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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/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}