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1/*
2 * Kernel Debug Core
3 *
4 * Maintainer: Jason Wessel <jason.wessel@windriver.com>
5 *
6 * Copyright (C) 2000-2001 VERITAS Software Corporation.
7 * Copyright (C) 2002-2004 Timesys Corporation
8 * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
9 * Copyright (C) 2004 Pavel Machek <pavel@ucw.cz>
10 * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
11 * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
12 * Copyright (C) 2005-2009 Wind River Systems, Inc.
13 * Copyright (C) 2007 MontaVista Software, Inc.
14 * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
15 *
16 * Contributors at various stages not listed above:
17 * Jason Wessel ( jason.wessel@windriver.com )
18 * George Anzinger <george@mvista.com>
19 * Anurekh Saxena (anurekh.saxena@timesys.com)
20 * Lake Stevens Instrument Division (Glenn Engel)
21 * Jim Kingdon, Cygnus Support.
22 *
23 * Original KGDB stub: David Grothe <dave@gcom.com>,
24 * Tigran Aivazian <tigran@sco.com>
25 *
26 * This file is licensed under the terms of the GNU General Public License
27 * version 2. This program is licensed "as is" without any warranty of any
28 * kind, whether express or implied.
29 */
30
31#include <linux/kernel.h>
32#include <linux/kgdb.h>
33#include <linux/kdb.h>
34#include <linux/serial_core.h>
35#include <linux/reboot.h>
36#include <linux/uaccess.h>
37#include <asm/cacheflush.h>
38#include <asm/unaligned.h>
39#include "debug_core.h"
40
41#define KGDB_MAX_THREAD_QUERY 17
42
43/* Our I/O buffers. */
44static char remcom_in_buffer[BUFMAX];
45static char remcom_out_buffer[BUFMAX];
46static int gdbstub_use_prev_in_buf;
47static int gdbstub_prev_in_buf_pos;
48
49/* Storage for the registers, in GDB format. */
50static unsigned long gdb_regs[(NUMREGBYTES +
51 sizeof(unsigned long) - 1) /
52 sizeof(unsigned long)];
53
54/*
55 * GDB remote protocol parser:
56 */
57
58#ifdef CONFIG_KGDB_KDB
59static int gdbstub_read_wait(void)
60{
61 int ret = -1;
62 int i;
63
64 if (unlikely(gdbstub_use_prev_in_buf)) {
65 if (gdbstub_prev_in_buf_pos < gdbstub_use_prev_in_buf)
66 return remcom_in_buffer[gdbstub_prev_in_buf_pos++];
67 else
68 gdbstub_use_prev_in_buf = 0;
69 }
70
71 /* poll any additional I/O interfaces that are defined */
72 while (ret < 0)
73 for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
74 ret = kdb_poll_funcs[i]();
75 if (ret > 0)
76 break;
77 }
78 return ret;
79}
80#else
81static int gdbstub_read_wait(void)
82{
83 int ret = dbg_io_ops->read_char();
84 while (ret == NO_POLL_CHAR)
85 ret = dbg_io_ops->read_char();
86 return ret;
87}
88#endif
89/* scan for the sequence $<data>#<checksum> */
90static void get_packet(char *buffer)
91{
92 unsigned char checksum;
93 unsigned char xmitcsum;
94 int count;
95 char ch;
96
97 do {
98 /*
99 * Spin and wait around for the start character, ignore all
100 * other characters:
101 */
102 while ((ch = (gdbstub_read_wait())) != '$')
103 /* nothing */;
104
105 kgdb_connected = 1;
106 checksum = 0;
107 xmitcsum = -1;
108
109 count = 0;
110
111 /*
112 * now, read until a # or end of buffer is found:
113 */
114 while (count < (BUFMAX - 1)) {
115 ch = gdbstub_read_wait();
116 if (ch == '#')
117 break;
118 checksum = checksum + ch;
119 buffer[count] = ch;
120 count = count + 1;
121 }
122
123 if (ch == '#') {
124 xmitcsum = hex_to_bin(gdbstub_read_wait()) << 4;
125 xmitcsum += hex_to_bin(gdbstub_read_wait());
126
127 if (checksum != xmitcsum)
128 /* failed checksum */
129 dbg_io_ops->write_char('-');
130 else
131 /* successful transfer */
132 dbg_io_ops->write_char('+');
133 if (dbg_io_ops->flush)
134 dbg_io_ops->flush();
135 }
136 buffer[count] = 0;
137 } while (checksum != xmitcsum);
138}
139
140/*
141 * Send the packet in buffer.
142 * Check for gdb connection if asked for.
143 */
144static void put_packet(char *buffer)
145{
146 unsigned char checksum;
147 int count;
148 char ch;
149
150 /*
151 * $<packet info>#<checksum>.
152 */
153 while (1) {
154 dbg_io_ops->write_char('$');
155 checksum = 0;
156 count = 0;
157
158 while ((ch = buffer[count])) {
159 dbg_io_ops->write_char(ch);
160 checksum += ch;
161 count++;
162 }
163
164 dbg_io_ops->write_char('#');
165 dbg_io_ops->write_char(hex_asc_hi(checksum));
166 dbg_io_ops->write_char(hex_asc_lo(checksum));
167 if (dbg_io_ops->flush)
168 dbg_io_ops->flush();
169
170 /* Now see what we get in reply. */
171 ch = gdbstub_read_wait();
172
173 if (ch == 3)
174 ch = gdbstub_read_wait();
175
176 /* If we get an ACK, we are done. */
177 if (ch == '+')
178 return;
179
180 /*
181 * If we get the start of another packet, this means
182 * that GDB is attempting to reconnect. We will NAK
183 * the packet being sent, and stop trying to send this
184 * packet.
185 */
186 if (ch == '$') {
187 dbg_io_ops->write_char('-');
188 if (dbg_io_ops->flush)
189 dbg_io_ops->flush();
190 return;
191 }
192 }
193}
194
195static char gdbmsgbuf[BUFMAX + 1];
196
197void gdbstub_msg_write(const char *s, int len)
198{
199 char *bufptr;
200 int wcount;
201 int i;
202
203 if (len == 0)
204 len = strlen(s);
205
206 /* 'O'utput */
207 gdbmsgbuf[0] = 'O';
208
209 /* Fill and send buffers... */
210 while (len > 0) {
211 bufptr = gdbmsgbuf + 1;
212
213 /* Calculate how many this time */
214 if ((len << 1) > (BUFMAX - 2))
215 wcount = (BUFMAX - 2) >> 1;
216 else
217 wcount = len;
218
219 /* Pack in hex chars */
220 for (i = 0; i < wcount; i++)
221 bufptr = hex_byte_pack(bufptr, s[i]);
222 *bufptr = '\0';
223
224 /* Move up */
225 s += wcount;
226 len -= wcount;
227
228 /* Write packet */
229 put_packet(gdbmsgbuf);
230 }
231}
232
233/*
234 * Convert the memory pointed to by mem into hex, placing result in
235 * buf. Return a pointer to the last char put in buf (null). May
236 * return an error.
237 */
238char *kgdb_mem2hex(char *mem, char *buf, int count)
239{
240 char *tmp;
241 int err;
242
243 /*
244 * We use the upper half of buf as an intermediate buffer for the
245 * raw memory copy. Hex conversion will work against this one.
246 */
247 tmp = buf + count;
248
249 err = probe_kernel_read(tmp, mem, count);
250 if (err)
251 return NULL;
252 while (count > 0) {
253 buf = hex_byte_pack(buf, *tmp);
254 tmp++;
255 count--;
256 }
257 *buf = 0;
258
259 return buf;
260}
261
262/*
263 * Convert the hex array pointed to by buf into binary to be placed in
264 * mem. Return a pointer to the character AFTER the last byte
265 * written. May return an error.
266 */
267int kgdb_hex2mem(char *buf, char *mem, int count)
268{
269 char *tmp_raw;
270 char *tmp_hex;
271
272 /*
273 * We use the upper half of buf as an intermediate buffer for the
274 * raw memory that is converted from hex.
275 */
276 tmp_raw = buf + count * 2;
277
278 tmp_hex = tmp_raw - 1;
279 while (tmp_hex >= buf) {
280 tmp_raw--;
281 *tmp_raw = hex_to_bin(*tmp_hex--);
282 *tmp_raw |= hex_to_bin(*tmp_hex--) << 4;
283 }
284
285 return probe_kernel_write(mem, tmp_raw, count);
286}
287
288/*
289 * While we find nice hex chars, build a long_val.
290 * Return number of chars processed.
291 */
292int kgdb_hex2long(char **ptr, unsigned long *long_val)
293{
294 int hex_val;
295 int num = 0;
296 int negate = 0;
297
298 *long_val = 0;
299
300 if (**ptr == '-') {
301 negate = 1;
302 (*ptr)++;
303 }
304 while (**ptr) {
305 hex_val = hex_to_bin(**ptr);
306 if (hex_val < 0)
307 break;
308
309 *long_val = (*long_val << 4) | hex_val;
310 num++;
311 (*ptr)++;
312 }
313
314 if (negate)
315 *long_val = -*long_val;
316
317 return num;
318}
319
320/*
321 * Copy the binary array pointed to by buf into mem. Fix $, #, and
322 * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success.
323 * The input buf is overwitten with the result to write to mem.
324 */
325static int kgdb_ebin2mem(char *buf, char *mem, int count)
326{
327 int size = 0;
328 char *c = buf;
329
330 while (count-- > 0) {
331 c[size] = *buf++;
332 if (c[size] == 0x7d)
333 c[size] = *buf++ ^ 0x20;
334 size++;
335 }
336
337 return probe_kernel_write(mem, c, size);
338}
339
340#if DBG_MAX_REG_NUM > 0
341void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
342{
343 int i;
344 int idx = 0;
345 char *ptr = (char *)gdb_regs;
346
347 for (i = 0; i < DBG_MAX_REG_NUM; i++) {
348 dbg_get_reg(i, ptr + idx, regs);
349 idx += dbg_reg_def[i].size;
350 }
351}
352
353void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
354{
355 int i;
356 int idx = 0;
357 char *ptr = (char *)gdb_regs;
358
359 for (i = 0; i < DBG_MAX_REG_NUM; i++) {
360 dbg_set_reg(i, ptr + idx, regs);
361 idx += dbg_reg_def[i].size;
362 }
363}
364#endif /* DBG_MAX_REG_NUM > 0 */
365
366/* Write memory due to an 'M' or 'X' packet. */
367static int write_mem_msg(int binary)
368{
369 char *ptr = &remcom_in_buffer[1];
370 unsigned long addr;
371 unsigned long length;
372 int err;
373
374 if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
375 kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
376 if (binary)
377 err = kgdb_ebin2mem(ptr, (char *)addr, length);
378 else
379 err = kgdb_hex2mem(ptr, (char *)addr, length);
380 if (err)
381 return err;
382 if (CACHE_FLUSH_IS_SAFE)
383 flush_icache_range(addr, addr + length);
384 return 0;
385 }
386
387 return -EINVAL;
388}
389
390static void error_packet(char *pkt, int error)
391{
392 error = -error;
393 pkt[0] = 'E';
394 pkt[1] = hex_asc[(error / 10)];
395 pkt[2] = hex_asc[(error % 10)];
396 pkt[3] = '\0';
397}
398
399/*
400 * Thread ID accessors. We represent a flat TID space to GDB, where
401 * the per CPU idle threads (which under Linux all have PID 0) are
402 * remapped to negative TIDs.
403 */
404
405#define BUF_THREAD_ID_SIZE 8
406
407static char *pack_threadid(char *pkt, unsigned char *id)
408{
409 unsigned char *limit;
410 int lzero = 1;
411
412 limit = id + (BUF_THREAD_ID_SIZE / 2);
413 while (id < limit) {
414 if (!lzero || *id != 0) {
415 pkt = hex_byte_pack(pkt, *id);
416 lzero = 0;
417 }
418 id++;
419 }
420
421 if (lzero)
422 pkt = hex_byte_pack(pkt, 0);
423
424 return pkt;
425}
426
427static void int_to_threadref(unsigned char *id, int value)
428{
429 put_unaligned_be32(value, id);
430}
431
432static struct task_struct *getthread(struct pt_regs *regs, int tid)
433{
434 /*
435 * Non-positive TIDs are remapped to the cpu shadow information
436 */
437 if (tid == 0 || tid == -1)
438 tid = -atomic_read(&kgdb_active) - 2;
439 if (tid < -1 && tid > -NR_CPUS - 2) {
440 if (kgdb_info[-tid - 2].task)
441 return kgdb_info[-tid - 2].task;
442 else
443 return idle_task(-tid - 2);
444 }
445 if (tid <= 0) {
446 printk(KERN_ERR "KGDB: Internal thread select error\n");
447 dump_stack();
448 return NULL;
449 }
450
451 /*
452 * find_task_by_pid_ns() does not take the tasklist lock anymore
453 * but is nicely RCU locked - hence is a pretty resilient
454 * thing to use:
455 */
456 return find_task_by_pid_ns(tid, &init_pid_ns);
457}
458
459
460/*
461 * Remap normal tasks to their real PID,
462 * CPU shadow threads are mapped to -CPU - 2
463 */
464static inline int shadow_pid(int realpid)
465{
466 if (realpid)
467 return realpid;
468
469 return -raw_smp_processor_id() - 2;
470}
471
472/*
473 * All the functions that start with gdb_cmd are the various
474 * operations to implement the handlers for the gdbserial protocol
475 * where KGDB is communicating with an external debugger
476 */
477
478/* Handle the '?' status packets */
479static void gdb_cmd_status(struct kgdb_state *ks)
480{
481 /*
482 * We know that this packet is only sent
483 * during initial connect. So to be safe,
484 * we clear out our breakpoints now in case
485 * GDB is reconnecting.
486 */
487 dbg_remove_all_break();
488
489 remcom_out_buffer[0] = 'S';
490 hex_byte_pack(&remcom_out_buffer[1], ks->signo);
491}
492
493static void gdb_get_regs_helper(struct kgdb_state *ks)
494{
495 struct task_struct *thread;
496 void *local_debuggerinfo;
497 int i;
498
499 thread = kgdb_usethread;
500 if (!thread) {
501 thread = kgdb_info[ks->cpu].task;
502 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
503 } else {
504 local_debuggerinfo = NULL;
505 for_each_online_cpu(i) {
506 /*
507 * Try to find the task on some other
508 * or possibly this node if we do not
509 * find the matching task then we try
510 * to approximate the results.
511 */
512 if (thread == kgdb_info[i].task)
513 local_debuggerinfo = kgdb_info[i].debuggerinfo;
514 }
515 }
516
517 /*
518 * All threads that don't have debuggerinfo should be
519 * in schedule() sleeping, since all other CPUs
520 * are in kgdb_wait, and thus have debuggerinfo.
521 */
522 if (local_debuggerinfo) {
523 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
524 } else {
525 /*
526 * Pull stuff saved during switch_to; nothing
527 * else is accessible (or even particularly
528 * relevant).
529 *
530 * This should be enough for a stack trace.
531 */
532 sleeping_thread_to_gdb_regs(gdb_regs, thread);
533 }
534}
535
536/* Handle the 'g' get registers request */
537static void gdb_cmd_getregs(struct kgdb_state *ks)
538{
539 gdb_get_regs_helper(ks);
540 kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
541}
542
543/* Handle the 'G' set registers request */
544static void gdb_cmd_setregs(struct kgdb_state *ks)
545{
546 kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
547
548 if (kgdb_usethread && kgdb_usethread != current) {
549 error_packet(remcom_out_buffer, -EINVAL);
550 } else {
551 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
552 strcpy(remcom_out_buffer, "OK");
553 }
554}
555
556/* Handle the 'm' memory read bytes */
557static void gdb_cmd_memread(struct kgdb_state *ks)
558{
559 char *ptr = &remcom_in_buffer[1];
560 unsigned long length;
561 unsigned long addr;
562 char *err;
563
564 if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
565 kgdb_hex2long(&ptr, &length) > 0) {
566 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
567 if (!err)
568 error_packet(remcom_out_buffer, -EINVAL);
569 } else {
570 error_packet(remcom_out_buffer, -EINVAL);
571 }
572}
573
574/* Handle the 'M' memory write bytes */
575static void gdb_cmd_memwrite(struct kgdb_state *ks)
576{
577 int err = write_mem_msg(0);
578
579 if (err)
580 error_packet(remcom_out_buffer, err);
581 else
582 strcpy(remcom_out_buffer, "OK");
583}
584
585#if DBG_MAX_REG_NUM > 0
586static char *gdb_hex_reg_helper(int regnum, char *out)
587{
588 int i;
589 int offset = 0;
590
591 for (i = 0; i < regnum; i++)
592 offset += dbg_reg_def[i].size;
593 return kgdb_mem2hex((char *)gdb_regs + offset, out,
594 dbg_reg_def[i].size);
595}
596
597/* Handle the 'p' individual regster get */
598static void gdb_cmd_reg_get(struct kgdb_state *ks)
599{
600 unsigned long regnum;
601 char *ptr = &remcom_in_buffer[1];
602
603 kgdb_hex2long(&ptr, ®num);
604 if (regnum >= DBG_MAX_REG_NUM) {
605 error_packet(remcom_out_buffer, -EINVAL);
606 return;
607 }
608 gdb_get_regs_helper(ks);
609 gdb_hex_reg_helper(regnum, remcom_out_buffer);
610}
611
612/* Handle the 'P' individual regster set */
613static void gdb_cmd_reg_set(struct kgdb_state *ks)
614{
615 unsigned long regnum;
616 char *ptr = &remcom_in_buffer[1];
617 int i = 0;
618
619 kgdb_hex2long(&ptr, ®num);
620 if (*ptr++ != '=' ||
621 !(!kgdb_usethread || kgdb_usethread == current) ||
622 !dbg_get_reg(regnum, gdb_regs, ks->linux_regs)) {
623 error_packet(remcom_out_buffer, -EINVAL);
624 return;
625 }
626 memset(gdb_regs, 0, sizeof(gdb_regs));
627 while (i < sizeof(gdb_regs) * 2)
628 if (hex_to_bin(ptr[i]) >= 0)
629 i++;
630 else
631 break;
632 i = i / 2;
633 kgdb_hex2mem(ptr, (char *)gdb_regs, i);
634 dbg_set_reg(regnum, gdb_regs, ks->linux_regs);
635 strcpy(remcom_out_buffer, "OK");
636}
637#endif /* DBG_MAX_REG_NUM > 0 */
638
639/* Handle the 'X' memory binary write bytes */
640static void gdb_cmd_binwrite(struct kgdb_state *ks)
641{
642 int err = write_mem_msg(1);
643
644 if (err)
645 error_packet(remcom_out_buffer, err);
646 else
647 strcpy(remcom_out_buffer, "OK");
648}
649
650/* Handle the 'D' or 'k', detach or kill packets */
651static void gdb_cmd_detachkill(struct kgdb_state *ks)
652{
653 int error;
654
655 /* The detach case */
656 if (remcom_in_buffer[0] == 'D') {
657 error = dbg_remove_all_break();
658 if (error < 0) {
659 error_packet(remcom_out_buffer, error);
660 } else {
661 strcpy(remcom_out_buffer, "OK");
662 kgdb_connected = 0;
663 }
664 put_packet(remcom_out_buffer);
665 } else {
666 /*
667 * Assume the kill case, with no exit code checking,
668 * trying to force detach the debugger:
669 */
670 dbg_remove_all_break();
671 kgdb_connected = 0;
672 }
673}
674
675/* Handle the 'R' reboot packets */
676static int gdb_cmd_reboot(struct kgdb_state *ks)
677{
678 /* For now, only honor R0 */
679 if (strcmp(remcom_in_buffer, "R0") == 0) {
680 printk(KERN_CRIT "Executing emergency reboot\n");
681 strcpy(remcom_out_buffer, "OK");
682 put_packet(remcom_out_buffer);
683
684 /*
685 * Execution should not return from
686 * machine_emergency_restart()
687 */
688 machine_emergency_restart();
689 kgdb_connected = 0;
690
691 return 1;
692 }
693 return 0;
694}
695
696/* Handle the 'q' query packets */
697static void gdb_cmd_query(struct kgdb_state *ks)
698{
699 struct task_struct *g;
700 struct task_struct *p;
701 unsigned char thref[BUF_THREAD_ID_SIZE];
702 char *ptr;
703 int i;
704 int cpu;
705 int finished = 0;
706
707 switch (remcom_in_buffer[1]) {
708 case 's':
709 case 'f':
710 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10))
711 break;
712
713 i = 0;
714 remcom_out_buffer[0] = 'm';
715 ptr = remcom_out_buffer + 1;
716 if (remcom_in_buffer[1] == 'f') {
717 /* Each cpu is a shadow thread */
718 for_each_online_cpu(cpu) {
719 ks->thr_query = 0;
720 int_to_threadref(thref, -cpu - 2);
721 ptr = pack_threadid(ptr, thref);
722 *(ptr++) = ',';
723 i++;
724 }
725 }
726
727 do_each_thread(g, p) {
728 if (i >= ks->thr_query && !finished) {
729 int_to_threadref(thref, p->pid);
730 ptr = pack_threadid(ptr, thref);
731 *(ptr++) = ',';
732 ks->thr_query++;
733 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
734 finished = 1;
735 }
736 i++;
737 } while_each_thread(g, p);
738
739 *(--ptr) = '\0';
740 break;
741
742 case 'C':
743 /* Current thread id */
744 strcpy(remcom_out_buffer, "QC");
745 ks->threadid = shadow_pid(current->pid);
746 int_to_threadref(thref, ks->threadid);
747 pack_threadid(remcom_out_buffer + 2, thref);
748 break;
749 case 'T':
750 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16))
751 break;
752
753 ks->threadid = 0;
754 ptr = remcom_in_buffer + 17;
755 kgdb_hex2long(&ptr, &ks->threadid);
756 if (!getthread(ks->linux_regs, ks->threadid)) {
757 error_packet(remcom_out_buffer, -EINVAL);
758 break;
759 }
760 if ((int)ks->threadid > 0) {
761 kgdb_mem2hex(getthread(ks->linux_regs,
762 ks->threadid)->comm,
763 remcom_out_buffer, 16);
764 } else {
765 static char tmpstr[23 + BUF_THREAD_ID_SIZE];
766
767 sprintf(tmpstr, "shadowCPU%d",
768 (int)(-ks->threadid - 2));
769 kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
770 }
771 break;
772#ifdef CONFIG_KGDB_KDB
773 case 'R':
774 if (strncmp(remcom_in_buffer, "qRcmd,", 6) == 0) {
775 int len = strlen(remcom_in_buffer + 6);
776
777 if ((len % 2) != 0) {
778 strcpy(remcom_out_buffer, "E01");
779 break;
780 }
781 kgdb_hex2mem(remcom_in_buffer + 6,
782 remcom_out_buffer, len);
783 len = len / 2;
784 remcom_out_buffer[len++] = 0;
785
786 kdb_common_init_state(ks);
787 kdb_parse(remcom_out_buffer);
788 kdb_common_deinit_state();
789
790 strcpy(remcom_out_buffer, "OK");
791 }
792 break;
793#endif
794 }
795}
796
797/* Handle the 'H' task query packets */
798static void gdb_cmd_task(struct kgdb_state *ks)
799{
800 struct task_struct *thread;
801 char *ptr;
802
803 switch (remcom_in_buffer[1]) {
804 case 'g':
805 ptr = &remcom_in_buffer[2];
806 kgdb_hex2long(&ptr, &ks->threadid);
807 thread = getthread(ks->linux_regs, ks->threadid);
808 if (!thread && ks->threadid > 0) {
809 error_packet(remcom_out_buffer, -EINVAL);
810 break;
811 }
812 kgdb_usethread = thread;
813 ks->kgdb_usethreadid = ks->threadid;
814 strcpy(remcom_out_buffer, "OK");
815 break;
816 case 'c':
817 ptr = &remcom_in_buffer[2];
818 kgdb_hex2long(&ptr, &ks->threadid);
819 if (!ks->threadid) {
820 kgdb_contthread = NULL;
821 } else {
822 thread = getthread(ks->linux_regs, ks->threadid);
823 if (!thread && ks->threadid > 0) {
824 error_packet(remcom_out_buffer, -EINVAL);
825 break;
826 }
827 kgdb_contthread = thread;
828 }
829 strcpy(remcom_out_buffer, "OK");
830 break;
831 }
832}
833
834/* Handle the 'T' thread query packets */
835static void gdb_cmd_thread(struct kgdb_state *ks)
836{
837 char *ptr = &remcom_in_buffer[1];
838 struct task_struct *thread;
839
840 kgdb_hex2long(&ptr, &ks->threadid);
841 thread = getthread(ks->linux_regs, ks->threadid);
842 if (thread)
843 strcpy(remcom_out_buffer, "OK");
844 else
845 error_packet(remcom_out_buffer, -EINVAL);
846}
847
848/* Handle the 'z' or 'Z' breakpoint remove or set packets */
849static void gdb_cmd_break(struct kgdb_state *ks)
850{
851 /*
852 * Since GDB-5.3, it's been drafted that '0' is a software
853 * breakpoint, '1' is a hardware breakpoint, so let's do that.
854 */
855 char *bpt_type = &remcom_in_buffer[1];
856 char *ptr = &remcom_in_buffer[2];
857 unsigned long addr;
858 unsigned long length;
859 int error = 0;
860
861 if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
862 /* Unsupported */
863 if (*bpt_type > '4')
864 return;
865 } else {
866 if (*bpt_type != '0' && *bpt_type != '1')
867 /* Unsupported. */
868 return;
869 }
870
871 /*
872 * Test if this is a hardware breakpoint, and
873 * if we support it:
874 */
875 if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
876 /* Unsupported. */
877 return;
878
879 if (*(ptr++) != ',') {
880 error_packet(remcom_out_buffer, -EINVAL);
881 return;
882 }
883 if (!kgdb_hex2long(&ptr, &addr)) {
884 error_packet(remcom_out_buffer, -EINVAL);
885 return;
886 }
887 if (*(ptr++) != ',' ||
888 !kgdb_hex2long(&ptr, &length)) {
889 error_packet(remcom_out_buffer, -EINVAL);
890 return;
891 }
892
893 if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
894 error = dbg_set_sw_break(addr);
895 else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
896 error = dbg_remove_sw_break(addr);
897 else if (remcom_in_buffer[0] == 'Z')
898 error = arch_kgdb_ops.set_hw_breakpoint(addr,
899 (int)length, *bpt_type - '0');
900 else if (remcom_in_buffer[0] == 'z')
901 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
902 (int) length, *bpt_type - '0');
903
904 if (error == 0)
905 strcpy(remcom_out_buffer, "OK");
906 else
907 error_packet(remcom_out_buffer, error);
908}
909
910/* Handle the 'C' signal / exception passing packets */
911static int gdb_cmd_exception_pass(struct kgdb_state *ks)
912{
913 /* C09 == pass exception
914 * C15 == detach kgdb, pass exception
915 */
916 if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
917
918 ks->pass_exception = 1;
919 remcom_in_buffer[0] = 'c';
920
921 } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
922
923 ks->pass_exception = 1;
924 remcom_in_buffer[0] = 'D';
925 dbg_remove_all_break();
926 kgdb_connected = 0;
927 return 1;
928
929 } else {
930 gdbstub_msg_write("KGDB only knows signal 9 (pass)"
931 " and 15 (pass and disconnect)\n"
932 "Executing a continue without signal passing\n", 0);
933 remcom_in_buffer[0] = 'c';
934 }
935
936 /* Indicate fall through */
937 return -1;
938}
939
940/*
941 * This function performs all gdbserial command procesing
942 */
943int gdb_serial_stub(struct kgdb_state *ks)
944{
945 int error = 0;
946 int tmp;
947
948 /* Initialize comm buffer and globals. */
949 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
950 kgdb_usethread = kgdb_info[ks->cpu].task;
951 ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
952 ks->pass_exception = 0;
953
954 if (kgdb_connected) {
955 unsigned char thref[BUF_THREAD_ID_SIZE];
956 char *ptr;
957
958 /* Reply to host that an exception has occurred */
959 ptr = remcom_out_buffer;
960 *ptr++ = 'T';
961 ptr = hex_byte_pack(ptr, ks->signo);
962 ptr += strlen(strcpy(ptr, "thread:"));
963 int_to_threadref(thref, shadow_pid(current->pid));
964 ptr = pack_threadid(ptr, thref);
965 *ptr++ = ';';
966 put_packet(remcom_out_buffer);
967 }
968
969 while (1) {
970 error = 0;
971
972 /* Clear the out buffer. */
973 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
974
975 get_packet(remcom_in_buffer);
976
977 switch (remcom_in_buffer[0]) {
978 case '?': /* gdbserial status */
979 gdb_cmd_status(ks);
980 break;
981 case 'g': /* return the value of the CPU registers */
982 gdb_cmd_getregs(ks);
983 break;
984 case 'G': /* set the value of the CPU registers - return OK */
985 gdb_cmd_setregs(ks);
986 break;
987 case 'm': /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */
988 gdb_cmd_memread(ks);
989 break;
990 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
991 gdb_cmd_memwrite(ks);
992 break;
993#if DBG_MAX_REG_NUM > 0
994 case 'p': /* pXX Return gdb register XX (in hex) */
995 gdb_cmd_reg_get(ks);
996 break;
997 case 'P': /* PXX=aaaa Set gdb register XX to aaaa (in hex) */
998 gdb_cmd_reg_set(ks);
999 break;
1000#endif /* DBG_MAX_REG_NUM > 0 */
1001 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1002 gdb_cmd_binwrite(ks);
1003 break;
1004 /* kill or detach. KGDB should treat this like a
1005 * continue.
1006 */
1007 case 'D': /* Debugger detach */
1008 case 'k': /* Debugger detach via kill */
1009 gdb_cmd_detachkill(ks);
1010 goto default_handle;
1011 case 'R': /* Reboot */
1012 if (gdb_cmd_reboot(ks))
1013 goto default_handle;
1014 break;
1015 case 'q': /* query command */
1016 gdb_cmd_query(ks);
1017 break;
1018 case 'H': /* task related */
1019 gdb_cmd_task(ks);
1020 break;
1021 case 'T': /* Query thread status */
1022 gdb_cmd_thread(ks);
1023 break;
1024 case 'z': /* Break point remove */
1025 case 'Z': /* Break point set */
1026 gdb_cmd_break(ks);
1027 break;
1028#ifdef CONFIG_KGDB_KDB
1029 case '3': /* Escape into back into kdb */
1030 if (remcom_in_buffer[1] == '\0') {
1031 gdb_cmd_detachkill(ks);
1032 return DBG_PASS_EVENT;
1033 }
1034#endif
1035 case 'C': /* Exception passing */
1036 tmp = gdb_cmd_exception_pass(ks);
1037 if (tmp > 0)
1038 goto default_handle;
1039 if (tmp == 0)
1040 break;
1041 /* Fall through on tmp < 0 */
1042 case 'c': /* Continue packet */
1043 case 's': /* Single step packet */
1044 if (kgdb_contthread && kgdb_contthread != current) {
1045 /* Can't switch threads in kgdb */
1046 error_packet(remcom_out_buffer, -EINVAL);
1047 break;
1048 }
1049 dbg_activate_sw_breakpoints();
1050 /* Fall through to default processing */
1051 default:
1052default_handle:
1053 error = kgdb_arch_handle_exception(ks->ex_vector,
1054 ks->signo,
1055 ks->err_code,
1056 remcom_in_buffer,
1057 remcom_out_buffer,
1058 ks->linux_regs);
1059 /*
1060 * Leave cmd processing on error, detach,
1061 * kill, continue, or single step.
1062 */
1063 if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1064 remcom_in_buffer[0] == 'k') {
1065 error = 0;
1066 goto kgdb_exit;
1067 }
1068
1069 }
1070
1071 /* reply to the request */
1072 put_packet(remcom_out_buffer);
1073 }
1074
1075kgdb_exit:
1076 if (ks->pass_exception)
1077 error = 1;
1078 return error;
1079}
1080
1081int gdbstub_state(struct kgdb_state *ks, char *cmd)
1082{
1083 int error;
1084
1085 switch (cmd[0]) {
1086 case 'e':
1087 error = kgdb_arch_handle_exception(ks->ex_vector,
1088 ks->signo,
1089 ks->err_code,
1090 remcom_in_buffer,
1091 remcom_out_buffer,
1092 ks->linux_regs);
1093 return error;
1094 case 's':
1095 case 'c':
1096 strcpy(remcom_in_buffer, cmd);
1097 return 0;
1098 case '$':
1099 strcpy(remcom_in_buffer, cmd);
1100 gdbstub_use_prev_in_buf = strlen(remcom_in_buffer);
1101 gdbstub_prev_in_buf_pos = 0;
1102 return 0;
1103 }
1104 dbg_io_ops->write_char('+');
1105 put_packet(remcom_out_buffer);
1106 return 0;
1107}
1108
1109/**
1110 * gdbstub_exit - Send an exit message to GDB
1111 * @status: The exit code to report.
1112 */
1113void gdbstub_exit(int status)
1114{
1115 unsigned char checksum, ch, buffer[3];
1116 int loop;
1117
1118 if (!kgdb_connected)
1119 return;
1120 kgdb_connected = 0;
1121
1122 if (!dbg_io_ops || dbg_kdb_mode)
1123 return;
1124
1125 buffer[0] = 'W';
1126 buffer[1] = hex_asc_hi(status);
1127 buffer[2] = hex_asc_lo(status);
1128
1129 dbg_io_ops->write_char('$');
1130 checksum = 0;
1131
1132 for (loop = 0; loop < 3; loop++) {
1133 ch = buffer[loop];
1134 checksum += ch;
1135 dbg_io_ops->write_char(ch);
1136 }
1137
1138 dbg_io_ops->write_char('#');
1139 dbg_io_ops->write_char(hex_asc_hi(checksum));
1140 dbg_io_ops->write_char(hex_asc_lo(checksum));
1141
1142 /* make sure the output is flushed, lest the bootloader clobber it */
1143 if (dbg_io_ops->flush)
1144 dbg_io_ops->flush();
1145}
1/*
2 * Kernel Debug Core
3 *
4 * Maintainer: Jason Wessel <jason.wessel@windriver.com>
5 *
6 * Copyright (C) 2000-2001 VERITAS Software Corporation.
7 * Copyright (C) 2002-2004 Timesys Corporation
8 * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
9 * Copyright (C) 2004 Pavel Machek <pavel@ucw.cz>
10 * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
11 * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
12 * Copyright (C) 2005-2009 Wind River Systems, Inc.
13 * Copyright (C) 2007 MontaVista Software, Inc.
14 * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
15 *
16 * Contributors at various stages not listed above:
17 * Jason Wessel ( jason.wessel@windriver.com )
18 * George Anzinger <george@mvista.com>
19 * Anurekh Saxena (anurekh.saxena@timesys.com)
20 * Lake Stevens Instrument Division (Glenn Engel)
21 * Jim Kingdon, Cygnus Support.
22 *
23 * Original KGDB stub: David Grothe <dave@gcom.com>,
24 * Tigran Aivazian <tigran@sco.com>
25 *
26 * This file is licensed under the terms of the GNU General Public License
27 * version 2. This program is licensed "as is" without any warranty of any
28 * kind, whether express or implied.
29 */
30
31#include <linux/kernel.h>
32#include <linux/kgdb.h>
33#include <linux/kdb.h>
34#include <linux/reboot.h>
35#include <linux/uaccess.h>
36#include <asm/cacheflush.h>
37#include <asm/unaligned.h>
38#include "debug_core.h"
39
40#define KGDB_MAX_THREAD_QUERY 17
41
42/* Our I/O buffers. */
43static char remcom_in_buffer[BUFMAX];
44static char remcom_out_buffer[BUFMAX];
45static int gdbstub_use_prev_in_buf;
46static int gdbstub_prev_in_buf_pos;
47
48/* Storage for the registers, in GDB format. */
49static unsigned long gdb_regs[(NUMREGBYTES +
50 sizeof(unsigned long) - 1) /
51 sizeof(unsigned long)];
52
53/*
54 * GDB remote protocol parser:
55 */
56
57#ifdef CONFIG_KGDB_KDB
58static int gdbstub_read_wait(void)
59{
60 int ret = -1;
61 int i;
62
63 if (unlikely(gdbstub_use_prev_in_buf)) {
64 if (gdbstub_prev_in_buf_pos < gdbstub_use_prev_in_buf)
65 return remcom_in_buffer[gdbstub_prev_in_buf_pos++];
66 else
67 gdbstub_use_prev_in_buf = 0;
68 }
69
70 /* poll any additional I/O interfaces that are defined */
71 while (ret < 0)
72 for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
73 ret = kdb_poll_funcs[i]();
74 if (ret > 0)
75 break;
76 }
77 return ret;
78}
79#else
80static int gdbstub_read_wait(void)
81{
82 int ret = dbg_io_ops->read_char();
83 while (ret == NO_POLL_CHAR)
84 ret = dbg_io_ops->read_char();
85 return ret;
86}
87#endif
88/* scan for the sequence $<data>#<checksum> */
89static void get_packet(char *buffer)
90{
91 unsigned char checksum;
92 unsigned char xmitcsum;
93 int count;
94 char ch;
95
96 do {
97 /*
98 * Spin and wait around for the start character, ignore all
99 * other characters:
100 */
101 while ((ch = (gdbstub_read_wait())) != '$')
102 /* nothing */;
103
104 kgdb_connected = 1;
105 checksum = 0;
106 xmitcsum = -1;
107
108 count = 0;
109
110 /*
111 * now, read until a # or end of buffer is found:
112 */
113 while (count < (BUFMAX - 1)) {
114 ch = gdbstub_read_wait();
115 if (ch == '#')
116 break;
117 checksum = checksum + ch;
118 buffer[count] = ch;
119 count = count + 1;
120 }
121
122 if (ch == '#') {
123 xmitcsum = hex_to_bin(gdbstub_read_wait()) << 4;
124 xmitcsum += hex_to_bin(gdbstub_read_wait());
125
126 if (checksum != xmitcsum)
127 /* failed checksum */
128 dbg_io_ops->write_char('-');
129 else
130 /* successful transfer */
131 dbg_io_ops->write_char('+');
132 if (dbg_io_ops->flush)
133 dbg_io_ops->flush();
134 }
135 buffer[count] = 0;
136 } while (checksum != xmitcsum);
137}
138
139/*
140 * Send the packet in buffer.
141 * Check for gdb connection if asked for.
142 */
143static void put_packet(char *buffer)
144{
145 unsigned char checksum;
146 int count;
147 char ch;
148
149 /*
150 * $<packet info>#<checksum>.
151 */
152 while (1) {
153 dbg_io_ops->write_char('$');
154 checksum = 0;
155 count = 0;
156
157 while ((ch = buffer[count])) {
158 dbg_io_ops->write_char(ch);
159 checksum += ch;
160 count++;
161 }
162
163 dbg_io_ops->write_char('#');
164 dbg_io_ops->write_char(hex_asc_hi(checksum));
165 dbg_io_ops->write_char(hex_asc_lo(checksum));
166 if (dbg_io_ops->flush)
167 dbg_io_ops->flush();
168
169 /* Now see what we get in reply. */
170 ch = gdbstub_read_wait();
171
172 if (ch == 3)
173 ch = gdbstub_read_wait();
174
175 /* If we get an ACK, we are done. */
176 if (ch == '+')
177 return;
178
179 /*
180 * If we get the start of another packet, this means
181 * that GDB is attempting to reconnect. We will NAK
182 * the packet being sent, and stop trying to send this
183 * packet.
184 */
185 if (ch == '$') {
186 dbg_io_ops->write_char('-');
187 if (dbg_io_ops->flush)
188 dbg_io_ops->flush();
189 return;
190 }
191 }
192}
193
194static char gdbmsgbuf[BUFMAX + 1];
195
196void gdbstub_msg_write(const char *s, int len)
197{
198 char *bufptr;
199 int wcount;
200 int i;
201
202 if (len == 0)
203 len = strlen(s);
204
205 /* 'O'utput */
206 gdbmsgbuf[0] = 'O';
207
208 /* Fill and send buffers... */
209 while (len > 0) {
210 bufptr = gdbmsgbuf + 1;
211
212 /* Calculate how many this time */
213 if ((len << 1) > (BUFMAX - 2))
214 wcount = (BUFMAX - 2) >> 1;
215 else
216 wcount = len;
217
218 /* Pack in hex chars */
219 for (i = 0; i < wcount; i++)
220 bufptr = pack_hex_byte(bufptr, s[i]);
221 *bufptr = '\0';
222
223 /* Move up */
224 s += wcount;
225 len -= wcount;
226
227 /* Write packet */
228 put_packet(gdbmsgbuf);
229 }
230}
231
232/*
233 * Convert the memory pointed to by mem into hex, placing result in
234 * buf. Return a pointer to the last char put in buf (null). May
235 * return an error.
236 */
237char *kgdb_mem2hex(char *mem, char *buf, int count)
238{
239 char *tmp;
240 int err;
241
242 /*
243 * We use the upper half of buf as an intermediate buffer for the
244 * raw memory copy. Hex conversion will work against this one.
245 */
246 tmp = buf + count;
247
248 err = probe_kernel_read(tmp, mem, count);
249 if (err)
250 return NULL;
251 while (count > 0) {
252 buf = pack_hex_byte(buf, *tmp);
253 tmp++;
254 count--;
255 }
256 *buf = 0;
257
258 return buf;
259}
260
261/*
262 * Convert the hex array pointed to by buf into binary to be placed in
263 * mem. Return a pointer to the character AFTER the last byte
264 * written. May return an error.
265 */
266int kgdb_hex2mem(char *buf, char *mem, int count)
267{
268 char *tmp_raw;
269 char *tmp_hex;
270
271 /*
272 * We use the upper half of buf as an intermediate buffer for the
273 * raw memory that is converted from hex.
274 */
275 tmp_raw = buf + count * 2;
276
277 tmp_hex = tmp_raw - 1;
278 while (tmp_hex >= buf) {
279 tmp_raw--;
280 *tmp_raw = hex_to_bin(*tmp_hex--);
281 *tmp_raw |= hex_to_bin(*tmp_hex--) << 4;
282 }
283
284 return probe_kernel_write(mem, tmp_raw, count);
285}
286
287/*
288 * While we find nice hex chars, build a long_val.
289 * Return number of chars processed.
290 */
291int kgdb_hex2long(char **ptr, unsigned long *long_val)
292{
293 int hex_val;
294 int num = 0;
295 int negate = 0;
296
297 *long_val = 0;
298
299 if (**ptr == '-') {
300 negate = 1;
301 (*ptr)++;
302 }
303 while (**ptr) {
304 hex_val = hex_to_bin(**ptr);
305 if (hex_val < 0)
306 break;
307
308 *long_val = (*long_val << 4) | hex_val;
309 num++;
310 (*ptr)++;
311 }
312
313 if (negate)
314 *long_val = -*long_val;
315
316 return num;
317}
318
319/*
320 * Copy the binary array pointed to by buf into mem. Fix $, #, and
321 * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success.
322 * The input buf is overwitten with the result to write to mem.
323 */
324static int kgdb_ebin2mem(char *buf, char *mem, int count)
325{
326 int size = 0;
327 char *c = buf;
328
329 while (count-- > 0) {
330 c[size] = *buf++;
331 if (c[size] == 0x7d)
332 c[size] = *buf++ ^ 0x20;
333 size++;
334 }
335
336 return probe_kernel_write(mem, c, size);
337}
338
339#if DBG_MAX_REG_NUM > 0
340void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
341{
342 int i;
343 int idx = 0;
344 char *ptr = (char *)gdb_regs;
345
346 for (i = 0; i < DBG_MAX_REG_NUM; i++) {
347 dbg_get_reg(i, ptr + idx, regs);
348 idx += dbg_reg_def[i].size;
349 }
350}
351
352void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
353{
354 int i;
355 int idx = 0;
356 char *ptr = (char *)gdb_regs;
357
358 for (i = 0; i < DBG_MAX_REG_NUM; i++) {
359 dbg_set_reg(i, ptr + idx, regs);
360 idx += dbg_reg_def[i].size;
361 }
362}
363#endif /* DBG_MAX_REG_NUM > 0 */
364
365/* Write memory due to an 'M' or 'X' packet. */
366static int write_mem_msg(int binary)
367{
368 char *ptr = &remcom_in_buffer[1];
369 unsigned long addr;
370 unsigned long length;
371 int err;
372
373 if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
374 kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
375 if (binary)
376 err = kgdb_ebin2mem(ptr, (char *)addr, length);
377 else
378 err = kgdb_hex2mem(ptr, (char *)addr, length);
379 if (err)
380 return err;
381 if (CACHE_FLUSH_IS_SAFE)
382 flush_icache_range(addr, addr + length);
383 return 0;
384 }
385
386 return -EINVAL;
387}
388
389static void error_packet(char *pkt, int error)
390{
391 error = -error;
392 pkt[0] = 'E';
393 pkt[1] = hex_asc[(error / 10)];
394 pkt[2] = hex_asc[(error % 10)];
395 pkt[3] = '\0';
396}
397
398/*
399 * Thread ID accessors. We represent a flat TID space to GDB, where
400 * the per CPU idle threads (which under Linux all have PID 0) are
401 * remapped to negative TIDs.
402 */
403
404#define BUF_THREAD_ID_SIZE 8
405
406static char *pack_threadid(char *pkt, unsigned char *id)
407{
408 unsigned char *limit;
409 int lzero = 1;
410
411 limit = id + (BUF_THREAD_ID_SIZE / 2);
412 while (id < limit) {
413 if (!lzero || *id != 0) {
414 pkt = pack_hex_byte(pkt, *id);
415 lzero = 0;
416 }
417 id++;
418 }
419
420 if (lzero)
421 pkt = pack_hex_byte(pkt, 0);
422
423 return pkt;
424}
425
426static void int_to_threadref(unsigned char *id, int value)
427{
428 put_unaligned_be32(value, id);
429}
430
431static struct task_struct *getthread(struct pt_regs *regs, int tid)
432{
433 /*
434 * Non-positive TIDs are remapped to the cpu shadow information
435 */
436 if (tid == 0 || tid == -1)
437 tid = -atomic_read(&kgdb_active) - 2;
438 if (tid < -1 && tid > -NR_CPUS - 2) {
439 if (kgdb_info[-tid - 2].task)
440 return kgdb_info[-tid - 2].task;
441 else
442 return idle_task(-tid - 2);
443 }
444 if (tid <= 0) {
445 printk(KERN_ERR "KGDB: Internal thread select error\n");
446 dump_stack();
447 return NULL;
448 }
449
450 /*
451 * find_task_by_pid_ns() does not take the tasklist lock anymore
452 * but is nicely RCU locked - hence is a pretty resilient
453 * thing to use:
454 */
455 return find_task_by_pid_ns(tid, &init_pid_ns);
456}
457
458
459/*
460 * Remap normal tasks to their real PID,
461 * CPU shadow threads are mapped to -CPU - 2
462 */
463static inline int shadow_pid(int realpid)
464{
465 if (realpid)
466 return realpid;
467
468 return -raw_smp_processor_id() - 2;
469}
470
471/*
472 * All the functions that start with gdb_cmd are the various
473 * operations to implement the handlers for the gdbserial protocol
474 * where KGDB is communicating with an external debugger
475 */
476
477/* Handle the '?' status packets */
478static void gdb_cmd_status(struct kgdb_state *ks)
479{
480 /*
481 * We know that this packet is only sent
482 * during initial connect. So to be safe,
483 * we clear out our breakpoints now in case
484 * GDB is reconnecting.
485 */
486 dbg_remove_all_break();
487
488 remcom_out_buffer[0] = 'S';
489 pack_hex_byte(&remcom_out_buffer[1], ks->signo);
490}
491
492static void gdb_get_regs_helper(struct kgdb_state *ks)
493{
494 struct task_struct *thread;
495 void *local_debuggerinfo;
496 int i;
497
498 thread = kgdb_usethread;
499 if (!thread) {
500 thread = kgdb_info[ks->cpu].task;
501 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
502 } else {
503 local_debuggerinfo = NULL;
504 for_each_online_cpu(i) {
505 /*
506 * Try to find the task on some other
507 * or possibly this node if we do not
508 * find the matching task then we try
509 * to approximate the results.
510 */
511 if (thread == kgdb_info[i].task)
512 local_debuggerinfo = kgdb_info[i].debuggerinfo;
513 }
514 }
515
516 /*
517 * All threads that don't have debuggerinfo should be
518 * in schedule() sleeping, since all other CPUs
519 * are in kgdb_wait, and thus have debuggerinfo.
520 */
521 if (local_debuggerinfo) {
522 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
523 } else {
524 /*
525 * Pull stuff saved during switch_to; nothing
526 * else is accessible (or even particularly
527 * relevant).
528 *
529 * This should be enough for a stack trace.
530 */
531 sleeping_thread_to_gdb_regs(gdb_regs, thread);
532 }
533}
534
535/* Handle the 'g' get registers request */
536static void gdb_cmd_getregs(struct kgdb_state *ks)
537{
538 gdb_get_regs_helper(ks);
539 kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
540}
541
542/* Handle the 'G' set registers request */
543static void gdb_cmd_setregs(struct kgdb_state *ks)
544{
545 kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
546
547 if (kgdb_usethread && kgdb_usethread != current) {
548 error_packet(remcom_out_buffer, -EINVAL);
549 } else {
550 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
551 strcpy(remcom_out_buffer, "OK");
552 }
553}
554
555/* Handle the 'm' memory read bytes */
556static void gdb_cmd_memread(struct kgdb_state *ks)
557{
558 char *ptr = &remcom_in_buffer[1];
559 unsigned long length;
560 unsigned long addr;
561 char *err;
562
563 if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
564 kgdb_hex2long(&ptr, &length) > 0) {
565 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
566 if (!err)
567 error_packet(remcom_out_buffer, -EINVAL);
568 } else {
569 error_packet(remcom_out_buffer, -EINVAL);
570 }
571}
572
573/* Handle the 'M' memory write bytes */
574static void gdb_cmd_memwrite(struct kgdb_state *ks)
575{
576 int err = write_mem_msg(0);
577
578 if (err)
579 error_packet(remcom_out_buffer, err);
580 else
581 strcpy(remcom_out_buffer, "OK");
582}
583
584#if DBG_MAX_REG_NUM > 0
585static char *gdb_hex_reg_helper(int regnum, char *out)
586{
587 int i;
588 int offset = 0;
589
590 for (i = 0; i < regnum; i++)
591 offset += dbg_reg_def[i].size;
592 return kgdb_mem2hex((char *)gdb_regs + offset, out,
593 dbg_reg_def[i].size);
594}
595
596/* Handle the 'p' individual regster get */
597static void gdb_cmd_reg_get(struct kgdb_state *ks)
598{
599 unsigned long regnum;
600 char *ptr = &remcom_in_buffer[1];
601
602 kgdb_hex2long(&ptr, ®num);
603 if (regnum >= DBG_MAX_REG_NUM) {
604 error_packet(remcom_out_buffer, -EINVAL);
605 return;
606 }
607 gdb_get_regs_helper(ks);
608 gdb_hex_reg_helper(regnum, remcom_out_buffer);
609}
610
611/* Handle the 'P' individual regster set */
612static void gdb_cmd_reg_set(struct kgdb_state *ks)
613{
614 unsigned long regnum;
615 char *ptr = &remcom_in_buffer[1];
616 int i = 0;
617
618 kgdb_hex2long(&ptr, ®num);
619 if (*ptr++ != '=' ||
620 !(!kgdb_usethread || kgdb_usethread == current) ||
621 !dbg_get_reg(regnum, gdb_regs, ks->linux_regs)) {
622 error_packet(remcom_out_buffer, -EINVAL);
623 return;
624 }
625 memset(gdb_regs, 0, sizeof(gdb_regs));
626 while (i < sizeof(gdb_regs) * 2)
627 if (hex_to_bin(ptr[i]) >= 0)
628 i++;
629 else
630 break;
631 i = i / 2;
632 kgdb_hex2mem(ptr, (char *)gdb_regs, i);
633 dbg_set_reg(regnum, gdb_regs, ks->linux_regs);
634 strcpy(remcom_out_buffer, "OK");
635}
636#endif /* DBG_MAX_REG_NUM > 0 */
637
638/* Handle the 'X' memory binary write bytes */
639static void gdb_cmd_binwrite(struct kgdb_state *ks)
640{
641 int err = write_mem_msg(1);
642
643 if (err)
644 error_packet(remcom_out_buffer, err);
645 else
646 strcpy(remcom_out_buffer, "OK");
647}
648
649/* Handle the 'D' or 'k', detach or kill packets */
650static void gdb_cmd_detachkill(struct kgdb_state *ks)
651{
652 int error;
653
654 /* The detach case */
655 if (remcom_in_buffer[0] == 'D') {
656 error = dbg_remove_all_break();
657 if (error < 0) {
658 error_packet(remcom_out_buffer, error);
659 } else {
660 strcpy(remcom_out_buffer, "OK");
661 kgdb_connected = 0;
662 }
663 put_packet(remcom_out_buffer);
664 } else {
665 /*
666 * Assume the kill case, with no exit code checking,
667 * trying to force detach the debugger:
668 */
669 dbg_remove_all_break();
670 kgdb_connected = 0;
671 }
672}
673
674/* Handle the 'R' reboot packets */
675static int gdb_cmd_reboot(struct kgdb_state *ks)
676{
677 /* For now, only honor R0 */
678 if (strcmp(remcom_in_buffer, "R0") == 0) {
679 printk(KERN_CRIT "Executing emergency reboot\n");
680 strcpy(remcom_out_buffer, "OK");
681 put_packet(remcom_out_buffer);
682
683 /*
684 * Execution should not return from
685 * machine_emergency_restart()
686 */
687 machine_emergency_restart();
688 kgdb_connected = 0;
689
690 return 1;
691 }
692 return 0;
693}
694
695/* Handle the 'q' query packets */
696static void gdb_cmd_query(struct kgdb_state *ks)
697{
698 struct task_struct *g;
699 struct task_struct *p;
700 unsigned char thref[BUF_THREAD_ID_SIZE];
701 char *ptr;
702 int i;
703 int cpu;
704 int finished = 0;
705
706 switch (remcom_in_buffer[1]) {
707 case 's':
708 case 'f':
709 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10))
710 break;
711
712 i = 0;
713 remcom_out_buffer[0] = 'm';
714 ptr = remcom_out_buffer + 1;
715 if (remcom_in_buffer[1] == 'f') {
716 /* Each cpu is a shadow thread */
717 for_each_online_cpu(cpu) {
718 ks->thr_query = 0;
719 int_to_threadref(thref, -cpu - 2);
720 ptr = pack_threadid(ptr, thref);
721 *(ptr++) = ',';
722 i++;
723 }
724 }
725
726 do_each_thread(g, p) {
727 if (i >= ks->thr_query && !finished) {
728 int_to_threadref(thref, p->pid);
729 ptr = pack_threadid(ptr, thref);
730 *(ptr++) = ',';
731 ks->thr_query++;
732 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
733 finished = 1;
734 }
735 i++;
736 } while_each_thread(g, p);
737
738 *(--ptr) = '\0';
739 break;
740
741 case 'C':
742 /* Current thread id */
743 strcpy(remcom_out_buffer, "QC");
744 ks->threadid = shadow_pid(current->pid);
745 int_to_threadref(thref, ks->threadid);
746 pack_threadid(remcom_out_buffer + 2, thref);
747 break;
748 case 'T':
749 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16))
750 break;
751
752 ks->threadid = 0;
753 ptr = remcom_in_buffer + 17;
754 kgdb_hex2long(&ptr, &ks->threadid);
755 if (!getthread(ks->linux_regs, ks->threadid)) {
756 error_packet(remcom_out_buffer, -EINVAL);
757 break;
758 }
759 if ((int)ks->threadid > 0) {
760 kgdb_mem2hex(getthread(ks->linux_regs,
761 ks->threadid)->comm,
762 remcom_out_buffer, 16);
763 } else {
764 static char tmpstr[23 + BUF_THREAD_ID_SIZE];
765
766 sprintf(tmpstr, "shadowCPU%d",
767 (int)(-ks->threadid - 2));
768 kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
769 }
770 break;
771#ifdef CONFIG_KGDB_KDB
772 case 'R':
773 if (strncmp(remcom_in_buffer, "qRcmd,", 6) == 0) {
774 int len = strlen(remcom_in_buffer + 6);
775
776 if ((len % 2) != 0) {
777 strcpy(remcom_out_buffer, "E01");
778 break;
779 }
780 kgdb_hex2mem(remcom_in_buffer + 6,
781 remcom_out_buffer, len);
782 len = len / 2;
783 remcom_out_buffer[len++] = 0;
784
785 kdb_parse(remcom_out_buffer);
786 strcpy(remcom_out_buffer, "OK");
787 }
788 break;
789#endif
790 }
791}
792
793/* Handle the 'H' task query packets */
794static void gdb_cmd_task(struct kgdb_state *ks)
795{
796 struct task_struct *thread;
797 char *ptr;
798
799 switch (remcom_in_buffer[1]) {
800 case 'g':
801 ptr = &remcom_in_buffer[2];
802 kgdb_hex2long(&ptr, &ks->threadid);
803 thread = getthread(ks->linux_regs, ks->threadid);
804 if (!thread && ks->threadid > 0) {
805 error_packet(remcom_out_buffer, -EINVAL);
806 break;
807 }
808 kgdb_usethread = thread;
809 ks->kgdb_usethreadid = ks->threadid;
810 strcpy(remcom_out_buffer, "OK");
811 break;
812 case 'c':
813 ptr = &remcom_in_buffer[2];
814 kgdb_hex2long(&ptr, &ks->threadid);
815 if (!ks->threadid) {
816 kgdb_contthread = NULL;
817 } else {
818 thread = getthread(ks->linux_regs, ks->threadid);
819 if (!thread && ks->threadid > 0) {
820 error_packet(remcom_out_buffer, -EINVAL);
821 break;
822 }
823 kgdb_contthread = thread;
824 }
825 strcpy(remcom_out_buffer, "OK");
826 break;
827 }
828}
829
830/* Handle the 'T' thread query packets */
831static void gdb_cmd_thread(struct kgdb_state *ks)
832{
833 char *ptr = &remcom_in_buffer[1];
834 struct task_struct *thread;
835
836 kgdb_hex2long(&ptr, &ks->threadid);
837 thread = getthread(ks->linux_regs, ks->threadid);
838 if (thread)
839 strcpy(remcom_out_buffer, "OK");
840 else
841 error_packet(remcom_out_buffer, -EINVAL);
842}
843
844/* Handle the 'z' or 'Z' breakpoint remove or set packets */
845static void gdb_cmd_break(struct kgdb_state *ks)
846{
847 /*
848 * Since GDB-5.3, it's been drafted that '0' is a software
849 * breakpoint, '1' is a hardware breakpoint, so let's do that.
850 */
851 char *bpt_type = &remcom_in_buffer[1];
852 char *ptr = &remcom_in_buffer[2];
853 unsigned long addr;
854 unsigned long length;
855 int error = 0;
856
857 if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
858 /* Unsupported */
859 if (*bpt_type > '4')
860 return;
861 } else {
862 if (*bpt_type != '0' && *bpt_type != '1')
863 /* Unsupported. */
864 return;
865 }
866
867 /*
868 * Test if this is a hardware breakpoint, and
869 * if we support it:
870 */
871 if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
872 /* Unsupported. */
873 return;
874
875 if (*(ptr++) != ',') {
876 error_packet(remcom_out_buffer, -EINVAL);
877 return;
878 }
879 if (!kgdb_hex2long(&ptr, &addr)) {
880 error_packet(remcom_out_buffer, -EINVAL);
881 return;
882 }
883 if (*(ptr++) != ',' ||
884 !kgdb_hex2long(&ptr, &length)) {
885 error_packet(remcom_out_buffer, -EINVAL);
886 return;
887 }
888
889 if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
890 error = dbg_set_sw_break(addr);
891 else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
892 error = dbg_remove_sw_break(addr);
893 else if (remcom_in_buffer[0] == 'Z')
894 error = arch_kgdb_ops.set_hw_breakpoint(addr,
895 (int)length, *bpt_type - '0');
896 else if (remcom_in_buffer[0] == 'z')
897 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
898 (int) length, *bpt_type - '0');
899
900 if (error == 0)
901 strcpy(remcom_out_buffer, "OK");
902 else
903 error_packet(remcom_out_buffer, error);
904}
905
906/* Handle the 'C' signal / exception passing packets */
907static int gdb_cmd_exception_pass(struct kgdb_state *ks)
908{
909 /* C09 == pass exception
910 * C15 == detach kgdb, pass exception
911 */
912 if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
913
914 ks->pass_exception = 1;
915 remcom_in_buffer[0] = 'c';
916
917 } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
918
919 ks->pass_exception = 1;
920 remcom_in_buffer[0] = 'D';
921 dbg_remove_all_break();
922 kgdb_connected = 0;
923 return 1;
924
925 } else {
926 gdbstub_msg_write("KGDB only knows signal 9 (pass)"
927 " and 15 (pass and disconnect)\n"
928 "Executing a continue without signal passing\n", 0);
929 remcom_in_buffer[0] = 'c';
930 }
931
932 /* Indicate fall through */
933 return -1;
934}
935
936/*
937 * This function performs all gdbserial command procesing
938 */
939int gdb_serial_stub(struct kgdb_state *ks)
940{
941 int error = 0;
942 int tmp;
943
944 /* Initialize comm buffer and globals. */
945 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
946 kgdb_usethread = kgdb_info[ks->cpu].task;
947 ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
948 ks->pass_exception = 0;
949
950 if (kgdb_connected) {
951 unsigned char thref[BUF_THREAD_ID_SIZE];
952 char *ptr;
953
954 /* Reply to host that an exception has occurred */
955 ptr = remcom_out_buffer;
956 *ptr++ = 'T';
957 ptr = pack_hex_byte(ptr, ks->signo);
958 ptr += strlen(strcpy(ptr, "thread:"));
959 int_to_threadref(thref, shadow_pid(current->pid));
960 ptr = pack_threadid(ptr, thref);
961 *ptr++ = ';';
962 put_packet(remcom_out_buffer);
963 }
964
965 while (1) {
966 error = 0;
967
968 /* Clear the out buffer. */
969 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
970
971 get_packet(remcom_in_buffer);
972
973 switch (remcom_in_buffer[0]) {
974 case '?': /* gdbserial status */
975 gdb_cmd_status(ks);
976 break;
977 case 'g': /* return the value of the CPU registers */
978 gdb_cmd_getregs(ks);
979 break;
980 case 'G': /* set the value of the CPU registers - return OK */
981 gdb_cmd_setregs(ks);
982 break;
983 case 'm': /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */
984 gdb_cmd_memread(ks);
985 break;
986 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
987 gdb_cmd_memwrite(ks);
988 break;
989#if DBG_MAX_REG_NUM > 0
990 case 'p': /* pXX Return gdb register XX (in hex) */
991 gdb_cmd_reg_get(ks);
992 break;
993 case 'P': /* PXX=aaaa Set gdb register XX to aaaa (in hex) */
994 gdb_cmd_reg_set(ks);
995 break;
996#endif /* DBG_MAX_REG_NUM > 0 */
997 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
998 gdb_cmd_binwrite(ks);
999 break;
1000 /* kill or detach. KGDB should treat this like a
1001 * continue.
1002 */
1003 case 'D': /* Debugger detach */
1004 case 'k': /* Debugger detach via kill */
1005 gdb_cmd_detachkill(ks);
1006 goto default_handle;
1007 case 'R': /* Reboot */
1008 if (gdb_cmd_reboot(ks))
1009 goto default_handle;
1010 break;
1011 case 'q': /* query command */
1012 gdb_cmd_query(ks);
1013 break;
1014 case 'H': /* task related */
1015 gdb_cmd_task(ks);
1016 break;
1017 case 'T': /* Query thread status */
1018 gdb_cmd_thread(ks);
1019 break;
1020 case 'z': /* Break point remove */
1021 case 'Z': /* Break point set */
1022 gdb_cmd_break(ks);
1023 break;
1024#ifdef CONFIG_KGDB_KDB
1025 case '3': /* Escape into back into kdb */
1026 if (remcom_in_buffer[1] == '\0') {
1027 gdb_cmd_detachkill(ks);
1028 return DBG_PASS_EVENT;
1029 }
1030#endif
1031 case 'C': /* Exception passing */
1032 tmp = gdb_cmd_exception_pass(ks);
1033 if (tmp > 0)
1034 goto default_handle;
1035 if (tmp == 0)
1036 break;
1037 /* Fall through on tmp < 0 */
1038 case 'c': /* Continue packet */
1039 case 's': /* Single step packet */
1040 if (kgdb_contthread && kgdb_contthread != current) {
1041 /* Can't switch threads in kgdb */
1042 error_packet(remcom_out_buffer, -EINVAL);
1043 break;
1044 }
1045 dbg_activate_sw_breakpoints();
1046 /* Fall through to default processing */
1047 default:
1048default_handle:
1049 error = kgdb_arch_handle_exception(ks->ex_vector,
1050 ks->signo,
1051 ks->err_code,
1052 remcom_in_buffer,
1053 remcom_out_buffer,
1054 ks->linux_regs);
1055 /*
1056 * Leave cmd processing on error, detach,
1057 * kill, continue, or single step.
1058 */
1059 if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1060 remcom_in_buffer[0] == 'k') {
1061 error = 0;
1062 goto kgdb_exit;
1063 }
1064
1065 }
1066
1067 /* reply to the request */
1068 put_packet(remcom_out_buffer);
1069 }
1070
1071kgdb_exit:
1072 if (ks->pass_exception)
1073 error = 1;
1074 return error;
1075}
1076
1077int gdbstub_state(struct kgdb_state *ks, char *cmd)
1078{
1079 int error;
1080
1081 switch (cmd[0]) {
1082 case 'e':
1083 error = kgdb_arch_handle_exception(ks->ex_vector,
1084 ks->signo,
1085 ks->err_code,
1086 remcom_in_buffer,
1087 remcom_out_buffer,
1088 ks->linux_regs);
1089 return error;
1090 case 's':
1091 case 'c':
1092 strcpy(remcom_in_buffer, cmd);
1093 return 0;
1094 case '$':
1095 strcpy(remcom_in_buffer, cmd);
1096 gdbstub_use_prev_in_buf = strlen(remcom_in_buffer);
1097 gdbstub_prev_in_buf_pos = 0;
1098 return 0;
1099 }
1100 dbg_io_ops->write_char('+');
1101 put_packet(remcom_out_buffer);
1102 return 0;
1103}
1104
1105/**
1106 * gdbstub_exit - Send an exit message to GDB
1107 * @status: The exit code to report.
1108 */
1109void gdbstub_exit(int status)
1110{
1111 unsigned char checksum, ch, buffer[3];
1112 int loop;
1113
1114 buffer[0] = 'W';
1115 buffer[1] = hex_asc_hi(status);
1116 buffer[2] = hex_asc_lo(status);
1117
1118 dbg_io_ops->write_char('$');
1119 checksum = 0;
1120
1121 for (loop = 0; loop < 3; loop++) {
1122 ch = buffer[loop];
1123 checksum += ch;
1124 dbg_io_ops->write_char(ch);
1125 }
1126
1127 dbg_io_ops->write_char('#');
1128 dbg_io_ops->write_char(hex_asc_hi(checksum));
1129 dbg_io_ops->write_char(hex_asc_lo(checksum));
1130
1131 /* make sure the output is flushed, lest the bootloader clobber it */
1132 dbg_io_ops->flush();
1133}