xref: /openbmc/linux/kernel/debug/kdb/kdb_io.c (revision 9e58df60)
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
29 char kdb_prompt_str[CMD_BUFLEN];
30 
31 int kdb_trap_printk;
32 int kdb_printf_cpu = -1;
33 
kgdb_transition_check(char * buffer)34 static 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  */
kdb_handle_escape(char * buf,size_t sz)61 static 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  */
kdb_getchar(void)125 char 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  */
kdb_position_cursor(char * prompt,char * buffer,char * cp)207 static 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 
kdb_read(char * buffer,size_t bufsize)235 static 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 	static char tmpbuffer[CMD_BUFLEN];
243 	int len = strlen(buffer);
244 	int len_tmp;
245 	int tab = 0;
246 	int count;
247 	int i;
248 	int diag, dtab_count;
249 	int key, buf_size, ret;
250 
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);
265 poll_again:
266 	key = kdb_getchar();
267 	if (key != 9)
268 		tab = 0;
269 	switch (key) {
270 	case 8: /* backspace */
271 		if (cp > buffer) {
272 			if (cp < lastchar) {
273 				memcpy(tmpbuffer, cp, lastchar - cp);
274 				memcpy(cp-1, tmpbuffer, lastchar - cp);
275 			}
276 			*(--lastchar) = '\0';
277 			--cp;
278 			kdb_printf("\b%s ", cp);
279 			kdb_position_cursor(kdb_prompt_str, buffer, cp);
280 		}
281 		break;
282 	case 10: /* linefeed */
283 	case 13: /* carriage return */
284 		*lastchar++ = '\n';
285 		*lastchar++ = '\0';
286 		if (!KDB_STATE(KGDB_TRANS)) {
287 			KDB_STATE_SET(KGDB_TRANS);
288 			kdb_printf("%s", buffer);
289 		}
290 		kdb_printf("\n");
291 		return buffer;
292 	case 4: /* Del */
293 		if (cp < lastchar) {
294 			memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
295 			memcpy(cp, tmpbuffer, lastchar - cp - 1);
296 			*(--lastchar) = '\0';
297 			kdb_printf("%s ", cp);
298 			kdb_position_cursor(kdb_prompt_str, buffer, cp);
299 		}
300 		break;
301 	case 1: /* Home */
302 		if (cp > buffer) {
303 			cp = buffer;
304 			kdb_position_cursor(kdb_prompt_str, buffer, cp);
305 		}
306 		break;
307 	case 5: /* End */
308 		if (cp < lastchar) {
309 			kdb_printf("%s", cp);
310 			cp = lastchar;
311 		}
312 		break;
313 	case 2: /* Left */
314 		if (cp > buffer) {
315 			kdb_printf("\b");
316 			--cp;
317 		}
318 		break;
319 	case 14: /* Down */
320 	case 16: /* Up */
321 		kdb_printf("\r%*c\r",
322 			   (int)(strlen(kdb_prompt_str) + (lastchar - buffer)),
323 			   ' ');
324 		*lastchar = (char)key;
325 		*(lastchar+1) = '\0';
326 		return lastchar;
327 	case 6: /* Right */
328 		if (cp < lastchar) {
329 			kdb_printf("%c", *cp);
330 			++cp;
331 		}
332 		break;
333 	case 9: /* Tab */
334 		if (tab < 2)
335 			++tab;
336 		p_tmp = buffer;
337 		while (*p_tmp == ' ')
338 			p_tmp++;
339 		if (p_tmp > cp)
340 			break;
341 		memcpy(tmpbuffer, p_tmp, cp-p_tmp);
342 		*(tmpbuffer + (cp-p_tmp)) = '\0';
343 		p_tmp = strrchr(tmpbuffer, ' ');
344 		if (p_tmp)
345 			++p_tmp;
346 		else
347 			p_tmp = tmpbuffer;
348 		len = strlen(p_tmp);
349 		buf_size = sizeof(tmpbuffer) - (p_tmp - tmpbuffer);
350 		count = kallsyms_symbol_complete(p_tmp, buf_size);
351 		if (tab == 2 && count > 0) {
352 			kdb_printf("\n%d symbols are found.", count);
353 			if (count > dtab_count) {
354 				count = dtab_count;
355 				kdb_printf(" But only first %d symbols will"
356 					   " be printed.\nYou can change the"
357 					   " environment variable DTABCOUNT.",
358 					   count);
359 			}
360 			kdb_printf("\n");
361 			for (i = 0; i < count; i++) {
362 				ret = kallsyms_symbol_next(p_tmp, i, buf_size);
363 				if (WARN_ON(!ret))
364 					break;
365 				if (ret != -E2BIG)
366 					kdb_printf("%s ", p_tmp);
367 				else
368 					kdb_printf("%s... ", p_tmp);
369 				*(p_tmp + len) = '\0';
370 			}
371 			if (i >= dtab_count)
372 				kdb_printf("...");
373 			kdb_printf("\n");
374 			kdb_printf("%s",  kdb_prompt_str);
375 			kdb_printf("%s", buffer);
376 			if (cp != lastchar)
377 				kdb_position_cursor(kdb_prompt_str, buffer, cp);
378 		} else if (tab != 2 && count > 0) {
379 			/* How many new characters do we want from tmpbuffer? */
380 			len_tmp = strlen(p_tmp) - len;
381 			if (lastchar + len_tmp >= bufend)
382 				len_tmp = bufend - lastchar;
383 
384 			if (len_tmp) {
385 				/* + 1 ensures the '\0' is memmove'd */
386 				memmove(cp+len_tmp, cp, (lastchar-cp) + 1);
387 				memcpy(cp, p_tmp+len, len_tmp);
388 				kdb_printf("%s", cp);
389 				cp += len_tmp;
390 				lastchar += len_tmp;
391 				if (cp != lastchar)
392 					kdb_position_cursor(kdb_prompt_str,
393 							    buffer, cp);
394 			}
395 		}
396 		kdb_nextline = 1; /* reset output line number */
397 		break;
398 	default:
399 		if (key >= 32 && lastchar < bufend) {
400 			if (cp < lastchar) {
401 				memcpy(tmpbuffer, cp, lastchar - cp);
402 				memcpy(cp+1, tmpbuffer, lastchar - cp);
403 				*++lastchar = '\0';
404 				*cp = key;
405 				kdb_printf("%s", cp);
406 				++cp;
407 				kdb_position_cursor(kdb_prompt_str, buffer, cp);
408 			} else {
409 				*++lastchar = '\0';
410 				*cp++ = key;
411 				/* The kgdb transition check will hide
412 				 * printed characters if we think that
413 				 * kgdb is connecting, until the check
414 				 * fails */
415 				if (!KDB_STATE(KGDB_TRANS)) {
416 					if (kgdb_transition_check(buffer))
417 						return buffer;
418 				} else {
419 					kdb_printf("%c", key);
420 				}
421 			}
422 			/* Special escape to kgdb */
423 			if (lastchar - buffer >= 5 &&
424 			    strcmp(lastchar - 5, "$?#3f") == 0) {
425 				kdb_gdb_state_pass(lastchar - 5);
426 				strcpy(buffer, "kgdb");
427 				KDB_STATE_SET(DOING_KGDB);
428 				return buffer;
429 			}
430 			if (lastchar - buffer >= 11 &&
431 			    strcmp(lastchar - 11, "$qSupported") == 0) {
432 				kdb_gdb_state_pass(lastchar - 11);
433 				strcpy(buffer, "kgdb");
434 				KDB_STATE_SET(DOING_KGDB);
435 				return buffer;
436 			}
437 		}
438 		break;
439 	}
440 	goto poll_again;
441 }
442 
443 /*
444  * kdb_getstr
445  *
446  *	Print the prompt string and read a command from the
447  *	input device.
448  *
449  * Parameters:
450  *	buffer	Address of buffer to receive command
451  *	bufsize Size of buffer in bytes
452  *	prompt	Pointer to string to use as prompt string
453  * Returns:
454  *	Pointer to command buffer.
455  * Locking:
456  *	None.
457  * Remarks:
458  *	For SMP kernels, the processor number will be
459  *	substituted for %d, %x or %o in the prompt.
460  */
461 
kdb_getstr(char * buffer,size_t bufsize,const char * prompt)462 char *kdb_getstr(char *buffer, size_t bufsize, const char *prompt)
463 {
464 	if (prompt && kdb_prompt_str != prompt)
465 		strscpy(kdb_prompt_str, prompt, CMD_BUFLEN);
466 	kdb_printf("%s", kdb_prompt_str);
467 	kdb_nextline = 1;	/* Prompt and input resets line number */
468 	return kdb_read(buffer, bufsize);
469 }
470 
471 /*
472  * kdb_input_flush
473  *
474  *	Get rid of any buffered console input.
475  *
476  * Parameters:
477  *	none
478  * Returns:
479  *	nothing
480  * Locking:
481  *	none
482  * Remarks:
483  *	Call this function whenever you want to flush input.  If there is any
484  *	outstanding input, it ignores all characters until there has been no
485  *	data for approximately 1ms.
486  */
487 
kdb_input_flush(void)488 static void kdb_input_flush(void)
489 {
490 	get_char_func *f;
491 	int res;
492 	int flush_delay = 1;
493 	while (flush_delay) {
494 		flush_delay--;
495 empty:
496 		touch_nmi_watchdog();
497 		for (f = &kdb_poll_funcs[0]; *f; ++f) {
498 			res = (*f)();
499 			if (res != -1) {
500 				flush_delay = 1;
501 				goto empty;
502 			}
503 		}
504 		if (flush_delay)
505 			mdelay(1);
506 	}
507 }
508 
509 /*
510  * kdb_printf
511  *
512  *	Print a string to the output device(s).
513  *
514  * Parameters:
515  *	printf-like format and optional args.
516  * Returns:
517  *	0
518  * Locking:
519  *	None.
520  * Remarks:
521  *	use 'kdbcons->write()' to avoid polluting 'log_buf' with
522  *	kdb output.
523  *
524  *  If the user is doing a cmd args | grep srch
525  *  then kdb_grepping_flag is set.
526  *  In that case we need to accumulate full lines (ending in \n) before
527  *  searching for the pattern.
528  */
529 
530 static char kdb_buffer[256];	/* A bit too big to go on stack */
531 static char *next_avail = kdb_buffer;
532 static int  size_avail;
533 static int  suspend_grep;
534 
535 /*
536  * search arg1 to see if it contains arg2
537  * (kdmain.c provides flags for ^pat and pat$)
538  *
539  * return 1 for found, 0 for not found
540  */
kdb_search_string(char * searched,char * searchfor)541 static int kdb_search_string(char *searched, char *searchfor)
542 {
543 	char firstchar, *cp;
544 	int len1, len2;
545 
546 	/* not counting the newline at the end of "searched" */
547 	len1 = strlen(searched)-1;
548 	len2 = strlen(searchfor);
549 	if (len1 < len2)
550 		return 0;
551 	if (kdb_grep_leading && kdb_grep_trailing && len1 != len2)
552 		return 0;
553 	if (kdb_grep_leading) {
554 		if (!strncmp(searched, searchfor, len2))
555 			return 1;
556 	} else if (kdb_grep_trailing) {
557 		if (!strncmp(searched+len1-len2, searchfor, len2))
558 			return 1;
559 	} else {
560 		firstchar = *searchfor;
561 		cp = searched;
562 		while ((cp = strchr(cp, firstchar))) {
563 			if (!strncmp(cp, searchfor, len2))
564 				return 1;
565 			cp++;
566 		}
567 	}
568 	return 0;
569 }
570 
kdb_msg_write(const char * msg,int msg_len)571 static void kdb_msg_write(const char *msg, int msg_len)
572 {
573 	struct console *c;
574 	const char *cp;
575 	int cookie;
576 	int len;
577 
578 	if (msg_len == 0)
579 		return;
580 
581 	cp = msg;
582 	len = msg_len;
583 
584 	while (len--) {
585 		dbg_io_ops->write_char(*cp);
586 		cp++;
587 	}
588 
589 	/*
590 	 * The console_srcu_read_lock() only provides safe console list
591 	 * traversal. The use of the ->write() callback relies on all other
592 	 * CPUs being stopped at the moment and console drivers being able to
593 	 * handle reentrance when @oops_in_progress is set.
594 	 *
595 	 * There is no guarantee that every console driver can handle
596 	 * reentrance in this way; the developer deploying the debugger
597 	 * is responsible for ensuring that the console drivers they
598 	 * have selected handle reentrance appropriately.
599 	 */
600 	cookie = console_srcu_read_lock();
601 	for_each_console_srcu(c) {
602 		if (!(console_srcu_read_flags(c) & CON_ENABLED))
603 			continue;
604 		if (c == dbg_io_ops->cons)
605 			continue;
606 		if (!c->write)
607 			continue;
608 		/*
609 		 * Set oops_in_progress to encourage the console drivers to
610 		 * disregard their internal spin locks: in the current calling
611 		 * context the risk of deadlock is a bigger problem than risks
612 		 * due to re-entering the console driver. We operate directly on
613 		 * oops_in_progress rather than using bust_spinlocks() because
614 		 * the calls bust_spinlocks() makes on exit are not appropriate
615 		 * for this calling context.
616 		 */
617 		++oops_in_progress;
618 		c->write(c, msg, msg_len);
619 		--oops_in_progress;
620 		touch_nmi_watchdog();
621 	}
622 	console_srcu_read_unlock(cookie);
623 }
624 
vkdb_printf(enum kdb_msgsrc src,const char * fmt,va_list ap)625 int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
626 {
627 	int diag;
628 	int linecount;
629 	int colcount;
630 	int logging, saved_loglevel = 0;
631 	int retlen = 0;
632 	int fnd, len;
633 	int this_cpu, old_cpu;
634 	char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
635 	char *moreprompt = "more> ";
636 	unsigned long flags;
637 
638 	/* Serialize kdb_printf if multiple cpus try to write at once.
639 	 * But if any cpu goes recursive in kdb, just print the output,
640 	 * even if it is interleaved with any other text.
641 	 */
642 	local_irq_save(flags);
643 	this_cpu = smp_processor_id();
644 	for (;;) {
645 		old_cpu = cmpxchg(&kdb_printf_cpu, -1, this_cpu);
646 		if (old_cpu == -1 || old_cpu == this_cpu)
647 			break;
648 
649 		cpu_relax();
650 	}
651 
652 	diag = kdbgetintenv("LINES", &linecount);
653 	if (diag || linecount <= 1)
654 		linecount = 24;
655 
656 	diag = kdbgetintenv("COLUMNS", &colcount);
657 	if (diag || colcount <= 1)
658 		colcount = 80;
659 
660 	diag = kdbgetintenv("LOGGING", &logging);
661 	if (diag)
662 		logging = 0;
663 
664 	if (!kdb_grepping_flag || suspend_grep) {
665 		/* normally, every vsnprintf starts a new buffer */
666 		next_avail = kdb_buffer;
667 		size_avail = sizeof(kdb_buffer);
668 	}
669 	vsnprintf(next_avail, size_avail, fmt, ap);
670 
671 	/*
672 	 * If kdb_parse() found that the command was cmd xxx | grep yyy
673 	 * then kdb_grepping_flag is set, and kdb_grep_string contains yyy
674 	 *
675 	 * Accumulate the print data up to a newline before searching it.
676 	 * (vsnprintf does null-terminate the string that it generates)
677 	 */
678 
679 	/* skip the search if prints are temporarily unconditional */
680 	if (!suspend_grep && kdb_grepping_flag) {
681 		cp = strchr(kdb_buffer, '\n');
682 		if (!cp) {
683 			/*
684 			 * Special cases that don't end with newlines
685 			 * but should be written without one:
686 			 *   The "[nn]kdb> " prompt should
687 			 *   appear at the front of the buffer.
688 			 *
689 			 *   The "[nn]more " prompt should also be
690 			 *     (MOREPROMPT -> moreprompt)
691 			 *   written *   but we print that ourselves,
692 			 *   we set the suspend_grep flag to make
693 			 *   it unconditional.
694 			 *
695 			 */
696 			if (next_avail == kdb_buffer) {
697 				/*
698 				 * these should occur after a newline,
699 				 * so they will be at the front of the
700 				 * buffer
701 				 */
702 				cp2 = kdb_buffer;
703 				len = strlen(kdb_prompt_str);
704 				if (!strncmp(cp2, kdb_prompt_str, len)) {
705 					/*
706 					 * We're about to start a new
707 					 * command, so we can go back
708 					 * to normal mode.
709 					 */
710 					kdb_grepping_flag = 0;
711 					goto kdb_printit;
712 				}
713 			}
714 			/* no newline; don't search/write the buffer
715 			   until one is there */
716 			len = strlen(kdb_buffer);
717 			next_avail = kdb_buffer + len;
718 			size_avail = sizeof(kdb_buffer) - len;
719 			goto kdb_print_out;
720 		}
721 
722 		/*
723 		 * The newline is present; print through it or discard
724 		 * it, depending on the results of the search.
725 		 */
726 		cp++;	 	     /* to byte after the newline */
727 		replaced_byte = *cp; /* remember what/where it was */
728 		cphold = cp;
729 		*cp = '\0';	     /* end the string for our search */
730 
731 		/*
732 		 * We now have a newline at the end of the string
733 		 * Only continue with this output if it contains the
734 		 * search string.
735 		 */
736 		fnd = kdb_search_string(kdb_buffer, kdb_grep_string);
737 		if (!fnd) {
738 			/*
739 			 * At this point the complete line at the start
740 			 * of kdb_buffer can be discarded, as it does
741 			 * not contain what the user is looking for.
742 			 * Shift the buffer left.
743 			 */
744 			*cphold = replaced_byte;
745 			strcpy(kdb_buffer, cphold);
746 			len = strlen(kdb_buffer);
747 			next_avail = kdb_buffer + len;
748 			size_avail = sizeof(kdb_buffer) - len;
749 			goto kdb_print_out;
750 		}
751 		if (kdb_grepping_flag >= KDB_GREPPING_FLAG_SEARCH) {
752 			/*
753 			 * This was a interactive search (using '/' at more
754 			 * prompt) and it has completed. Replace the \0 with
755 			 * its original value to ensure multi-line strings
756 			 * are handled properly, and return to normal mode.
757 			 */
758 			*cphold = replaced_byte;
759 			kdb_grepping_flag = 0;
760 		}
761 		/*
762 		 * at this point the string is a full line and
763 		 * should be printed, up to the null.
764 		 */
765 	}
766 kdb_printit:
767 
768 	/*
769 	 * Write to all consoles.
770 	 */
771 	retlen = strlen(kdb_buffer);
772 	cp = (char *) printk_skip_headers(kdb_buffer);
773 	if (!dbg_kdb_mode && kgdb_connected)
774 		gdbstub_msg_write(cp, retlen - (cp - kdb_buffer));
775 	else
776 		kdb_msg_write(cp, retlen - (cp - kdb_buffer));
777 
778 	if (logging) {
779 		saved_loglevel = console_loglevel;
780 		console_loglevel = CONSOLE_LOGLEVEL_SILENT;
781 		if (printk_get_level(kdb_buffer) || src == KDB_MSGSRC_PRINTK)
782 			printk("%s", kdb_buffer);
783 		else
784 			pr_info("%s", kdb_buffer);
785 	}
786 
787 	if (KDB_STATE(PAGER)) {
788 		/*
789 		 * Check printed string to decide how to bump the
790 		 * kdb_nextline to control when the more prompt should
791 		 * show up.
792 		 */
793 		int got = 0;
794 		len = retlen;
795 		while (len--) {
796 			if (kdb_buffer[len] == '\n') {
797 				kdb_nextline++;
798 				got = 0;
799 			} else if (kdb_buffer[len] == '\r') {
800 				got = 0;
801 			} else {
802 				got++;
803 			}
804 		}
805 		kdb_nextline += got / (colcount + 1);
806 	}
807 
808 	/* check for having reached the LINES number of printed lines */
809 	if (kdb_nextline >= linecount) {
810 		char ch;
811 
812 		/* Watch out for recursion here.  Any routine that calls
813 		 * kdb_printf will come back through here.  And kdb_read
814 		 * uses kdb_printf to echo on serial consoles ...
815 		 */
816 		kdb_nextline = 1;	/* In case of recursion */
817 
818 		/*
819 		 * Pause until cr.
820 		 */
821 		moreprompt = kdbgetenv("MOREPROMPT");
822 		if (moreprompt == NULL)
823 			moreprompt = "more> ";
824 
825 		kdb_input_flush();
826 		kdb_msg_write(moreprompt, strlen(moreprompt));
827 
828 		if (logging)
829 			printk("%s", moreprompt);
830 
831 		ch = kdb_getchar();
832 		kdb_nextline = 1;	/* Really set output line 1 */
833 
834 		/* empty and reset the buffer: */
835 		kdb_buffer[0] = '\0';
836 		next_avail = kdb_buffer;
837 		size_avail = sizeof(kdb_buffer);
838 		if ((ch == 'q') || (ch == 'Q')) {
839 			/* user hit q or Q */
840 			KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
841 			KDB_STATE_CLEAR(PAGER);
842 			/* end of command output; back to normal mode */
843 			kdb_grepping_flag = 0;
844 			kdb_printf("\n");
845 		} else if (ch == ' ') {
846 			kdb_printf("\r");
847 			suspend_grep = 1; /* for this recursion */
848 		} else if (ch == '\n' || ch == '\r') {
849 			kdb_nextline = linecount - 1;
850 			kdb_printf("\r");
851 			suspend_grep = 1; /* for this recursion */
852 		} else if (ch == '/' && !kdb_grepping_flag) {
853 			kdb_printf("\r");
854 			kdb_getstr(kdb_grep_string, KDB_GREP_STRLEN,
855 				   kdbgetenv("SEARCHPROMPT") ?: "search> ");
856 			*strchrnul(kdb_grep_string, '\n') = '\0';
857 			kdb_grepping_flag += KDB_GREPPING_FLAG_SEARCH;
858 			suspend_grep = 1; /* for this recursion */
859 		} else if (ch) {
860 			/* user hit something unexpected */
861 			suspend_grep = 1; /* for this recursion */
862 			if (ch != '/')
863 				kdb_printf(
864 				    "\nOnly 'q', 'Q' or '/' are processed at "
865 				    "more prompt, input ignored\n");
866 			else
867 				kdb_printf("\n'/' cannot be used during | "
868 					   "grep filtering, input ignored\n");
869 		} else if (kdb_grepping_flag) {
870 			/* user hit enter */
871 			suspend_grep = 1; /* for this recursion */
872 			kdb_printf("\n");
873 		}
874 		kdb_input_flush();
875 	}
876 
877 	/*
878 	 * For grep searches, shift the printed string left.
879 	 *  replaced_byte contains the character that was overwritten with
880 	 *  the terminating null, and cphold points to the null.
881 	 * Then adjust the notion of available space in the buffer.
882 	 */
883 	if (kdb_grepping_flag && !suspend_grep) {
884 		*cphold = replaced_byte;
885 		strcpy(kdb_buffer, cphold);
886 		len = strlen(kdb_buffer);
887 		next_avail = kdb_buffer + len;
888 		size_avail = sizeof(kdb_buffer) - len;
889 	}
890 
891 kdb_print_out:
892 	suspend_grep = 0; /* end of what may have been a recursive call */
893 	if (logging)
894 		console_loglevel = saved_loglevel;
895 	/* kdb_printf_cpu locked the code above. */
896 	smp_store_release(&kdb_printf_cpu, old_cpu);
897 	local_irq_restore(flags);
898 	return retlen;
899 }
900 
kdb_printf(const char * fmt,...)901 int kdb_printf(const char *fmt, ...)
902 {
903 	va_list ap;
904 	int r;
905 
906 	va_start(ap, fmt);
907 	r = vkdb_printf(KDB_MSGSRC_INTERNAL, fmt, ap);
908 	va_end(ap);
909 
910 	return r;
911 }
912 EXPORT_SYMBOL_GPL(kdb_printf);
913