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/types.h>
  13 #include <linux/ctype.h>
  14 #include <linux/kernel.h>
  15 #include <linux/init.h>
  16 #include <linux/kdev_t.h>
  17 #include <linux/console.h>
  18 #include <linux/string.h>
  19 #include <linux/sched.h>
  20 #include <linux/smp.h>
  21 #include <linux/nmi.h>
  22 #include <linux/delay.h>
  23 #include <linux/kgdb.h>
  24 #include <linux/kdb.h>
  25 #include <linux/kallsyms.h>
  26 #include "kdb_private.h"
  27
  28 #define CMD_BUFLEN 256
  29 char kdb_prompt_str[CMD_BUFLEN];
  30
  31 int kdb_trap_printk;
  32 int kdb_printf_cpu = -1;
  33
  34 static int kgdb_transition_check(char *buffer)
  35 {
  36         if (buffer[0] != '+' && buffer[0] != '$') {
  37                 KDB_STATE_SET(KGDB_TRANS);
  38                 kdb_printf("%s", buffer);
  39         } else {
  40                 int slen = strlen(buffer);
  41                 if (slen > 3 && buffer[slen - 3] == '#') {
  42                         kdb_gdb_state_pass(buffer);
  43                         strcpy(buffer, "kgdb");
  44                         KDB_STATE_SET(DOING_KGDB);
  45                         return 1;
  46                 }
  47         }
  48         return 0;
  49 }
  50
  51 /**
  52  * kdb_handle_escape() - validity check on an accumulated escape sequence.
  53  * @buf:        Accumulated escape characters to be examined. Note that buf
  54  *              is not a string, it is an array of characters and need not be
  55  *              nil terminated.
  56  * @sz:         Number of accumulated escape characters.
  57  *
  58  * Return: -1 if the escape sequence is unwanted, 0 if it is incomplete,
  59  * otherwise it returns a mapped key value to pass to the upper layers.
  60  */
  61 static int kdb_handle_escape(char *buf, size_t sz)
  62 {
  63         char *lastkey = buf + sz - 1;
  64
  65         switch (sz) {
  66         case 1:
  67                 if (*lastkey == '\e')
  68                         return 0;
  69                 break;
  70
  71         case 2: /* \e<something> */
  72                 if (*lastkey == '[')
  73                         return 0;
  74                 break;
  75
  76         case 3:
  77                 switch (*lastkey) {
  78                 case 'A': /* \e[A, up arrow */
  79                         return 16;
  80                 case 'B': /* \e[B, down arrow */
  81                         return 14;
  82                 case 'C': /* \e[C, right arrow */
  83                         return 6;
  84                 case 'D': /* \e[D, left arrow */
  85                         return 2;
  86                 case '1': /* \e[<1,3,4>], may be home, del, end */
  87                 case '3':
  88                 case '4':
  89                         return 0;
  90                 }
  91                 break;
  92
  93         case 4:
  94                 if (*lastkey == '~') {
  95                         switch (buf[2]) {
  96                         case '1': /* \e[1~, home */
  97                                 return 1;
  98                         case '3': /* \e[3~, del */
  99                                 return 4;
 100                         case '4': /* \e[4~, end */
 101                                 return 5;
 102                         }
 103                 }
 104                 break;
 105         }
 106
 107         return -1;
 108 }
 109
 110 /**
 111  * kdb_getchar() - Read a single character from a kdb console (or consoles).
 112  *
 113  * Other than polling the various consoles that are currently enabled,
 114  * most of the work done in this function is dealing with escape sequences.
 115  *
 116  * An escape key could be the start of a vt100 control sequence such as \e[D
 117  * (left arrow) or it could be a character in its own right.  The standard
 118  * method for detecting the difference is to wait for 2 seconds to see if there
 119  * are any other characters.  kdb is complicated by the lack of a timer service
 120  * (interrupts are off), by multiple input sources. Escape sequence processing
 121  * has to be done as states in the polling loop.
 122  *
 123  * Return: The key pressed or a control code derived from an escape sequence.
 124  */
 125 char kdb_getchar(void)
 126 {
 127 #define ESCAPE_UDELAY 1000
 128 #define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
 129         char buf[4];    /* longest vt100 escape sequence is 4 bytes */
 130         char *pbuf = buf;
 131         int escape_delay = 0;
 132         get_char_func *f, *f_prev = NULL;
 133         int key;
 134         static bool last_char_was_cr;
 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                  * The caller expects that newlines are either CR or LF. However
 155                  * some terminals send _both_ CR and LF. Avoid having to handle
 156                  * this in the caller by stripping the LF if we saw a CR right
 157                  * before.
 158                  */
 159                 if (last_char_was_cr && key == '\n') {
 160                         last_char_was_cr = false;
 161                         continue;
 162                 }
 163                 last_char_was_cr = (key == '\r');
 164
 165                 /*
 166                  * When the first character is received (or we get a change
 167                  * input source) we set ourselves up to handle an escape
 168                  * sequences (just in case).
 169                  */
 170                 if (f_prev != f) {
 171                         f_prev = f;
 172                         pbuf = buf;
 173                         escape_delay = ESCAPE_DELAY;
 174                 }
 175
 176                 *pbuf++ = key;
 177                 key = kdb_handle_escape(buf, pbuf - buf);
 178                 if (key < 0) /* no escape sequence; return best character */
 179                         return buf[pbuf - buf == 2 ? 1 : 0];
 180                 if (key > 0)
 181                         return key;
 182         }
 183
 184         unreachable();
 185 }
 186
 187 /*
 188  * kdb_read
 189  *
 190  *      This function reads a string of characters, terminated by
 191  *      a newline, or by reaching the end of the supplied buffer,
 192  *      from the current kernel debugger console device.
 193  * Parameters:
 194  *      buffer  - Address of character buffer to receive input characters.
 195  *      bufsize - size, in bytes, of the character buffer
 196  * Returns:
 197  *      Returns a pointer to the buffer containing the received
 198  *      character string.  This string will be terminated by a
 199  *      newline character.
 200  * Locking:
 201  *      No locks are required to be held upon entry to this
 202  *      function.  It is not reentrant - it relies on the fact
 203  *      that while kdb is running on only one "master debug" cpu.
 204  * Remarks:
 205  *      The buffer size must be >= 2.
 206  */
 207
 208 static char *kdb_read(char *buffer, size_t bufsize)
 209 {
 210         char *cp = buffer;
 211         char *bufend = buffer+bufsize-2;        /* Reserve space for newline
 212                                                  * and null byte */
 213         char *lastchar;
 214         char *p_tmp;
 215         char tmp;
 216         static char tmpbuffer[CMD_BUFLEN];
 217         int len = strlen(buffer);
 218         int len_tmp;
 219         int tab = 0;
 220         int count;
 221         int i;
 222         int diag, dtab_count;
 223         int key, buf_size, ret;
 224
 225
 226         diag = kdbgetintenv("DTABCOUNT", &dtab_count);
 227         if (diag)
 228                 dtab_count = 30;
 229
 230         if (len > 0) {
 231                 cp += len;
 232                 if (*(buffer+len-1) == '\n')
 233                         cp--;
 234         }
 235
 236         lastchar = cp;
 237         *cp = '\0';
 238         kdb_printf("%s", buffer);
 239 poll_again:
 240         key = kdb_getchar();
 241         if (key != 9)
 242                 tab = 0;
 243         switch (key) {
 244         case 8: /* backspace */
 245                 if (cp > buffer) {
 246                         if (cp < lastchar) {
 247                                 memcpy(tmpbuffer, cp, lastchar - cp);
 248                                 memcpy(cp-1, tmpbuffer, lastchar - cp);
 249                         }
 250                         *(--lastchar) = '\0';
 251                         --cp;
 252                         kdb_printf("\b%s \r", cp);
 253                         tmp = *cp;
 254                         *cp = '\0';
 255                         kdb_printf(kdb_prompt_str);
 256                         kdb_printf("%s", buffer);
 257                         *cp = tmp;
 258                 }
 259                 break;
 260         case 10: /* linefeed */
 261         case 13: /* carriage return */
 262                 *lastchar++ = '\n';
 263                 *lastchar++ = '\0';
 264                 if (!KDB_STATE(KGDB_TRANS)) {
 265                         KDB_STATE_SET(KGDB_TRANS);
 266                         kdb_printf("%s", buffer);
 267                 }
 268                 kdb_printf("\n");
 269                 return buffer;
 270         case 4: /* Del */
 271                 if (cp < lastchar) {
 272                         memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
 273                         memcpy(cp, tmpbuffer, lastchar - cp - 1);
 274                         *(--lastchar) = '\0';
 275                         kdb_printf("%s \r", cp);
 276                         tmp = *cp;
 277                         *cp = '\0';
 278                         kdb_printf(kdb_prompt_str);
 279                         kdb_printf("%s", buffer);
 280                         *cp = tmp;
 281                 }
 282                 break;
 283         case 1: /* Home */
 284                 if (cp > buffer) {
 285                         kdb_printf("\r");
 286                         kdb_printf(kdb_prompt_str);
 287                         cp = buffer;
 288                 }
 289                 break;
 290         case 5: /* End */
 291                 if (cp < lastchar) {
 292                         kdb_printf("%s", cp);
 293                         cp = lastchar;
 294                 }
 295                 break;
 296         case 2: /* Left */
 297                 if (cp > buffer) {
 298                         kdb_printf("\b");
 299                         --cp;
 300                 }
 301                 break;
 302         case 14: /* Down */
 303                 memset(tmpbuffer, ' ',
 304                        strlen(kdb_prompt_str) + (lastchar-buffer));
 305                 *(tmpbuffer+strlen(kdb_prompt_str) +
 306                   (lastchar-buffer)) = '\0';
 307                 kdb_printf("\r%s\r", tmpbuffer);
 308                 *lastchar = (char)key;
 309                 *(lastchar+1) = '\0';
 310                 return lastchar;
 311         case 6: /* Right */
 312                 if (cp < lastchar) {
 313                         kdb_printf("%c", *cp);
 314                         ++cp;
 315                 }
 316                 break;
 317         case 16: /* Up */
 318                 memset(tmpbuffer, ' ',
 319                        strlen(kdb_prompt_str) + (lastchar-buffer));
 320                 *(tmpbuffer+strlen(kdb_prompt_str) +
 321                   (lastchar-buffer)) = '\0';
 322                 kdb_printf("\r%s\r", tmpbuffer);
 323                 *lastchar = (char)key;
 324                 *(lastchar+1) = '\0';
 325                 return lastchar;
 326         case 9: /* Tab */
 327                 if (tab < 2)
 328                         ++tab;
 329                 p_tmp = buffer;
 330                 while (*p_tmp == ' ')
 331                         p_tmp++;
 332                 if (p_tmp > cp)
 333                         break;
 334                 memcpy(tmpbuffer, p_tmp, cp-p_tmp);
 335                 *(tmpbuffer + (cp-p_tmp)) = '\0';
 336                 p_tmp = strrchr(tmpbuffer, ' ');
 337                 if (p_tmp)
 338                         ++p_tmp;
 339                 else
 340                         p_tmp = tmpbuffer;
 341                 len = strlen(p_tmp);
 342                 buf_size = sizeof(tmpbuffer) - (p_tmp - tmpbuffer);
 343                 count = kallsyms_symbol_complete(p_tmp, buf_size);
 344                 if (tab == 2 && count > 0) {
 345                         kdb_printf("\n%d symbols are found.", count);
 346                         if (count > dtab_count) {
 347                                 count = dtab_count;
 348                                 kdb_printf(" But only first %d symbols will"
 349                                            " be printed.\nYou can change the"
 350                                            " environment variable DTABCOUNT.",
 351                                            count);
 352                         }
 353                         kdb_printf("\n");
 354                         for (i = 0; i < count; i++) {
 355                                 ret = kallsyms_symbol_next(p_tmp, i, buf_size);
 356                                 if (WARN_ON(!ret))
 357                                         break;
 358                                 if (ret != -E2BIG)
 359                                         kdb_printf("%s ", p_tmp);
 360                                 else
 361                                         kdb_printf("%s... ", p_tmp);
 362                                 *(p_tmp + len) = '\0';
 363                         }
 364                         if (i >= dtab_count)
 365                                 kdb_printf("...");
 366                         kdb_printf("\n");
 367                         kdb_printf(kdb_prompt_str);
 368                         kdb_printf("%s", buffer);
 369                 } else if (tab != 2 && count > 0) {
 370                         len_tmp = strlen(p_tmp);
 371                         strncpy(p_tmp+len_tmp, cp, lastchar-cp+1);
 372                         len_tmp = strlen(p_tmp);
 373                         strncpy(cp, p_tmp+len, len_tmp-len + 1);
 374                         len = len_tmp - len;
 375                         kdb_printf("%s", cp);
 376                         cp += len;
 377                         lastchar += len;
 378                 }
 379                 kdb_nextline = 1; /* reset output line number */
 380                 break;
 381         default:
 382                 if (key >= 32 && lastchar < bufend) {
 383                         if (cp < lastchar) {
 384                                 memcpy(tmpbuffer, cp, lastchar - cp);
 385                                 memcpy(cp+1, tmpbuffer, lastchar - cp);
 386                                 *++lastchar = '\0';
 387                                 *cp = key;
 388                                 kdb_printf("%s\r", cp);
 389                                 ++cp;
 390                                 tmp = *cp;
 391                                 *cp = '\0';
 392                                 kdb_printf(kdb_prompt_str);
 393                                 kdb_printf("%s", buffer);
 394                                 *cp = tmp;
 395                         } else {
 396                                 *++lastchar = '\0';
 397                                 *cp++ = key;
 398                                 /* The kgdb transition check will hide
 399                                  * printed characters if we think that
 400                                  * kgdb is connecting, until the check
 401                                  * fails */
 402                                 if (!KDB_STATE(KGDB_TRANS)) {
 403                                         if (kgdb_transition_check(buffer))
 404                                                 return buffer;
 405                                 } else {
 406                                         kdb_printf("%c", key);
 407                                 }
 408                         }
 409                         /* Special escape to kgdb */
 410                         if (lastchar - buffer >= 5 &&
 411                             strcmp(lastchar - 5, "$?#3f") == 0) {
 412                                 kdb_gdb_state_pass(lastchar - 5);
 413                                 strcpy(buffer, "kgdb");
 414                                 KDB_STATE_SET(DOING_KGDB);
 415                                 return buffer;
 416                         }
 417                         if (lastchar - buffer >= 11 &&
 418                             strcmp(lastchar - 11, "$qSupported") == 0) {
 419                                 kdb_gdb_state_pass(lastchar - 11);
 420                                 strcpy(buffer, "kgdb");
 421                                 KDB_STATE_SET(DOING_KGDB);
 422                                 return buffer;
 423                         }
 424                 }
 425                 break;
 426         }
 427         goto poll_again;
 428 }
 429
 430 /*
 431  * kdb_getstr
 432  *
 433  *      Print the prompt string and read a command from the
 434  *      input device.
 435  *
 436  * Parameters:
 437  *      buffer  Address of buffer to receive command
 438  *      bufsize Size of buffer in bytes
 439  *      prompt  Pointer to string to use as prompt string
 440  * Returns:
 441  *      Pointer to command buffer.
 442  * Locking:
 443  *      None.
 444  * Remarks:
 445  *      For SMP kernels, the processor number will be
 446  *      substituted for %d, %x or %o in the prompt.
 447  */
 448
 449 char *kdb_getstr(char *buffer, size_t bufsize, const char *prompt)
 450 {
 451         if (prompt && kdb_prompt_str != prompt)
 452                 strscpy(kdb_prompt_str, prompt, CMD_BUFLEN);
 453         kdb_printf(kdb_prompt_str);
 454         kdb_nextline = 1;       /* Prompt and input resets line number */
 455         return kdb_read(buffer, bufsize);
 456 }
 457
 458 /*
 459  * kdb_input_flush
 460  *
 461  *      Get rid of any buffered console input.
 462  *
 463  * Parameters:
 464  *      none
 465  * Returns:
 466  *      nothing
 467  * Locking:
 468  *      none
 469  * Remarks:
 470  *      Call this function whenever you want to flush input.  If there is any
 471  *      outstanding input, it ignores all characters until there has been no
 472  *      data for approximately 1ms.
 473  */
 474
 475 static void kdb_input_flush(void)
 476 {
 477         get_char_func *f;
 478         int res;
 479         int flush_delay = 1;
 480         while (flush_delay) {
 481                 flush_delay--;
 482 empty:
 483                 touch_nmi_watchdog();
 484                 for (f = &kdb_poll_funcs[0]; *f; ++f) {
 485                         res = (*f)();
 486                         if (res != -1) {
 487                                 flush_delay = 1;
 488                                 goto empty;
 489                         }
 490                 }
 491                 if (flush_delay)
 492                         mdelay(1);
 493         }
 494 }
 495
 496 /*
 497  * kdb_printf
 498  *
 499  *      Print a string to the output device(s).
 500  *
 501  * Parameters:
 502  *      printf-like format and optional args.
 503  * Returns:
 504  *      0
 505  * Locking:
 506  *      None.
 507  * Remarks:
 508  *      use 'kdbcons->write()' to avoid polluting 'log_buf' with
 509  *      kdb output.
 510  *
 511  *  If the user is doing a cmd args | grep srch
 512  *  then kdb_grepping_flag is set.
 513  *  In that case we need to accumulate full lines (ending in \n) before
 514  *  searching for the pattern.
 515  */
 516
 517 static char kdb_buffer[256];    /* A bit too big to go on stack */
 518 static char *next_avail = kdb_buffer;
 519 static int  size_avail;
 520 static int  suspend_grep;
 521
 522 /*
 523  * search arg1 to see if it contains arg2
 524  * (kdmain.c provides flags for ^pat and pat$)
 525  *
 526  * return 1 for found, 0 for not found
 527  */
 528 static int kdb_search_string(char *searched, char *searchfor)
 529 {
 530         char firstchar, *cp;
 531         int len1, len2;
 532
 533         /* not counting the newline at the end of "searched" */
 534         len1 = strlen(searched)-1;
 535         len2 = strlen(searchfor);
 536         if (len1 < len2)
 537                 return 0;
 538         if (kdb_grep_leading && kdb_grep_trailing && len1 != len2)
 539                 return 0;
 540         if (kdb_grep_leading) {
 541                 if (!strncmp(searched, searchfor, len2))
 542                         return 1;
 543         } else if (kdb_grep_trailing) {
 544                 if (!strncmp(searched+len1-len2, searchfor, len2))
 545                         return 1;
 546         } else {
 547                 firstchar = *searchfor;
 548                 cp = searched;
 549                 while ((cp = strchr(cp, firstchar))) {
 550                         if (!strncmp(cp, searchfor, len2))
 551                                 return 1;
 552                         cp++;
 553                 }
 554         }
 555         return 0;
 556 }
 557
 558 static void kdb_msg_write(const char *msg, int msg_len)
 559 {
 560         struct console *c;
 561         const char *cp;
 562         int cookie;
 563         int len;
 564
 565         if (msg_len == 0)
 566                 return;
 567
 568         cp = msg;
 569         len = msg_len;
 570
 571         while (len--) {
 572                 dbg_io_ops->write_char(*cp);
 573                 cp++;
 574         }
 575
 576         /*
 577          * The console_srcu_read_lock() only provides safe console list
 578          * traversal. The use of the ->write() callback relies on all other
 579          * CPUs being stopped at the moment and console drivers being able to
 580          * handle reentrance when @oops_in_progress is set.
 581          *
 582          * There is no guarantee that every console driver can handle
 583          * reentrance in this way; the developer deploying the debugger
 584          * is responsible for ensuring that the console drivers they
 585          * have selected handle reentrance appropriately.
 586          */
 587         cookie = console_srcu_read_lock();
 588         for_each_console_srcu(c) {
 589                 if (!(console_srcu_read_flags(c) & CON_ENABLED))
 590                         continue;
 591                 if (c == dbg_io_ops->cons)
 592                         continue;
 593                 if (!c->write)
 594                         continue;
 595                 /*
 596                  * Set oops_in_progress to encourage the console drivers to
 597                  * disregard their internal spin locks: in the current calling
 598                  * context the risk of deadlock is a bigger problem than risks
 599                  * due to re-entering the console driver. We operate directly on
 600                  * oops_in_progress rather than using bust_spinlocks() because
 601                  * the calls bust_spinlocks() makes on exit are not appropriate
 602                  * for this calling context.
 603                  */
 604                 ++oops_in_progress;
 605                 c->write(c, msg, msg_len);
 606                 --oops_in_progress;
 607                 touch_nmi_watchdog();
 608         }
 609         console_srcu_read_unlock(cookie);
 610 }
 611
 612 int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
 613 {
 614         int diag;
 615         int linecount;
 616         int colcount;
 617         int logging, saved_loglevel = 0;
 618         int retlen = 0;
 619         int fnd, len;
 620         int this_cpu, old_cpu;
 621         char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
 622         char *moreprompt = "more> ";
 623         unsigned long flags;
 624
 625         /* Serialize kdb_printf if multiple cpus try to write at once.
 626          * But if any cpu goes recursive in kdb, just print the output,
 627          * even if it is interleaved with any other text.
 628          */
 629         local_irq_save(flags);
 630         this_cpu = smp_processor_id();
 631         for (;;) {
 632                 old_cpu = cmpxchg(&kdb_printf_cpu, -1, this_cpu);
 633                 if (old_cpu == -1 || old_cpu == this_cpu)
 634                         break;
 635
 636                 cpu_relax();
 637         }
 638
 639         diag = kdbgetintenv("LINES", &linecount);
 640         if (diag || linecount <= 1)
 641                 linecount = 24;
 642
 643         diag = kdbgetintenv("COLUMNS", &colcount);
 644         if (diag || colcount <= 1)
 645                 colcount = 80;
 646
 647         diag = kdbgetintenv("LOGGING", &logging);
 648         if (diag)
 649                 logging = 0;
 650
 651         if (!kdb_grepping_flag || suspend_grep) {
 652                 /* normally, every vsnprintf starts a new buffer */
 653                 next_avail = kdb_buffer;
 654                 size_avail = sizeof(kdb_buffer);
 655         }
 656         vsnprintf(next_avail, size_avail, fmt, ap);
 657
 658         /*
 659          * If kdb_parse() found that the command was cmd xxx | grep yyy
 660          * then kdb_grepping_flag is set, and kdb_grep_string contains yyy
 661          *
 662          * Accumulate the print data up to a newline before searching it.
 663          * (vsnprintf does null-terminate the string that it generates)
 664          */
 665
 666         /* skip the search if prints are temporarily unconditional */
 667         if (!suspend_grep && kdb_grepping_flag) {
 668                 cp = strchr(kdb_buffer, '\n');
 669                 if (!cp) {
 670                         /*
 671                          * Special cases that don't end with newlines
 672                          * but should be written without one:
 673                          *   The "[nn]kdb> " prompt should
 674                          *   appear at the front of the buffer.
 675                          *
 676                          *   The "[nn]more " prompt should also be
 677                          *     (MOREPROMPT -> moreprompt)
 678                          *   written *   but we print that ourselves,
 679                          *   we set the suspend_grep flag to make
 680                          *   it unconditional.
 681                          *
 682                          */
 683                         if (next_avail == kdb_buffer) {
 684                                 /*
 685                                  * these should occur after a newline,
 686                                  * so they will be at the front of the
 687                                  * buffer
 688                                  */
 689                                 cp2 = kdb_buffer;
 690                                 len = strlen(kdb_prompt_str);
 691                                 if (!strncmp(cp2, kdb_prompt_str, len)) {
 692                                         /*
 693                                          * We're about to start a new
 694                                          * command, so we can go back
 695                                          * to normal mode.
 696                                          */
 697                                         kdb_grepping_flag = 0;
 698                                         goto kdb_printit;
 699                                 }
 700                         }
 701                         /* no newline; don't search/write the buffer
 702                            until one is there */
 703                         len = strlen(kdb_buffer);
 704                         next_avail = kdb_buffer + len;
 705                         size_avail = sizeof(kdb_buffer) - len;
 706                         goto kdb_print_out;
 707                 }
 708
 709                 /*
 710                  * The newline is present; print through it or discard
 711                  * it, depending on the results of the search.
 712                  */
 713                 cp++;                /* to byte after the newline */
 714                 replaced_byte = *cp; /* remember what/where it was */
 715                 cphold = cp;
 716                 *cp = '\0';          /* end the string for our search */
 717
 718                 /*
 719                  * We now have a newline at the end of the string
 720                  * Only continue with this output if it contains the
 721                  * search string.
 722                  */
 723                 fnd = kdb_search_string(kdb_buffer, kdb_grep_string);
 724                 if (!fnd) {
 725                         /*
 726                          * At this point the complete line at the start
 727                          * of kdb_buffer can be discarded, as it does
 728                          * not contain what the user is looking for.
 729                          * Shift the buffer left.
 730                          */
 731                         *cphold = replaced_byte;
 732                         strcpy(kdb_buffer, cphold);
 733                         len = strlen(kdb_buffer);
 734                         next_avail = kdb_buffer + len;
 735                         size_avail = sizeof(kdb_buffer) - len;
 736                         goto kdb_print_out;
 737                 }
 738                 if (kdb_grepping_flag >= KDB_GREPPING_FLAG_SEARCH) {
 739                         /*
 740                          * This was a interactive search (using '/' at more
 741                          * prompt) and it has completed. Replace the \0 with
 742                          * its original value to ensure multi-line strings
 743                          * are handled properly, and return to normal mode.
 744                          */
 745                         *cphold = replaced_byte;
 746                         kdb_grepping_flag = 0;
 747                 }
 748                 /*
 749                  * at this point the string is a full line and
 750                  * should be printed, up to the null.
 751                  */
 752         }
 753 kdb_printit:
 754
 755         /*
 756          * Write to all consoles.
 757          */
 758         retlen = strlen(kdb_buffer);
 759         cp = (char *) printk_skip_headers(kdb_buffer);
 760         if (!dbg_kdb_mode && kgdb_connected)
 761                 gdbstub_msg_write(cp, retlen - (cp - kdb_buffer));
 762         else
 763                 kdb_msg_write(cp, retlen - (cp - kdb_buffer));
 764
 765         if (logging) {
 766                 saved_loglevel = console_loglevel;
 767                 console_loglevel = CONSOLE_LOGLEVEL_SILENT;
 768                 if (printk_get_level(kdb_buffer) || src == KDB_MSGSRC_PRINTK)
 769                         printk("%s", kdb_buffer);
 770                 else
 771                         pr_info("%s", kdb_buffer);
 772         }
 773
 774         if (KDB_STATE(PAGER)) {
 775                 /*
 776                  * Check printed string to decide how to bump the
 777                  * kdb_nextline to control when the more prompt should
 778                  * show up.
 779                  */
 780                 int got = 0;
 781                 len = retlen;
 782                 while (len--) {
 783                         if (kdb_buffer[len] == '\n') {
 784                                 kdb_nextline++;
 785                                 got = 0;
 786                         } else if (kdb_buffer[len] == '\r') {
 787                                 got = 0;
 788                         } else {
 789                                 got++;
 790                         }
 791                 }
 792                 kdb_nextline += got / (colcount + 1);
 793         }
 794
 795         /* check for having reached the LINES number of printed lines */
 796         if (kdb_nextline >= linecount) {
 797                 char ch;
 798
 799                 /* Watch out for recursion here.  Any routine that calls
 800                  * kdb_printf will come back through here.  And kdb_read
 801                  * uses kdb_printf to echo on serial consoles ...
 802                  */
 803                 kdb_nextline = 1;       /* In case of recursion */
 804
 805                 /*
 806                  * Pause until cr.
 807                  */
 808                 moreprompt = kdbgetenv("MOREPROMPT");
 809                 if (moreprompt == NULL)
 810                         moreprompt = "more> ";
 811
 812                 kdb_input_flush();
 813                 kdb_msg_write(moreprompt, strlen(moreprompt));
 814
 815                 if (logging)
 816                         printk("%s", moreprompt);
 817
 818                 ch = kdb_getchar();
 819                 kdb_nextline = 1;       /* Really set output line 1 */
 820
 821                 /* empty and reset the buffer: */
 822                 kdb_buffer[0] = '\0';
 823                 next_avail = kdb_buffer;
 824                 size_avail = sizeof(kdb_buffer);
 825                 if ((ch == 'q') || (ch == 'Q')) {
 826                         /* user hit q or Q */
 827                         KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
 828                         KDB_STATE_CLEAR(PAGER);
 829                         /* end of command output; back to normal mode */
 830                         kdb_grepping_flag = 0;
 831                         kdb_printf("\n");
 832                 } else if (ch == ' ') {
 833                         kdb_printf("\r");
 834                         suspend_grep = 1; /* for this recursion */
 835                 } else if (ch == '\n' || ch == '\r') {
 836                         kdb_nextline = linecount - 1;
 837                         kdb_printf("\r");
 838                         suspend_grep = 1; /* for this recursion */
 839                 } else if (ch == '/' && !kdb_grepping_flag) {
 840                         kdb_printf("\r");
 841                         kdb_getstr(kdb_grep_string, KDB_GREP_STRLEN,
 842                                    kdbgetenv("SEARCHPROMPT") ?: "search> ");
 843                         *strchrnul(kdb_grep_string, '\n') = '\0';
 844                         kdb_grepping_flag += KDB_GREPPING_FLAG_SEARCH;
 845                         suspend_grep = 1; /* for this recursion */
 846                 } else if (ch) {
 847                         /* user hit something unexpected */
 848                         suspend_grep = 1; /* for this recursion */
 849                         if (ch != '/')
 850                                 kdb_printf(
 851                                     "\nOnly 'q', 'Q' or '/' are processed at "
 852                                     "more prompt, input ignored\n");
 853                         else
 854                                 kdb_printf("\n'/' cannot be used during | "
 855                                            "grep filtering, input ignored\n");
 856                 } else if (kdb_grepping_flag) {
 857                         /* user hit enter */
 858                         suspend_grep = 1; /* for this recursion */
 859                         kdb_printf("\n");
 860                 }
 861                 kdb_input_flush();
 862         }
 863
 864         /*
 865          * For grep searches, shift the printed string left.
 866          *  replaced_byte contains the character that was overwritten with
 867          *  the terminating null, and cphold points to the null.
 868          * Then adjust the notion of available space in the buffer.
 869          */
 870         if (kdb_grepping_flag && !suspend_grep) {
 871                 *cphold = replaced_byte;
 872                 strcpy(kdb_buffer, cphold);
 873                 len = strlen(kdb_buffer);
 874                 next_avail = kdb_buffer + len;
 875                 size_avail = sizeof(kdb_buffer) - len;
 876         }
 877
 878 kdb_print_out:
 879         suspend_grep = 0; /* end of what may have been a recursive call */
 880         if (logging)
 881                 console_loglevel = saved_loglevel;
 882         /* kdb_printf_cpu locked the code above. */
 883         smp_store_release(&kdb_printf_cpu, old_cpu);
 884         local_irq_restore(flags);
 885         return retlen;
 886 }
 887
 888 int kdb_printf(const char *fmt, ...)
 889 {
 890         va_list ap;
 891         int r;
 892
 893         va_start(ap, fmt);
 894         r = vkdb_printf(KDB_MSGSRC_INTERNAL, fmt, ap);
 895         va_end(ap);
 896
 897         return r;
 898 }
 899 EXPORT_SYMBOL_GPL(kdb_printf);