kdb: Check status of console prior to invoking handlers
[sfrench/cifs-2.6.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 int kdb_printf_cpu = -1;
34
35 static int kgdb_transition_check(char *buffer)
36 {
37         if (buffer[0] != '+' && buffer[0] != '$') {
38                 KDB_STATE_SET(KGDB_TRANS);
39                 kdb_printf("%s", buffer);
40         } else {
41                 int slen = strlen(buffer);
42                 if (slen > 3 && buffer[slen - 3] == '#') {
43                         kdb_gdb_state_pass(buffer);
44                         strcpy(buffer, "kgdb");
45                         KDB_STATE_SET(DOING_KGDB);
46                         return 1;
47                 }
48         }
49         return 0;
50 }
51
52 /**
53  * kdb_handle_escape() - validity check on an accumulated escape sequence.
54  * @buf:        Accumulated escape characters to be examined. Note that buf
55  *              is not a string, it is an array of characters and need not be
56  *              nil terminated.
57  * @sz:         Number of accumulated escape characters.
58  *
59  * Return: -1 if the escape sequence is unwanted, 0 if it is incomplete,
60  * otherwise it returns a mapped key value to pass to the upper layers.
61  */
62 static int kdb_handle_escape(char *buf, size_t sz)
63 {
64         char *lastkey = buf + sz - 1;
65
66         switch (sz) {
67         case 1:
68                 if (*lastkey == '\e')
69                         return 0;
70                 break;
71
72         case 2: /* \e<something> */
73                 if (*lastkey == '[')
74                         return 0;
75                 break;
76
77         case 3:
78                 switch (*lastkey) {
79                 case 'A': /* \e[A, up arrow */
80                         return 16;
81                 case 'B': /* \e[B, down arrow */
82                         return 14;
83                 case 'C': /* \e[C, right arrow */
84                         return 6;
85                 case 'D': /* \e[D, left arrow */
86                         return 2;
87                 case '1': /* \e[<1,3,4>], may be home, del, end */
88                 case '3':
89                 case '4':
90                         return 0;
91                 }
92                 break;
93
94         case 4:
95                 if (*lastkey == '~') {
96                         switch (buf[2]) {
97                         case '1': /* \e[1~, home */
98                                 return 1;
99                         case '3': /* \e[3~, del */
100                                 return 4;
101                         case '4': /* \e[4~, end */
102                                 return 5;
103                         }
104                 }
105                 break;
106         }
107
108         return -1;
109 }
110
111 /**
112  * kdb_getchar() - Read a single character from a kdb console (or consoles).
113  *
114  * Other than polling the various consoles that are currently enabled,
115  * most of the work done in this function is dealing with escape sequences.
116  *
117  * An escape key could be the start of a vt100 control sequence such as \e[D
118  * (left arrow) or it could be a character in its own right.  The standard
119  * method for detecting the difference is to wait for 2 seconds to see if there
120  * are any other characters.  kdb is complicated by the lack of a timer service
121  * (interrupts are off), by multiple input sources. Escape sequence processing
122  * has to be done as states in the polling loop.
123  *
124  * Return: The key pressed or a control code derived from an escape sequence.
125  */
126 char kdb_getchar(void)
127 {
128 #define ESCAPE_UDELAY 1000
129 #define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
130         char buf[4];    /* longest vt100 escape sequence is 4 bytes */
131         char *pbuf = buf;
132         int escape_delay = 0;
133         get_char_func *f, *f_prev = NULL;
134         int key;
135
136         for (f = &kdb_poll_funcs[0]; ; ++f) {
137                 if (*f == NULL) {
138                         /* Reset NMI watchdog once per poll loop */
139                         touch_nmi_watchdog();
140                         f = &kdb_poll_funcs[0];
141                 }
142
143                 key = (*f)();
144                 if (key == -1) {
145                         if (escape_delay) {
146                                 udelay(ESCAPE_UDELAY);
147                                 if (--escape_delay == 0)
148                                         return '\e';
149                         }
150                         continue;
151                 }
152
153                 /*
154                  * When the first character is received (or we get a change
155                  * input source) we set ourselves up to handle an escape
156                  * sequences (just in case).
157                  */
158                 if (f_prev != f) {
159                         f_prev = f;
160                         pbuf = buf;
161                         escape_delay = ESCAPE_DELAY;
162                 }
163
164                 *pbuf++ = key;
165                 key = kdb_handle_escape(buf, pbuf - buf);
166                 if (key < 0) /* no escape sequence; return best character */
167                         return buf[pbuf - buf == 2 ? 1 : 0];
168                 if (key > 0)
169                         return key;
170         }
171
172         unreachable();
173 }
174
175 /*
176  * kdb_read
177  *
178  *      This function reads a string of characters, terminated by
179  *      a newline, or by reaching the end of the supplied buffer,
180  *      from the current kernel debugger console device.
181  * Parameters:
182  *      buffer  - Address of character buffer to receive input characters.
183  *      bufsize - size, in bytes, of the character buffer
184  * Returns:
185  *      Returns a pointer to the buffer containing the received
186  *      character string.  This string will be terminated by a
187  *      newline character.
188  * Locking:
189  *      No locks are required to be held upon entry to this
190  *      function.  It is not reentrant - it relies on the fact
191  *      that while kdb is running on only one "master debug" cpu.
192  * Remarks:
193  *      The buffer size must be >= 2.
194  */
195
196 static char *kdb_read(char *buffer, size_t bufsize)
197 {
198         char *cp = buffer;
199         char *bufend = buffer+bufsize-2;        /* Reserve space for newline
200                                                  * and null byte */
201         char *lastchar;
202         char *p_tmp;
203         char tmp;
204         static char tmpbuffer[CMD_BUFLEN];
205         int len = strlen(buffer);
206         int len_tmp;
207         int tab = 0;
208         int count;
209         int i;
210         int diag, dtab_count;
211         int key, buf_size, ret;
212
213
214         diag = kdbgetintenv("DTABCOUNT", &dtab_count);
215         if (diag)
216                 dtab_count = 30;
217
218         if (len > 0) {
219                 cp += len;
220                 if (*(buffer+len-1) == '\n')
221                         cp--;
222         }
223
224         lastchar = cp;
225         *cp = '\0';
226         kdb_printf("%s", buffer);
227 poll_again:
228         key = kdb_getchar();
229         if (key != 9)
230                 tab = 0;
231         switch (key) {
232         case 8: /* backspace */
233                 if (cp > buffer) {
234                         if (cp < lastchar) {
235                                 memcpy(tmpbuffer, cp, lastchar - cp);
236                                 memcpy(cp-1, tmpbuffer, lastchar - cp);
237                         }
238                         *(--lastchar) = '\0';
239                         --cp;
240                         kdb_printf("\b%s \r", cp);
241                         tmp = *cp;
242                         *cp = '\0';
243                         kdb_printf(kdb_prompt_str);
244                         kdb_printf("%s", buffer);
245                         *cp = tmp;
246                 }
247                 break;
248         case 13: /* enter */
249                 *lastchar++ = '\n';
250                 *lastchar++ = '\0';
251                 if (!KDB_STATE(KGDB_TRANS)) {
252                         KDB_STATE_SET(KGDB_TRANS);
253                         kdb_printf("%s", buffer);
254                 }
255                 kdb_printf("\n");
256                 return buffer;
257         case 4: /* Del */
258                 if (cp < lastchar) {
259                         memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
260                         memcpy(cp, tmpbuffer, lastchar - cp - 1);
261                         *(--lastchar) = '\0';
262                         kdb_printf("%s \r", cp);
263                         tmp = *cp;
264                         *cp = '\0';
265                         kdb_printf(kdb_prompt_str);
266                         kdb_printf("%s", buffer);
267                         *cp = tmp;
268                 }
269                 break;
270         case 1: /* Home */
271                 if (cp > buffer) {
272                         kdb_printf("\r");
273                         kdb_printf(kdb_prompt_str);
274                         cp = buffer;
275                 }
276                 break;
277         case 5: /* End */
278                 if (cp < lastchar) {
279                         kdb_printf("%s", cp);
280                         cp = lastchar;
281                 }
282                 break;
283         case 2: /* Left */
284                 if (cp > buffer) {
285                         kdb_printf("\b");
286                         --cp;
287                 }
288                 break;
289         case 14: /* Down */
290                 memset(tmpbuffer, ' ',
291                        strlen(kdb_prompt_str) + (lastchar-buffer));
292                 *(tmpbuffer+strlen(kdb_prompt_str) +
293                   (lastchar-buffer)) = '\0';
294                 kdb_printf("\r%s\r", tmpbuffer);
295                 *lastchar = (char)key;
296                 *(lastchar+1) = '\0';
297                 return lastchar;
298         case 6: /* Right */
299                 if (cp < lastchar) {
300                         kdb_printf("%c", *cp);
301                         ++cp;
302                 }
303                 break;
304         case 16: /* Up */
305                 memset(tmpbuffer, ' ',
306                        strlen(kdb_prompt_str) + (lastchar-buffer));
307                 *(tmpbuffer+strlen(kdb_prompt_str) +
308                   (lastchar-buffer)) = '\0';
309                 kdb_printf("\r%s\r", tmpbuffer);
310                 *lastchar = (char)key;
311                 *(lastchar+1) = '\0';
312                 return lastchar;
313         case 9: /* Tab */
314                 if (tab < 2)
315                         ++tab;
316                 p_tmp = buffer;
317                 while (*p_tmp == ' ')
318                         p_tmp++;
319                 if (p_tmp > cp)
320                         break;
321                 memcpy(tmpbuffer, p_tmp, cp-p_tmp);
322                 *(tmpbuffer + (cp-p_tmp)) = '\0';
323                 p_tmp = strrchr(tmpbuffer, ' ');
324                 if (p_tmp)
325                         ++p_tmp;
326                 else
327                         p_tmp = tmpbuffer;
328                 len = strlen(p_tmp);
329                 buf_size = sizeof(tmpbuffer) - (p_tmp - tmpbuffer);
330                 count = kallsyms_symbol_complete(p_tmp, buf_size);
331                 if (tab == 2 && count > 0) {
332                         kdb_printf("\n%d symbols are found.", count);
333                         if (count > dtab_count) {
334                                 count = dtab_count;
335                                 kdb_printf(" But only first %d symbols will"
336                                            " be printed.\nYou can change the"
337                                            " environment variable DTABCOUNT.",
338                                            count);
339                         }
340                         kdb_printf("\n");
341                         for (i = 0; i < count; i++) {
342                                 ret = kallsyms_symbol_next(p_tmp, i, buf_size);
343                                 if (WARN_ON(!ret))
344                                         break;
345                                 if (ret != -E2BIG)
346                                         kdb_printf("%s ", p_tmp);
347                                 else
348                                         kdb_printf("%s... ", p_tmp);
349                                 *(p_tmp + len) = '\0';
350                         }
351                         if (i >= dtab_count)
352                                 kdb_printf("...");
353                         kdb_printf("\n");
354                         kdb_printf(kdb_prompt_str);
355                         kdb_printf("%s", buffer);
356                 } else if (tab != 2 && count > 0) {
357                         len_tmp = strlen(p_tmp);
358                         strncpy(p_tmp+len_tmp, cp, lastchar-cp+1);
359                         len_tmp = strlen(p_tmp);
360                         strncpy(cp, p_tmp+len, len_tmp-len + 1);
361                         len = len_tmp - len;
362                         kdb_printf("%s", cp);
363                         cp += len;
364                         lastchar += len;
365                 }
366                 kdb_nextline = 1; /* reset output line number */
367                 break;
368         default:
369                 if (key >= 32 && lastchar < bufend) {
370                         if (cp < lastchar) {
371                                 memcpy(tmpbuffer, cp, lastchar - cp);
372                                 memcpy(cp+1, tmpbuffer, lastchar - cp);
373                                 *++lastchar = '\0';
374                                 *cp = key;
375                                 kdb_printf("%s\r", cp);
376                                 ++cp;
377                                 tmp = *cp;
378                                 *cp = '\0';
379                                 kdb_printf(kdb_prompt_str);
380                                 kdb_printf("%s", buffer);
381                                 *cp = tmp;
382                         } else {
383                                 *++lastchar = '\0';
384                                 *cp++ = key;
385                                 /* The kgdb transition check will hide
386                                  * printed characters if we think that
387                                  * kgdb is connecting, until the check
388                                  * fails */
389                                 if (!KDB_STATE(KGDB_TRANS)) {
390                                         if (kgdb_transition_check(buffer))
391                                                 return buffer;
392                                 } else {
393                                         kdb_printf("%c", key);
394                                 }
395                         }
396                         /* Special escape to kgdb */
397                         if (lastchar - buffer >= 5 &&
398                             strcmp(lastchar - 5, "$?#3f") == 0) {
399                                 kdb_gdb_state_pass(lastchar - 5);
400                                 strcpy(buffer, "kgdb");
401                                 KDB_STATE_SET(DOING_KGDB);
402                                 return buffer;
403                         }
404                         if (lastchar - buffer >= 11 &&
405                             strcmp(lastchar - 11, "$qSupported") == 0) {
406                                 kdb_gdb_state_pass(lastchar - 11);
407                                 strcpy(buffer, "kgdb");
408                                 KDB_STATE_SET(DOING_KGDB);
409                                 return buffer;
410                         }
411                 }
412                 break;
413         }
414         goto poll_again;
415 }
416
417 /*
418  * kdb_getstr
419  *
420  *      Print the prompt string and read a command from the
421  *      input device.
422  *
423  * Parameters:
424  *      buffer  Address of buffer to receive command
425  *      bufsize Size of buffer in bytes
426  *      prompt  Pointer to string to use as prompt string
427  * Returns:
428  *      Pointer to command buffer.
429  * Locking:
430  *      None.
431  * Remarks:
432  *      For SMP kernels, the processor number will be
433  *      substituted for %d, %x or %o in the prompt.
434  */
435
436 char *kdb_getstr(char *buffer, size_t bufsize, const char *prompt)
437 {
438         if (prompt && kdb_prompt_str != prompt)
439                 strscpy(kdb_prompt_str, prompt, CMD_BUFLEN);
440         kdb_printf(kdb_prompt_str);
441         kdb_nextline = 1;       /* Prompt and input resets line number */
442         return kdb_read(buffer, bufsize);
443 }
444
445 /*
446  * kdb_input_flush
447  *
448  *      Get rid of any buffered console input.
449  *
450  * Parameters:
451  *      none
452  * Returns:
453  *      nothing
454  * Locking:
455  *      none
456  * Remarks:
457  *      Call this function whenever you want to flush input.  If there is any
458  *      outstanding input, it ignores all characters until there has been no
459  *      data for approximately 1ms.
460  */
461
462 static void kdb_input_flush(void)
463 {
464         get_char_func *f;
465         int res;
466         int flush_delay = 1;
467         while (flush_delay) {
468                 flush_delay--;
469 empty:
470                 touch_nmi_watchdog();
471                 for (f = &kdb_poll_funcs[0]; *f; ++f) {
472                         res = (*f)();
473                         if (res != -1) {
474                                 flush_delay = 1;
475                                 goto empty;
476                         }
477                 }
478                 if (flush_delay)
479                         mdelay(1);
480         }
481 }
482
483 /*
484  * kdb_printf
485  *
486  *      Print a string to the output device(s).
487  *
488  * Parameters:
489  *      printf-like format and optional args.
490  * Returns:
491  *      0
492  * Locking:
493  *      None.
494  * Remarks:
495  *      use 'kdbcons->write()' to avoid polluting 'log_buf' with
496  *      kdb output.
497  *
498  *  If the user is doing a cmd args | grep srch
499  *  then kdb_grepping_flag is set.
500  *  In that case we need to accumulate full lines (ending in \n) before
501  *  searching for the pattern.
502  */
503
504 static char kdb_buffer[256];    /* A bit too big to go on stack */
505 static char *next_avail = kdb_buffer;
506 static int  size_avail;
507 static int  suspend_grep;
508
509 /*
510  * search arg1 to see if it contains arg2
511  * (kdmain.c provides flags for ^pat and pat$)
512  *
513  * return 1 for found, 0 for not found
514  */
515 static int kdb_search_string(char *searched, char *searchfor)
516 {
517         char firstchar, *cp;
518         int len1, len2;
519
520         /* not counting the newline at the end of "searched" */
521         len1 = strlen(searched)-1;
522         len2 = strlen(searchfor);
523         if (len1 < len2)
524                 return 0;
525         if (kdb_grep_leading && kdb_grep_trailing && len1 != len2)
526                 return 0;
527         if (kdb_grep_leading) {
528                 if (!strncmp(searched, searchfor, len2))
529                         return 1;
530         } else if (kdb_grep_trailing) {
531                 if (!strncmp(searched+len1-len2, searchfor, len2))
532                         return 1;
533         } else {
534                 firstchar = *searchfor;
535                 cp = searched;
536                 while ((cp = strchr(cp, firstchar))) {
537                         if (!strncmp(cp, searchfor, len2))
538                                 return 1;
539                         cp++;
540                 }
541         }
542         return 0;
543 }
544
545 static void kdb_msg_write(const char *msg, int msg_len)
546 {
547         struct console *c;
548
549         if (msg_len == 0)
550                 return;
551
552         if (dbg_io_ops && !dbg_io_ops->is_console) {
553                 const char *cp = msg;
554                 int len = msg_len;
555
556                 while (len--) {
557                         dbg_io_ops->write_char(*cp);
558                         cp++;
559                 }
560         }
561
562         for_each_console(c) {
563                 if (!(c->flags & CON_ENABLED))
564                         continue;
565                 c->write(c, msg, msg_len);
566                 touch_nmi_watchdog();
567         }
568 }
569
570 int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
571 {
572         int diag;
573         int linecount;
574         int colcount;
575         int logging, saved_loglevel = 0;
576         int retlen = 0;
577         int fnd, len;
578         int this_cpu, old_cpu;
579         char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
580         char *moreprompt = "more> ";
581         unsigned long uninitialized_var(flags);
582
583         /* Serialize kdb_printf if multiple cpus try to write at once.
584          * But if any cpu goes recursive in kdb, just print the output,
585          * even if it is interleaved with any other text.
586          */
587         local_irq_save(flags);
588         this_cpu = smp_processor_id();
589         for (;;) {
590                 old_cpu = cmpxchg(&kdb_printf_cpu, -1, this_cpu);
591                 if (old_cpu == -1 || old_cpu == this_cpu)
592                         break;
593
594                 cpu_relax();
595         }
596
597         diag = kdbgetintenv("LINES", &linecount);
598         if (diag || linecount <= 1)
599                 linecount = 24;
600
601         diag = kdbgetintenv("COLUMNS", &colcount);
602         if (diag || colcount <= 1)
603                 colcount = 80;
604
605         diag = kdbgetintenv("LOGGING", &logging);
606         if (diag)
607                 logging = 0;
608
609         if (!kdb_grepping_flag || suspend_grep) {
610                 /* normally, every vsnprintf starts a new buffer */
611                 next_avail = kdb_buffer;
612                 size_avail = sizeof(kdb_buffer);
613         }
614         vsnprintf(next_avail, size_avail, fmt, ap);
615
616         /*
617          * If kdb_parse() found that the command was cmd xxx | grep yyy
618          * then kdb_grepping_flag is set, and kdb_grep_string contains yyy
619          *
620          * Accumulate the print data up to a newline before searching it.
621          * (vsnprintf does null-terminate the string that it generates)
622          */
623
624         /* skip the search if prints are temporarily unconditional */
625         if (!suspend_grep && kdb_grepping_flag) {
626                 cp = strchr(kdb_buffer, '\n');
627                 if (!cp) {
628                         /*
629                          * Special cases that don't end with newlines
630                          * but should be written without one:
631                          *   The "[nn]kdb> " prompt should
632                          *   appear at the front of the buffer.
633                          *
634                          *   The "[nn]more " prompt should also be
635                          *     (MOREPROMPT -> moreprompt)
636                          *   written *   but we print that ourselves,
637                          *   we set the suspend_grep flag to make
638                          *   it unconditional.
639                          *
640                          */
641                         if (next_avail == kdb_buffer) {
642                                 /*
643                                  * these should occur after a newline,
644                                  * so they will be at the front of the
645                                  * buffer
646                                  */
647                                 cp2 = kdb_buffer;
648                                 len = strlen(kdb_prompt_str);
649                                 if (!strncmp(cp2, kdb_prompt_str, len)) {
650                                         /*
651                                          * We're about to start a new
652                                          * command, so we can go back
653                                          * to normal mode.
654                                          */
655                                         kdb_grepping_flag = 0;
656                                         goto kdb_printit;
657                                 }
658                         }
659                         /* no newline; don't search/write the buffer
660                            until one is there */
661                         len = strlen(kdb_buffer);
662                         next_avail = kdb_buffer + len;
663                         size_avail = sizeof(kdb_buffer) - len;
664                         goto kdb_print_out;
665                 }
666
667                 /*
668                  * The newline is present; print through it or discard
669                  * it, depending on the results of the search.
670                  */
671                 cp++;                /* to byte after the newline */
672                 replaced_byte = *cp; /* remember what/where it was */
673                 cphold = cp;
674                 *cp = '\0';          /* end the string for our search */
675
676                 /*
677                  * We now have a newline at the end of the string
678                  * Only continue with this output if it contains the
679                  * search string.
680                  */
681                 fnd = kdb_search_string(kdb_buffer, kdb_grep_string);
682                 if (!fnd) {
683                         /*
684                          * At this point the complete line at the start
685                          * of kdb_buffer can be discarded, as it does
686                          * not contain what the user is looking for.
687                          * Shift the buffer left.
688                          */
689                         *cphold = replaced_byte;
690                         strcpy(kdb_buffer, cphold);
691                         len = strlen(kdb_buffer);
692                         next_avail = kdb_buffer + len;
693                         size_avail = sizeof(kdb_buffer) - len;
694                         goto kdb_print_out;
695                 }
696                 if (kdb_grepping_flag >= KDB_GREPPING_FLAG_SEARCH)
697                         /*
698                          * This was a interactive search (using '/' at more
699                          * prompt) and it has completed. Clear the flag.
700                          */
701                         kdb_grepping_flag = 0;
702                 /*
703                  * at this point the string is a full line and
704                  * should be printed, up to the null.
705                  */
706         }
707 kdb_printit:
708
709         /*
710          * Write to all consoles.
711          */
712         retlen = strlen(kdb_buffer);
713         cp = (char *) printk_skip_headers(kdb_buffer);
714         if (!dbg_kdb_mode && kgdb_connected)
715                 gdbstub_msg_write(cp, retlen - (cp - kdb_buffer));
716         else
717                 kdb_msg_write(cp, retlen - (cp - kdb_buffer));
718
719         if (logging) {
720                 saved_loglevel = console_loglevel;
721                 console_loglevel = CONSOLE_LOGLEVEL_SILENT;
722                 if (printk_get_level(kdb_buffer) || src == KDB_MSGSRC_PRINTK)
723                         printk("%s", kdb_buffer);
724                 else
725                         pr_info("%s", kdb_buffer);
726         }
727
728         if (KDB_STATE(PAGER)) {
729                 /*
730                  * Check printed string to decide how to bump the
731                  * kdb_nextline to control when the more prompt should
732                  * show up.
733                  */
734                 int got = 0;
735                 len = retlen;
736                 while (len--) {
737                         if (kdb_buffer[len] == '\n') {
738                                 kdb_nextline++;
739                                 got = 0;
740                         } else if (kdb_buffer[len] == '\r') {
741                                 got = 0;
742                         } else {
743                                 got++;
744                         }
745                 }
746                 kdb_nextline += got / (colcount + 1);
747         }
748
749         /* check for having reached the LINES number of printed lines */
750         if (kdb_nextline >= linecount) {
751                 char ch;
752
753                 /* Watch out for recursion here.  Any routine that calls
754                  * kdb_printf will come back through here.  And kdb_read
755                  * uses kdb_printf to echo on serial consoles ...
756                  */
757                 kdb_nextline = 1;       /* In case of recursion */
758
759                 /*
760                  * Pause until cr.
761                  */
762                 moreprompt = kdbgetenv("MOREPROMPT");
763                 if (moreprompt == NULL)
764                         moreprompt = "more> ";
765
766                 kdb_input_flush();
767                 kdb_msg_write(moreprompt, strlen(moreprompt));
768
769                 if (logging)
770                         printk("%s", moreprompt);
771
772                 ch = kdb_getchar();
773                 kdb_nextline = 1;       /* Really set output line 1 */
774
775                 /* empty and reset the buffer: */
776                 kdb_buffer[0] = '\0';
777                 next_avail = kdb_buffer;
778                 size_avail = sizeof(kdb_buffer);
779                 if ((ch == 'q') || (ch == 'Q')) {
780                         /* user hit q or Q */
781                         KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
782                         KDB_STATE_CLEAR(PAGER);
783                         /* end of command output; back to normal mode */
784                         kdb_grepping_flag = 0;
785                         kdb_printf("\n");
786                 } else if (ch == ' ') {
787                         kdb_printf("\r");
788                         suspend_grep = 1; /* for this recursion */
789                 } else if (ch == '\n' || ch == '\r') {
790                         kdb_nextline = linecount - 1;
791                         kdb_printf("\r");
792                         suspend_grep = 1; /* for this recursion */
793                 } else if (ch == '/' && !kdb_grepping_flag) {
794                         kdb_printf("\r");
795                         kdb_getstr(kdb_grep_string, KDB_GREP_STRLEN,
796                                    kdbgetenv("SEARCHPROMPT") ?: "search> ");
797                         *strchrnul(kdb_grep_string, '\n') = '\0';
798                         kdb_grepping_flag += KDB_GREPPING_FLAG_SEARCH;
799                         suspend_grep = 1; /* for this recursion */
800                 } else if (ch) {
801                         /* user hit something unexpected */
802                         suspend_grep = 1; /* for this recursion */
803                         if (ch != '/')
804                                 kdb_printf(
805                                     "\nOnly 'q', 'Q' or '/' are processed at "
806                                     "more prompt, input ignored\n");
807                         else
808                                 kdb_printf("\n'/' cannot be used during | "
809                                            "grep filtering, input ignored\n");
810                 } else if (kdb_grepping_flag) {
811                         /* user hit enter */
812                         suspend_grep = 1; /* for this recursion */
813                         kdb_printf("\n");
814                 }
815                 kdb_input_flush();
816         }
817
818         /*
819          * For grep searches, shift the printed string left.
820          *  replaced_byte contains the character that was overwritten with
821          *  the terminating null, and cphold points to the null.
822          * Then adjust the notion of available space in the buffer.
823          */
824         if (kdb_grepping_flag && !suspend_grep) {
825                 *cphold = replaced_byte;
826                 strcpy(kdb_buffer, cphold);
827                 len = strlen(kdb_buffer);
828                 next_avail = kdb_buffer + len;
829                 size_avail = sizeof(kdb_buffer) - len;
830         }
831
832 kdb_print_out:
833         suspend_grep = 0; /* end of what may have been a recursive call */
834         if (logging)
835                 console_loglevel = saved_loglevel;
836         /* kdb_printf_cpu locked the code above. */
837         smp_store_release(&kdb_printf_cpu, old_cpu);
838         local_irq_restore(flags);
839         return retlen;
840 }
841
842 int kdb_printf(const char *fmt, ...)
843 {
844         va_list ap;
845         int r;
846
847         va_start(ap, fmt);
848         r = vkdb_printf(KDB_MSGSRC_INTERNAL, fmt, ap);
849         va_end(ap);
850
851         return r;
852 }
853 EXPORT_SYMBOL_GPL(kdb_printf);