kdb,kgdb: Allow arbitrary kgdb magic knock sequences
[linux-3.10.git] / 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
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 static int kdb_read_get_key(char *buffer, size_t bufsize)
52 {
53 #define ESCAPE_UDELAY 1000
54 #define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
55         char escape_data[5];    /* longest vt100 escape sequence is 4 bytes */
56         char *ped = escape_data;
57         int escape_delay = 0;
58         get_char_func *f, *f_escape = NULL;
59         int key;
60
61         for (f = &kdb_poll_funcs[0]; ; ++f) {
62                 if (*f == NULL) {
63                         /* Reset NMI watchdog once per poll loop */
64                         touch_nmi_watchdog();
65                         f = &kdb_poll_funcs[0];
66                 }
67                 if (escape_delay == 2) {
68                         *ped = '\0';
69                         ped = escape_data;
70                         --escape_delay;
71                 }
72                 if (escape_delay == 1) {
73                         key = *ped++;
74                         if (!*ped)
75                                 --escape_delay;
76                         break;
77                 }
78                 key = (*f)();
79                 if (key == -1) {
80                         if (escape_delay) {
81                                 udelay(ESCAPE_UDELAY);
82                                 --escape_delay;
83                         }
84                         continue;
85                 }
86                 if (bufsize <= 2) {
87                         if (key == '\r')
88                                 key = '\n';
89                         *buffer++ = key;
90                         *buffer = '\0';
91                         return -1;
92                 }
93                 if (escape_delay == 0 && key == '\e') {
94                         escape_delay = ESCAPE_DELAY;
95                         ped = escape_data;
96                         f_escape = f;
97                 }
98                 if (escape_delay) {
99                         *ped++ = key;
100                         if (f_escape != f) {
101                                 escape_delay = 2;
102                                 continue;
103                         }
104                         if (ped - escape_data == 1) {
105                                 /* \e */
106                                 continue;
107                         } else if (ped - escape_data == 2) {
108                                 /* \e<something> */
109                                 if (key != '[')
110                                         escape_delay = 2;
111                                 continue;
112                         } else if (ped - escape_data == 3) {
113                                 /* \e[<something> */
114                                 int mapkey = 0;
115                                 switch (key) {
116                                 case 'A': /* \e[A, up arrow */
117                                         mapkey = 16;
118                                         break;
119                                 case 'B': /* \e[B, down arrow */
120                                         mapkey = 14;
121                                         break;
122                                 case 'C': /* \e[C, right arrow */
123                                         mapkey = 6;
124                                         break;
125                                 case 'D': /* \e[D, left arrow */
126                                         mapkey = 2;
127                                         break;
128                                 case '1': /* dropthrough */
129                                 case '3': /* dropthrough */
130                                 /* \e[<1,3,4>], may be home, del, end */
131                                 case '4':
132                                         mapkey = -1;
133                                         break;
134                                 }
135                                 if (mapkey != -1) {
136                                         if (mapkey > 0) {
137                                                 escape_data[0] = mapkey;
138                                                 escape_data[1] = '\0';
139                                         }
140                                         escape_delay = 2;
141                                 }
142                                 continue;
143                         } else if (ped - escape_data == 4) {
144                                 /* \e[<1,3,4><something> */
145                                 int mapkey = 0;
146                                 if (key == '~') {
147                                         switch (escape_data[2]) {
148                                         case '1': /* \e[1~, home */
149                                                 mapkey = 1;
150                                                 break;
151                                         case '3': /* \e[3~, del */
152                                                 mapkey = 4;
153                                                 break;
154                                         case '4': /* \e[4~, end */
155                                                 mapkey = 5;
156                                                 break;
157                                         }
158                                 }
159                                 if (mapkey > 0) {
160                                         escape_data[0] = mapkey;
161                                         escape_data[1] = '\0';
162                                 }
163                                 escape_delay = 2;
164                                 continue;
165                         }
166                 }
167                 break;  /* A key to process */
168         }
169         return key;
170 }
171
172 /*
173  * kdb_read
174  *
175  *      This function reads a string of characters, terminated by
176  *      a newline, or by reaching the end of the supplied buffer,
177  *      from the current kernel debugger console device.
178  * Parameters:
179  *      buffer  - Address of character buffer to receive input characters.
180  *      bufsize - size, in bytes, of the character buffer
181  * Returns:
182  *      Returns a pointer to the buffer containing the received
183  *      character string.  This string will be terminated by a
184  *      newline character.
185  * Locking:
186  *      No locks are required to be held upon entry to this
187  *      function.  It is not reentrant - it relies on the fact
188  *      that while kdb is running on only one "master debug" cpu.
189  * Remarks:
190  *
191  * The buffer size must be >= 2.  A buffer size of 2 means that the caller only
192  * wants a single key.
193  *
194  * An escape key could be the start of a vt100 control sequence such as \e[D
195  * (left arrow) or it could be a character in its own right.  The standard
196  * method for detecting the difference is to wait for 2 seconds to see if there
197  * are any other characters.  kdb is complicated by the lack of a timer service
198  * (interrupts are off), by multiple input sources and by the need to sometimes
199  * return after just one key.  Escape sequence processing has to be done as
200  * states in the polling loop.
201  */
202
203 static char *kdb_read(char *buffer, size_t bufsize)
204 {
205         char *cp = buffer;
206         char *bufend = buffer+bufsize-2;        /* Reserve space for newline
207                                                  * and null byte */
208         char *lastchar;
209         char *p_tmp;
210         char tmp;
211         static char tmpbuffer[CMD_BUFLEN];
212         int len = strlen(buffer);
213         int len_tmp;
214         int tab = 0;
215         int count;
216         int i;
217         int diag, dtab_count;
218         int key;
219
220
221         diag = kdbgetintenv("DTABCOUNT", &dtab_count);
222         if (diag)
223                 dtab_count = 30;
224
225         if (len > 0) {
226                 cp += len;
227                 if (*(buffer+len-1) == '\n')
228                         cp--;
229         }
230
231         lastchar = cp;
232         *cp = '\0';
233         kdb_printf("%s", buffer);
234 poll_again:
235         key = kdb_read_get_key(buffer, bufsize);
236         if (key == -1)
237                 return buffer;
238         if (key != 9)
239                 tab = 0;
240         switch (key) {
241         case 8: /* backspace */
242                 if (cp > buffer) {
243                         if (cp < lastchar) {
244                                 memcpy(tmpbuffer, cp, lastchar - cp);
245                                 memcpy(cp-1, tmpbuffer, lastchar - cp);
246                         }
247                         *(--lastchar) = '\0';
248                         --cp;
249                         kdb_printf("\b%s \r", cp);
250                         tmp = *cp;
251                         *cp = '\0';
252                         kdb_printf(kdb_prompt_str);
253                         kdb_printf("%s", buffer);
254                         *cp = tmp;
255                 }
256                 break;
257         case 13: /* enter */
258                 *lastchar++ = '\n';
259                 *lastchar++ = '\0';
260                 if (!KDB_STATE(KGDB_TRANS)) {
261                         KDB_STATE_SET(KGDB_TRANS);
262                         kdb_printf("%s", buffer);
263                 }
264                 kdb_printf("\n");
265                 return buffer;
266         case 4: /* Del */
267                 if (cp < lastchar) {
268                         memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
269                         memcpy(cp, tmpbuffer, lastchar - cp - 1);
270                         *(--lastchar) = '\0';
271                         kdb_printf("%s \r", cp);
272                         tmp = *cp;
273                         *cp = '\0';
274                         kdb_printf(kdb_prompt_str);
275                         kdb_printf("%s", buffer);
276                         *cp = tmp;
277                 }
278                 break;
279         case 1: /* Home */
280                 if (cp > buffer) {
281                         kdb_printf("\r");
282                         kdb_printf(kdb_prompt_str);
283                         cp = buffer;
284                 }
285                 break;
286         case 5: /* End */
287                 if (cp < lastchar) {
288                         kdb_printf("%s", cp);
289                         cp = lastchar;
290                 }
291                 break;
292         case 2: /* Left */
293                 if (cp > buffer) {
294                         kdb_printf("\b");
295                         --cp;
296                 }
297                 break;
298         case 14: /* Down */
299                 memset(tmpbuffer, ' ',
300                        strlen(kdb_prompt_str) + (lastchar-buffer));
301                 *(tmpbuffer+strlen(kdb_prompt_str) +
302                   (lastchar-buffer)) = '\0';
303                 kdb_printf("\r%s\r", tmpbuffer);
304                 *lastchar = (char)key;
305                 *(lastchar+1) = '\0';
306                 return lastchar;
307         case 6: /* Right */
308                 if (cp < lastchar) {
309                         kdb_printf("%c", *cp);
310                         ++cp;
311                 }
312                 break;
313         case 16: /* Up */
314                 memset(tmpbuffer, ' ',
315                        strlen(kdb_prompt_str) + (lastchar-buffer));
316                 *(tmpbuffer+strlen(kdb_prompt_str) +
317                   (lastchar-buffer)) = '\0';
318                 kdb_printf("\r%s\r", tmpbuffer);
319                 *lastchar = (char)key;
320                 *(lastchar+1) = '\0';
321                 return lastchar;
322         case 9: /* Tab */
323                 if (tab < 2)
324                         ++tab;
325                 p_tmp = buffer;
326                 while (*p_tmp == ' ')
327                         p_tmp++;
328                 if (p_tmp > cp)
329                         break;
330                 memcpy(tmpbuffer, p_tmp, cp-p_tmp);
331                 *(tmpbuffer + (cp-p_tmp)) = '\0';
332                 p_tmp = strrchr(tmpbuffer, ' ');
333                 if (p_tmp)
334                         ++p_tmp;
335                 else
336                         p_tmp = tmpbuffer;
337                 len = strlen(p_tmp);
338                 count = kallsyms_symbol_complete(p_tmp,
339                                                  sizeof(tmpbuffer) -
340                                                  (p_tmp - tmpbuffer));
341                 if (tab == 2 && count > 0) {
342                         kdb_printf("\n%d symbols are found.", count);
343                         if (count > dtab_count) {
344                                 count = dtab_count;
345                                 kdb_printf(" But only first %d symbols will"
346                                            " be printed.\nYou can change the"
347                                            " environment variable DTABCOUNT.",
348                                            count);
349                         }
350                         kdb_printf("\n");
351                         for (i = 0; i < count; i++) {
352                                 if (kallsyms_symbol_next(p_tmp, i) < 0)
353                                         break;
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, char *prompt)
443 {
444         if (prompt && kdb_prompt_str != prompt)
445                 strncpy(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(const char *fmt, va_list ap)
552 {
553         int diag;
554         int linecount;
555         int logging, saved_loglevel = 0;
556         int saved_trap_printk;
557         int got_printf_lock = 0;
558         int retlen = 0;
559         int fnd, len;
560         char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
561         char *moreprompt = "more> ";
562         struct console *c = console_drivers;
563         static DEFINE_SPINLOCK(kdb_printf_lock);
564         unsigned long uninitialized_var(flags);
565
566         preempt_disable();
567         saved_trap_printk = kdb_trap_printk;
568         kdb_trap_printk = 0;
569
570         /* Serialize kdb_printf if multiple cpus try to write at once.
571          * But if any cpu goes recursive in kdb, just print the output,
572          * even if it is interleaved with any other text.
573          */
574         if (!KDB_STATE(PRINTF_LOCK)) {
575                 KDB_STATE_SET(PRINTF_LOCK);
576                 spin_lock_irqsave(&kdb_printf_lock, flags);
577                 got_printf_lock = 1;
578                 atomic_inc(&kdb_event);
579         } else {
580                 __acquire(kdb_printf_lock);
581         }
582
583         diag = kdbgetintenv("LINES", &linecount);
584         if (diag || linecount <= 1)
585                 linecount = 24;
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                 /*
679                  * at this point the string is a full line and
680                  * should be printed, up to the null.
681                  */
682         }
683 kdb_printit:
684
685         /*
686          * Write to all consoles.
687          */
688         retlen = strlen(kdb_buffer);
689         if (!dbg_kdb_mode && kgdb_connected) {
690                 gdbstub_msg_write(kdb_buffer, retlen);
691         } else {
692                 if (!dbg_io_ops->is_console) {
693                         len = strlen(kdb_buffer);
694                         cp = kdb_buffer;
695                         while (len--) {
696                                 dbg_io_ops->write_char(*cp);
697                                 cp++;
698                         }
699                 }
700                 while (c) {
701                         c->write(c, kdb_buffer, retlen);
702                         touch_nmi_watchdog();
703                         c = c->next;
704                 }
705         }
706         if (logging) {
707                 saved_loglevel = console_loglevel;
708                 console_loglevel = 0;
709                 printk(KERN_INFO "%s", kdb_buffer);
710         }
711
712         if (KDB_STATE(PAGER) && strchr(kdb_buffer, '\n'))
713                 kdb_nextline++;
714
715         /* check for having reached the LINES number of printed lines */
716         if (kdb_nextline == linecount) {
717                 char buf1[16] = "";
718 #if defined(CONFIG_SMP)
719                 char buf2[32];
720 #endif
721
722                 /* Watch out for recursion here.  Any routine that calls
723                  * kdb_printf will come back through here.  And kdb_read
724                  * uses kdb_printf to echo on serial consoles ...
725                  */
726                 kdb_nextline = 1;       /* In case of recursion */
727
728                 /*
729                  * Pause until cr.
730                  */
731                 moreprompt = kdbgetenv("MOREPROMPT");
732                 if (moreprompt == NULL)
733                         moreprompt = "more> ";
734
735 #if defined(CONFIG_SMP)
736                 if (strchr(moreprompt, '%')) {
737                         sprintf(buf2, moreprompt, get_cpu());
738                         put_cpu();
739                         moreprompt = buf2;
740                 }
741 #endif
742
743                 kdb_input_flush();
744                 c = console_drivers;
745
746                 if (!dbg_io_ops->is_console) {
747                         len = strlen(moreprompt);
748                         cp = moreprompt;
749                         while (len--) {
750                                 dbg_io_ops->write_char(*cp);
751                                 cp++;
752                         }
753                 }
754                 while (c) {
755                         c->write(c, moreprompt, strlen(moreprompt));
756                         touch_nmi_watchdog();
757                         c = c->next;
758                 }
759
760                 if (logging)
761                         printk("%s", moreprompt);
762
763                 kdb_read(buf1, 2); /* '2' indicates to return
764                                     * immediately after getting one key. */
765                 kdb_nextline = 1;       /* Really set output line 1 */
766
767                 /* empty and reset the buffer: */
768                 kdb_buffer[0] = '\0';
769                 next_avail = kdb_buffer;
770                 size_avail = sizeof(kdb_buffer);
771                 if ((buf1[0] == 'q') || (buf1[0] == 'Q')) {
772                         /* user hit q or Q */
773                         KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
774                         KDB_STATE_CLEAR(PAGER);
775                         /* end of command output; back to normal mode */
776                         kdb_grepping_flag = 0;
777                         kdb_printf("\n");
778                 } else if (buf1[0] == ' ') {
779                         kdb_printf("\n");
780                         suspend_grep = 1; /* for this recursion */
781                 } else if (buf1[0] == '\n') {
782                         kdb_nextline = linecount - 1;
783                         kdb_printf("\r");
784                         suspend_grep = 1; /* for this recursion */
785                 } else if (buf1[0] && buf1[0] != '\n') {
786                         /* user hit something other than enter */
787                         suspend_grep = 1; /* for this recursion */
788                         kdb_printf("\nOnly 'q' or 'Q' are processed at more "
789                                    "prompt, input ignored\n");
790                 } else if (kdb_grepping_flag) {
791                         /* user hit enter */
792                         suspend_grep = 1; /* for this recursion */
793                         kdb_printf("\n");
794                 }
795                 kdb_input_flush();
796         }
797
798         /*
799          * For grep searches, shift the printed string left.
800          *  replaced_byte contains the character that was overwritten with
801          *  the terminating null, and cphold points to the null.
802          * Then adjust the notion of available space in the buffer.
803          */
804         if (kdb_grepping_flag && !suspend_grep) {
805                 *cphold = replaced_byte;
806                 strcpy(kdb_buffer, cphold);
807                 len = strlen(kdb_buffer);
808                 next_avail = kdb_buffer + len;
809                 size_avail = sizeof(kdb_buffer) - len;
810         }
811
812 kdb_print_out:
813         suspend_grep = 0; /* end of what may have been a recursive call */
814         if (logging)
815                 console_loglevel = saved_loglevel;
816         if (KDB_STATE(PRINTF_LOCK) && got_printf_lock) {
817                 got_printf_lock = 0;
818                 spin_unlock_irqrestore(&kdb_printf_lock, flags);
819                 KDB_STATE_CLEAR(PRINTF_LOCK);
820                 atomic_dec(&kdb_event);
821         } else {
822                 __release(kdb_printf_lock);
823         }
824         kdb_trap_printk = saved_trap_printk;
825         preempt_enable();
826         return retlen;
827 }
828
829 int kdb_printf(const char *fmt, ...)
830 {
831         va_list ap;
832         int r;
833
834         va_start(ap, fmt);
835         r = vkdb_printf(fmt, ap);
836         va_end(ap);
837
838         return r;
839 }
840 EXPORT_SYMBOL_GPL(kdb_printf);