kdb_io.c

  1/*
  2 * Kernel Debugger Architecture Independent Console I/O handler
  3 *
  4 * This file is subject to the terms and conditions of the GNU General Public
  5 * License.  See the file "COPYING" in the main directory of this archive
  6 * for more details.
  7 *
  8 * Copyright (c) 1999-2006 Silicon Graphics, Inc.  All Rights Reserved.
  9 * Copyright (c) 2009 Wind River Systems, Inc.  All Rights Reserved.
 10 */
 11
 12#include <linux/types.h>
 13#include <linux/ctype.h>
 14#include <linux/kernel.h>
 15#include <linux/init.h>
 16#include <linux/kdev_t.h>
 17#include <linux/console.h>
 18#include <linux/string.h>
 19#include <linux/sched.h>
 20#include <linux/smp.h>
 21#include <linux/nmi.h>
 22#include <linux/delay.h>
 23#include <linux/kgdb.h>
 24#include <linux/kdb.h>
 25#include <linux/kallsyms.h>
 26#include "kdb_private.h"
 27
 28#define CMD_BUFLEN 256
 29char kdb_prompt_str[CMD_BUFLEN];
 30
 31int kdb_trap_printk;
 32int kdb_printf_cpu = -1;
 33
 34static int kgdb_transition_check(char *buffer)
 35{
 36	if (buffer[0] != '+' && buffer[0] != '$') {
 37		KDB_STATE_SET(KGDB_TRANS);
 38		kdb_printf("%s", buffer);
 39	} else {
 40		int slen = strlen(buffer);
 41		if (slen > 3 && buffer[slen - 3] == '#') {
 42			kdb_gdb_state_pass(buffer);
 43			strcpy(buffer, "kgdb");
 44			KDB_STATE_SET(DOING_KGDB);
 45			return 1;
 46		}
 47	}
 48	return 0;
 49}
 50
 51/**
 52 * kdb_handle_escape() - validity check on an accumulated escape sequence.
 53 * @buf:	Accumulated escape characters to be examined. Note that buf
 54 *		is not a string, it is an array of characters and need not be
 55 *		nil terminated.
 56 * @sz:		Number of accumulated escape characters.
 57 *
 58 * Return: -1 if the escape sequence is unwanted, 0 if it is incomplete,
 59 * otherwise it returns a mapped key value to pass to the upper layers.
 60 */
 61static int kdb_handle_escape(char *buf, size_t sz)
 62{
 63	char *lastkey = buf + sz - 1;
 64
 65	switch (sz) {
 66	case 1:
 67		if (*lastkey == '\e')
 68			return 0;
 69		break;
 70
 71	case 2: /* \e<something> */
 72		if (*lastkey == '[')
 73			return 0;
 74		break;
 75
 76	case 3:
 77		switch (*lastkey) {
 78		case 'A': /* \e[A, up arrow */
 79			return 16;
 80		case 'B': /* \e[B, down arrow */
 81			return 14;
 82		case 'C': /* \e[C, right arrow */
 83			return 6;
 84		case 'D': /* \e[D, left arrow */
 85			return 2;
 86		case '1': /* \e[<1,3,4>], may be home, del, end */
 87		case '3':
 88		case '4':
 89			return 0;
 90		}
 91		break;
 92
 93	case 4:
 94		if (*lastkey == '~') {
 95			switch (buf[2]) {
 96			case '1': /* \e[1~, home */
 97				return 1;
 98			case '3': /* \e[3~, del */
 99				return 4;
100			case '4': /* \e[4~, end */
101				return 5;
102			}
103		}
104		break;
105	}
106
107	return -1;
108}
109
110/**
111 * kdb_getchar() - Read a single character from a kdb console (or consoles).
112 *
113 * Other than polling the various consoles that are currently enabled,
114 * most of the work done in this function is dealing with escape sequences.
115 *
116 * An escape key could be the start of a vt100 control sequence such as \e[D
117 * (left arrow) or it could be a character in its own right.  The standard
118 * method for detecting the difference is to wait for 2 seconds to see if there
119 * are any other characters.  kdb is complicated by the lack of a timer service
120 * (interrupts are off), by multiple input sources. Escape sequence processing
121 * has to be done as states in the polling loop.
122 *
123 * Return: The key pressed or a control code derived from an escape sequence.
124 */
125char kdb_getchar(void)
126{
127#define ESCAPE_UDELAY 1000
128#define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
129	char buf[4];	/* longest vt100 escape sequence is 4 bytes */
130	char *pbuf = buf;
131	int escape_delay = 0;
132	get_char_func *f, *f_prev = NULL;
133	int key;
134	static bool last_char_was_cr;
135
136	for (f = &kdb_poll_funcs[0]; ; ++f) {
137		if (*f == NULL) {
138			/* Reset NMI watchdog once per poll loop */
139			touch_nmi_watchdog();
140			f = &kdb_poll_funcs[0];
141		}
142
143		key = (*f)();
144		if (key == -1) {
145			if (escape_delay) {
146				udelay(ESCAPE_UDELAY);
147				if (--escape_delay == 0)
148					return '\e';
149			}
150			continue;
151		}
152
153		/*
154		 * The caller expects that newlines are either CR or LF. However
155		 * some terminals send _both_ CR and LF. Avoid having to handle
156		 * this in the caller by stripping the LF if we saw a CR right
157		 * before.
158		 */
159		if (last_char_was_cr && key == '\n') {
160			last_char_was_cr = false;
161			continue;
162		}
163		last_char_was_cr = (key == '\r');
164
165		/*
166		 * When the first character is received (or we get a change
167		 * input source) we set ourselves up to handle an escape
168		 * sequences (just in case).
169		 */
170		if (f_prev != f) {
171			f_prev = f;
172			pbuf = buf;
173			escape_delay = ESCAPE_DELAY;
174		}
175
176		*pbuf++ = key;
177		key = kdb_handle_escape(buf, pbuf - buf);
178		if (key < 0) /* no escape sequence; return best character */
179			return buf[pbuf - buf == 2 ? 1 : 0];
180		if (key > 0)
181			return key;
182	}
183
184	unreachable();
185}
186
187/**
188 * kdb_position_cursor() - Place cursor in the correct horizontal position
189 * @prompt: Nil-terminated string containing the prompt string
190 * @buffer: Nil-terminated string containing the entire command line
191 * @cp: Cursor position, pointer the character in buffer where the cursor
192 *      should be positioned.
193 *
194 * The cursor is positioned by sending a carriage-return and then printing
195 * the content of the line until we reach the correct cursor position.
196 *
197 * There is some additional fine detail here.
198 *
199 * Firstly, even though kdb_printf() will correctly format zero-width fields
200 * we want the second call to kdb_printf() to be conditional. That keeps things
201 * a little cleaner when LOGGING=1.
202 *
203 * Secondly, we can't combine everything into one call to kdb_printf() since
204 * that renders into a fixed length buffer and the combined print could result
205 * in unwanted truncation.
206 */
207static void kdb_position_cursor(char *prompt, char *buffer, char *cp)
208{
209	kdb_printf("\r%s", prompt);
210	if (cp > buffer)
211		kdb_printf("%.*s", (int)(cp - buffer), buffer);
212}
213
214/*
215 * kdb_read
216 *
217 *	This function reads a string of characters, terminated by
218 *	a newline, or by reaching the end of the supplied buffer,
219 *	from the current kernel debugger console device.
220 * Parameters:
221 *	buffer	- Address of character buffer to receive input characters.
222 *	bufsize - size, in bytes, of the character buffer
223 * Returns:
224 *	Returns a pointer to the buffer containing the received
225 *	character string.  This string will be terminated by a
226 *	newline character.
227 * Locking:
228 *	No locks are required to be held upon entry to this
229 *	function.  It is not reentrant - it relies on the fact
230 *	that while kdb is running on only one "master debug" cpu.
231 * Remarks:
232 *	The buffer size must be >= 2.
233 */
234
235static char *kdb_read(char *buffer, size_t bufsize)
236{
237	char *cp = buffer;
238	char *bufend = buffer+bufsize-2;	/* Reserve space for newline
239						 * and null byte */
240	char *lastchar;
241	char *p_tmp;
242	char tmp;
243	static char tmpbuffer[CMD_BUFLEN];
244	int len = strlen(buffer);
245	int len_tmp;
246	int tab = 0;
247	int count;
248	int i;
249	int diag, dtab_count;
250	int key, ret;
251
252	diag = kdbgetintenv("DTABCOUNT", &dtab_count);
253	if (diag)
254		dtab_count = 30;
255
256	if (len > 0) {
257		cp += len;
258		if (*(buffer+len-1) == '\n')
259			cp--;
260	}
261
262	lastchar = cp;
263	*cp = '\0';
264	kdb_printf("%s", buffer);
265poll_again:
266	key = kdb_getchar();
267	if (key != 9)
268		tab = 0;
269	switch (key) {
270	case 8: /* backspace */
271		if (cp > buffer) {
272			memmove(cp-1, cp, lastchar - cp + 1);
273			lastchar--;
274			cp--;
275			kdb_printf("\b%s ", cp);
276			kdb_position_cursor(kdb_prompt_str, buffer, cp);
277		}
278		break;
279	case 10: /* linefeed */
280	case 13: /* carriage return */
281		*lastchar++ = '\n';
282		*lastchar++ = '\0';
283		if (!KDB_STATE(KGDB_TRANS)) {
284			KDB_STATE_SET(KGDB_TRANS);
285			kdb_printf("%s", buffer);
286		}
287		kdb_printf("\n");
288		return buffer;
289	case 4: /* Del */
290		if (cp < lastchar) {
291			memmove(cp, cp+1, lastchar - cp);
292			lastchar--;
293			kdb_printf("%s ", cp);
294			kdb_position_cursor(kdb_prompt_str, buffer, cp);
295		}
296		break;
297	case 1: /* Home */
298		if (cp > buffer) {
299			cp = buffer;
300			kdb_position_cursor(kdb_prompt_str, buffer, cp);
301		}
302		break;
303	case 5: /* End */
304		if (cp < lastchar) {
305			kdb_printf("%s", cp);
306			cp = lastchar;
307		}
308		break;
309	case 2: /* Left */
310		if (cp > buffer) {
311			kdb_printf("\b");
312			--cp;
313		}
314		break;
315	case 14: /* Down */
316	case 16: /* Up */
317		kdb_printf("\r%*c\r",
318			   (int)(strlen(kdb_prompt_str) + (lastchar - buffer)),
319			   ' ');
320		*lastchar = (char)key;
321		*(lastchar+1) = '\0';
322		return lastchar;
323	case 6: /* Right */
324		if (cp < lastchar) {
325			kdb_printf("%c", *cp);
326			++cp;
327		}
328		break;
329	case 9: /* Tab */
330		if (tab < 2)
331			++tab;
332
333		tmp = *cp;
334		*cp = '\0';
335		p_tmp = strrchr(buffer, ' ');
336		p_tmp = (p_tmp ? p_tmp + 1 : buffer);
337		strscpy(tmpbuffer, p_tmp);
338		*cp = tmp;
339
340		len = strlen(tmpbuffer);
341		count = kallsyms_symbol_complete(tmpbuffer, sizeof(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				ret = kallsyms_symbol_next(tmpbuffer, i, sizeof(tmpbuffer));
354				if (WARN_ON(!ret))
355					break;
356				if (ret != -E2BIG)
357					kdb_printf("%s ", tmpbuffer);
358				else
359					kdb_printf("%s... ", tmpbuffer);
360				tmpbuffer[len] = '\0';
361			}
362			if (i >= dtab_count)
363				kdb_printf("...");
364			kdb_printf("\n");
365			kdb_printf("%s",  kdb_prompt_str);
366			kdb_printf("%s", buffer);
367			if (cp != lastchar)
368				kdb_position_cursor(kdb_prompt_str, buffer, cp);
369		} else if (tab != 2 && count > 0) {
370			/* How many new characters do we want from tmpbuffer? */
371			len_tmp = strlen(tmpbuffer) - len;
372			if (lastchar + len_tmp >= bufend)
373				len_tmp = bufend - lastchar;
374
375			if (len_tmp) {
376				/* + 1 ensures the '\0' is memmove'd */
377				memmove(cp+len_tmp, cp, (lastchar-cp) + 1);
378				memcpy(cp, tmpbuffer+len, len_tmp);
379				kdb_printf("%s", cp);
380				cp += len_tmp;
381				lastchar += len_tmp;
382				if (cp != lastchar)
383					kdb_position_cursor(kdb_prompt_str,
384							    buffer, cp);
385			}
386		}
387		kdb_nextline = 1; /* reset output line number */
388		break;
389	default:
390		if (key >= 32 && lastchar < bufend) {
391			if (cp < lastchar) {
392				memmove(cp+1, cp, lastchar - cp + 1);
393				lastchar++;
394				*cp = key;
395				kdb_printf("%s", cp);
396				++cp;
397				kdb_position_cursor(kdb_prompt_str, buffer, cp);
398			} else {
399				*++lastchar = '\0';
400				*cp++ = key;
401				/* The kgdb transition check will hide
402				 * printed characters if we think that
403				 * kgdb is connecting, until the check
404				 * fails */
405				if (!KDB_STATE(KGDB_TRANS)) {
406					if (kgdb_transition_check(buffer))
407						return buffer;
408				} else {
409					kdb_printf("%c", key);
410				}
411			}
412			/* Special escape to kgdb */
413			if (lastchar - buffer >= 5 &&
414			    strcmp(lastchar - 5, "$?#3f") == 0) {
415				kdb_gdb_state_pass(lastchar - 5);
416				strcpy(buffer, "kgdb");
417				KDB_STATE_SET(DOING_KGDB);
418				return buffer;
419			}
420			if (lastchar - buffer >= 11 &&
421			    strcmp(lastchar - 11, "$qSupported") == 0) {
422				kdb_gdb_state_pass(lastchar - 11);
423				strcpy(buffer, "kgdb");
424				KDB_STATE_SET(DOING_KGDB);
425				return buffer;
426			}
427		}
428		break;
429	}
430	goto poll_again;
431}
432
433/*
434 * kdb_getstr
435 *
436 *	Print the prompt string and read a command from the
437 *	input device.
438 *
439 * Parameters:
440 *	buffer	Address of buffer to receive command
441 *	bufsize Size of buffer in bytes
442 *	prompt	Pointer to string to use as prompt string
443 * Returns:
444 *	Pointer to command buffer.
445 * Locking:
446 *	None.
447 * Remarks:
448 *	For SMP kernels, the processor number will be
449 *	substituted for %d, %x or %o in the prompt.
450 */
451
452char *kdb_getstr(char *buffer, size_t bufsize, const char *prompt)
453{
454	if (prompt && kdb_prompt_str != prompt)
455		strscpy(kdb_prompt_str, prompt);
456	kdb_printf("%s", kdb_prompt_str);
457	kdb_nextline = 1;	/* Prompt and input resets line number */
458	return kdb_read(buffer, bufsize);
459}
460
461/*
462 * kdb_input_flush
463 *
464 *	Get rid of any buffered console input.
465 *
466 * Parameters:
467 *	none
468 * Returns:
469 *	nothing
470 * Locking:
471 *	none
472 * Remarks:
473 *	Call this function whenever you want to flush input.  If there is any
474 *	outstanding input, it ignores all characters until there has been no
475 *	data for approximately 1ms.
476 */
477
478static void kdb_input_flush(void)
479{
480	get_char_func *f;
481	int res;
482	int flush_delay = 1;
483	while (flush_delay) {
484		flush_delay--;
485empty:
486		touch_nmi_watchdog();
487		for (f = &kdb_poll_funcs[0]; *f; ++f) {
488			res = (*f)();
489			if (res != -1) {
490				flush_delay = 1;
491				goto empty;
492			}
493		}
494		if (flush_delay)
495			mdelay(1);
496	}
497}
498
499/*
500 * kdb_printf
501 *
502 *	Print a string to the output device(s).
503 *
504 * Parameters:
505 *	printf-like format and optional args.
506 * Returns:
507 *	0
508 * Locking:
509 *	None.
510 * Remarks:
511 *	use 'kdbcons->write()' to avoid polluting 'log_buf' with
512 *	kdb output.
513 *
514 *  If the user is doing a cmd args | grep srch
515 *  then kdb_grepping_flag is set.
516 *  In that case we need to accumulate full lines (ending in \n) before
517 *  searching for the pattern.
518 */
519
520static char kdb_buffer[256];	/* A bit too big to go on stack */
521static char *next_avail = kdb_buffer;
522static int  size_avail;
523static int  suspend_grep;
524
525/*
526 * search arg1 to see if it contains arg2
527 * (kdmain.c provides flags for ^pat and pat$)
528 *
529 * return 1 for found, 0 for not found
530 */
531static int kdb_search_string(char *searched, char *searchfor)
532{
533	char firstchar, *cp;
534	int len1, len2;
535
536	/* not counting the newline at the end of "searched" */
537	len1 = strlen(searched)-1;
538	len2 = strlen(searchfor);
539	if (len1 < len2)
540		return 0;
541	if (kdb_grep_leading && kdb_grep_trailing && len1 != len2)
542		return 0;
543	if (kdb_grep_leading) {
544		if (!strncmp(searched, searchfor, len2))
545			return 1;
546	} else if (kdb_grep_trailing) {
547		if (!strncmp(searched+len1-len2, searchfor, len2))
548			return 1;
549	} else {
550		firstchar = *searchfor;
551		cp = searched;
552		while ((cp = strchr(cp, firstchar))) {
553			if (!strncmp(cp, searchfor, len2))
554				return 1;
555			cp++;
556		}
557	}
558	return 0;
559}
560
561static void kdb_msg_write(const char *msg, int msg_len)
562{
563	struct console *c;
564	const char *cp;
565	int cookie;
566	int len;
567
568	if (msg_len == 0)
569		return;
570
571	cp = msg;
572	len = msg_len;
573
574	while (len--) {
575		dbg_io_ops->write_char(*cp);
576		cp++;
577	}
578
579	/*
580	 * The console_srcu_read_lock() only provides safe console list
581	 * traversal. The use of the ->write() callback relies on all other
582	 * CPUs being stopped at the moment and console drivers being able to
583	 * handle reentrance when @oops_in_progress is set.
584	 *
585	 * There is no guarantee that every console driver can handle
586	 * reentrance in this way; the developer deploying the debugger
587	 * is responsible for ensuring that the console drivers they
588	 * have selected handle reentrance appropriately.
589	 */
590	cookie = console_srcu_read_lock();
591	for_each_console_srcu(c) {
592		short flags = console_srcu_read_flags(c);
593
594		if (!console_is_usable(c, flags, true))
595			continue;
596		if (c == dbg_io_ops->cons)
597			continue;
598
599		if (flags & CON_NBCON) {
600			struct nbcon_write_context wctxt = { };
601
602			/*
603			 * Do not continue if the console is NBCON and the context
604			 * can't be acquired.
605			 */
606			if (!nbcon_kdb_try_acquire(c, &wctxt))
607				continue;
608
609			nbcon_write_context_set_buf(&wctxt, (char *)msg, msg_len);
610
611			c->write_atomic(c, &wctxt);
612			nbcon_kdb_release(&wctxt);
613		} else {
614			/*
615			 * Set oops_in_progress to encourage the console drivers to
616			 * disregard their internal spin locks: in the current calling
617			 * context the risk of deadlock is a bigger problem than risks
618			 * due to re-entering the console driver. We operate directly on
619			 * oops_in_progress rather than using bust_spinlocks() because
620			 * the calls bust_spinlocks() makes on exit are not appropriate
621			 * for this calling context.
622			 */
623			++oops_in_progress;
624			c->write(c, msg, msg_len);
625			--oops_in_progress;
626		}
627		touch_nmi_watchdog();
628	}
629	console_srcu_read_unlock(cookie);
630}
631
632int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
633{
634	int diag;
635	int linecount;
636	int colcount;
637	int logging, saved_loglevel = 0;
638	int retlen = 0;
639	int fnd, len;
640	int this_cpu, old_cpu;
641	char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
642	char *moreprompt = "more> ";
643	unsigned long flags;
644
645	/* Serialize kdb_printf if multiple cpus try to write at once.
646	 * But if any cpu goes recursive in kdb, just print the output,
647	 * even if it is interleaved with any other text.
648	 */
649	local_irq_save(flags);
650	this_cpu = smp_processor_id();
651	for (;;) {
652		old_cpu = cmpxchg(&kdb_printf_cpu, -1, this_cpu);
653		if (old_cpu == -1 || old_cpu == this_cpu)
654			break;
655
656		cpu_relax();
657	}
658
659	diag = kdbgetintenv("LINES", &linecount);
660	if (diag || linecount <= 1)
661		linecount = 24;
662
663	diag = kdbgetintenv("COLUMNS", &colcount);
664	if (diag || colcount <= 1)
665		colcount = 80;
666
667	diag = kdbgetintenv("LOGGING", &logging);
668	if (diag)
669		logging = 0;
670
671	if (!kdb_grepping_flag || suspend_grep) {
672		/* normally, every vsnprintf starts a new buffer */
673		next_avail = kdb_buffer;
674		size_avail = sizeof(kdb_buffer);
675	}
676	vsnprintf(next_avail, size_avail, fmt, ap);
677
678	/*
679	 * If kdb_parse() found that the command was cmd xxx | grep yyy
680	 * then kdb_grepping_flag is set, and kdb_grep_string contains yyy
681	 *
682	 * Accumulate the print data up to a newline before searching it.
683	 * (vsnprintf does null-terminate the string that it generates)
684	 */
685
686	/* skip the search if prints are temporarily unconditional */
687	if (!suspend_grep && kdb_grepping_flag) {
688		cp = strchr(kdb_buffer, '\n');
689		if (!cp) {
690			/*
691			 * Special cases that don't end with newlines
692			 * but should be written without one:
693			 *   The "[nn]kdb> " prompt should
694			 *   appear at the front of the buffer.
695			 *
696			 *   The "[nn]more " prompt should also be
697			 *     (MOREPROMPT -> moreprompt)
698			 *   written *   but we print that ourselves,
699			 *   we set the suspend_grep flag to make
700			 *   it unconditional.
701			 *
702			 */
703			if (next_avail == kdb_buffer) {
704				/*
705				 * these should occur after a newline,
706				 * so they will be at the front of the
707				 * buffer
708				 */
709				cp2 = kdb_buffer;
710				len = strlen(kdb_prompt_str);
711				if (!strncmp(cp2, kdb_prompt_str, len)) {
712					/*
713					 * We're about to start a new
714					 * command, so we can go back
715					 * to normal mode.
716					 */
717					kdb_grepping_flag = 0;
718					goto kdb_printit;
719				}
720			}
721			/* no newline; don't search/write the buffer
722			   until one is there */
723			len = strlen(kdb_buffer);
724			next_avail = kdb_buffer + len;
725			size_avail = sizeof(kdb_buffer) - len;
726			goto kdb_print_out;
727		}
728
729		/*
730		 * The newline is present; print through it or discard
731		 * it, depending on the results of the search.
732		 */
733		cp++;	 	     /* to byte after the newline */
734		replaced_byte = *cp; /* remember what it was */
735		cphold = cp;	     /* remember where it was */
736		*cp = '\0';	     /* end the string for our search */
737
738		/*
739		 * We now have a newline at the end of the string
740		 * Only continue with this output if it contains the
741		 * search string.
742		 */
743		fnd = kdb_search_string(kdb_buffer, kdb_grep_string);
744		if (!fnd) {
745			/*
746			 * At this point the complete line at the start
747			 * of kdb_buffer can be discarded, as it does
748			 * not contain what the user is looking for.
749			 * Shift the buffer left.
750			 */
751			*cphold = replaced_byte;
752			len = strlen(cphold);
753			/* Use memmove() because the buffers overlap */
754			memmove(kdb_buffer, cphold, len + 1);
755			next_avail = kdb_buffer + len;
756			size_avail = sizeof(kdb_buffer) - len;
757			goto kdb_print_out;
758		}
759		if (kdb_grepping_flag >= KDB_GREPPING_FLAG_SEARCH) {
760			/*
761			 * This was a interactive search (using '/' at more
762			 * prompt) and it has completed. Replace the \0 with
763			 * its original value to ensure multi-line strings
764			 * are handled properly, and return to normal mode.
765			 */
766			*cphold = replaced_byte;
767			kdb_grepping_flag = 0;
768		}
769		/*
770		 * at this point the string is a full line and
771		 * should be printed, up to the null.
772		 */
773	}
774kdb_printit:
775
776	/*
777	 * Write to all consoles.
778	 */
779	retlen = strlen(kdb_buffer);
780	cp = (char *) printk_skip_headers(kdb_buffer);
781	if (!dbg_kdb_mode && kgdb_connected)
782		gdbstub_msg_write(cp, retlen - (cp - kdb_buffer));
783	else
784		kdb_msg_write(cp, retlen - (cp - kdb_buffer));
785
786	if (logging) {
787		saved_loglevel = console_loglevel;
788		console_loglevel = CONSOLE_LOGLEVEL_SILENT;
789		if (printk_get_level(kdb_buffer) || src == KDB_MSGSRC_PRINTK)
790			printk("%s", kdb_buffer);
791		else
792			pr_info("%s", kdb_buffer);
793	}
794
795	if (KDB_STATE(PAGER)) {
796		/*
797		 * Check printed string to decide how to bump the
798		 * kdb_nextline to control when the more prompt should
799		 * show up.
800		 */
801		int got = 0;
802		len = retlen;
803		while (len--) {
804			if (kdb_buffer[len] == '\n') {
805				kdb_nextline++;
806				got = 0;
807			} else if (kdb_buffer[len] == '\r') {
808				got = 0;
809			} else {
810				got++;
811			}
812		}
813		kdb_nextline += got / (colcount + 1);
814	}
815
816	/* check for having reached the LINES number of printed lines */
817	if (kdb_nextline >= linecount) {
818		char ch;
819
820		/* Watch out for recursion here.  Any routine that calls
821		 * kdb_printf will come back through here.  And kdb_read
822		 * uses kdb_printf to echo on serial consoles ...
823		 */
824		kdb_nextline = 1;	/* In case of recursion */
825
826		/*
827		 * Pause until cr.
828		 */
829		moreprompt = kdbgetenv("MOREPROMPT");
830		if (moreprompt == NULL)
831			moreprompt = "more> ";
832
833		kdb_input_flush();
834		kdb_msg_write(moreprompt, strlen(moreprompt));
835
836		if (logging)
837			printk("%s", moreprompt);
838
839		ch = kdb_getchar();
840		kdb_nextline = 1;	/* Really set output line 1 */
841
842		/* empty and reset the buffer: */
843		kdb_buffer[0] = '\0';
844		next_avail = kdb_buffer;
845		size_avail = sizeof(kdb_buffer);
846		if ((ch == 'q') || (ch == 'Q')) {
847			/* user hit q or Q */
848			KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
849			KDB_STATE_CLEAR(PAGER);
850			/* end of command output; back to normal mode */
851			kdb_grepping_flag = 0;
852			kdb_printf("\n");
853		} else if (ch == ' ') {
854			kdb_printf("\r");
855			suspend_grep = 1; /* for this recursion */
856		} else if (ch == '\n' || ch == '\r') {
857			kdb_nextline = linecount - 1;
858			kdb_printf("\r");
859			suspend_grep = 1; /* for this recursion */
860		} else if (ch == '/' && !kdb_grepping_flag) {
861			kdb_printf("\r");
862			kdb_getstr(kdb_grep_string, KDB_GREP_STRLEN,
863				   kdbgetenv("SEARCHPROMPT") ?: "search> ");
864			*strchrnul(kdb_grep_string, '\n') = '\0';
865			kdb_grepping_flag += KDB_GREPPING_FLAG_SEARCH;
866			suspend_grep = 1; /* for this recursion */
867		} else if (ch) {
868			/* user hit something unexpected */
869			suspend_grep = 1; /* for this recursion */
870			if (ch != '/')
871				kdb_printf(
872				    "\nOnly 'q', 'Q' or '/' are processed at "
873				    "more prompt, input ignored\n");
874			else
875				kdb_printf("\n'/' cannot be used during | "
876					   "grep filtering, input ignored\n");
877		} else if (kdb_grepping_flag) {
878			/* user hit enter */
879			suspend_grep = 1; /* for this recursion */
880			kdb_printf("\n");
881		}
882		kdb_input_flush();
883	}
884
885	/*
886	 * For grep searches, shift the printed string left.
887	 *  replaced_byte contains the character that was overwritten with
888	 *  the terminating null, and cphold points to the null.
889	 * Then adjust the notion of available space in the buffer.
890	 */
891	if (kdb_grepping_flag && !suspend_grep) {
892		*cphold = replaced_byte;
893		len = strlen(cphold);
894		/* Use memmove() because the buffers overlap */
895		memmove(kdb_buffer, cphold, len + 1);
896		next_avail = kdb_buffer + len;
897		size_avail = sizeof(kdb_buffer) - len;
898	}
899
900kdb_print_out:
901	suspend_grep = 0; /* end of what may have been a recursive call */
902	if (logging)
903		console_loglevel = saved_loglevel;
904	/* kdb_printf_cpu locked the code above. */
905	smp_store_release(&kdb_printf_cpu, old_cpu);
906	local_irq_restore(flags);
907	return retlen;
908}
909
910int kdb_printf(const char *fmt, ...)
911{
912	va_list ap;
913	int r;
914
915	va_start(ap, fmt);
916	r = vkdb_printf(KDB_MSGSRC_INTERNAL, fmt, ap);
917	va_end(ap);
918
919	return r;
920}
921EXPORT_SYMBOL_GPL(kdb_printf);