1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Kernel Debug Core
4 *
5 * Maintainer: Jason Wessel <jason.wessel@windriver.com>
6 *
7 * Copyright (C) 2000-2001 VERITAS Software Corporation.
8 * Copyright (C) 2002-2004 Timesys Corporation
9 * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
10 * Copyright (C) 2004 Pavel Machek <pavel@ucw.cz>
11 * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
12 * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
13 * Copyright (C) 2005-2009 Wind River Systems, Inc.
14 * Copyright (C) 2007 MontaVista Software, Inc.
15 * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
16 *
17 * Contributors at various stages not listed above:
18 * Jason Wessel ( jason.wessel@windriver.com )
19 * George Anzinger <george@mvista.com>
20 * Anurekh Saxena (anurekh.saxena@timesys.com)
21 * Lake Stevens Instrument Division (Glenn Engel)
22 * Jim Kingdon, Cygnus Support.
23 *
24 * Original KGDB stub: David Grothe <dave@gcom.com>,
25 * Tigran Aivazian <tigran@sco.com>
26 */
27
28 #include <linux/kernel.h>
29 #include <linux/sched/signal.h>
30 #include <linux/kgdb.h>
31 #include <linux/kdb.h>
32 #include <linux/serial_core.h>
33 #include <linux/string.h>
34 #include <linux/reboot.h>
35 #include <linux/uaccess.h>
36 #include <asm/cacheflush.h>
37 #include <linux/unaligned.h>
38 #include "debug_core.h"
39
40 #define KGDB_MAX_THREAD_QUERY 17
41
42 /* Our I/O buffers. */
43 static char remcom_in_buffer[BUFMAX];
44 static char remcom_out_buffer[BUFMAX];
45 static int gdbstub_use_prev_in_buf;
46 static int gdbstub_prev_in_buf_pos;
47
48 /* Storage for the registers, in GDB format. */
49 static 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
gdbstub_read_wait(void)58 static 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
gdbstub_read_wait(void)80 static 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 $<data>#<checksum> */
get_packet(char * buffer)89 static void get_packet(char *buffer)
90 {
91 unsigned char checksum;
92 unsigned char xmitcsum;
93 int count;
94 char ch;
95
96 do {
97 /*
98 * Spin and wait around for the start character, ignore all
99 * other characters:
100 */
101 while ((ch = (gdbstub_read_wait())) != '$')
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 */
put_packet(char * buffer)143 static 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
194 static char gdbmsgbuf[BUFMAX + 1];
195
gdbstub_msg_write(const char * s,int len)196 void 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 = hex_byte_pack(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 */
kgdb_mem2hex(char * mem,char * buf,int count)237 char *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 = copy_from_kernel_nofault(tmp, mem, count);
249 if (err)
250 return NULL;
251 while (count > 0) {
252 buf = hex_byte_pack(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 */
kgdb_hex2mem(char * buf,char * mem,int count)266 int 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 copy_to_kernel_nofault(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 */
kgdb_hex2long(char ** ptr,unsigned long * long_val)291 int 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 overwritten with the result to write to mem.
323 */
kgdb_ebin2mem(char * buf,char * mem,int count)324 static 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 copy_to_kernel_nofault(mem, c, size);
337 }
338
339 #if DBG_MAX_REG_NUM > 0
pt_regs_to_gdb_regs(unsigned long * gdb_regs,struct pt_regs * regs)340 void 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
gdb_regs_to_pt_regs(unsigned long * gdb_regs,struct pt_regs * regs)352 void 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. */
write_mem_msg(int binary)366 static 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
error_packet(char * pkt,int error)389 static 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
pack_threadid(char * pkt,unsigned char * id)406 static 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 = hex_byte_pack(pkt, *id);
415 lzero = 0;
416 }
417 id++;
418 }
419
420 if (lzero)
421 pkt = hex_byte_pack(pkt, 0);
422
423 return pkt;
424 }
425
int_to_threadref(unsigned char * id,int value)426 static void int_to_threadref(unsigned char *id, int value)
427 {
428 put_unaligned_be32(value, id);
429 }
430
getthread(struct pt_regs * regs,int tid)431 static 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 */
shadow_pid(int realpid)463 static 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 */
gdb_cmd_status(struct kgdb_state * ks)478 static 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 hex_byte_pack(&remcom_out_buffer[1], ks->signo);
490 }
491
gdb_get_regs_helper(struct kgdb_state * ks)492 static 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 */
gdb_cmd_getregs(struct kgdb_state * ks)536 static 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 */
gdb_cmd_setregs(struct kgdb_state * ks)543 static 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 strscpy(remcom_out_buffer, "OK");
552 }
553 }
554
555 /* Handle the 'm' memory read bytes */
gdb_cmd_memread(struct kgdb_state * ks)556 static 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 */
gdb_cmd_memwrite(struct kgdb_state * ks)574 static 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 strscpy(remcom_out_buffer, "OK");
582 }
583
584 #if DBG_MAX_REG_NUM > 0
gdb_hex_reg_helper(int regnum,char * out)585 static 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 register get */
gdb_cmd_reg_get(struct kgdb_state * ks)597 static 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 register set */
gdb_cmd_reg_set(struct kgdb_state * ks)612 static 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 strscpy(remcom_out_buffer, "OK");
635 }
636 #endif /* DBG_MAX_REG_NUM > 0 */
637
638 /* Handle the 'X' memory binary write bytes */
gdb_cmd_binwrite(struct kgdb_state * ks)639 static 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 strscpy(remcom_out_buffer, "OK");
647 }
648
649 /* Handle the 'D' or 'k', detach or kill packets */
gdb_cmd_detachkill(struct kgdb_state * ks)650 static 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 strscpy(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 */
gdb_cmd_reboot(struct kgdb_state * ks)675 static 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 strscpy(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 */
gdb_cmd_query(struct kgdb_state * ks)696 static 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 for_each_process_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 }
737
738 *(--ptr) = '\0';
739 break;
740
741 case 'C':
742 /* Current thread id */
743 strscpy(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 strscpy(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_common_init_state(ks);
786 kdb_parse(remcom_out_buffer);
787 kdb_common_deinit_state();
788
789 strscpy(remcom_out_buffer, "OK");
790 }
791 break;
792 #endif
793 #ifdef CONFIG_HAVE_ARCH_KGDB_QXFER_PKT
794 case 'S':
795 if (!strncmp(remcom_in_buffer, "qSupported:", 11))
796 strscpy(remcom_out_buffer, kgdb_arch_gdb_stub_feature);
797 break;
798 case 'X':
799 if (!strncmp(remcom_in_buffer, "qXfer:", 6))
800 kgdb_arch_handle_qxfer_pkt(remcom_in_buffer,
801 remcom_out_buffer);
802 break;
803 #endif
804 default:
805 break;
806 }
807 }
808
809 /* Handle the 'H' task query packets */
gdb_cmd_task(struct kgdb_state * ks)810 static void gdb_cmd_task(struct kgdb_state *ks)
811 {
812 struct task_struct *thread;
813 char *ptr;
814
815 switch (remcom_in_buffer[1]) {
816 case 'g':
817 ptr = &remcom_in_buffer[2];
818 kgdb_hex2long(&ptr, &ks->threadid);
819 thread = getthread(ks->linux_regs, ks->threadid);
820 if (!thread && ks->threadid > 0) {
821 error_packet(remcom_out_buffer, -EINVAL);
822 break;
823 }
824 kgdb_usethread = thread;
825 ks->kgdb_usethreadid = ks->threadid;
826 strscpy(remcom_out_buffer, "OK");
827 break;
828 case 'c':
829 ptr = &remcom_in_buffer[2];
830 kgdb_hex2long(&ptr, &ks->threadid);
831 if (!ks->threadid) {
832 kgdb_contthread = NULL;
833 } else {
834 thread = getthread(ks->linux_regs, ks->threadid);
835 if (!thread && ks->threadid > 0) {
836 error_packet(remcom_out_buffer, -EINVAL);
837 break;
838 }
839 kgdb_contthread = thread;
840 }
841 strscpy(remcom_out_buffer, "OK");
842 break;
843 }
844 }
845
846 /* Handle the 'T' thread query packets */
gdb_cmd_thread(struct kgdb_state * ks)847 static void gdb_cmd_thread(struct kgdb_state *ks)
848 {
849 char *ptr = &remcom_in_buffer[1];
850 struct task_struct *thread;
851
852 kgdb_hex2long(&ptr, &ks->threadid);
853 thread = getthread(ks->linux_regs, ks->threadid);
854 if (thread)
855 strscpy(remcom_out_buffer, "OK");
856 else
857 error_packet(remcom_out_buffer, -EINVAL);
858 }
859
860 /* Handle the 'z' or 'Z' breakpoint remove or set packets */
gdb_cmd_break(struct kgdb_state * ks)861 static void gdb_cmd_break(struct kgdb_state *ks)
862 {
863 /*
864 * Since GDB-5.3, it's been drafted that '0' is a software
865 * breakpoint, '1' is a hardware breakpoint, so let's do that.
866 */
867 char *bpt_type = &remcom_in_buffer[1];
868 char *ptr = &remcom_in_buffer[2];
869 unsigned long addr;
870 unsigned long length;
871 int error = 0;
872
873 if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
874 /* Unsupported */
875 if (*bpt_type > '4')
876 return;
877 } else {
878 if (*bpt_type != '0' && *bpt_type != '1')
879 /* Unsupported. */
880 return;
881 }
882
883 /*
884 * Test if this is a hardware breakpoint, and
885 * if we support it:
886 */
887 if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
888 /* Unsupported. */
889 return;
890
891 if (*(ptr++) != ',') {
892 error_packet(remcom_out_buffer, -EINVAL);
893 return;
894 }
895 if (!kgdb_hex2long(&ptr, &addr)) {
896 error_packet(remcom_out_buffer, -EINVAL);
897 return;
898 }
899 if (*(ptr++) != ',' ||
900 !kgdb_hex2long(&ptr, &length)) {
901 error_packet(remcom_out_buffer, -EINVAL);
902 return;
903 }
904
905 if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
906 error = dbg_set_sw_break(addr);
907 else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
908 error = dbg_remove_sw_break(addr);
909 else if (remcom_in_buffer[0] == 'Z')
910 error = arch_kgdb_ops.set_hw_breakpoint(addr,
911 (int)length, *bpt_type - '0');
912 else if (remcom_in_buffer[0] == 'z')
913 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
914 (int) length, *bpt_type - '0');
915
916 if (error == 0)
917 strscpy(remcom_out_buffer, "OK");
918 else
919 error_packet(remcom_out_buffer, error);
920 }
921
922 /* Handle the 'C' signal / exception passing packets */
gdb_cmd_exception_pass(struct kgdb_state * ks)923 static int gdb_cmd_exception_pass(struct kgdb_state *ks)
924 {
925 /* C09 == pass exception
926 * C15 == detach kgdb, pass exception
927 */
928 if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
929
930 ks->pass_exception = 1;
931 remcom_in_buffer[0] = 'c';
932
933 } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
934
935 ks->pass_exception = 1;
936 remcom_in_buffer[0] = 'D';
937 dbg_remove_all_break();
938 kgdb_connected = 0;
939 return 1;
940
941 } else {
942 gdbstub_msg_write("KGDB only knows signal 9 (pass)"
943 " and 15 (pass and disconnect)\n"
944 "Executing a continue without signal passing\n", 0);
945 remcom_in_buffer[0] = 'c';
946 }
947
948 /* Indicate fall through */
949 return -1;
950 }
951
952 /*
953 * This function performs all gdbserial command processing
954 */
gdb_serial_stub(struct kgdb_state * ks)955 int gdb_serial_stub(struct kgdb_state *ks)
956 {
957 int error = 0;
958 int tmp;
959
960 /* Initialize comm buffer and globals. */
961 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
962 kgdb_usethread = kgdb_info[ks->cpu].task;
963 ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
964 ks->pass_exception = 0;
965
966 if (kgdb_connected) {
967 unsigned char thref[BUF_THREAD_ID_SIZE];
968 char *ptr;
969
970 /* Reply to host that an exception has occurred */
971 ptr = remcom_out_buffer;
972 *ptr++ = 'T';
973 ptr = hex_byte_pack(ptr, ks->signo);
974 ptr += strlen(strcpy(ptr, "thread:"));
975 int_to_threadref(thref, shadow_pid(current->pid));
976 ptr = pack_threadid(ptr, thref);
977 *ptr++ = ';';
978 put_packet(remcom_out_buffer);
979 }
980
981 while (1) {
982 error = 0;
983
984 /* Clear the out buffer. */
985 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
986
987 get_packet(remcom_in_buffer);
988
989 switch (remcom_in_buffer[0]) {
990 case '?': /* gdbserial status */
991 gdb_cmd_status(ks);
992 break;
993 case 'g': /* return the value of the CPU registers */
994 gdb_cmd_getregs(ks);
995 break;
996 case 'G': /* set the value of the CPU registers - return OK */
997 gdb_cmd_setregs(ks);
998 break;
999 case 'm': /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */
1000 gdb_cmd_memread(ks);
1001 break;
1002 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1003 gdb_cmd_memwrite(ks);
1004 break;
1005 #if DBG_MAX_REG_NUM > 0
1006 case 'p': /* pXX Return gdb register XX (in hex) */
1007 gdb_cmd_reg_get(ks);
1008 break;
1009 case 'P': /* PXX=aaaa Set gdb register XX to aaaa (in hex) */
1010 gdb_cmd_reg_set(ks);
1011 break;
1012 #endif /* DBG_MAX_REG_NUM > 0 */
1013 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1014 gdb_cmd_binwrite(ks);
1015 break;
1016 /* kill or detach. KGDB should treat this like a
1017 * continue.
1018 */
1019 case 'D': /* Debugger detach */
1020 case 'k': /* Debugger detach via kill */
1021 gdb_cmd_detachkill(ks);
1022 goto default_handle;
1023 case 'R': /* Reboot */
1024 if (gdb_cmd_reboot(ks))
1025 goto default_handle;
1026 break;
1027 case 'q': /* query command */
1028 gdb_cmd_query(ks);
1029 break;
1030 case 'H': /* task related */
1031 gdb_cmd_task(ks);
1032 break;
1033 case 'T': /* Query thread status */
1034 gdb_cmd_thread(ks);
1035 break;
1036 case 'z': /* Break point remove */
1037 case 'Z': /* Break point set */
1038 gdb_cmd_break(ks);
1039 break;
1040 #ifdef CONFIG_KGDB_KDB
1041 case '3': /* Escape into back into kdb */
1042 if (remcom_in_buffer[1] == '\0') {
1043 gdb_cmd_detachkill(ks);
1044 return DBG_PASS_EVENT;
1045 }
1046 fallthrough;
1047 #endif
1048 case 'C': /* Exception passing */
1049 tmp = gdb_cmd_exception_pass(ks);
1050 if (tmp > 0)
1051 goto default_handle;
1052 if (tmp == 0)
1053 break;
1054 fallthrough; /* on tmp < 0 */
1055 case 'c': /* Continue packet */
1056 case 's': /* Single step packet */
1057 if (kgdb_contthread && kgdb_contthread != current) {
1058 /* Can't switch threads in kgdb */
1059 error_packet(remcom_out_buffer, -EINVAL);
1060 break;
1061 }
1062 fallthrough; /* to default processing */
1063 default:
1064 default_handle:
1065 error = kgdb_arch_handle_exception(ks->ex_vector,
1066 ks->signo,
1067 ks->err_code,
1068 remcom_in_buffer,
1069 remcom_out_buffer,
1070 ks->linux_regs);
1071 /*
1072 * Leave cmd processing on error, detach,
1073 * kill, continue, or single step.
1074 */
1075 if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1076 remcom_in_buffer[0] == 'k') {
1077 error = 0;
1078 goto kgdb_exit;
1079 }
1080
1081 }
1082
1083 /* reply to the request */
1084 put_packet(remcom_out_buffer);
1085 }
1086
1087 kgdb_exit:
1088 if (ks->pass_exception)
1089 error = 1;
1090 return error;
1091 }
1092
gdbstub_state(struct kgdb_state * ks,char * cmd)1093 int gdbstub_state(struct kgdb_state *ks, char *cmd)
1094 {
1095 int error;
1096
1097 switch (cmd[0]) {
1098 case 'e':
1099 error = kgdb_arch_handle_exception(ks->ex_vector,
1100 ks->signo,
1101 ks->err_code,
1102 remcom_in_buffer,
1103 remcom_out_buffer,
1104 ks->linux_regs);
1105 return error;
1106 case 's':
1107 case 'c':
1108 strscpy(remcom_in_buffer, cmd, sizeof(remcom_in_buffer));
1109 return 0;
1110 case '$':
1111 strscpy(remcom_in_buffer, cmd, sizeof(remcom_in_buffer));
1112 gdbstub_use_prev_in_buf = strlen(remcom_in_buffer);
1113 gdbstub_prev_in_buf_pos = 0;
1114 return 0;
1115 }
1116 dbg_io_ops->write_char('+');
1117 put_packet(remcom_out_buffer);
1118 return 0;
1119 }
1120
1121 /**
1122 * gdbstub_exit - Send an exit message to GDB
1123 * @status: The exit code to report.
1124 */
gdbstub_exit(int status)1125 void gdbstub_exit(int status)
1126 {
1127 unsigned char checksum, ch, buffer[3];
1128 int loop;
1129
1130 if (!kgdb_connected)
1131 return;
1132 kgdb_connected = 0;
1133
1134 if (!dbg_io_ops || dbg_kdb_mode)
1135 return;
1136
1137 buffer[0] = 'W';
1138 buffer[1] = hex_asc_hi(status);
1139 buffer[2] = hex_asc_lo(status);
1140
1141 dbg_io_ops->write_char('$');
1142 checksum = 0;
1143
1144 for (loop = 0; loop < 3; loop++) {
1145 ch = buffer[loop];
1146 checksum += ch;
1147 dbg_io_ops->write_char(ch);
1148 }
1149
1150 dbg_io_ops->write_char('#');
1151 dbg_io_ops->write_char(hex_asc_hi(checksum));
1152 dbg_io_ops->write_char(hex_asc_lo(checksum));
1153
1154 /* make sure the output is flushed, lest the bootloader clobber it */
1155 if (dbg_io_ops->flush)
1156 dbg_io_ops->flush();
1157 }
1158