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TOMOYO Linux Cross Reference
Linux/kernel/debug/kdb/kdb_io.c

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  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 static int kdb_read_get_key(char *buffer, size_t bufsize)
 53 {
 54 #define ESCAPE_UDELAY 1000
 55 #define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
 56         char escape_data[5];    /* longest vt100 escape sequence is 4 bytes */
 57         char *ped = escape_data;
 58         int escape_delay = 0;
 59         get_char_func *f, *f_escape = NULL;
 60         int key;
 61 
 62         for (f = &kdb_poll_funcs[0]; ; ++f) {
 63                 if (*f == NULL) {
 64                         /* Reset NMI watchdog once per poll loop */
 65                         touch_nmi_watchdog();
 66                         f = &kdb_poll_funcs[0];
 67                 }
 68                 if (escape_delay == 2) {
 69                         *ped = '\0';
 70                         ped = escape_data;
 71                         --escape_delay;
 72                 }
 73                 if (escape_delay == 1) {
 74                         key = *ped++;
 75                         if (!*ped)
 76                                 --escape_delay;
 77                         break;
 78                 }
 79                 key = (*f)();
 80                 if (key == -1) {
 81                         if (escape_delay) {
 82                                 udelay(ESCAPE_UDELAY);
 83                                 --escape_delay;
 84                         }
 85                         continue;
 86                 }
 87                 if (bufsize <= 2) {
 88                         if (key == '\r')
 89                                 key = '\n';
 90                         *buffer++ = key;
 91                         *buffer = '\0';
 92                         return -1;
 93                 }
 94                 if (escape_delay == 0 && key == '\e') {
 95                         escape_delay = ESCAPE_DELAY;
 96                         ped = escape_data;
 97                         f_escape = f;
 98                 }
 99                 if (escape_delay) {
100                         *ped++ = key;
101                         if (f_escape != f) {
102                                 escape_delay = 2;
103                                 continue;
104                         }
105                         if (ped - escape_data == 1) {
106                                 /* \e */
107                                 continue;
108                         } else if (ped - escape_data == 2) {
109                                 /* \e<something> */
110                                 if (key != '[')
111                                         escape_delay = 2;
112                                 continue;
113                         } else if (ped - escape_data == 3) {
114                                 /* \e[<something> */
115                                 int mapkey = 0;
116                                 switch (key) {
117                                 case 'A': /* \e[A, up arrow */
118                                         mapkey = 16;
119                                         break;
120                                 case 'B': /* \e[B, down arrow */
121                                         mapkey = 14;
122                                         break;
123                                 case 'C': /* \e[C, right arrow */
124                                         mapkey = 6;
125                                         break;
126                                 case 'D': /* \e[D, left arrow */
127                                         mapkey = 2;
128                                         break;
129                                 case '1': /* dropthrough */
130                                 case '3': /* dropthrough */
131                                 /* \e[<1,3,4>], may be home, del, end */
132                                 case '4':
133                                         mapkey = -1;
134                                         break;
135                                 }
136                                 if (mapkey != -1) {
137                                         if (mapkey > 0) {
138                                                 escape_data[0] = mapkey;
139                                                 escape_data[1] = '\0';
140                                         }
141                                         escape_delay = 2;
142                                 }
143                                 continue;
144                         } else if (ped - escape_data == 4) {
145                                 /* \e[<1,3,4><something> */
146                                 int mapkey = 0;
147                                 if (key == '~') {
148                                         switch (escape_data[2]) {
149                                         case '1': /* \e[1~, home */
150                                                 mapkey = 1;
151                                                 break;
152                                         case '3': /* \e[3~, del */
153                                                 mapkey = 4;
154                                                 break;
155                                         case '4': /* \e[4~, end */
156                                                 mapkey = 5;
157                                                 break;
158                                         }
159                                 }
160                                 if (mapkey > 0) {
161                                         escape_data[0] = mapkey;
162                                         escape_data[1] = '\0';
163                                 }
164                                 escape_delay = 2;
165                                 continue;
166                         }
167                 }
168                 break;  /* A key to process */
169         }
170         return key;
171 }
172 
173 /*
174  * kdb_read
175  *
176  *      This function reads a string of characters, terminated by
177  *      a newline, or by reaching the end of the supplied buffer,
178  *      from the current kernel debugger console device.
179  * Parameters:
180  *      buffer  - Address of character buffer to receive input characters.
181  *      bufsize - size, in bytes, of the character buffer
182  * Returns:
183  *      Returns a pointer to the buffer containing the received
184  *      character string.  This string will be terminated by a
185  *      newline character.
186  * Locking:
187  *      No locks are required to be held upon entry to this
188  *      function.  It is not reentrant - it relies on the fact
189  *      that while kdb is running on only one "master debug" cpu.
190  * Remarks:
191  *
192  * The buffer size must be >= 2.  A buffer size of 2 means that the caller only
193  * wants a single key.
194  *
195  * An escape key could be the start of a vt100 control sequence such as \e[D
196  * (left arrow) or it could be a character in its own right.  The standard
197  * method for detecting the difference is to wait for 2 seconds to see if there
198  * are any other characters.  kdb is complicated by the lack of a timer service
199  * (interrupts are off), by multiple input sources and by the need to sometimes
200  * return after just one key.  Escape sequence processing has to be done as
201  * states in the polling loop.
202  */
203 
204 static char *kdb_read(char *buffer, size_t bufsize)
205 {
206         char *cp = buffer;
207         char *bufend = buffer+bufsize-2;        /* Reserve space for newline
208                                                  * and null byte */
209         char *lastchar;
210         char *p_tmp;
211         char tmp;
212         static char tmpbuffer[CMD_BUFLEN];
213         int len = strlen(buffer);
214         int len_tmp;
215         int tab = 0;
216         int count;
217         int i;
218         int diag, dtab_count;
219         int key;
220 
221 
222         diag = kdbgetintenv("DTABCOUNT", &dtab_count);
223         if (diag)
224                 dtab_count = 30;
225 
226         if (len > 0) {
227                 cp += len;
228                 if (*(buffer+len-1) == '\n')
229                         cp--;
230         }
231 
232         lastchar = cp;
233         *cp = '\0';
234         kdb_printf("%s", buffer);
235 poll_again:
236         key = kdb_read_get_key(buffer, bufsize);
237         if (key == -1)
238                 return buffer;
239         if (key != 9)
240                 tab = 0;
241         switch (key) {
242         case 8: /* backspace */
243                 if (cp > buffer) {
244                         if (cp < lastchar) {
245                                 memcpy(tmpbuffer, cp, lastchar - cp);
246                                 memcpy(cp-1, tmpbuffer, lastchar - cp);
247                         }
248                         *(--lastchar) = '\0';
249                         --cp;
250                         kdb_printf("\b%s \r", cp);
251                         tmp = *cp;
252                         *cp = '\0';
253                         kdb_printf(kdb_prompt_str);
254                         kdb_printf("%s", buffer);
255                         *cp = tmp;
256                 }
257                 break;
258         case 13: /* enter */
259                 *lastchar++ = '\n';
260                 *lastchar++ = '\0';
261                 if (!KDB_STATE(KGDB_TRANS)) {
262                         KDB_STATE_SET(KGDB_TRANS);
263                         kdb_printf("%s", buffer);
264                 }
265                 kdb_printf("\n");
266                 return buffer;
267         case 4: /* Del */
268                 if (cp < lastchar) {
269                         memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
270                         memcpy(cp, tmpbuffer, lastchar - cp - 1);
271                         *(--lastchar) = '\0';
272                         kdb_printf("%s \r", cp);
273                         tmp = *cp;
274                         *cp = '\0';
275                         kdb_printf(kdb_prompt_str);
276                         kdb_printf("%s", buffer);
277                         *cp = tmp;
278                 }
279                 break;
280         case 1: /* Home */
281                 if (cp > buffer) {
282                         kdb_printf("\r");
283                         kdb_printf(kdb_prompt_str);
284                         cp = buffer;
285                 }
286                 break;
287         case 5: /* End */
288                 if (cp < lastchar) {
289                         kdb_printf("%s", cp);
290                         cp = lastchar;
291                 }
292                 break;
293         case 2: /* Left */
294                 if (cp > buffer) {
295                         kdb_printf("\b");
296                         --cp;
297                 }
298                 break;
299         case 14: /* Down */
300                 memset(tmpbuffer, ' ',
301                        strlen(kdb_prompt_str) + (lastchar-buffer));
302                 *(tmpbuffer+strlen(kdb_prompt_str) +
303                   (lastchar-buffer)) = '\0';
304                 kdb_printf("\r%s\r", tmpbuffer);
305                 *lastchar = (char)key;
306                 *(lastchar+1) = '\0';
307                 return lastchar;
308         case 6: /* Right */
309                 if (cp < lastchar) {
310                         kdb_printf("%c", *cp);
311                         ++cp;
312                 }
313                 break;
314         case 16: /* Up */
315                 memset(tmpbuffer, ' ',
316                        strlen(kdb_prompt_str) + (lastchar-buffer));
317                 *(tmpbuffer+strlen(kdb_prompt_str) +
318                   (lastchar-buffer)) = '\0';
319                 kdb_printf("\r%s\r", tmpbuffer);
320                 *lastchar = (char)key;
321                 *(lastchar+1) = '\0';
322                 return lastchar;
323         case 9: /* Tab */
324                 if (tab < 2)
325                         ++tab;
326                 p_tmp = buffer;
327                 while (*p_tmp == ' ')
328                         p_tmp++;
329                 if (p_tmp > cp)
330                         break;
331                 memcpy(tmpbuffer, p_tmp, cp-p_tmp);
332                 *(tmpbuffer + (cp-p_tmp)) = '\0';
333                 p_tmp = strrchr(tmpbuffer, ' ');
334                 if (p_tmp)
335                         ++p_tmp;
336                 else
337                         p_tmp = tmpbuffer;
338                 len = strlen(p_tmp);
339                 count = kallsyms_symbol_complete(p_tmp,
340                                                  sizeof(tmpbuffer) -
341                                                  (p_tmp - tmpbuffer));
342                 if (tab == 2 && count > 0) {
343                         kdb_printf("\n%d symbols are found.", count);
344                         if (count > dtab_count) {
345                                 count = dtab_count;
346                                 kdb_printf(" But only first %d symbols will"
347                                            " be printed.\nYou can change the"
348                                            " environment variable DTABCOUNT.",
349                                            count);
350                         }
351                         kdb_printf("\n");
352                         for (i = 0; i < count; i++) {
353                                 if (kallsyms_symbol_next(p_tmp, i) < 0)
354                                         break;
355                                 kdb_printf("%s ", p_tmp);
356                                 *(p_tmp + len) = '\0';
357                         }
358                         if (i >= dtab_count)
359                                 kdb_printf("...");
360                         kdb_printf("\n");
361                         kdb_printf(kdb_prompt_str);
362                         kdb_printf("%s", buffer);
363                 } else if (tab != 2 && count > 0) {
364                         len_tmp = strlen(p_tmp);
365                         strncpy(p_tmp+len_tmp, cp, lastchar-cp+1);
366                         len_tmp = strlen(p_tmp);
367                         strncpy(cp, p_tmp+len, len_tmp-len + 1);
368                         len = len_tmp - len;
369                         kdb_printf("%s", cp);
370                         cp += len;
371                         lastchar += len;
372                 }
373                 kdb_nextline = 1; /* reset output line number */
374                 break;
375         default:
376                 if (key >= 32 && lastchar < bufend) {
377                         if (cp < lastchar) {
378                                 memcpy(tmpbuffer, cp, lastchar - cp);
379                                 memcpy(cp+1, tmpbuffer, lastchar - cp);
380                                 *++lastchar = '\0';
381                                 *cp = key;
382                                 kdb_printf("%s\r", cp);
383                                 ++cp;
384                                 tmp = *cp;
385                                 *cp = '\0';
386                                 kdb_printf(kdb_prompt_str);
387                                 kdb_printf("%s", buffer);
388                                 *cp = tmp;
389                         } else {
390                                 *++lastchar = '\0';
391                                 *cp++ = key;
392                                 /* The kgdb transition check will hide
393                                  * printed characters if we think that
394                                  * kgdb is connecting, until the check
395                                  * fails */
396                                 if (!KDB_STATE(KGDB_TRANS)) {
397                                         if (kgdb_transition_check(buffer))
398                                                 return buffer;
399                                 } else {
400                                         kdb_printf("%c", key);
401                                 }
402                         }
403                         /* Special escape to kgdb */
404                         if (lastchar - buffer >= 5 &&
405                             strcmp(lastchar - 5, "$?#3f") == 0) {
406                                 kdb_gdb_state_pass(lastchar - 5);
407                                 strcpy(buffer, "kgdb");
408                                 KDB_STATE_SET(DOING_KGDB);
409                                 return buffer;
410                         }
411                         if (lastchar - buffer >= 11 &&
412                             strcmp(lastchar - 11, "$qSupported") == 0) {
413                                 kdb_gdb_state_pass(lastchar - 11);
414                                 strcpy(buffer, "kgdb");
415                                 KDB_STATE_SET(DOING_KGDB);
416                                 return buffer;
417                         }
418                 }
419                 break;
420         }
421         goto poll_again;
422 }
423 
424 /*
425  * kdb_getstr
426  *
427  *      Print the prompt string and read a command from the
428  *      input device.
429  *
430  * Parameters:
431  *      buffer  Address of buffer to receive command
432  *      bufsize Size of buffer in bytes
433  *      prompt  Pointer to string to use as prompt string
434  * Returns:
435  *      Pointer to command buffer.
436  * Locking:
437  *      None.
438  * Remarks:
439  *      For SMP kernels, the processor number will be
440  *      substituted for %d, %x or %o in the prompt.
441  */
442 
443 char *kdb_getstr(char *buffer, size_t bufsize, const char *prompt)
444 {
445         if (prompt && kdb_prompt_str != prompt)
446                 strncpy(kdb_prompt_str, prompt, CMD_BUFLEN);
447         kdb_printf(kdb_prompt_str);
448         kdb_nextline = 1;       /* Prompt and input resets line number */
449         return kdb_read(buffer, bufsize);
450 }
451 
452 /*
453  * kdb_input_flush
454  *
455  *      Get rid of any buffered console input.
456  *
457  * Parameters:
458  *      none
459  * Returns:
460  *      nothing
461  * Locking:
462  *      none
463  * Remarks:
464  *      Call this function whenever you want to flush input.  If there is any
465  *      outstanding input, it ignores all characters until there has been no
466  *      data for approximately 1ms.
467  */
468 
469 static void kdb_input_flush(void)
470 {
471         get_char_func *f;
472         int res;
473         int flush_delay = 1;
474         while (flush_delay) {
475                 flush_delay--;
476 empty:
477                 touch_nmi_watchdog();
478                 for (f = &kdb_poll_funcs[0]; *f; ++f) {
479                         res = (*f)();
480                         if (res != -1) {
481                                 flush_delay = 1;
482                                 goto empty;
483                         }
484                 }
485                 if (flush_delay)
486                         mdelay(1);
487         }
488 }
489 
490 /*
491  * kdb_printf
492  *
493  *      Print a string to the output device(s).
494  *
495  * Parameters:
496  *      printf-like format and optional args.
497  * Returns:
498  *      0
499  * Locking:
500  *      None.
501  * Remarks:
502  *      use 'kdbcons->write()' to avoid polluting 'log_buf' with
503  *      kdb output.
504  *
505  *  If the user is doing a cmd args | grep srch
506  *  then kdb_grepping_flag is set.
507  *  In that case we need to accumulate full lines (ending in \n) before
508  *  searching for the pattern.
509  */
510 
511 static char kdb_buffer[256];    /* A bit too big to go on stack */
512 static char *next_avail = kdb_buffer;
513 static int  size_avail;
514 static int  suspend_grep;
515 
516 /*
517  * search arg1 to see if it contains arg2
518  * (kdmain.c provides flags for ^pat and pat$)
519  *
520  * return 1 for found, 0 for not found
521  */
522 static int kdb_search_string(char *searched, char *searchfor)
523 {
524         char firstchar, *cp;
525         int len1, len2;
526 
527         /* not counting the newline at the end of "searched" */
528         len1 = strlen(searched)-1;
529         len2 = strlen(searchfor);
530         if (len1 < len2)
531                 return 0;
532         if (kdb_grep_leading && kdb_grep_trailing && len1 != len2)
533                 return 0;
534         if (kdb_grep_leading) {
535                 if (!strncmp(searched, searchfor, len2))
536                         return 1;
537         } else if (kdb_grep_trailing) {
538                 if (!strncmp(searched+len1-len2, searchfor, len2))
539                         return 1;
540         } else {
541                 firstchar = *searchfor;
542                 cp = searched;
543                 while ((cp = strchr(cp, firstchar))) {
544                         if (!strncmp(cp, searchfor, len2))
545                                 return 1;
546                         cp++;
547                 }
548         }
549         return 0;
550 }
551 
552 int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
553 {
554         int diag;
555         int linecount;
556         int colcount;
557         int logging, saved_loglevel = 0;
558         int retlen = 0;
559         int fnd, len;
560         int this_cpu, old_cpu;
561         char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
562         char *moreprompt = "more> ";
563         struct console *c = console_drivers;
564         unsigned long uninitialized_var(flags);
565 
566         /* Serialize kdb_printf if multiple cpus try to write at once.
567          * But if any cpu goes recursive in kdb, just print the output,
568          * even if it is interleaved with any other text.
569          */
570         local_irq_save(flags);
571         this_cpu = smp_processor_id();
572         for (;;) {
573                 old_cpu = cmpxchg(&kdb_printf_cpu, -1, this_cpu);
574                 if (old_cpu == -1 || old_cpu == this_cpu)
575                         break;
576 
577                 cpu_relax();
578         }
579 
580         diag = kdbgetintenv("LINES", &linecount);
581         if (diag || linecount <= 1)
582                 linecount = 24;
583 
584         diag = kdbgetintenv("COLUMNS", &colcount);
585         if (diag || colcount <= 1)
586                 colcount = 80;
587 
588         diag = kdbgetintenv("LOGGING", &logging);
589         if (diag)
590                 logging = 0;
591 
592         if (!kdb_grepping_flag || suspend_grep) {
593                 /* normally, every vsnprintf starts a new buffer */
594                 next_avail = kdb_buffer;
595                 size_avail = sizeof(kdb_buffer);
596         }
597         vsnprintf(next_avail, size_avail, fmt, ap);
598 
599         /*
600          * If kdb_parse() found that the command was cmd xxx | grep yyy
601          * then kdb_grepping_flag is set, and kdb_grep_string contains yyy
602          *
603          * Accumulate the print data up to a newline before searching it.
604          * (vsnprintf does null-terminate the string that it generates)
605          */
606 
607         /* skip the search if prints are temporarily unconditional */
608         if (!suspend_grep && kdb_grepping_flag) {
609                 cp = strchr(kdb_buffer, '\n');
610                 if (!cp) {
611                         /*
612                          * Special cases that don't end with newlines
613                          * but should be written without one:
614                          *   The "[nn]kdb> " prompt should
615                          *   appear at the front of the buffer.
616                          *
617                          *   The "[nn]more " prompt should also be
618                          *     (MOREPROMPT -> moreprompt)
619                          *   written *   but we print that ourselves,
620                          *   we set the suspend_grep flag to make
621                          *   it unconditional.
622                          *
623                          */
624                         if (next_avail == kdb_buffer) {
625                                 /*
626                                  * these should occur after a newline,
627                                  * so they will be at the front of the
628                                  * buffer
629                                  */
630                                 cp2 = kdb_buffer;
631                                 len = strlen(kdb_prompt_str);
632                                 if (!strncmp(cp2, kdb_prompt_str, len)) {
633                                         /*
634                                          * We're about to start a new
635                                          * command, so we can go back
636                                          * to normal mode.
637                                          */
638                                         kdb_grepping_flag = 0;
639                                         goto kdb_printit;
640                                 }
641                         }
642                         /* no newline; don't search/write the buffer
643                            until one is there */
644                         len = strlen(kdb_buffer);
645                         next_avail = kdb_buffer + len;
646                         size_avail = sizeof(kdb_buffer) - len;
647                         goto kdb_print_out;
648                 }
649 
650                 /*
651                  * The newline is present; print through it or discard
652                  * it, depending on the results of the search.
653                  */
654                 cp++;                /* to byte after the newline */
655                 replaced_byte = *cp; /* remember what/where it was */
656                 cphold = cp;
657                 *cp = '\0';          /* end the string for our search */
658 
659                 /*
660                  * We now have a newline at the end of the string
661                  * Only continue with this output if it contains the
662                  * search string.
663                  */
664                 fnd = kdb_search_string(kdb_buffer, kdb_grep_string);
665                 if (!fnd) {
666                         /*
667                          * At this point the complete line at the start
668                          * of kdb_buffer can be discarded, as it does
669                          * not contain what the user is looking for.
670                          * Shift the buffer left.
671                          */
672                         *cphold = replaced_byte;
673                         strcpy(kdb_buffer, cphold);
674                         len = strlen(kdb_buffer);
675                         next_avail = kdb_buffer + len;
676                         size_avail = sizeof(kdb_buffer) - len;
677                         goto kdb_print_out;
678                 }
679                 if (kdb_grepping_flag >= KDB_GREPPING_FLAG_SEARCH)
680                         /*
681                          * This was a interactive search (using '/' at more
682                          * prompt) and it has completed. Clear the flag.
683                          */
684                         kdb_grepping_flag = 0;
685                 /*
686                  * at this point the string is a full line and
687                  * should be printed, up to the null.
688                  */
689         }
690 kdb_printit:
691 
692         /*
693          * Write to all consoles.
694          */
695         retlen = strlen(kdb_buffer);
696         cp = (char *) printk_skip_headers(kdb_buffer);
697         if (!dbg_kdb_mode && kgdb_connected) {
698                 gdbstub_msg_write(cp, retlen - (cp - kdb_buffer));
699         } else {
700                 if (dbg_io_ops && !dbg_io_ops->is_console) {
701                         len = retlen - (cp - kdb_buffer);
702                         cp2 = cp;
703                         while (len--) {
704                                 dbg_io_ops->write_char(*cp2);
705                                 cp2++;
706                         }
707                 }
708                 while (c) {
709                         c->write(c, cp, retlen - (cp - kdb_buffer));
710                         touch_nmi_watchdog();
711                         c = c->next;
712                 }
713         }
714         if (logging) {
715                 saved_loglevel = console_loglevel;
716                 console_loglevel = CONSOLE_LOGLEVEL_SILENT;
717                 if (printk_get_level(kdb_buffer) || src == KDB_MSGSRC_PRINTK)
718                         printk("%s", kdb_buffer);
719                 else
720                         pr_info("%s", kdb_buffer);
721         }
722 
723         if (KDB_STATE(PAGER)) {
724                 /*
725                  * Check printed string to decide how to bump the
726                  * kdb_nextline to control when the more prompt should
727                  * show up.
728                  */
729                 int got = 0;
730                 len = retlen;
731                 while (len--) {
732                         if (kdb_buffer[len] == '\n') {
733                                 kdb_nextline++;
734                                 got = 0;
735                         } else if (kdb_buffer[len] == '\r') {
736                                 got = 0;
737                         } else {
738                                 got++;
739                         }
740                 }
741                 kdb_nextline += got / (colcount + 1);
742         }
743 
744         /* check for having reached the LINES number of printed lines */
745         if (kdb_nextline >= linecount) {
746                 char buf1[16] = "";
747 
748                 /* Watch out for recursion here.  Any routine that calls
749                  * kdb_printf will come back through here.  And kdb_read
750                  * uses kdb_printf to echo on serial consoles ...
751                  */
752                 kdb_nextline = 1;       /* In case of recursion */
753 
754                 /*
755                  * Pause until cr.
756                  */
757                 moreprompt = kdbgetenv("MOREPROMPT");
758                 if (moreprompt == NULL)
759                         moreprompt = "more> ";
760 
761                 kdb_input_flush();
762                 c = console_drivers;
763 
764                 if (dbg_io_ops && !dbg_io_ops->is_console) {
765                         len = strlen(moreprompt);
766                         cp = moreprompt;
767                         while (len--) {
768                                 dbg_io_ops->write_char(*cp);
769                                 cp++;
770                         }
771                 }
772                 while (c) {
773                         c->write(c, moreprompt, strlen(moreprompt));
774                         touch_nmi_watchdog();
775                         c = c->next;
776                 }
777 
778                 if (logging)
779                         printk("%s", moreprompt);
780 
781                 kdb_read(buf1, 2); /* '2' indicates to return
782                                     * immediately after getting one key. */
783                 kdb_nextline = 1;       /* Really set output line 1 */
784 
785                 /* empty and reset the buffer: */
786                 kdb_buffer[0] = '\0';
787                 next_avail = kdb_buffer;
788                 size_avail = sizeof(kdb_buffer);
789                 if ((buf1[0] == 'q') || (buf1[0] == 'Q')) {
790                         /* user hit q or Q */
791                         KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
792                         KDB_STATE_CLEAR(PAGER);
793                         /* end of command output; back to normal mode */
794                         kdb_grepping_flag = 0;
795                         kdb_printf("\n");
796                 } else if (buf1[0] == ' ') {
797                         kdb_printf("\r");
798                         suspend_grep = 1; /* for this recursion */
799                 } else if (buf1[0] == '\n') {
800                         kdb_nextline = linecount - 1;
801                         kdb_printf("\r");
802                         suspend_grep = 1; /* for this recursion */
803                 } else if (buf1[0] == '/' && !kdb_grepping_flag) {
804                         kdb_printf("\r");
805                         kdb_getstr(kdb_grep_string, KDB_GREP_STRLEN,
806                                    kdbgetenv("SEARCHPROMPT") ?: "search> ");
807                         *strchrnul(kdb_grep_string, '\n') = '\0';
808                         kdb_grepping_flag += KDB_GREPPING_FLAG_SEARCH;
809                         suspend_grep = 1; /* for this recursion */
810                 } else if (buf1[0] && buf1[0] != '\n') {
811                         /* user hit something other than enter */
812                         suspend_grep = 1; /* for this recursion */
813                         if (buf1[0] != '/')
814                                 kdb_printf(
815                                     "\nOnly 'q', 'Q' or '/' are processed at "
816                                     "more prompt, input ignored\n");
817                         else
818                                 kdb_printf("\n'/' cannot be used during | "
819                                            "grep filtering, input ignored\n");
820                 } else if (kdb_grepping_flag) {
821                         /* user hit enter */
822                         suspend_grep = 1; /* for this recursion */
823                         kdb_printf("\n");
824                 }
825                 kdb_input_flush();
826         }
827 
828         /*
829          * For grep searches, shift the printed string left.
830          *  replaced_byte contains the character that was overwritten with
831          *  the terminating null, and cphold points to the null.
832          * Then adjust the notion of available space in the buffer.
833          */
834         if (kdb_grepping_flag && !suspend_grep) {
835                 *cphold = replaced_byte;
836                 strcpy(kdb_buffer, cphold);
837                 len = strlen(kdb_buffer);
838                 next_avail = kdb_buffer + len;
839                 size_avail = sizeof(kdb_buffer) - len;
840         }
841 
842 kdb_print_out:
843         suspend_grep = 0; /* end of what may have been a recursive call */
844         if (logging)
845                 console_loglevel = saved_loglevel;
846         /* kdb_printf_cpu locked the code above. */
847         smp_store_release(&kdb_printf_cpu, old_cpu);
848         local_irq_restore(flags);
849         return retlen;
850 }
851 
852 int kdb_printf(const char *fmt, ...)
853 {
854         va_list ap;
855         int r;
856 
857         va_start(ap, fmt);
858         r = vkdb_printf(KDB_MSGSRC_INTERNAL, fmt, ap);
859         va_end(ap);
860 
861         return r;
862 }
863 EXPORT_SYMBOL_GPL(kdb_printf);
864 

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