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_read
189 *
190 *	This function reads a string of characters, terminated by
191 *	a newline, or by reaching the end of the supplied buffer,
192 *	from the current kernel debugger console device.
193 * Parameters:
194 *	buffer	- Address of character buffer to receive input characters.
195 *	bufsize - size, in bytes, of the character buffer
196 * Returns:
197 *	Returns a pointer to the buffer containing the received
198 *	character string.  This string will be terminated by a
199 *	newline character.
200 * Locking:
201 *	No locks are required to be held upon entry to this
202 *	function.  It is not reentrant - it relies on the fact
203 *	that while kdb is running on only one "master debug" cpu.
204 * Remarks:
205 *	The buffer size must be >= 2.
206 */
207
208static char *kdb_read(char *buffer, size_t bufsize)
209{
210	char *cp = buffer;
211	char *bufend = buffer+bufsize-2;	/* Reserve space for newline
212						 * and null byte */
213	char *lastchar;
214	char *p_tmp;
215	char tmp;
216	static char tmpbuffer[CMD_BUFLEN];
217	int len = strlen(buffer);
218	int len_tmp;
219	int tab = 0;
220	int count;
221	int i;
222	int diag, dtab_count;
223	int key, buf_size, ret;
224
225
226	diag = kdbgetintenv("DTABCOUNT", &dtab_count);
227	if (diag)
228		dtab_count = 30;
229
230	if (len > 0) {
231		cp += len;
232		if (*(buffer+len-1) == '\n')
233			cp--;
234	}
235
236	lastchar = cp;
237	*cp = '\0';
238	kdb_printf("%s", buffer);
239poll_again:
240	key = kdb_getchar();
241	if (key != 9)
242		tab = 0;
243	switch (key) {
244	case 8: /* backspace */
245		if (cp > buffer) {
246			if (cp < lastchar) {
247				memcpy(tmpbuffer, cp, lastchar - cp);
248				memcpy(cp-1, tmpbuffer, lastchar - cp);
249			}
250			*(--lastchar) = '\0';
251			--cp;
252			kdb_printf("\b%s \r", cp);
253			tmp = *cp;
254			*cp = '\0';
255			kdb_printf(kdb_prompt_str);
256			kdb_printf("%s", buffer);
257			*cp = tmp;
258		}
259		break;
260	case 10: /* linefeed */
261	case 13: /* carriage return */
262		*lastchar++ = '\n';
263		*lastchar++ = '\0';
264		if (!KDB_STATE(KGDB_TRANS)) {
265			KDB_STATE_SET(KGDB_TRANS);
266			kdb_printf("%s", buffer);
267		}
268		kdb_printf("\n");
269		return buffer;
270	case 4: /* Del */
271		if (cp < lastchar) {
272			memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
273			memcpy(cp, tmpbuffer, lastchar - cp - 1);
274			*(--lastchar) = '\0';
275			kdb_printf("%s \r", cp);
276			tmp = *cp;
277			*cp = '\0';
278			kdb_printf(kdb_prompt_str);
279			kdb_printf("%s", buffer);
280			*cp = tmp;
281		}
282		break;
283	case 1: /* Home */
284		if (cp > buffer) {
285			kdb_printf("\r");
286			kdb_printf(kdb_prompt_str);
287			cp = buffer;
288		}
289		break;
290	case 5: /* End */
291		if (cp < lastchar) {
292			kdb_printf("%s", cp);
293			cp = lastchar;
294		}
295		break;
296	case 2: /* Left */
297		if (cp > buffer) {
298			kdb_printf("\b");
299			--cp;
300		}
301		break;
302	case 14: /* Down */
303		memset(tmpbuffer, ' ',
304		       strlen(kdb_prompt_str) + (lastchar-buffer));
305		*(tmpbuffer+strlen(kdb_prompt_str) +
306		  (lastchar-buffer)) = '\0';
307		kdb_printf("\r%s\r", tmpbuffer);
308		*lastchar = (char)key;
309		*(lastchar+1) = '\0';
310		return lastchar;
311	case 6: /* Right */
312		if (cp < lastchar) {
313			kdb_printf("%c", *cp);
314			++cp;
315		}
316		break;
317	case 16: /* Up */
318		memset(tmpbuffer, ' ',
319		       strlen(kdb_prompt_str) + (lastchar-buffer));
320		*(tmpbuffer+strlen(kdb_prompt_str) +
321		  (lastchar-buffer)) = '\0';
322		kdb_printf("\r%s\r", tmpbuffer);
323		*lastchar = (char)key;
324		*(lastchar+1) = '\0';
325		return lastchar;
326	case 9: /* Tab */
327		if (tab < 2)
328			++tab;
329		p_tmp = buffer;
330		while (*p_tmp == ' ')
331			p_tmp++;
332		if (p_tmp > cp)
333			break;
334		memcpy(tmpbuffer, p_tmp, cp-p_tmp);
335		*(tmpbuffer + (cp-p_tmp)) = '\0';
336		p_tmp = strrchr(tmpbuffer, ' ');
337		if (p_tmp)
338			++p_tmp;
339		else
340			p_tmp = tmpbuffer;
341		len = strlen(p_tmp);
342		buf_size = sizeof(tmpbuffer) - (p_tmp - tmpbuffer);
343		count = kallsyms_symbol_complete(p_tmp, buf_size);
344		if (tab == 2 && count > 0) {
345			kdb_printf("\n%d symbols are found.", count);
346			if (count > dtab_count) {
347				count = dtab_count;
348				kdb_printf(" But only first %d symbols will"
349					   " be printed.\nYou can change the"
350					   " environment variable DTABCOUNT.",
351					   count);
352			}
353			kdb_printf("\n");
354			for (i = 0; i < count; i++) {
355				ret = kallsyms_symbol_next(p_tmp, i, buf_size);
356				if (WARN_ON(!ret))
357					break;
358				if (ret != -E2BIG)
359					kdb_printf("%s ", p_tmp);
360				else
361					kdb_printf("%s... ", p_tmp);
362				*(p_tmp + len) = '\0';
363			}
364			if (i >= dtab_count)
365				kdb_printf("...");
366			kdb_printf("\n");
367			kdb_printf(kdb_prompt_str);
368			kdb_printf("%s", buffer);
369		} else if (tab != 2 && count > 0) {
370			len_tmp = strlen(p_tmp);
371			strncpy(p_tmp+len_tmp, cp, lastchar-cp+1);
372			len_tmp = strlen(p_tmp);
373			strncpy(cp, p_tmp+len, len_tmp-len + 1);
374			len = len_tmp - len;
375			kdb_printf("%s", cp);
376			cp += len;
377			lastchar += len;
378		}
379		kdb_nextline = 1; /* reset output line number */
380		break;
381	default:
382		if (key >= 32 && lastchar < bufend) {
383			if (cp < lastchar) {
384				memcpy(tmpbuffer, cp, lastchar - cp);
385				memcpy(cp+1, tmpbuffer, lastchar - cp);
386				*++lastchar = '\0';
387				*cp = key;
388				kdb_printf("%s\r", cp);
389				++cp;
390				tmp = *cp;
391				*cp = '\0';
392				kdb_printf(kdb_prompt_str);
393				kdb_printf("%s", buffer);
394				*cp = tmp;
395			} else {
396				*++lastchar = '\0';
397				*cp++ = key;
398				/* The kgdb transition check will hide
399				 * printed characters if we think that
400				 * kgdb is connecting, until the check
401				 * fails */
402				if (!KDB_STATE(KGDB_TRANS)) {
403					if (kgdb_transition_check(buffer))
404						return buffer;
405				} else {
406					kdb_printf("%c", key);
407				}
408			}
409			/* Special escape to kgdb */
410			if (lastchar - buffer >= 5 &&
411			    strcmp(lastchar - 5, "$?#3f") == 0) {
412				kdb_gdb_state_pass(lastchar - 5);
413				strcpy(buffer, "kgdb");
414				KDB_STATE_SET(DOING_KGDB);
415				return buffer;
416			}
417			if (lastchar - buffer >= 11 &&
418			    strcmp(lastchar - 11, "$qSupported") == 0) {
419				kdb_gdb_state_pass(lastchar - 11);
420				strcpy(buffer, "kgdb");
421				KDB_STATE_SET(DOING_KGDB);
422				return buffer;
423			}
424		}
425		break;
426	}
427	goto poll_again;
428}
429
430/*
431 * kdb_getstr
432 *
433 *	Print the prompt string and read a command from the
434 *	input device.
435 *
436 * Parameters:
437 *	buffer	Address of buffer to receive command
438 *	bufsize Size of buffer in bytes
439 *	prompt	Pointer to string to use as prompt string
440 * Returns:
441 *	Pointer to command buffer.
442 * Locking:
443 *	None.
444 * Remarks:
445 *	For SMP kernels, the processor number will be
446 *	substituted for %d, %x or %o in the prompt.
447 */
448
449char *kdb_getstr(char *buffer, size_t bufsize, const char *prompt)
450{
451	if (prompt && kdb_prompt_str != prompt)
452		strscpy(kdb_prompt_str, prompt, CMD_BUFLEN);
453	kdb_printf(kdb_prompt_str);
454	kdb_nextline = 1;	/* Prompt and input resets line number */
455	return kdb_read(buffer, bufsize);
456}
457
458/*
459 * kdb_input_flush
460 *
461 *	Get rid of any buffered console input.
462 *
463 * Parameters:
464 *	none
465 * Returns:
466 *	nothing
467 * Locking:
468 *	none
469 * Remarks:
470 *	Call this function whenever you want to flush input.  If there is any
471 *	outstanding input, it ignores all characters until there has been no
472 *	data for approximately 1ms.
473 */
474
475static void kdb_input_flush(void)
476{
477	get_char_func *f;
478	int res;
479	int flush_delay = 1;
480	while (flush_delay) {
481		flush_delay--;
482empty:
483		touch_nmi_watchdog();
484		for (f = &kdb_poll_funcs[0]; *f; ++f) {
485			res = (*f)();
486			if (res != -1) {
487				flush_delay = 1;
488				goto empty;
489			}
490		}
491		if (flush_delay)
492			mdelay(1);
493	}
494}
495
496/*
497 * kdb_printf
498 *
499 *	Print a string to the output device(s).
500 *
501 * Parameters:
502 *	printf-like format and optional args.
503 * Returns:
504 *	0
505 * Locking:
506 *	None.
507 * Remarks:
508 *	use 'kdbcons->write()' to avoid polluting 'log_buf' with
509 *	kdb output.
510 *
511 *  If the user is doing a cmd args | grep srch
512 *  then kdb_grepping_flag is set.
513 *  In that case we need to accumulate full lines (ending in \n) before
514 *  searching for the pattern.
515 */
516
517static char kdb_buffer[256];	/* A bit too big to go on stack */
518static char *next_avail = kdb_buffer;
519static int  size_avail;
520static int  suspend_grep;
521
522/*
523 * search arg1 to see if it contains arg2
524 * (kdmain.c provides flags for ^pat and pat$)
525 *
526 * return 1 for found, 0 for not found
527 */
528static int kdb_search_string(char *searched, char *searchfor)
529{
530	char firstchar, *cp;
531	int len1, len2;
532
533	/* not counting the newline at the end of "searched" */
534	len1 = strlen(searched)-1;
535	len2 = strlen(searchfor);
536	if (len1 < len2)
537		return 0;
538	if (kdb_grep_leading && kdb_grep_trailing && len1 != len2)
539		return 0;
540	if (kdb_grep_leading) {
541		if (!strncmp(searched, searchfor, len2))
542			return 1;
543	} else if (kdb_grep_trailing) {
544		if (!strncmp(searched+len1-len2, searchfor, len2))
545			return 1;
546	} else {
547		firstchar = *searchfor;
548		cp = searched;
549		while ((cp = strchr(cp, firstchar))) {
550			if (!strncmp(cp, searchfor, len2))
551				return 1;
552			cp++;
553		}
554	}
555	return 0;
556}
557
558static void kdb_msg_write(const char *msg, int msg_len)
559{
560	struct console *c;
561	const char *cp;
562	int cookie;
563	int len;
564
565	if (msg_len == 0)
566		return;
567
568	cp = msg;
569	len = msg_len;
570
571	while (len--) {
572		dbg_io_ops->write_char(*cp);
573		cp++;
574	}
575
576	/*
577	 * The console_srcu_read_lock() only provides safe console list
578	 * traversal. The use of the ->write() callback relies on all other
579	 * CPUs being stopped at the moment and console drivers being able to
580	 * handle reentrance when @oops_in_progress is set.
581	 *
582	 * There is no guarantee that every console driver can handle
583	 * reentrance in this way; the developer deploying the debugger
584	 * is responsible for ensuring that the console drivers they
585	 * have selected handle reentrance appropriately.
586	 */
587	cookie = console_srcu_read_lock();
588	for_each_console_srcu(c) {
589		if (!(console_srcu_read_flags(c) & CON_ENABLED))
590			continue;
591		if (c == dbg_io_ops->cons)
592			continue;
593		if (!c->write)
594			continue;
595		/*
596		 * Set oops_in_progress to encourage the console drivers to
597		 * disregard their internal spin locks: in the current calling
598		 * context the risk of deadlock is a bigger problem than risks
599		 * due to re-entering the console driver. We operate directly on
600		 * oops_in_progress rather than using bust_spinlocks() because
601		 * the calls bust_spinlocks() makes on exit are not appropriate
602		 * for this calling context.
603		 */
604		++oops_in_progress;
605		c->write(c, msg, msg_len);
606		--oops_in_progress;
607		touch_nmi_watchdog();
608	}
609	console_srcu_read_unlock(cookie);
610}
611
612int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
613{
614	int diag;
615	int linecount;
616	int colcount;
617	int logging, saved_loglevel = 0;
618	int retlen = 0;
619	int fnd, len;
620	int this_cpu, old_cpu;
621	char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
622	char *moreprompt = "more> ";
623	unsigned long flags;
624
625	/* Serialize kdb_printf if multiple cpus try to write at once.
626	 * But if any cpu goes recursive in kdb, just print the output,
627	 * even if it is interleaved with any other text.
628	 */
629	local_irq_save(flags);
630	this_cpu = smp_processor_id();
631	for (;;) {
632		old_cpu = cmpxchg(&kdb_printf_cpu, -1, this_cpu);
633		if (old_cpu == -1 || old_cpu == this_cpu)
634			break;
635
636		cpu_relax();
637	}
638
639	diag = kdbgetintenv("LINES", &linecount);
640	if (diag || linecount <= 1)
641		linecount = 24;
642
643	diag = kdbgetintenv("COLUMNS", &colcount);
644	if (diag || colcount <= 1)
645		colcount = 80;
646
647	diag = kdbgetintenv("LOGGING", &logging);
648	if (diag)
649		logging = 0;
650
651	if (!kdb_grepping_flag || suspend_grep) {
652		/* normally, every vsnprintf starts a new buffer */
653		next_avail = kdb_buffer;
654		size_avail = sizeof(kdb_buffer);
655	}
656	vsnprintf(next_avail, size_avail, fmt, ap);
657
658	/*
659	 * If kdb_parse() found that the command was cmd xxx | grep yyy
660	 * then kdb_grepping_flag is set, and kdb_grep_string contains yyy
661	 *
662	 * Accumulate the print data up to a newline before searching it.
663	 * (vsnprintf does null-terminate the string that it generates)
664	 */
665
666	/* skip the search if prints are temporarily unconditional */
667	if (!suspend_grep && kdb_grepping_flag) {
668		cp = strchr(kdb_buffer, '\n');
669		if (!cp) {
670			/*
671			 * Special cases that don't end with newlines
672			 * but should be written without one:
673			 *   The "[nn]kdb> " prompt should
674			 *   appear at the front of the buffer.
675			 *
676			 *   The "[nn]more " prompt should also be
677			 *     (MOREPROMPT -> moreprompt)
678			 *   written *   but we print that ourselves,
679			 *   we set the suspend_grep flag to make
680			 *   it unconditional.
681			 *
682			 */
683			if (next_avail == kdb_buffer) {
684				/*
685				 * these should occur after a newline,
686				 * so they will be at the front of the
687				 * buffer
688				 */
689				cp2 = kdb_buffer;
690				len = strlen(kdb_prompt_str);
691				if (!strncmp(cp2, kdb_prompt_str, len)) {
692					/*
693					 * We're about to start a new
694					 * command, so we can go back
695					 * to normal mode.
696					 */
697					kdb_grepping_flag = 0;
698					goto kdb_printit;
699				}
700			}
701			/* no newline; don't search/write the buffer
702			   until one is there */
703			len = strlen(kdb_buffer);
704			next_avail = kdb_buffer + len;
705			size_avail = sizeof(kdb_buffer) - len;
706			goto kdb_print_out;
707		}
708
709		/*
710		 * The newline is present; print through it or discard
711		 * it, depending on the results of the search.
712		 */
713		cp++;	 	     /* to byte after the newline */
714		replaced_byte = *cp; /* remember what/where it was */
715		cphold = cp;
716		*cp = '\0';	     /* end the string for our search */
717
718		/*
719		 * We now have a newline at the end of the string
720		 * Only continue with this output if it contains the
721		 * search string.
722		 */
723		fnd = kdb_search_string(kdb_buffer, kdb_grep_string);
724		if (!fnd) {
725			/*
726			 * At this point the complete line at the start
727			 * of kdb_buffer can be discarded, as it does
728			 * not contain what the user is looking for.
729			 * Shift the buffer left.
730			 */
731			*cphold = replaced_byte;
732			strcpy(kdb_buffer, cphold);
733			len = strlen(kdb_buffer);
734			next_avail = kdb_buffer + len;
735			size_avail = sizeof(kdb_buffer) - len;
736			goto kdb_print_out;
737		}
738		if (kdb_grepping_flag >= KDB_GREPPING_FLAG_SEARCH) {
739			/*
740			 * This was a interactive search (using '/' at more
741			 * prompt) and it has completed. Replace the \0 with
742			 * its original value to ensure multi-line strings
743			 * are handled properly, and return to normal mode.
744			 */
745			*cphold = replaced_byte;
746			kdb_grepping_flag = 0;
747		}
748		/*
749		 * at this point the string is a full line and
750		 * should be printed, up to the null.
751		 */
752	}
753kdb_printit:
754
755	/*
756	 * Write to all consoles.
757	 */
758	retlen = strlen(kdb_buffer);
759	cp = (char *) printk_skip_headers(kdb_buffer);
760	if (!dbg_kdb_mode && kgdb_connected)
761		gdbstub_msg_write(cp, retlen - (cp - kdb_buffer));
762	else
763		kdb_msg_write(cp, retlen - (cp - kdb_buffer));
764
765	if (logging) {
766		saved_loglevel = console_loglevel;
767		console_loglevel = CONSOLE_LOGLEVEL_SILENT;
768		if (printk_get_level(kdb_buffer) || src == KDB_MSGSRC_PRINTK)
769			printk("%s", kdb_buffer);
770		else
771			pr_info("%s", kdb_buffer);
772	}
773
774	if (KDB_STATE(PAGER)) {
775		/*
776		 * Check printed string to decide how to bump the
777		 * kdb_nextline to control when the more prompt should
778		 * show up.
779		 */
780		int got = 0;
781		len = retlen;
782		while (len--) {
783			if (kdb_buffer[len] == '\n') {
784				kdb_nextline++;
785				got = 0;
786			} else if (kdb_buffer[len] == '\r') {
787				got = 0;
788			} else {
789				got++;
790			}
791		}
792		kdb_nextline += got / (colcount + 1);
793	}
794
795	/* check for having reached the LINES number of printed lines */
796	if (kdb_nextline >= linecount) {
797		char ch;
798
799		/* Watch out for recursion here.  Any routine that calls
800		 * kdb_printf will come back through here.  And kdb_read
801		 * uses kdb_printf to echo on serial consoles ...
802		 */
803		kdb_nextline = 1;	/* In case of recursion */
804
805		/*
806		 * Pause until cr.
807		 */
808		moreprompt = kdbgetenv("MOREPROMPT");
809		if (moreprompt == NULL)
810			moreprompt = "more> ";
811
812		kdb_input_flush();
813		kdb_msg_write(moreprompt, strlen(moreprompt));
814
815		if (logging)
816			printk("%s", moreprompt);
817
818		ch = kdb_getchar();
819		kdb_nextline = 1;	/* Really set output line 1 */
820
821		/* empty and reset the buffer: */
822		kdb_buffer[0] = '\0';
823		next_avail = kdb_buffer;
824		size_avail = sizeof(kdb_buffer);
825		if ((ch == 'q') || (ch == 'Q')) {
826			/* user hit q or Q */
827			KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
828			KDB_STATE_CLEAR(PAGER);
829			/* end of command output; back to normal mode */
830			kdb_grepping_flag = 0;
831			kdb_printf("\n");
832		} else if (ch == ' ') {
833			kdb_printf("\r");
834			suspend_grep = 1; /* for this recursion */
835		} else if (ch == '\n' || ch == '\r') {
836			kdb_nextline = linecount - 1;
837			kdb_printf("\r");
838			suspend_grep = 1; /* for this recursion */
839		} else if (ch == '/' && !kdb_grepping_flag) {
840			kdb_printf("\r");
841			kdb_getstr(kdb_grep_string, KDB_GREP_STRLEN,
842				   kdbgetenv("SEARCHPROMPT") ?: "search> ");
843			*strchrnul(kdb_grep_string, '\n') = '\0';
844			kdb_grepping_flag += KDB_GREPPING_FLAG_SEARCH;
845			suspend_grep = 1; /* for this recursion */
846		} else if (ch) {
847			/* user hit something unexpected */
848			suspend_grep = 1; /* for this recursion */
849			if (ch != '/')
850				kdb_printf(
851				    "\nOnly 'q', 'Q' or '/' are processed at "
852				    "more prompt, input ignored\n");
853			else
854				kdb_printf("\n'/' cannot be used during | "
855					   "grep filtering, input ignored\n");
856		} else if (kdb_grepping_flag) {
857			/* user hit enter */
858			suspend_grep = 1; /* for this recursion */
859			kdb_printf("\n");
860		}
861		kdb_input_flush();
862	}
863
864	/*
865	 * For grep searches, shift the printed string left.
866	 *  replaced_byte contains the character that was overwritten with
867	 *  the terminating null, and cphold points to the null.
868	 * Then adjust the notion of available space in the buffer.
869	 */
870	if (kdb_grepping_flag && !suspend_grep) {
871		*cphold = replaced_byte;
872		strcpy(kdb_buffer, cphold);
873		len = strlen(kdb_buffer);
874		next_avail = kdb_buffer + len;
875		size_avail = sizeof(kdb_buffer) - len;
876	}
877
878kdb_print_out:
879	suspend_grep = 0; /* end of what may have been a recursive call */
880	if (logging)
881		console_loglevel = saved_loglevel;
882	/* kdb_printf_cpu locked the code above. */
883	smp_store_release(&kdb_printf_cpu, old_cpu);
884	local_irq_restore(flags);
885	return retlen;
886}
887
888int kdb_printf(const char *fmt, ...)
889{
890	va_list ap;
891	int r;
892
893	va_start(ap, fmt);
894	r = vkdb_printf(KDB_MSGSRC_INTERNAL, fmt, ap);
895	va_end(ap);
896
897	return r;
898}
899EXPORT_SYMBOL_GPL(kdb_printf);
900