1) {
 474                                 flush_delay = 1;
 475                                 goto empty;
 476                         }
 477                 }
 478                 if (flush_delay)
 479                         mdelay(1);
 480         }
 481 }
 482
 483 /*
 484  * kdb_printf
 485  *
 486  *      Print a string to the output device(s).
 487  *
 488  * Parameters:
 489  *      printf-like format and optional args.
 490  * Returns:
 491  *      0
 492  * Locking:
 493  *      None.
 494  * Remarks:
 495  *      use 'kdbcons->write()' to avoid polluting 'log_buf' with
 496  *      kdb output.
 497  *
 498  *  If the user is doing a cmd args | grep srch
 499  *  then kdb_grepping_flag is set.
 500  *  In that case we need to accumulate full lines (ending in \n) before
 501  *  searching for the pattern.
 502  */
 503
 504 static char kdb_buffer[256];    /* A bit too big to go on stack */
 505 static char *next_avail = kdb_buffer;
 506 static int  size_avail;
 507 static int  suspend_grep;
 508
 509 /*
 510  * search arg1 to see if it contains arg2
 511  * (kdmain.c provides flags for ^pat and pat$)
 512  *
 513  * return 1 for found, 0 for not found
 514  */
 515 static int kdb_search_string(char *searched, char *searchfor)
 516 {
 517         char firstchar, *cp;
 518         int len1, len2;
 519
 520         /* not counting the newline at the end of "searched" */
 521         len1 = strlen(searched)-1;
 522         len2 = strlen(searchfor);
 523         if (len1 < len2)
 524                 return 0;
 525         if (kdb_grep_leading && kdb_grep_trailing && len1 != len2)
 526                 return 0;
 527         if (kdb_grep_leading) {
 528                 if (!strncmp(searched, searchfor, len2))
 529                         return 1;
 530         } else if (kdb_grep_trailing) {
 531                 if (!strncmp(searched+len1-len2, searchfor, len2))
 532                         return 1;
 533         } else {
 534                 firstchar = *searchfor;
 535                 cp = searched;
 536                 while ((cp = strchr(cp, firstchar))) {
 537                         if (!strncmp(cp, searchfor, len2))
 538                                 return 1;
 539                         cp++;
 540                 }
 541         }
 542         return 0;
 543 }
 544
 545 static void kdb_msg_write(const char *msg, int msg_len)
 546 {
 547         struct console *c;
 548         const char *cp;
 549         int len;
 550
 551         if (msg_len == 0)
 552                 return;
 553
 554         cp = msg;
 555         len = msg_len;
 556
 557         while (len--) {
 558                 dbg_io_ops->write_char(*cp);
 559                 cp++;
 560         }
 561
 562         /* mirror output on atomic consoles */
 563         for_each_console(c) {
 564                 if (!(c->flags & CON_ENABLED))
 565                         continue;
 566                 if (c == dbg_io_ops->cons)
 567                         continue;
 568
 569                 if (!c->write_atomic)
 570                         continue;
 571                 c->write_atomic(c, msg, msg_len);
 572
 573                 touch_nmi_watchdog();
 574         }
 575 }
 576
 577 int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
 578 {
 579         int diag;
 580         int linecount;
 581         int colcount;
 582         int logging, saved_loglevel = 0;
 583         int retlen = 0;
 584         int fnd, len;
 585         int this_cpu, old_cpu;
 586         char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
 587         char *moreprompt = "more> ";
 588         unsigned long flags;
 589
 590         /* Serialize kdb_printf if multiple cpus try to write at once.
 591          * But if any cpu goes recursive in kdb, just print the output,
 592          * even if it is interleaved with any other text.
 593          */
 594         local_irq_save(flags);
 595         this_cpu = smp_processor_id();
 596         for (;;) {
 597                 old_cpu = cmpxchg(&kdb_printf_cpu, -1, this_cpu);
 598                 if (old_cpu == -1 || old_cpu == this_cpu)
 599                         break;
 600
 601                 cpu_relax();
 602         }
 603
 604         diag = kdbgetintenv("LINES", &linecount);
 605         if (diag || linecount <= 1)
 606                 linecount = 24;
 607
 608         diag = kdbgetintenv("COLUMNS", &colcount);
 609         if (diag || colcount <= 1)
 610                 colcount = 80;
 611
 612         diag = kdbgetintenv("LOGGING", &logging);
 613         if (diag)
 614                 logging = 0;
 615
 616         if (!kdb_grepping_flag || suspend_grep) {
 617                 /* normally, every vsnprintf starts a new buffer */
 618                 next_avail = kdb_buffer;
 619                 size_avail = sizeof(kdb_buffer);
 620         }
 621         vsnprintf(next_avail, size_avail, fmt, ap);
 622
 623         /*
 624          * If kdb_parse() found that the command was cmd xxx | grep yyy
 625          * then kdb_grepping_flag is set, and kdb_grep_string contains yyy
 626          *
 627          * Accumulate the print data up to a newline before searching it.
 628          * (vsnprintf does null-terminate the string that it generates)
 629          */
 630
 631         /* skip the search if prints are temporarily unconditional */
 632         if (!suspend_grep && kdb_grepping_flag) {
 633                 cp = strchr(kdb_buffer, '\n');
 634                 if (!cp) {
 635                         /*
 636                          * Special cases that don't end with newlines
 637                          * but should be written without one:
 638                          *   The "[nn]kdb> " prompt should
 639                          *   appear at the front of the buffer.
 640                          *
 641                          *   The "[nn]more " prompt should also be
 642                          *     (MOREPROMPT -> moreprompt)
 643                          *   written *   but we print that ourselves,
 644                          *   we set the suspend_grep flag to make
 645                          *   it unconditional.
 646                          *
 647                          */
 648                         if (next_avail == kdb_buffer) {
 649                                 /*
 650                                  * these should occur after a newline,
 651                                  * so they will be at the front of the
 652                                  * buffer
 653                                  */
 654                                 cp2 = kdb_buffer;
 655                                 len = strlen(kdb_prompt_str);
 656                                 if (!strncmp(cp2, kdb_prompt_str, len)) {
 657                                         /*
 658                                          * We're about to start a new
 659                                          * command, so we can go back
 660                                          * to normal mode.
 661                                          */
 662                                         kdb_grepping_flag = 0;
 663                                         goto kdb_printit;
 664                                 }
 665                         }
 666                         /* no newline; don't search/write the buffer
 667                            until one is there */
 668                         len = strlen(kdb_buffer);
 669                         next_avail = kdb_buffer + len;
 670                         size_avail = sizeof(kdb_buffer) - len;
 671                         goto kdb_print_out;
 672                 }
 673
 674                 /*
 675                  * The newline is present; print through it or discard
 676                  * it, depending on the results of the search.
 677                  */
 678                 cp++;                /* to byte after the newline */
 679                 replaced_byte = *cp; /* remember what/where it was */
 680                 cphold = cp;
 681                 *cp = '\0';          /* end the string for our search */
 682
 683                 /*
 684                  * We now have a newline at the end of the string
 685                  * Only continue with this output if it contains the
 686                  * search string.
 687                  */
 688                 fnd = kdb_search_string(kdb_buffer, kdb_grep_string);
 689                 if (!fnd) {
 690                         /*
 691                          * At this point the complete line at the start
 692                          * of kdb_buffer can be discarded, as it does
 693                          * not contain what the user is looking for.
 694                          * Shift the buffer left.
 695                          */
 696                         *cphold = replaced_byte;
 697                         strcpy(kdb_buffer, cphold);
 698                         len = strlen(kdb_buffer);
 699                         next_avail = kdb_buffer + len;
 700                         size_avail = sizeof(kdb_buffer) - len;
 701                         goto kdb_print_out;
 702                 }
 703                 if (kdb_grepping_flag >= KDB_GREPPING_FLAG_SEARCH) {
 704                         /*
 705                          * This was a interactive search (using '/' at more
 706                          * prompt) and it has completed. Replace the \0 with
 707                          * its original value to ensure multi-line strings
 708                          * are handled properly, and return to normal mode.
 709                          */
 710                         *cphold = replaced_byte;
 711                         kdb_grepping_flag = 0;
 712                 }
 713                 /*
 714                  * at this point the string is a full line and
 715                  * should be printed, up to the null.
 716                  */
 717         }
 718 kdb_printit:
 719
 720         /*
 721          * Write to all consoles.
 722          */
 723         retlen = strlen(kdb_buffer);
 724         cp = (char *) printk_skip_headers(kdb_buffer);
 725         if (!dbg_kdb_mode && kgdb_connected)
 726                 gdbstub_msg_write(cp, retlen - (cp - kdb_buffer));
 727         else
 728                 kdb_msg_write(cp, retlen - (cp - kdb_buffer));
 729
 730         if (logging) {
 731                 saved_loglevel = console_loglevel;
 732                 console_loglevel = CONSOLE_LOGLEVEL_SILENT;
 733                 if (printk_get_level(kdb_buffer) || src == KDB_MSGSRC_PRINTK)
 734                         printk("%s", kdb_buffer);
 735                 else
 736                         pr_info("%s", kdb_buffer);
 737         }
 738
 739         if (KDB_STATE(PAGER)) {
 740                 /*
 741                  * Check printed string to decide how to bump the
 742                  * kdb_nextline to control when the more prompt should
 743                  * show up.
 744                  */
 745                 int got = 0;
 746                 len = retlen;
 747                 while (len--) {
 748                         if (kdb_buffer[len] == '\n') {
 749                                 kdb_nextline++;
 750                                 got = 0;
 751                         } else if (kdb_buffer[len] == '\r') {
 752                                 got = 0;
 753                         } else {
 754                                 got++;
 755                         }
 756                 }
 757                 kdb_nextline += got / (colcount + 1);
 758         }
 759
 760         /* check for having reached the LINES number of printed lines */
 761         if (kdb_nextline >= linecount) {
 762                 char ch;
 763
 764                 /* Watch out for recursion here.  Any routine that calls
 765                  * kdb_printf will come back through here.  And kdb_read
 766                  * uses kdb_printf to echo on serial consoles ...
 767                  */
 768                 kdb_nextline = 1;       /* In case of recursion */
 769
 770                 /*
 771                  * Pause until cr.
 772                  */
 773                 moreprompt = kdbgetenv("MOREPROMPT");
 774                 if (moreprompt == NULL)
 775                         moreprompt = "more> ";
 776
 777                 kdb_input_flush();
 778                 kdb_msg_write(moreprompt, strlen(moreprompt));
 779
 780                 if (logging)
 781                         printk("%s", moreprompt);
 782
 783                 ch = kdb_getchar();
 784                 kdb_nextline = 1;       /* Really set output line 1 */
 785
 786                 /* empty and reset the buffer: */
 787                 kdb_buffer[0] = '\0';
 788                 next_avail = kdb_buffer;
 789                 size_avail = sizeof(kdb_buffer);
 790                 if ((ch == 'q') || (ch == 'Q')) {
 791                         /* user hit q or Q */
 792                         KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
 793                         KDB_STATE_CLEAR(PAGER);
 794                         /* end of command output; back to normal mode */
 795                         kdb_grepping_flag = 0;
 796                         kdb_printf("\n");
 797                 } else if (ch == ' ') {
 798                         kdb_printf("\r");
 799                         suspend_grep = 1; /* for this recursion */
 800                 } else if (ch == '\n' || ch == '\r') {
 801                         kdb_nextline = linecount - 1;
 802                         kdb_printf("\r");
 803                         suspend_grep = 1; /* for this recursion */
 804                 } else if (ch == '/' && !kdb_grepping_flag) {
 805                         kdb_printf("\r");
 806                         kdb_getstr(kdb_grep_string, KDB_GREP_STRLEN,
 807                                    kdbgetenv("SEARCHPROMPT") ?: "search> ");
 808                         *strchrnul(kdb_grep_string, '\n') = '\0';
 809                         kdb_grepping_flag += KDB_GREPPING_FLAG_SEARCH;
 810                         suspend_grep = 1; /* for this recursion */
 811                 } else if (ch) {
 812                         /* user hit something unexpected */
 813                         suspend_grep = 1; /* for this recursion */
 814                         if (ch != '/')
 815                                 kdb_printf(
 816                                     "\nOnly 'q', 'Q' or '/' are processed at "
 817                                     "more prompt, input ignored\n");
 818                         else
 819                                 kdb_printf("\n'/' cannot be used during | "
 820                                            "grep filtering, input ignored\n");
 821                 } else if (kdb_grepping_flag) {
 822                         /* user hit enter */
 823                         suspend_grep = 1; /* for this recursion */
 824                         kdb_printf("\n");
 825                 }
 826                 kdb_input_flush();
 827         }
 828
 829         /*
 830          * For grep searches, shift the printed string left.
 831          *  replaced_byte contains the character that was overwritten with
 832          *  the terminating null, and cphold points to the null.
 833          * Then adjust the notion of available space in the buffer.
 834          */
 835         if (kdb_grepping_flag && !suspend_grep) {
 836                 *cphold = replaced_byte;
 837                 strcpy(kdb_buffer, cphold);
 838                 len = strlen(kdb_buffer);
 839                 next_avail = kdb_buffer + len;
 840                 size_avail = sizeof(kdb_buffer) - len;
 841         }
 842
 843 kdb_print_out:
 844         suspend_grep = 0; /* end of what may have been a recursive call */
 845         if (logging)
 846                 console_loglevel = saved_loglevel;
 847         /* kdb_printf_cpu locked the code above. */
 848         smp_store_release(&kdb_printf_cpu, old_cpu);
 849         local_irq_restore(flags);
 850         return retlen;
 851 }
 852
 853 int kdb_printf(const char *fmt, ...)
 854 {
 855         va_list ap;
 856         int r;
 857
 858         va_start(ap, fmt);
 859         r = vkdb_printf(KDB_MSGSRC_INTERNAL, fmt, ap);
 860         va_end(ap);
 861
 862         return r;
 863 }
 864 EXPORT_SYMBOL_GPL(kdb_printf);