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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/sched/signal.h>
33#include <linux/kgdb.h>
34#include <linux/kdb.h>
35#include <linux/serial_core.h>
36#include <linux/reboot.h>
37#include <linux/uaccess.h>
38#include <asm/cacheflush.h>
39#include <asm/unaligned.h>
40#include "debug_core.h"
41
42#define KGDB_MAX_THREAD_QUERY 17
43
44/* Our I/O buffers. */
45static char remcom_in_buffer[BUFMAX];
46static char remcom_out_buffer[BUFMAX];
47static int gdbstub_use_prev_in_buf;
48static int gdbstub_prev_in_buf_pos;
49
50/* Storage for the registers, in GDB format. */
51static unsigned long gdb_regs[(NUMREGBYTES +
52 sizeof(unsigned long) - 1) /
53 sizeof(unsigned long)];
54
55/*
56 * GDB remote protocol parser:
57 */
58
59#ifdef CONFIG_KGDB_KDB
60static int gdbstub_read_wait(void)
61{
62 int ret = -1;
63 int i;
64
65 if (unlikely(gdbstub_use_prev_in_buf)) {
66 if (gdbstub_prev_in_buf_pos < gdbstub_use_prev_in_buf)
67 return remcom_in_buffer[gdbstub_prev_in_buf_pos++];
68 else
69 gdbstub_use_prev_in_buf = 0;
70 }
71
72 /* poll any additional I/O interfaces that are defined */
73 while (ret < 0)
74 for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
75 ret = kdb_poll_funcs[i]();
76 if (ret > 0)
77 break;
78 }
79 return ret;
80}
81#else
82static int gdbstub_read_wait(void)
83{
84 int ret = dbg_io_ops->read_char();
85 while (ret == NO_POLL_CHAR)
86 ret = dbg_io_ops->read_char();
87 return ret;
88}
89#endif
90/* scan for the sequence $<data>#<checksum> */
91static void get_packet(char *buffer)
92{
93 unsigned char checksum;
94 unsigned char xmitcsum;
95 int count;
96 char ch;
97
98 do {
99 /*
100 * Spin and wait around for the start character, ignore all
101 * other characters:
102 */
103 while ((ch = (gdbstub_read_wait())) != '$')
104 /* nothing */;
105
106 kgdb_connected = 1;
107 checksum = 0;
108 xmitcsum = -1;
109
110 count = 0;
111
112 /*
113 * now, read until a # or end of buffer is found:
114 */
115 while (count < (BUFMAX - 1)) {
116 ch = gdbstub_read_wait();
117 if (ch == '#')
118 break;
119 checksum = checksum + ch;
120 buffer[count] = ch;
121 count = count + 1;
122 }
123
124 if (ch == '#') {
125 xmitcsum = hex_to_bin(gdbstub_read_wait()) << 4;
126 xmitcsum += hex_to_bin(gdbstub_read_wait());
127
128 if (checksum != xmitcsum)
129 /* failed checksum */
130 dbg_io_ops->write_char('-');
131 else
132 /* successful transfer */
133 dbg_io_ops->write_char('+');
134 if (dbg_io_ops->flush)
135 dbg_io_ops->flush();
136 }
137 buffer[count] = 0;
138 } while (checksum != xmitcsum);
139}
140
141/*
142 * Send the packet in buffer.
143 * Check for gdb connection if asked for.
144 */
145static void put_packet(char *buffer)
146{
147 unsigned char checksum;
148 int count;
149 char ch;
150
151 /*
152 * $<packet info>#<checksum>.
153 */
154 while (1) {
155 dbg_io_ops->write_char('$');
156 checksum = 0;
157 count = 0;
158
159 while ((ch = buffer[count])) {
160 dbg_io_ops->write_char(ch);
161 checksum += ch;
162 count++;
163 }
164
165 dbg_io_ops->write_char('#');
166 dbg_io_ops->write_char(hex_asc_hi(checksum));
167 dbg_io_ops->write_char(hex_asc_lo(checksum));
168 if (dbg_io_ops->flush)
169 dbg_io_ops->flush();
170
171 /* Now see what we get in reply. */
172 ch = gdbstub_read_wait();
173
174 if (ch == 3)
175 ch = gdbstub_read_wait();
176
177 /* If we get an ACK, we are done. */
178 if (ch == '+')
179 return;
180
181 /*
182 * If we get the start of another packet, this means
183 * that GDB is attempting to reconnect. We will NAK
184 * the packet being sent, and stop trying to send this
185 * packet.
186 */
187 if (ch == '$') {
188 dbg_io_ops->write_char('-');
189 if (dbg_io_ops->flush)
190 dbg_io_ops->flush();
191 return;
192 }
193 }
194}
195
196static char gdbmsgbuf[BUFMAX + 1];
197
198void gdbstub_msg_write(const char *s, int len)
199{
200 char *bufptr;
201 int wcount;
202 int i;
203
204 if (len == 0)
205 len = strlen(s);
206
207 /* 'O'utput */
208 gdbmsgbuf[0] = 'O';
209
210 /* Fill and send buffers... */
211 while (len > 0) {
212 bufptr = gdbmsgbuf + 1;
213
214 /* Calculate how many this time */
215 if ((len << 1) > (BUFMAX - 2))
216 wcount = (BUFMAX - 2) >> 1;
217 else
218 wcount = len;
219
220 /* Pack in hex chars */
221 for (i = 0; i < wcount; i++)
222 bufptr = hex_byte_pack(bufptr, s[i]);
223 *bufptr = '\0';
224
225 /* Move up */
226 s += wcount;
227 len -= wcount;
228
229 /* Write packet */
230 put_packet(gdbmsgbuf);
231 }
232}
233
234/*
235 * Convert the memory pointed to by mem into hex, placing result in
236 * buf. Return a pointer to the last char put in buf (null). May
237 * return an error.
238 */
239char *kgdb_mem2hex(char *mem, char *buf, int count)
240{
241 char *tmp;
242 int err;
243
244 /*
245 * We use the upper half of buf as an intermediate buffer for the
246 * raw memory copy. Hex conversion will work against this one.
247 */
248 tmp = buf + count;
249
250 err = probe_kernel_read(tmp, mem, count);
251 if (err)
252 return NULL;
253 while (count > 0) {
254 buf = hex_byte_pack(buf, *tmp);
255 tmp++;
256 count--;
257 }
258 *buf = 0;
259
260 return buf;
261}
262
263/*
264 * Convert the hex array pointed to by buf into binary to be placed in
265 * mem. Return a pointer to the character AFTER the last byte
266 * written. May return an error.
267 */
268int kgdb_hex2mem(char *buf, char *mem, int count)
269{
270 char *tmp_raw;
271 char *tmp_hex;
272
273 /*
274 * We use the upper half of buf as an intermediate buffer for the
275 * raw memory that is converted from hex.
276 */
277 tmp_raw = buf + count * 2;
278
279 tmp_hex = tmp_raw - 1;
280 while (tmp_hex >= buf) {
281 tmp_raw--;
282 *tmp_raw = hex_to_bin(*tmp_hex--);
283 *tmp_raw |= hex_to_bin(*tmp_hex--) << 4;
284 }
285
286 return probe_kernel_write(mem, tmp_raw, count);
287}
288
289/*
290 * While we find nice hex chars, build a long_val.
291 * Return number of chars processed.
292 */
293int kgdb_hex2long(char **ptr, unsigned long *long_val)
294{
295 int hex_val;
296 int num = 0;
297 int negate = 0;
298
299 *long_val = 0;
300
301 if (**ptr == '-') {
302 negate = 1;
303 (*ptr)++;
304 }
305 while (**ptr) {
306 hex_val = hex_to_bin(**ptr);
307 if (hex_val < 0)
308 break;
309
310 *long_val = (*long_val << 4) | hex_val;
311 num++;
312 (*ptr)++;
313 }
314
315 if (negate)
316 *long_val = -*long_val;
317
318 return num;
319}
320
321/*
322 * Copy the binary array pointed to by buf into mem. Fix $, #, and
323 * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success.
324 * The input buf is overwitten with the result to write to mem.
325 */
326static int kgdb_ebin2mem(char *buf, char *mem, int count)
327{
328 int size = 0;
329 char *c = buf;
330
331 while (count-- > 0) {
332 c[size] = *buf++;
333 if (c[size] == 0x7d)
334 c[size] = *buf++ ^ 0x20;
335 size++;
336 }
337
338 return probe_kernel_write(mem, c, size);
339}
340
341#if DBG_MAX_REG_NUM > 0
342void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
343{
344 int i;
345 int idx = 0;
346 char *ptr = (char *)gdb_regs;
347
348 for (i = 0; i < DBG_MAX_REG_NUM; i++) {
349 dbg_get_reg(i, ptr + idx, regs);
350 idx += dbg_reg_def[i].size;
351 }
352}
353
354void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
355{
356 int i;
357 int idx = 0;
358 char *ptr = (char *)gdb_regs;
359
360 for (i = 0; i < DBG_MAX_REG_NUM; i++) {
361 dbg_set_reg(i, ptr + idx, regs);
362 idx += dbg_reg_def[i].size;
363 }
364}
365#endif /* DBG_MAX_REG_NUM > 0 */
366
367/* Write memory due to an 'M' or 'X' packet. */
368static int write_mem_msg(int binary)
369{
370 char *ptr = &remcom_in_buffer[1];
371 unsigned long addr;
372 unsigned long length;
373 int err;
374
375 if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
376 kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
377 if (binary)
378 err = kgdb_ebin2mem(ptr, (char *)addr, length);
379 else
380 err = kgdb_hex2mem(ptr, (char *)addr, length);
381 if (err)
382 return err;
383 if (CACHE_FLUSH_IS_SAFE)
384 flush_icache_range(addr, addr + length);
385 return 0;
386 }
387
388 return -EINVAL;
389}
390
391static void error_packet(char *pkt, int error)
392{
393 error = -error;
394 pkt[0] = 'E';
395 pkt[1] = hex_asc[(error / 10)];
396 pkt[2] = hex_asc[(error % 10)];
397 pkt[3] = '\0';
398}
399
400/*
401 * Thread ID accessors. We represent a flat TID space to GDB, where
402 * the per CPU idle threads (which under Linux all have PID 0) are
403 * remapped to negative TIDs.
404 */
405
406#define BUF_THREAD_ID_SIZE 8
407
408static char *pack_threadid(char *pkt, unsigned char *id)
409{
410 unsigned char *limit;
411 int lzero = 1;
412
413 limit = id + (BUF_THREAD_ID_SIZE / 2);
414 while (id < limit) {
415 if (!lzero || *id != 0) {
416 pkt = hex_byte_pack(pkt, *id);
417 lzero = 0;
418 }
419 id++;
420 }
421
422 if (lzero)
423 pkt = hex_byte_pack(pkt, 0);
424
425 return pkt;
426}
427
428static void int_to_threadref(unsigned char *id, int value)
429{
430 put_unaligned_be32(value, id);
431}
432
433static struct task_struct *getthread(struct pt_regs *regs, int tid)
434{
435 /*
436 * Non-positive TIDs are remapped to the cpu shadow information
437 */
438 if (tid == 0 || tid == -1)
439 tid = -atomic_read(&kgdb_active) - 2;
440 if (tid < -1 && tid > -NR_CPUS - 2) {
441 if (kgdb_info[-tid - 2].task)
442 return kgdb_info[-tid - 2].task;
443 else
444 return idle_task(-tid - 2);
445 }
446 if (tid <= 0) {
447 printk(KERN_ERR "KGDB: Internal thread select error\n");
448 dump_stack();
449 return NULL;
450 }
451
452 /*
453 * find_task_by_pid_ns() does not take the tasklist lock anymore
454 * but is nicely RCU locked - hence is a pretty resilient
455 * thing to use:
456 */
457 return find_task_by_pid_ns(tid, &init_pid_ns);
458}
459
460
461/*
462 * Remap normal tasks to their real PID,
463 * CPU shadow threads are mapped to -CPU - 2
464 */
465static inline int shadow_pid(int realpid)
466{
467 if (realpid)
468 return realpid;
469
470 return -raw_smp_processor_id() - 2;
471}
472
473/*
474 * All the functions that start with gdb_cmd are the various
475 * operations to implement the handlers for the gdbserial protocol
476 * where KGDB is communicating with an external debugger
477 */
478
479/* Handle the '?' status packets */
480static void gdb_cmd_status(struct kgdb_state *ks)
481{
482 /*
483 * We know that this packet is only sent
484 * during initial connect. So to be safe,
485 * we clear out our breakpoints now in case
486 * GDB is reconnecting.
487 */
488 dbg_remove_all_break();
489
490 remcom_out_buffer[0] = 'S';
491 hex_byte_pack(&remcom_out_buffer[1], ks->signo);
492}
493
494static void gdb_get_regs_helper(struct kgdb_state *ks)
495{
496 struct task_struct *thread;
497 void *local_debuggerinfo;
498 int i;
499
500 thread = kgdb_usethread;
501 if (!thread) {
502 thread = kgdb_info[ks->cpu].task;
503 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
504 } else {
505 local_debuggerinfo = NULL;
506 for_each_online_cpu(i) {
507 /*
508 * Try to find the task on some other
509 * or possibly this node if we do not
510 * find the matching task then we try
511 * to approximate the results.
512 */
513 if (thread == kgdb_info[i].task)
514 local_debuggerinfo = kgdb_info[i].debuggerinfo;
515 }
516 }
517
518 /*
519 * All threads that don't have debuggerinfo should be
520 * in schedule() sleeping, since all other CPUs
521 * are in kgdb_wait, and thus have debuggerinfo.
522 */
523 if (local_debuggerinfo) {
524 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
525 } else {
526 /*
527 * Pull stuff saved during switch_to; nothing
528 * else is accessible (or even particularly
529 * relevant).
530 *
531 * This should be enough for a stack trace.
532 */
533 sleeping_thread_to_gdb_regs(gdb_regs, thread);
534 }
535}
536
537/* Handle the 'g' get registers request */
538static void gdb_cmd_getregs(struct kgdb_state *ks)
539{
540 gdb_get_regs_helper(ks);
541 kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
542}
543
544/* Handle the 'G' set registers request */
545static void gdb_cmd_setregs(struct kgdb_state *ks)
546{
547 kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
548
549 if (kgdb_usethread && kgdb_usethread != current) {
550 error_packet(remcom_out_buffer, -EINVAL);
551 } else {
552 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
553 strcpy(remcom_out_buffer, "OK");
554 }
555}
556
557/* Handle the 'm' memory read bytes */
558static void gdb_cmd_memread(struct kgdb_state *ks)
559{
560 char *ptr = &remcom_in_buffer[1];
561 unsigned long length;
562 unsigned long addr;
563 char *err;
564
565 if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
566 kgdb_hex2long(&ptr, &length) > 0) {
567 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
568 if (!err)
569 error_packet(remcom_out_buffer, -EINVAL);
570 } else {
571 error_packet(remcom_out_buffer, -EINVAL);
572 }
573}
574
575/* Handle the 'M' memory write bytes */
576static void gdb_cmd_memwrite(struct kgdb_state *ks)
577{
578 int err = write_mem_msg(0);
579
580 if (err)
581 error_packet(remcom_out_buffer, err);
582 else
583 strcpy(remcom_out_buffer, "OK");
584}
585
586#if DBG_MAX_REG_NUM > 0
587static char *gdb_hex_reg_helper(int regnum, char *out)
588{
589 int i;
590 int offset = 0;
591
592 for (i = 0; i < regnum; i++)
593 offset += dbg_reg_def[i].size;
594 return kgdb_mem2hex((char *)gdb_regs + offset, out,
595 dbg_reg_def[i].size);
596}
597
598/* Handle the 'p' individual regster get */
599static void gdb_cmd_reg_get(struct kgdb_state *ks)
600{
601 unsigned long regnum;
602 char *ptr = &remcom_in_buffer[1];
603
604 kgdb_hex2long(&ptr, ®num);
605 if (regnum >= DBG_MAX_REG_NUM) {
606 error_packet(remcom_out_buffer, -EINVAL);
607 return;
608 }
609 gdb_get_regs_helper(ks);
610 gdb_hex_reg_helper(regnum, remcom_out_buffer);
611}
612
613/* Handle the 'P' individual regster set */
614static void gdb_cmd_reg_set(struct kgdb_state *ks)
615{
616 unsigned long regnum;
617 char *ptr = &remcom_in_buffer[1];
618 int i = 0;
619
620 kgdb_hex2long(&ptr, ®num);
621 if (*ptr++ != '=' ||
622 !(!kgdb_usethread || kgdb_usethread == current) ||
623 !dbg_get_reg(regnum, gdb_regs, ks->linux_regs)) {
624 error_packet(remcom_out_buffer, -EINVAL);
625 return;
626 }
627 memset(gdb_regs, 0, sizeof(gdb_regs));
628 while (i < sizeof(gdb_regs) * 2)
629 if (hex_to_bin(ptr[i]) >= 0)
630 i++;
631 else
632 break;
633 i = i / 2;
634 kgdb_hex2mem(ptr, (char *)gdb_regs, i);
635 dbg_set_reg(regnum, gdb_regs, ks->linux_regs);
636 strcpy(remcom_out_buffer, "OK");
637}
638#endif /* DBG_MAX_REG_NUM > 0 */
639
640/* Handle the 'X' memory binary write bytes */
641static void gdb_cmd_binwrite(struct kgdb_state *ks)
642{
643 int err = write_mem_msg(1);
644
645 if (err)
646 error_packet(remcom_out_buffer, err);
647 else
648 strcpy(remcom_out_buffer, "OK");
649}
650
651/* Handle the 'D' or 'k', detach or kill packets */
652static void gdb_cmd_detachkill(struct kgdb_state *ks)
653{
654 int error;
655
656 /* The detach case */
657 if (remcom_in_buffer[0] == 'D') {
658 error = dbg_remove_all_break();
659 if (error < 0) {
660 error_packet(remcom_out_buffer, error);
661 } else {
662 strcpy(remcom_out_buffer, "OK");
663 kgdb_connected = 0;
664 }
665 put_packet(remcom_out_buffer);
666 } else {
667 /*
668 * Assume the kill case, with no exit code checking,
669 * trying to force detach the debugger:
670 */
671 dbg_remove_all_break();
672 kgdb_connected = 0;
673 }
674}
675
676/* Handle the 'R' reboot packets */
677static int gdb_cmd_reboot(struct kgdb_state *ks)
678{
679 /* For now, only honor R0 */
680 if (strcmp(remcom_in_buffer, "R0") == 0) {
681 printk(KERN_CRIT "Executing emergency reboot\n");
682 strcpy(remcom_out_buffer, "OK");
683 put_packet(remcom_out_buffer);
684
685 /*
686 * Execution should not return from
687 * machine_emergency_restart()
688 */
689 machine_emergency_restart();
690 kgdb_connected = 0;
691
692 return 1;
693 }
694 return 0;
695}
696
697/* Handle the 'q' query packets */
698static void gdb_cmd_query(struct kgdb_state *ks)
699{
700 struct task_struct *g;
701 struct task_struct *p;
702 unsigned char thref[BUF_THREAD_ID_SIZE];
703 char *ptr;
704 int i;
705 int cpu;
706 int finished = 0;
707
708 switch (remcom_in_buffer[1]) {
709 case 's':
710 case 'f':
711 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10))
712 break;
713
714 i = 0;
715 remcom_out_buffer[0] = 'm';
716 ptr = remcom_out_buffer + 1;
717 if (remcom_in_buffer[1] == 'f') {
718 /* Each cpu is a shadow thread */
719 for_each_online_cpu(cpu) {
720 ks->thr_query = 0;
721 int_to_threadref(thref, -cpu - 2);
722 ptr = pack_threadid(ptr, thref);
723 *(ptr++) = ',';
724 i++;
725 }
726 }
727
728 do_each_thread(g, p) {
729 if (i >= ks->thr_query && !finished) {
730 int_to_threadref(thref, p->pid);
731 ptr = pack_threadid(ptr, thref);
732 *(ptr++) = ',';
733 ks->thr_query++;
734 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
735 finished = 1;
736 }
737 i++;
738 } while_each_thread(g, p);
739
740 *(--ptr) = '\0';
741 break;
742
743 case 'C':
744 /* Current thread id */
745 strcpy(remcom_out_buffer, "QC");
746 ks->threadid = shadow_pid(current->pid);
747 int_to_threadref(thref, ks->threadid);
748 pack_threadid(remcom_out_buffer + 2, thref);
749 break;
750 case 'T':
751 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16))
752 break;
753
754 ks->threadid = 0;
755 ptr = remcom_in_buffer + 17;
756 kgdb_hex2long(&ptr, &ks->threadid);
757 if (!getthread(ks->linux_regs, ks->threadid)) {
758 error_packet(remcom_out_buffer, -EINVAL);
759 break;
760 }
761 if ((int)ks->threadid > 0) {
762 kgdb_mem2hex(getthread(ks->linux_regs,
763 ks->threadid)->comm,
764 remcom_out_buffer, 16);
765 } else {
766 static char tmpstr[23 + BUF_THREAD_ID_SIZE];
767
768 sprintf(tmpstr, "shadowCPU%d",
769 (int)(-ks->threadid - 2));
770 kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
771 }
772 break;
773#ifdef CONFIG_KGDB_KDB
774 case 'R':
775 if (strncmp(remcom_in_buffer, "qRcmd,", 6) == 0) {
776 int len = strlen(remcom_in_buffer + 6);
777
778 if ((len % 2) != 0) {
779 strcpy(remcom_out_buffer, "E01");
780 break;
781 }
782 kgdb_hex2mem(remcom_in_buffer + 6,
783 remcom_out_buffer, len);
784 len = len / 2;
785 remcom_out_buffer[len++] = 0;
786
787 kdb_common_init_state(ks);
788 kdb_parse(remcom_out_buffer);
789 kdb_common_deinit_state();
790
791 strcpy(remcom_out_buffer, "OK");
792 }
793 break;
794#endif
795 }
796}
797
798/* Handle the 'H' task query packets */
799static void gdb_cmd_task(struct kgdb_state *ks)
800{
801 struct task_struct *thread;
802 char *ptr;
803
804 switch (remcom_in_buffer[1]) {
805 case 'g':
806 ptr = &remcom_in_buffer[2];
807 kgdb_hex2long(&ptr, &ks->threadid);
808 thread = getthread(ks->linux_regs, ks->threadid);
809 if (!thread && ks->threadid > 0) {
810 error_packet(remcom_out_buffer, -EINVAL);
811 break;
812 }
813 kgdb_usethread = thread;
814 ks->kgdb_usethreadid = ks->threadid;
815 strcpy(remcom_out_buffer, "OK");
816 break;
817 case 'c':
818 ptr = &remcom_in_buffer[2];
819 kgdb_hex2long(&ptr, &ks->threadid);
820 if (!ks->threadid) {
821 kgdb_contthread = NULL;
822 } else {
823 thread = getthread(ks->linux_regs, ks->threadid);
824 if (!thread && ks->threadid > 0) {
825 error_packet(remcom_out_buffer, -EINVAL);
826 break;
827 }
828 kgdb_contthread = thread;
829 }
830 strcpy(remcom_out_buffer, "OK");
831 break;
832 }
833}
834
835/* Handle the 'T' thread query packets */
836static void gdb_cmd_thread(struct kgdb_state *ks)
837{
838 char *ptr = &remcom_in_buffer[1];
839 struct task_struct *thread;
840
841 kgdb_hex2long(&ptr, &ks->threadid);
842 thread = getthread(ks->linux_regs, ks->threadid);
843 if (thread)
844 strcpy(remcom_out_buffer, "OK");
845 else
846 error_packet(remcom_out_buffer, -EINVAL);
847}
848
849/* Handle the 'z' or 'Z' breakpoint remove or set packets */
850static void gdb_cmd_break(struct kgdb_state *ks)
851{
852 /*
853 * Since GDB-5.3, it's been drafted that '0' is a software
854 * breakpoint, '1' is a hardware breakpoint, so let's do that.
855 */
856 char *bpt_type = &remcom_in_buffer[1];
857 char *ptr = &remcom_in_buffer[2];
858 unsigned long addr;
859 unsigned long length;
860 int error = 0;
861
862 if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
863 /* Unsupported */
864 if (*bpt_type > '4')
865 return;
866 } else {
867 if (*bpt_type != '0' && *bpt_type != '1')
868 /* Unsupported. */
869 return;
870 }
871
872 /*
873 * Test if this is a hardware breakpoint, and
874 * if we support it:
875 */
876 if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
877 /* Unsupported. */
878 return;
879
880 if (*(ptr++) != ',') {
881 error_packet(remcom_out_buffer, -EINVAL);
882 return;
883 }
884 if (!kgdb_hex2long(&ptr, &addr)) {
885 error_packet(remcom_out_buffer, -EINVAL);
886 return;
887 }
888 if (*(ptr++) != ',' ||
889 !kgdb_hex2long(&ptr, &length)) {
890 error_packet(remcom_out_buffer, -EINVAL);
891 return;
892 }
893
894 if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
895 error = dbg_set_sw_break(addr);
896 else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
897 error = dbg_remove_sw_break(addr);
898 else if (remcom_in_buffer[0] == 'Z')
899 error = arch_kgdb_ops.set_hw_breakpoint(addr,
900 (int)length, *bpt_type - '0');
901 else if (remcom_in_buffer[0] == 'z')
902 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
903 (int) length, *bpt_type - '0');
904
905 if (error == 0)
906 strcpy(remcom_out_buffer, "OK");
907 else
908 error_packet(remcom_out_buffer, error);
909}
910
911/* Handle the 'C' signal / exception passing packets */
912static int gdb_cmd_exception_pass(struct kgdb_state *ks)
913{
914 /* C09 == pass exception
915 * C15 == detach kgdb, pass exception
916 */
917 if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
918
919 ks->pass_exception = 1;
920 remcom_in_buffer[0] = 'c';
921
922 } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
923
924 ks->pass_exception = 1;
925 remcom_in_buffer[0] = 'D';
926 dbg_remove_all_break();
927 kgdb_connected = 0;
928 return 1;
929
930 } else {
931 gdbstub_msg_write("KGDB only knows signal 9 (pass)"
932 " and 15 (pass and disconnect)\n"
933 "Executing a continue without signal passing\n", 0);
934 remcom_in_buffer[0] = 'c';
935 }
936
937 /* Indicate fall through */
938 return -1;
939}
940
941/*
942 * This function performs all gdbserial command procesing
943 */
944int gdb_serial_stub(struct kgdb_state *ks)
945{
946 int error = 0;
947 int tmp;
948
949 /* Initialize comm buffer and globals. */
950 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
951 kgdb_usethread = kgdb_info[ks->cpu].task;
952 ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
953 ks->pass_exception = 0;
954
955 if (kgdb_connected) {
956 unsigned char thref[BUF_THREAD_ID_SIZE];
957 char *ptr;
958
959 /* Reply to host that an exception has occurred */
960 ptr = remcom_out_buffer;
961 *ptr++ = 'T';
962 ptr = hex_byte_pack(ptr, ks->signo);
963 ptr += strlen(strcpy(ptr, "thread:"));
964 int_to_threadref(thref, shadow_pid(current->pid));
965 ptr = pack_threadid(ptr, thref);
966 *ptr++ = ';';
967 put_packet(remcom_out_buffer);
968 }
969
970 while (1) {
971 error = 0;
972
973 /* Clear the out buffer. */
974 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
975
976 get_packet(remcom_in_buffer);
977
978 switch (remcom_in_buffer[0]) {
979 case '?': /* gdbserial status */
980 gdb_cmd_status(ks);
981 break;
982 case 'g': /* return the value of the CPU registers */
983 gdb_cmd_getregs(ks);
984 break;
985 case 'G': /* set the value of the CPU registers - return OK */
986 gdb_cmd_setregs(ks);
987 break;
988 case 'm': /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */
989 gdb_cmd_memread(ks);
990 break;
991 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
992 gdb_cmd_memwrite(ks);
993 break;
994#if DBG_MAX_REG_NUM > 0
995 case 'p': /* pXX Return gdb register XX (in hex) */
996 gdb_cmd_reg_get(ks);
997 break;
998 case 'P': /* PXX=aaaa Set gdb register XX to aaaa (in hex) */
999 gdb_cmd_reg_set(ks);
1000 break;
1001#endif /* DBG_MAX_REG_NUM > 0 */
1002 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1003 gdb_cmd_binwrite(ks);
1004 break;
1005 /* kill or detach. KGDB should treat this like a
1006 * continue.
1007 */
1008 case 'D': /* Debugger detach */
1009 case 'k': /* Debugger detach via kill */
1010 gdb_cmd_detachkill(ks);
1011 goto default_handle;
1012 case 'R': /* Reboot */
1013 if (gdb_cmd_reboot(ks))
1014 goto default_handle;
1015 break;
1016 case 'q': /* query command */
1017 gdb_cmd_query(ks);
1018 break;
1019 case 'H': /* task related */
1020 gdb_cmd_task(ks);
1021 break;
1022 case 'T': /* Query thread status */
1023 gdb_cmd_thread(ks);
1024 break;
1025 case 'z': /* Break point remove */
1026 case 'Z': /* Break point set */
1027 gdb_cmd_break(ks);
1028 break;
1029#ifdef CONFIG_KGDB_KDB
1030 case '3': /* Escape into back into kdb */
1031 if (remcom_in_buffer[1] == '\0') {
1032 gdb_cmd_detachkill(ks);
1033 return DBG_PASS_EVENT;
1034 }
1035#endif
1036 /* Fall through */
1037 case 'C': /* Exception passing */
1038 tmp = gdb_cmd_exception_pass(ks);
1039 if (tmp > 0)
1040 goto default_handle;
1041 if (tmp == 0)
1042 break;
1043 /* Fall through - on tmp < 0 */
1044 case 'c': /* Continue packet */
1045 case 's': /* Single step packet */
1046 if (kgdb_contthread && kgdb_contthread != current) {
1047 /* Can't switch threads in kgdb */
1048 error_packet(remcom_out_buffer, -EINVAL);
1049 break;
1050 }
1051 dbg_activate_sw_breakpoints();
1052 /* Fall through - to default processing */
1053 default:
1054default_handle:
1055 error = kgdb_arch_handle_exception(ks->ex_vector,
1056 ks->signo,
1057 ks->err_code,
1058 remcom_in_buffer,
1059 remcom_out_buffer,
1060 ks->linux_regs);
1061 /*
1062 * Leave cmd processing on error, detach,
1063 * kill, continue, or single step.
1064 */
1065 if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1066 remcom_in_buffer[0] == 'k') {
1067 error = 0;
1068 goto kgdb_exit;
1069 }
1070
1071 }
1072
1073 /* reply to the request */
1074 put_packet(remcom_out_buffer);
1075 }
1076
1077kgdb_exit:
1078 if (ks->pass_exception)
1079 error = 1;
1080 return error;
1081}
1082
1083int gdbstub_state(struct kgdb_state *ks, char *cmd)
1084{
1085 int error;
1086
1087 switch (cmd[0]) {
1088 case 'e':
1089 error = kgdb_arch_handle_exception(ks->ex_vector,
1090 ks->signo,
1091 ks->err_code,
1092 remcom_in_buffer,
1093 remcom_out_buffer,
1094 ks->linux_regs);
1095 return error;
1096 case 's':
1097 case 'c':
1098 strscpy(remcom_in_buffer, cmd, sizeof(remcom_in_buffer));
1099 return 0;
1100 case '$':
1101 strscpy(remcom_in_buffer, cmd, sizeof(remcom_in_buffer));
1102 gdbstub_use_prev_in_buf = strlen(remcom_in_buffer);
1103 gdbstub_prev_in_buf_pos = 0;
1104 return 0;
1105 }
1106 dbg_io_ops->write_char('+');
1107 put_packet(remcom_out_buffer);
1108 return 0;
1109}
1110
1111/**
1112 * gdbstub_exit - Send an exit message to GDB
1113 * @status: The exit code to report.
1114 */
1115void gdbstub_exit(int status)
1116{
1117 unsigned char checksum, ch, buffer[3];
1118 int loop;
1119
1120 if (!kgdb_connected)
1121 return;
1122 kgdb_connected = 0;
1123
1124 if (!dbg_io_ops || dbg_kdb_mode)
1125 return;
1126
1127 buffer[0] = 'W';
1128 buffer[1] = hex_asc_hi(status);
1129 buffer[2] = hex_asc_lo(status);
1130
1131 dbg_io_ops->write_char('$');
1132 checksum = 0;
1133
1134 for (loop = 0; loop < 3; loop++) {
1135 ch = buffer[loop];
1136 checksum += ch;
1137 dbg_io_ops->write_char(ch);
1138 }
1139
1140 dbg_io_ops->write_char('#');
1141 dbg_io_ops->write_char(hex_asc_hi(checksum));
1142 dbg_io_ops->write_char(hex_asc_lo(checksum));
1143
1144 /* make sure the output is flushed, lest the bootloader clobber it */
1145 if (dbg_io_ops->flush)
1146 dbg_io_ops->flush();
1147}
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}