printk,kdb: capture printk() when in kdb shell
[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 void kgdb_transition_check(char *buffer)
35 {
36         int slen = strlen(buffer);
37         if (strncmp(buffer, "$?#3f", slen) != 0 &&
38             strncmp(buffer, "$qSupported#37", slen) != 0 &&
39             strncmp(buffer, "+$qSupported#37", slen) != 0) {
40                 KDB_STATE_SET(KGDB_TRANS);
41                 kdb_printf("%s", buffer);
42         }
43 }
44
45 static int kdb_read_get_key(char *buffer, size_t bufsize)
46 {
47 #define ESCAPE_UDELAY 1000
48 #define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
49         char escape_data[5];    /* longest vt100 escape sequence is 4 bytes */
50         char *ped = escape_data;
51         int escape_delay = 0;
52         get_char_func *f, *f_escape = NULL;
53         int key;
54
55         for (f = &kdb_poll_funcs[0]; ; ++f) {
56                 if (*f == NULL) {
57                         /* Reset NMI watchdog once per poll loop */
58                         touch_nmi_watchdog();
59                         f = &kdb_poll_funcs[0];
60                 }
61                 if (escape_delay == 2) {
62                         *ped = '\0';
63                         ped = escape_data;
64                         --escape_delay;
65                 }
66                 if (escape_delay == 1) {
67                         key = *ped++;
68                         if (!*ped)
69                                 --escape_delay;
70                         break;
71                 }
72                 key = (*f)();
73                 if (key == -1) {
74                         if (escape_delay) {
75                                 udelay(ESCAPE_UDELAY);
76                                 --escape_delay;
77                         }
78                         continue;
79                 }
80                 if (bufsize <= 2) {
81                         if (key == '\r')
82                                 key = '\n';
83                         *buffer++ = key;
84                         *buffer = '\0';
85                         return -1;
86                 }
87                 if (escape_delay == 0 && key == '\e') {
88                         escape_delay = ESCAPE_DELAY;
89                         ped = escape_data;
90                         f_escape = f;
91                 }
92                 if (escape_delay) {
93                         *ped++ = key;
94                         if (f_escape != f) {
95                                 escape_delay = 2;
96                                 continue;
97                         }
98                         if (ped - escape_data == 1) {
99                                 /* \e */
100                                 continue;
101                         } else if (ped - escape_data == 2) {
102                                 /* \e<something> */
103                                 if (key != '[')
104                                         escape_delay = 2;
105                                 continue;
106                         } else if (ped - escape_data == 3) {
107                                 /* \e[<something> */
108                                 int mapkey = 0;
109                                 switch (key) {
110                                 case 'A': /* \e[A, up arrow */
111                                         mapkey = 16;
112                                         break;
113                                 case 'B': /* \e[B, down arrow */
114                                         mapkey = 14;
115                                         break;
116                                 case 'C': /* \e[C, right arrow */
117                                         mapkey = 6;
118                                         break;
119                                 case 'D': /* \e[D, left arrow */
120                                         mapkey = 2;
121                                         break;
122                                 case '1': /* dropthrough */
123                                 case '3': /* dropthrough */
124                                 /* \e[<1,3,4>], may be home, del, end */
125                                 case '4':
126                                         mapkey = -1;
127                                         break;
128                                 }
129                                 if (mapkey != -1) {
130                                         if (mapkey > 0) {
131                                                 escape_data[0] = mapkey;
132                                                 escape_data[1] = '\0';
133                                         }
134                                         escape_delay = 2;
135                                 }
136                                 continue;
137                         } else if (ped - escape_data == 4) {
138                                 /* \e[<1,3,4><something> */
139                                 int mapkey = 0;
140                                 if (key == '~') {
141                                         switch (escape_data[2]) {
142                                         case '1': /* \e[1~, home */
143                                                 mapkey = 1;
144                                                 break;
145                                         case '3': /* \e[3~, del */
146                                                 mapkey = 4;
147                                                 break;
148                                         case '4': /* \e[4~, end */
149                                                 mapkey = 5;
150                                                 break;
151                                         }
152                                 }
153                                 if (mapkey > 0) {
154                                         escape_data[0] = mapkey;
155                                         escape_data[1] = '\0';
156                                 }
157                                 escape_delay = 2;
158                                 continue;
159                         }
160                 }
161                 break;  /* A key to process */
162         }
163         return key;
164 }
165
166 /*
167  * kdb_read
168  *
169  *      This function reads a string of characters, terminated by
170  *      a newline, or by reaching the end of the supplied buffer,
171  *      from the current kernel debugger console device.
172  * Parameters:
173  *      buffer  - Address of character buffer to receive input characters.
174  *      bufsize - size, in bytes, of the character buffer
175  * Returns:
176  *      Returns a pointer to the buffer containing the received
177  *      character string.  This string will be terminated by a
178  *      newline character.
179  * Locking:
180  *      No locks are required to be held upon entry to this
181  *      function.  It is not reentrant - it relies on the fact
182  *      that while kdb is running on only one "master debug" cpu.
183  * Remarks:
184  *
185  * The buffer size must be >= 2.  A buffer size of 2 means that the caller only
186  * wants a single key.
187  *
188  * An escape key could be the start of a vt100 control sequence such as \e[D
189  * (left arrow) or it could be a character in its own right.  The standard
190  * method for detecting the difference is to wait for 2 seconds to see if there
191  * are any other characters.  kdb is complicated by the lack of a timer service
192  * (interrupts are off), by multiple input sources and by the need to sometimes
193  * return after just one key.  Escape sequence processing has to be done as
194  * states in the polling loop.
195  */
196
197 static char *kdb_read(char *buffer, size_t bufsize)
198 {
199         char *cp = buffer;
200         char *bufend = buffer+bufsize-2;        /* Reserve space for newline
201                                                  * and null byte */
202         char *lastchar;
203         char *p_tmp;
204         char tmp;
205         static char tmpbuffer[CMD_BUFLEN];
206         int len = strlen(buffer);
207         int len_tmp;
208         int tab = 0;
209         int count;
210         int i;
211         int diag, dtab_count;
212         int key;
213
214
215         diag = kdbgetintenv("DTABCOUNT", &dtab_count);
216         if (diag)
217                 dtab_count = 30;
218
219         if (len > 0) {
220                 cp += len;
221                 if (*(buffer+len-1) == '\n')
222                         cp--;
223         }
224
225         lastchar = cp;
226         *cp = '\0';
227         kdb_printf("%s", buffer);
228 poll_again:
229         key = kdb_read_get_key(buffer, bufsize);
230         if (key == -1)
231                 return buffer;
232         if (key != 9)
233                 tab = 0;
234         switch (key) {
235         case 8: /* backspace */
236                 if (cp > buffer) {
237                         if (cp < lastchar) {
238                                 memcpy(tmpbuffer, cp, lastchar - cp);
239                                 memcpy(cp-1, tmpbuffer, lastchar - cp);
240                         }
241                         *(--lastchar) = '\0';
242                         --cp;
243                         kdb_printf("\b%s \r", cp);
244                         tmp = *cp;
245                         *cp = '\0';
246                         kdb_printf(kdb_prompt_str);
247                         kdb_printf("%s", buffer);
248                         *cp = tmp;
249                 }
250                 break;
251         case 13: /* enter */
252                 *lastchar++ = '\n';
253                 *lastchar++ = '\0';
254                 kdb_printf("\n");
255                 return buffer;
256         case 4: /* Del */
257                 if (cp < lastchar) {
258                         memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
259                         memcpy(cp, tmpbuffer, lastchar - cp - 1);
260                         *(--lastchar) = '\0';
261                         kdb_printf("%s \r", cp);
262                         tmp = *cp;
263                         *cp = '\0';
264                         kdb_printf(kdb_prompt_str);
265                         kdb_printf("%s", buffer);
266                         *cp = tmp;
267                 }
268                 break;
269         case 1: /* Home */
270                 if (cp > buffer) {
271                         kdb_printf("\r");
272                         kdb_printf(kdb_prompt_str);
273                         cp = buffer;
274                 }
275                 break;
276         case 5: /* End */
277                 if (cp < lastchar) {
278                         kdb_printf("%s", cp);
279                         cp = lastchar;
280                 }
281                 break;
282         case 2: /* Left */
283                 if (cp > buffer) {
284                         kdb_printf("\b");
285                         --cp;
286                 }
287                 break;
288         case 14: /* Down */
289                 memset(tmpbuffer, ' ',
290                        strlen(kdb_prompt_str) + (lastchar-buffer));
291                 *(tmpbuffer+strlen(kdb_prompt_str) +
292                   (lastchar-buffer)) = '\0';
293                 kdb_printf("\r%s\r", tmpbuffer);
294                 *lastchar = (char)key;
295                 *(lastchar+1) = '\0';
296                 return lastchar;
297         case 6: /* Right */
298                 if (cp < lastchar) {
299                         kdb_printf("%c", *cp);
300                         ++cp;
301                 }
302                 break;
303         case 16: /* Up */
304                 memset(tmpbuffer, ' ',
305                        strlen(kdb_prompt_str) + (lastchar-buffer));
306                 *(tmpbuffer+strlen(kdb_prompt_str) +
307                   (lastchar-buffer)) = '\0';
308                 kdb_printf("\r%s\r", tmpbuffer);
309                 *lastchar = (char)key;
310                 *(lastchar+1) = '\0';
311                 return lastchar;
312         case 9: /* Tab */
313                 if (tab < 2)
314                         ++tab;
315                 p_tmp = buffer;
316                 while (*p_tmp == ' ')
317                         p_tmp++;
318                 if (p_tmp > cp)
319                         break;
320                 memcpy(tmpbuffer, p_tmp, cp-p_tmp);
321                 *(tmpbuffer + (cp-p_tmp)) = '\0';
322                 p_tmp = strrchr(tmpbuffer, ' ');
323                 if (p_tmp)
324                         ++p_tmp;
325                 else
326                         p_tmp = tmpbuffer;
327                 len = strlen(p_tmp);
328                 count = kallsyms_symbol_complete(p_tmp,
329                                                  sizeof(tmpbuffer) -
330                                                  (p_tmp - tmpbuffer));
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                                 if (kallsyms_symbol_next(p_tmp, i) < 0)
343                                         break;
344                                 kdb_printf("%s ", p_tmp);
345                                 *(p_tmp + len) = '\0';
346                         }
347                         if (i >= dtab_count)
348                                 kdb_printf("...");
349                         kdb_printf("\n");
350                         kdb_printf(kdb_prompt_str);
351                         kdb_printf("%s", buffer);
352                 } else if (tab != 2 && count > 0) {
353                         len_tmp = strlen(p_tmp);
354                         strncpy(p_tmp+len_tmp, cp, lastchar-cp+1);
355                         len_tmp = strlen(p_tmp);
356                         strncpy(cp, p_tmp+len, len_tmp-len + 1);
357                         len = len_tmp - len;
358                         kdb_printf("%s", cp);
359                         cp += len;
360                         lastchar += len;
361                 }
362                 kdb_nextline = 1; /* reset output line number */
363                 break;
364         default:
365                 if (key >= 32 && lastchar < bufend) {
366                         if (cp < lastchar) {
367                                 memcpy(tmpbuffer, cp, lastchar - cp);
368                                 memcpy(cp+1, tmpbuffer, lastchar - cp);
369                                 *++lastchar = '\0';
370                                 *cp = key;
371                                 kdb_printf("%s\r", cp);
372                                 ++cp;
373                                 tmp = *cp;
374                                 *cp = '\0';
375                                 kdb_printf(kdb_prompt_str);
376                                 kdb_printf("%s", buffer);
377                                 *cp = tmp;
378                         } else {
379                                 *++lastchar = '\0';
380                                 *cp++ = key;
381                                 /* The kgdb transition check will hide
382                                  * printed characters if we think that
383                                  * kgdb is connecting, until the check
384                                  * fails */
385                                 if (!KDB_STATE(KGDB_TRANS))
386                                         kgdb_transition_check(buffer);
387                                 else
388                                         kdb_printf("%c", key);
389                         }
390                         /* Special escape to kgdb */
391                         if (lastchar - buffer >= 5 &&
392                             strcmp(lastchar - 5, "$?#3f") == 0) {
393                                 strcpy(buffer, "kgdb");
394                                 KDB_STATE_SET(DOING_KGDB);
395                                 return buffer;
396                         }
397                         if (lastchar - buffer >= 14 &&
398                             strcmp(lastchar - 14, "$qSupported#37") == 0) {
399                                 strcpy(buffer, "kgdb");
400                                 KDB_STATE_SET(DOING_KGDB2);
401                                 return buffer;
402                         }
403                 }
404                 break;
405         }
406         goto poll_again;
407 }
408
409 /*
410  * kdb_getstr
411  *
412  *      Print the prompt string and read a command from the
413  *      input device.
414  *
415  * Parameters:
416  *      buffer  Address of buffer to receive command
417  *      bufsize Size of buffer in bytes
418  *      prompt  Pointer to string to use as prompt string
419  * Returns:
420  *      Pointer to command buffer.
421  * Locking:
422  *      None.
423  * Remarks:
424  *      For SMP kernels, the processor number will be
425  *      substituted for %d, %x or %o in the prompt.
426  */
427
428 char *kdb_getstr(char *buffer, size_t bufsize, char *prompt)
429 {
430         if (prompt && kdb_prompt_str != prompt)
431                 strncpy(kdb_prompt_str, prompt, CMD_BUFLEN);
432         kdb_printf(kdb_prompt_str);
433         kdb_nextline = 1;       /* Prompt and input resets line number */
434         return kdb_read(buffer, bufsize);
435 }
436
437 /*
438  * kdb_input_flush
439  *
440  *      Get rid of any buffered console input.
441  *
442  * Parameters:
443  *      none
444  * Returns:
445  *      nothing
446  * Locking:
447  *      none
448  * Remarks:
449  *      Call this function whenever you want to flush input.  If there is any
450  *      outstanding input, it ignores all characters until there has been no
451  *      data for approximately 1ms.
452  */
453
454 static void kdb_input_flush(void)
455 {
456         get_char_func *f;
457         int res;
458         int flush_delay = 1;
459         while (flush_delay) {
460                 flush_delay--;
461 empty:
462                 touch_nmi_watchdog();
463                 for (f = &kdb_poll_funcs[0]; *f; ++f) {
464                         res = (*f)();
465                         if (res != -1) {
466                                 flush_delay = 1;
467                                 goto empty;
468                         }
469                 }
470                 if (flush_delay)
471                         mdelay(1);
472         }
473 }
474
475 /*
476  * kdb_printf
477  *
478  *      Print a string to the output device(s).
479  *
480  * Parameters:
481  *      printf-like format and optional args.
482  * Returns:
483  *      0
484  * Locking:
485  *      None.
486  * Remarks:
487  *      use 'kdbcons->write()' to avoid polluting 'log_buf' with
488  *      kdb output.
489  *
490  *  If the user is doing a cmd args | grep srch
491  *  then kdb_grepping_flag is set.
492  *  In that case we need to accumulate full lines (ending in \n) before
493  *  searching for the pattern.
494  */
495
496 static char kdb_buffer[256];    /* A bit too big to go on stack */
497 static char *next_avail = kdb_buffer;
498 static int  size_avail;
499 static int  suspend_grep;
500
501 /*
502  * search arg1 to see if it contains arg2
503  * (kdmain.c provides flags for ^pat and pat$)
504  *
505  * return 1 for found, 0 for not found
506  */
507 static int kdb_search_string(char *searched, char *searchfor)
508 {
509         char firstchar, *cp;
510         int len1, len2;
511
512         /* not counting the newline at the end of "searched" */
513         len1 = strlen(searched)-1;
514         len2 = strlen(searchfor);
515         if (len1 < len2)
516                 return 0;
517         if (kdb_grep_leading && kdb_grep_trailing && len1 != len2)
518                 return 0;
519         if (kdb_grep_leading) {
520                 if (!strncmp(searched, searchfor, len2))
521                         return 1;
522         } else if (kdb_grep_trailing) {
523                 if (!strncmp(searched+len1-len2, searchfor, len2))
524                         return 1;
525         } else {
526                 firstchar = *searchfor;
527                 cp = searched;
528                 while ((cp = strchr(cp, firstchar))) {
529                         if (!strncmp(cp, searchfor, len2))
530                                 return 1;
531                         cp++;
532                 }
533         }
534         return 0;
535 }
536
537 int vkdb_printf(const char *fmt, va_list ap)
538 {
539         int diag;
540         int linecount;
541         int logging, saved_loglevel = 0;
542         int saved_trap_printk;
543         int got_printf_lock = 0;
544         int retlen = 0;
545         int fnd, len;
546         char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
547         char *moreprompt = "more> ";
548         struct console *c = console_drivers;
549         static DEFINE_SPINLOCK(kdb_printf_lock);
550         unsigned long uninitialized_var(flags);
551
552         preempt_disable();
553         saved_trap_printk = kdb_trap_printk;
554         kdb_trap_printk = 0;
555
556         /* Serialize kdb_printf if multiple cpus try to write at once.
557          * But if any cpu goes recursive in kdb, just print the output,
558          * even if it is interleaved with any other text.
559          */
560         if (!KDB_STATE(PRINTF_LOCK)) {
561                 KDB_STATE_SET(PRINTF_LOCK);
562                 spin_lock_irqsave(&kdb_printf_lock, flags);
563                 got_printf_lock = 1;
564                 atomic_inc(&kdb_event);
565         } else {
566                 __acquire(kdb_printf_lock);
567         }
568
569         diag = kdbgetintenv("LINES", &linecount);
570         if (diag || linecount <= 1)
571                 linecount = 24;
572
573         diag = kdbgetintenv("LOGGING", &logging);
574         if (diag)
575                 logging = 0;
576
577         if (!kdb_grepping_flag || suspend_grep) {
578                 /* normally, every vsnprintf starts a new buffer */
579                 next_avail = kdb_buffer;
580                 size_avail = sizeof(kdb_buffer);
581         }
582         vsnprintf(next_avail, size_avail, fmt, ap);
583
584         /*
585          * If kdb_parse() found that the command was cmd xxx | grep yyy
586          * then kdb_grepping_flag is set, and kdb_grep_string contains yyy
587          *
588          * Accumulate the print data up to a newline before searching it.
589          * (vsnprintf does null-terminate the string that it generates)
590          */
591
592         /* skip the search if prints are temporarily unconditional */
593         if (!suspend_grep && kdb_grepping_flag) {
594                 cp = strchr(kdb_buffer, '\n');
595                 if (!cp) {
596                         /*
597                          * Special cases that don't end with newlines
598                          * but should be written without one:
599                          *   The "[nn]kdb> " prompt should
600                          *   appear at the front of the buffer.
601                          *
602                          *   The "[nn]more " prompt should also be
603                          *     (MOREPROMPT -> moreprompt)
604                          *   written *   but we print that ourselves,
605                          *   we set the suspend_grep flag to make
606                          *   it unconditional.
607                          *
608                          */
609                         if (next_avail == kdb_buffer) {
610                                 /*
611                                  * these should occur after a newline,
612                                  * so they will be at the front of the
613                                  * buffer
614                                  */
615                                 cp2 = kdb_buffer;
616                                 len = strlen(kdb_prompt_str);
617                                 if (!strncmp(cp2, kdb_prompt_str, len)) {
618                                         /*
619                                          * We're about to start a new
620                                          * command, so we can go back
621                                          * to normal mode.
622                                          */
623                                         kdb_grepping_flag = 0;
624                                         goto kdb_printit;
625                                 }
626                         }
627                         /* no newline; don't search/write the buffer
628                            until one is there */
629                         len = strlen(kdb_buffer);
630                         next_avail = kdb_buffer + len;
631                         size_avail = sizeof(kdb_buffer) - len;
632                         goto kdb_print_out;
633                 }
634
635                 /*
636                  * The newline is present; print through it or discard
637                  * it, depending on the results of the search.
638                  */
639                 cp++;                /* to byte after the newline */
640                 replaced_byte = *cp; /* remember what/where it was */
641                 cphold = cp;
642                 *cp = '\0';          /* end the string for our search */
643
644                 /*
645                  * We now have a newline at the end of the string
646                  * Only continue with this output if it contains the
647                  * search string.
648                  */
649                 fnd = kdb_search_string(kdb_buffer, kdb_grep_string);
650                 if (!fnd) {
651                         /*
652                          * At this point the complete line at the start
653                          * of kdb_buffer can be discarded, as it does
654                          * not contain what the user is looking for.
655                          * Shift the buffer left.
656                          */
657                         *cphold = replaced_byte;
658                         strcpy(kdb_buffer, cphold);
659                         len = strlen(kdb_buffer);
660                         next_avail = kdb_buffer + len;
661                         size_avail = sizeof(kdb_buffer) - len;
662                         goto kdb_print_out;
663                 }
664                 /*
665                  * at this point the string is a full line and
666                  * should be printed, up to the null.
667                  */
668         }
669 kdb_printit:
670
671         /*
672          * Write to all consoles.
673          */
674         retlen = strlen(kdb_buffer);
675         if (!dbg_kdb_mode && kgdb_connected) {
676                 gdbstub_msg_write(kdb_buffer, retlen);
677         } else {
678                 if (!dbg_io_ops->is_console) {
679                         len = strlen(kdb_buffer);
680                         cp = kdb_buffer;
681                         while (len--) {
682                                 dbg_io_ops->write_char(*cp);
683                                 cp++;
684                         }
685                 }
686                 while (c) {
687                         c->write(c, kdb_buffer, retlen);
688                         touch_nmi_watchdog();
689                         c = c->next;
690                 }
691         }
692         if (logging) {
693                 saved_loglevel = console_loglevel;
694                 console_loglevel = 0;
695                 printk(KERN_INFO "%s", kdb_buffer);
696         }
697
698         if (KDB_STATE(PAGER) && strchr(kdb_buffer, '\n'))
699                 kdb_nextline++;
700
701         /* check for having reached the LINES number of printed lines */
702         if (kdb_nextline == linecount) {
703                 char buf1[16] = "";
704 #if defined(CONFIG_SMP)
705                 char buf2[32];
706 #endif
707
708                 /* Watch out for recursion here.  Any routine that calls
709                  * kdb_printf will come back through here.  And kdb_read
710                  * uses kdb_printf to echo on serial consoles ...
711                  */
712                 kdb_nextline = 1;       /* In case of recursion */
713
714                 /*
715                  * Pause until cr.
716                  */
717                 moreprompt = kdbgetenv("MOREPROMPT");
718                 if (moreprompt == NULL)
719                         moreprompt = "more> ";
720
721 #if defined(CONFIG_SMP)
722                 if (strchr(moreprompt, '%')) {
723                         sprintf(buf2, moreprompt, get_cpu());
724                         put_cpu();
725                         moreprompt = buf2;
726                 }
727 #endif
728
729                 kdb_input_flush();
730                 c = console_drivers;
731
732                 if (!dbg_io_ops->is_console) {
733                         len = strlen(moreprompt);
734                         cp = moreprompt;
735                         while (len--) {
736                                 dbg_io_ops->write_char(*cp);
737                                 cp++;
738                         }
739                 }
740                 while (c) {
741                         c->write(c, moreprompt, strlen(moreprompt));
742                         touch_nmi_watchdog();
743                         c = c->next;
744                 }
745
746                 if (logging)
747                         printk("%s", moreprompt);
748
749                 kdb_read(buf1, 2); /* '2' indicates to return
750                                     * immediately after getting one key. */
751                 kdb_nextline = 1;       /* Really set output line 1 */
752
753                 /* empty and reset the buffer: */
754                 kdb_buffer[0] = '\0';
755                 next_avail = kdb_buffer;
756                 size_avail = sizeof(kdb_buffer);
757                 if ((buf1[0] == 'q') || (buf1[0] == 'Q')) {
758                         /* user hit q or Q */
759                         KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
760                         KDB_STATE_CLEAR(PAGER);
761                         /* end of command output; back to normal mode */
762                         kdb_grepping_flag = 0;
763                         kdb_printf("\n");
764                 } else if (buf1[0] == ' ') {
765                         kdb_printf("\n");
766                         suspend_grep = 1; /* for this recursion */
767                 } else if (buf1[0] == '\n') {
768                         kdb_nextline = linecount - 1;
769                         kdb_printf("\r");
770                         suspend_grep = 1; /* for this recursion */
771                 } else if (buf1[0] && buf1[0] != '\n') {
772                         /* user hit something other than enter */
773                         suspend_grep = 1; /* for this recursion */
774                         kdb_printf("\nOnly 'q' or 'Q' are processed at more "
775                                    "prompt, input ignored\n");
776                 } else if (kdb_grepping_flag) {
777                         /* user hit enter */
778                         suspend_grep = 1; /* for this recursion */
779                         kdb_printf("\n");
780                 }
781                 kdb_input_flush();
782         }
783
784         /*
785          * For grep searches, shift the printed string left.
786          *  replaced_byte contains the character that was overwritten with
787          *  the terminating null, and cphold points to the null.
788          * Then adjust the notion of available space in the buffer.
789          */
790         if (kdb_grepping_flag && !suspend_grep) {
791                 *cphold = replaced_byte;
792                 strcpy(kdb_buffer, cphold);
793                 len = strlen(kdb_buffer);
794                 next_avail = kdb_buffer + len;
795                 size_avail = sizeof(kdb_buffer) - len;
796         }
797
798 kdb_print_out:
799         suspend_grep = 0; /* end of what may have been a recursive call */
800         if (logging)
801                 console_loglevel = saved_loglevel;
802         if (KDB_STATE(PRINTF_LOCK) && got_printf_lock) {
803                 got_printf_lock = 0;
804                 spin_unlock_irqrestore(&kdb_printf_lock, flags);
805                 KDB_STATE_CLEAR(PRINTF_LOCK);
806                 atomic_dec(&kdb_event);
807         } else {
808                 __release(kdb_printf_lock);
809         }
810         kdb_trap_printk = saved_trap_printk;
811         preempt_enable();
812         return retlen;
813 }
814
815 int kdb_printf(const char *fmt, ...)
816 {
817         va_list ap;
818         int r;
819
820         va_start(ap, fmt);
821         r = vkdb_printf(fmt, ap);
822         va_end(ap);
823
824         return r;
825 }
826