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/reboot.h>
34 #include <linux/uaccess.h>
35 #include <asm/cacheflush.h>
36 #include <asm/unaligned.h>
37 #include "debug_core.h"
38
39 #define KGDB_MAX_THREAD_QUERY 17
40
41 /* Our I/O buffers. */
42 static char remcom_in_buffer[BUFMAX];
43 static char remcom_out_buffer[BUFMAX];
44 static int gdbstub_use_prev_in_buf;
45 static int gdbstub_prev_in_buf_pos;
46
47 /* Storage for the registers, in GDB format. */
48 static unsigned long gdb_regs[(NUMREGBYTES +
49 sizeof(unsigned long) - 1) /
50 sizeof(unsigned long)];
51
52 /*
53 * GDB remote protocol parser:
54 */
55
56 #ifdef CONFIG_KGDB_KDB
gdbstub_read_wait(void)57 static int gdbstub_read_wait(void)
58 {
59 int ret = -1;
60 int i;
61
62 if (unlikely(gdbstub_use_prev_in_buf)) {
63 if (gdbstub_prev_in_buf_pos < gdbstub_use_prev_in_buf)
64 return remcom_in_buffer[gdbstub_prev_in_buf_pos++];
65 else
66 gdbstub_use_prev_in_buf = 0;
67 }
68
69 /* poll any additional I/O interfaces that are defined */
70 while (ret < 0)
71 for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
72 ret = kdb_poll_funcs[i]();
73 if (ret > 0)
74 break;
75 }
76 return ret;
77 }
78 #else
gdbstub_read_wait(void)79 static int gdbstub_read_wait(void)
80 {
81 int ret = dbg_io_ops->read_char();
82 while (ret == NO_POLL_CHAR)
83 ret = dbg_io_ops->read_char();
84 return ret;
85 }
86 #endif
87 /* scan for the sequence $<data>#<checksum> */
get_packet(char * buffer)88 static void get_packet(char *buffer)
89 {
90 unsigned char checksum;
91 unsigned char xmitcsum;
92 int count;
93 char ch;
94
95 do {
96 /*
97 * Spin and wait around for the start character, ignore all
98 * other characters:
99 */
100 while ((ch = (gdbstub_read_wait())) != '$')
101 /* nothing */;
102
103 kgdb_connected = 1;
104 checksum = 0;
105 xmitcsum = -1;
106
107 count = 0;
108
109 /*
110 * now, read until a # or end of buffer is found:
111 */
112 while (count < (BUFMAX - 1)) {
113 ch = gdbstub_read_wait();
114 if (ch == '#')
115 break;
116 checksum = checksum + ch;
117 buffer[count] = ch;
118 count = count + 1;
119 }
120
121 if (ch == '#') {
122 xmitcsum = hex_to_bin(gdbstub_read_wait()) << 4;
123 xmitcsum += hex_to_bin(gdbstub_read_wait());
124
125 if (checksum != xmitcsum)
126 /* failed checksum */
127 dbg_io_ops->write_char('-');
128 else
129 /* successful transfer */
130 dbg_io_ops->write_char('+');
131 if (dbg_io_ops->flush)
132 dbg_io_ops->flush();
133 }
134 buffer[count] = 0;
135 } while (checksum != xmitcsum);
136 }
137
138 /*
139 * Send the packet in buffer.
140 * Check for gdb connection if asked for.
141 */
put_packet(char * buffer)142 static void put_packet(char *buffer)
143 {
144 unsigned char checksum;
145 int count;
146 char ch;
147
148 /*
149 * $<packet info>#<checksum>.
150 */
151 while (1) {
152 dbg_io_ops->write_char('$');
153 checksum = 0;
154 count = 0;
155
156 while ((ch = buffer[count])) {
157 dbg_io_ops->write_char(ch);
158 checksum += ch;
159 count++;
160 }
161
162 dbg_io_ops->write_char('#');
163 dbg_io_ops->write_char(hex_asc_hi(checksum));
164 dbg_io_ops->write_char(hex_asc_lo(checksum));
165 if (dbg_io_ops->flush)
166 dbg_io_ops->flush();
167
168 /* Now see what we get in reply. */
169 ch = gdbstub_read_wait();
170
171 if (ch == 3)
172 ch = gdbstub_read_wait();
173
174 /* If we get an ACK, we are done. */
175 if (ch == '+')
176 return;
177
178 /*
179 * If we get the start of another packet, this means
180 * that GDB is attempting to reconnect. We will NAK
181 * the packet being sent, and stop trying to send this
182 * packet.
183 */
184 if (ch == '$') {
185 dbg_io_ops->write_char('-');
186 if (dbg_io_ops->flush)
187 dbg_io_ops->flush();
188 return;
189 }
190 }
191 }
192
193 static char gdbmsgbuf[BUFMAX + 1];
194
gdbstub_msg_write(const char * s,int len)195 void gdbstub_msg_write(const char *s, int len)
196 {
197 char *bufptr;
198 int wcount;
199 int i;
200
201 if (len == 0)
202 len = strlen(s);
203
204 /* 'O'utput */
205 gdbmsgbuf[0] = 'O';
206
207 /* Fill and send buffers... */
208 while (len > 0) {
209 bufptr = gdbmsgbuf + 1;
210
211 /* Calculate how many this time */
212 if ((len << 1) > (BUFMAX - 2))
213 wcount = (BUFMAX - 2) >> 1;
214 else
215 wcount = len;
216
217 /* Pack in hex chars */
218 for (i = 0; i < wcount; i++)
219 bufptr = hex_byte_pack(bufptr, s[i]);
220 *bufptr = '\0';
221
222 /* Move up */
223 s += wcount;
224 len -= wcount;
225
226 /* Write packet */
227 put_packet(gdbmsgbuf);
228 }
229 }
230
231 /*
232 * Convert the memory pointed to by mem into hex, placing result in
233 * buf. Return a pointer to the last char put in buf (null). May
234 * return an error.
235 */
kgdb_mem2hex(char * mem,char * buf,int count)236 char *kgdb_mem2hex(char *mem, char *buf, int count)
237 {
238 char *tmp;
239 int err;
240
241 /*
242 * We use the upper half of buf as an intermediate buffer for the
243 * raw memory copy. Hex conversion will work against this one.
244 */
245 tmp = buf + count;
246
247 err = copy_from_kernel_nofault(tmp, mem, count);
248 if (err)
249 return NULL;
250 while (count > 0) {
251 buf = hex_byte_pack(buf, *tmp);
252 tmp++;
253 count--;
254 }
255 *buf = 0;
256
257 return buf;
258 }
259
260 /*
261 * Convert the hex array pointed to by buf into binary to be placed in
262 * mem. Return a pointer to the character AFTER the last byte
263 * written. May return an error.
264 */
kgdb_hex2mem(char * buf,char * mem,int count)265 int kgdb_hex2mem(char *buf, char *mem, int count)
266 {
267 char *tmp_raw;
268 char *tmp_hex;
269
270 /*
271 * We use the upper half of buf as an intermediate buffer for the
272 * raw memory that is converted from hex.
273 */
274 tmp_raw = buf + count * 2;
275
276 tmp_hex = tmp_raw - 1;
277 while (tmp_hex >= buf) {
278 tmp_raw--;
279 *tmp_raw = hex_to_bin(*tmp_hex--);
280 *tmp_raw |= hex_to_bin(*tmp_hex--) << 4;
281 }
282
283 return copy_to_kernel_nofault(mem, tmp_raw, count);
284 }
285
286 /*
287 * While we find nice hex chars, build a long_val.
288 * Return number of chars processed.
289 */
kgdb_hex2long(char ** ptr,unsigned long * long_val)290 int kgdb_hex2long(char **ptr, unsigned long *long_val)
291 {
292 int hex_val;
293 int num = 0;
294 int negate = 0;
295
296 *long_val = 0;
297
298 if (**ptr == '-') {
299 negate = 1;
300 (*ptr)++;
301 }
302 while (**ptr) {
303 hex_val = hex_to_bin(**ptr);
304 if (hex_val < 0)
305 break;
306
307 *long_val = (*long_val << 4) | hex_val;
308 num++;
309 (*ptr)++;
310 }
311
312 if (negate)
313 *long_val = -*long_val;
314
315 return num;
316 }
317
318 /*
319 * Copy the binary array pointed to by buf into mem. Fix $, #, and
320 * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success.
321 * The input buf is overwritten with the result to write to mem.
322 */
kgdb_ebin2mem(char * buf,char * mem,int count)323 static int kgdb_ebin2mem(char *buf, char *mem, int count)
324 {
325 int size = 0;
326 char *c = buf;
327
328 while (count-- > 0) {
329 c[size] = *buf++;
330 if (c[size] == 0x7d)
331 c[size] = *buf++ ^ 0x20;
332 size++;
333 }
334
335 return copy_to_kernel_nofault(mem, c, size);
336 }
337
338 #if DBG_MAX_REG_NUM > 0
pt_regs_to_gdb_regs(unsigned long * gdb_regs,struct pt_regs * regs)339 void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
340 {
341 int i;
342 int idx = 0;
343 char *ptr = (char *)gdb_regs;
344
345 for (i = 0; i < DBG_MAX_REG_NUM; i++) {
346 dbg_get_reg(i, ptr + idx, regs);
347 idx += dbg_reg_def[i].size;
348 }
349 }
350
gdb_regs_to_pt_regs(unsigned long * gdb_regs,struct pt_regs * regs)351 void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
352 {
353 int i;
354 int idx = 0;
355 char *ptr = (char *)gdb_regs;
356
357 for (i = 0; i < DBG_MAX_REG_NUM; i++) {
358 dbg_set_reg(i, ptr + idx, regs);
359 idx += dbg_reg_def[i].size;
360 }
361 }
362 #endif /* DBG_MAX_REG_NUM > 0 */
363
364 /* Write memory due to an 'M' or 'X' packet. */
write_mem_msg(int binary)365 static int write_mem_msg(int binary)
366 {
367 char *ptr = &remcom_in_buffer[1];
368 unsigned long addr;
369 unsigned long length;
370 int err;
371
372 if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
373 kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
374 if (binary)
375 err = kgdb_ebin2mem(ptr, (char *)addr, length);
376 else
377 err = kgdb_hex2mem(ptr, (char *)addr, length);
378 if (err)
379 return err;
380 if (CACHE_FLUSH_IS_SAFE)
381 flush_icache_range(addr, addr + length);
382 return 0;
383 }
384
385 return -EINVAL;
386 }
387
error_packet(char * pkt,int error)388 static void error_packet(char *pkt, int error)
389 {
390 error = -error;
391 pkt[0] = 'E';
392 pkt[1] = hex_asc[(error / 10)];
393 pkt[2] = hex_asc[(error % 10)];
394 pkt[3] = '\0';
395 }
396
397 /*
398 * Thread ID accessors. We represent a flat TID space to GDB, where
399 * the per CPU idle threads (which under Linux all have PID 0) are
400 * remapped to negative TIDs.
401 */
402
403 #define BUF_THREAD_ID_SIZE 8
404
pack_threadid(char * pkt,unsigned char * id)405 static char *pack_threadid(char *pkt, unsigned char *id)
406 {
407 unsigned char *limit;
408 int lzero = 1;
409
410 limit = id + (BUF_THREAD_ID_SIZE / 2);
411 while (id < limit) {
412 if (!lzero || *id != 0) {
413 pkt = hex_byte_pack(pkt, *id);
414 lzero = 0;
415 }
416 id++;
417 }
418
419 if (lzero)
420 pkt = hex_byte_pack(pkt, 0);
421
422 return pkt;
423 }
424
int_to_threadref(unsigned char * id,int value)425 static void int_to_threadref(unsigned char *id, int value)
426 {
427 put_unaligned_be32(value, id);
428 }
429
getthread(struct pt_regs * regs,int tid)430 static struct task_struct *getthread(struct pt_regs *regs, int tid)
431 {
432 /*
433 * Non-positive TIDs are remapped to the cpu shadow information
434 */
435 if (tid == 0 || tid == -1)
436 tid = -atomic_read(&kgdb_active) - 2;
437 if (tid < -1 && tid > -NR_CPUS - 2) {
438 if (kgdb_info[-tid - 2].task)
439 return kgdb_info[-tid - 2].task;
440 else
441 return idle_task(-tid - 2);
442 }
443 if (tid <= 0) {
444 printk(KERN_ERR "KGDB: Internal thread select error\n");
445 dump_stack();
446 return NULL;
447 }
448
449 /*
450 * find_task_by_pid_ns() does not take the tasklist lock anymore
451 * but is nicely RCU locked - hence is a pretty resilient
452 * thing to use:
453 */
454 return find_task_by_pid_ns(tid, &init_pid_ns);
455 }
456
457
458 /*
459 * Remap normal tasks to their real PID,
460 * CPU shadow threads are mapped to -CPU - 2
461 */
shadow_pid(int realpid)462 static inline int shadow_pid(int realpid)
463 {
464 if (realpid)
465 return realpid;
466
467 return -raw_smp_processor_id() - 2;
468 }
469
470 /*
471 * All the functions that start with gdb_cmd are the various
472 * operations to implement the handlers for the gdbserial protocol
473 * where KGDB is communicating with an external debugger
474 */
475
476 /* Handle the '?' status packets */
gdb_cmd_status(struct kgdb_state * ks)477 static void gdb_cmd_status(struct kgdb_state *ks)
478 {
479 /*
480 * We know that this packet is only sent
481 * during initial connect. So to be safe,
482 * we clear out our breakpoints now in case
483 * GDB is reconnecting.
484 */
485 dbg_remove_all_break();
486
487 remcom_out_buffer[0] = 'S';
488 hex_byte_pack(&remcom_out_buffer[1], ks->signo);
489 }
490
gdb_get_regs_helper(struct kgdb_state * ks)491 static void gdb_get_regs_helper(struct kgdb_state *ks)
492 {
493 struct task_struct *thread;
494 void *local_debuggerinfo;
495 int i;
496
497 thread = kgdb_usethread;
498 if (!thread) {
499 thread = kgdb_info[ks->cpu].task;
500 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
501 } else {
502 local_debuggerinfo = NULL;
503 for_each_online_cpu(i) {
504 /*
505 * Try to find the task on some other
506 * or possibly this node if we do not
507 * find the matching task then we try
508 * to approximate the results.
509 */
510 if (thread == kgdb_info[i].task)
511 local_debuggerinfo = kgdb_info[i].debuggerinfo;
512 }
513 }
514
515 /*
516 * All threads that don't have debuggerinfo should be
517 * in schedule() sleeping, since all other CPUs
518 * are in kgdb_wait, and thus have debuggerinfo.
519 */
520 if (local_debuggerinfo) {
521 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
522 } else {
523 /*
524 * Pull stuff saved during switch_to; nothing
525 * else is accessible (or even particularly
526 * relevant).
527 *
528 * This should be enough for a stack trace.
529 */
530 sleeping_thread_to_gdb_regs(gdb_regs, thread);
531 }
532 }
533
534 /* Handle the 'g' get registers request */
gdb_cmd_getregs(struct kgdb_state * ks)535 static void gdb_cmd_getregs(struct kgdb_state *ks)
536 {
537 gdb_get_regs_helper(ks);
538 kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
539 }
540
541 /* Handle the 'G' set registers request */
gdb_cmd_setregs(struct kgdb_state * ks)542 static void gdb_cmd_setregs(struct kgdb_state *ks)
543 {
544 kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
545
546 if (kgdb_usethread && kgdb_usethread != current) {
547 error_packet(remcom_out_buffer, -EINVAL);
548 } else {
549 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
550 strcpy(remcom_out_buffer, "OK");
551 }
552 }
553
554 /* Handle the 'm' memory read bytes */
gdb_cmd_memread(struct kgdb_state * ks)555 static void gdb_cmd_memread(struct kgdb_state *ks)
556 {
557 char *ptr = &remcom_in_buffer[1];
558 unsigned long length;
559 unsigned long addr;
560 char *err;
561
562 if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
563 kgdb_hex2long(&ptr, &length) > 0) {
564 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
565 if (!err)
566 error_packet(remcom_out_buffer, -EINVAL);
567 } else {
568 error_packet(remcom_out_buffer, -EINVAL);
569 }
570 }
571
572 /* Handle the 'M' memory write bytes */
gdb_cmd_memwrite(struct kgdb_state * ks)573 static void gdb_cmd_memwrite(struct kgdb_state *ks)
574 {
575 int err = write_mem_msg(0);
576
577 if (err)
578 error_packet(remcom_out_buffer, err);
579 else
580 strcpy(remcom_out_buffer, "OK");
581 }
582
583 #if DBG_MAX_REG_NUM > 0
gdb_hex_reg_helper(int regnum,char * out)584 static char *gdb_hex_reg_helper(int regnum, char *out)
585 {
586 int i;
587 int offset = 0;
588
589 for (i = 0; i < regnum; i++)
590 offset += dbg_reg_def[i].size;
591 return kgdb_mem2hex((char *)gdb_regs + offset, out,
592 dbg_reg_def[i].size);
593 }
594
595 /* Handle the 'p' individual register get */
gdb_cmd_reg_get(struct kgdb_state * ks)596 static void gdb_cmd_reg_get(struct kgdb_state *ks)
597 {
598 unsigned long regnum;
599 char *ptr = &remcom_in_buffer[1];
600
601 kgdb_hex2long(&ptr, ®num);
602 if (regnum >= DBG_MAX_REG_NUM) {
603 error_packet(remcom_out_buffer, -EINVAL);
604 return;
605 }
606 gdb_get_regs_helper(ks);
607 gdb_hex_reg_helper(regnum, remcom_out_buffer);
608 }
609
610 /* Handle the 'P' individual register set */
gdb_cmd_reg_set(struct kgdb_state * ks)611 static void gdb_cmd_reg_set(struct kgdb_state *ks)
612 {
613 unsigned long regnum;
614 char *ptr = &remcom_in_buffer[1];
615 int i = 0;
616
617 kgdb_hex2long(&ptr, ®num);
618 if (*ptr++ != '=' ||
619 !(!kgdb_usethread || kgdb_usethread == current) ||
620 !dbg_get_reg(regnum, gdb_regs, ks->linux_regs)) {
621 error_packet(remcom_out_buffer, -EINVAL);
622 return;
623 }
624 memset(gdb_regs, 0, sizeof(gdb_regs));
625 while (i < sizeof(gdb_regs) * 2)
626 if (hex_to_bin(ptr[i]) >= 0)
627 i++;
628 else
629 break;
630 i = i / 2;
631 kgdb_hex2mem(ptr, (char *)gdb_regs, i);
632 dbg_set_reg(regnum, gdb_regs, ks->linux_regs);
633 strcpy(remcom_out_buffer, "OK");
634 }
635 #endif /* DBG_MAX_REG_NUM > 0 */
636
637 /* Handle the 'X' memory binary write bytes */
gdb_cmd_binwrite(struct kgdb_state * ks)638 static void gdb_cmd_binwrite(struct kgdb_state *ks)
639 {
640 int err = write_mem_msg(1);
641
642 if (err)
643 error_packet(remcom_out_buffer, err);
644 else
645 strcpy(remcom_out_buffer, "OK");
646 }
647
648 /* Handle the 'D' or 'k', detach or kill packets */
gdb_cmd_detachkill(struct kgdb_state * ks)649 static void gdb_cmd_detachkill(struct kgdb_state *ks)
650 {
651 int error;
652
653 /* The detach case */
654 if (remcom_in_buffer[0] == 'D') {
655 error = dbg_remove_all_break();
656 if (error < 0) {
657 error_packet(remcom_out_buffer, error);
658 } else {
659 strcpy(remcom_out_buffer, "OK");
660 kgdb_connected = 0;
661 }
662 put_packet(remcom_out_buffer);
663 } else {
664 /*
665 * Assume the kill case, with no exit code checking,
666 * trying to force detach the debugger:
667 */
668 dbg_remove_all_break();
669 kgdb_connected = 0;
670 }
671 }
672
673 /* Handle the 'R' reboot packets */
gdb_cmd_reboot(struct kgdb_state * ks)674 static int gdb_cmd_reboot(struct kgdb_state *ks)
675 {
676 /* For now, only honor R0 */
677 if (strcmp(remcom_in_buffer, "R0") == 0) {
678 printk(KERN_CRIT "Executing emergency reboot\n");
679 strcpy(remcom_out_buffer, "OK");
680 put_packet(remcom_out_buffer);
681
682 /*
683 * Execution should not return from
684 * machine_emergency_restart()
685 */
686 machine_emergency_restart();
687 kgdb_connected = 0;
688
689 return 1;
690 }
691 return 0;
692 }
693
694 /* Handle the 'q' query packets */
gdb_cmd_query(struct kgdb_state * ks)695 static void gdb_cmd_query(struct kgdb_state *ks)
696 {
697 struct task_struct *g;
698 struct task_struct *p;
699 unsigned char thref[BUF_THREAD_ID_SIZE];
700 char *ptr;
701 int i;
702 int cpu;
703 int finished = 0;
704
705 switch (remcom_in_buffer[1]) {
706 case 's':
707 case 'f':
708 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10))
709 break;
710
711 i = 0;
712 remcom_out_buffer[0] = 'm';
713 ptr = remcom_out_buffer + 1;
714 if (remcom_in_buffer[1] == 'f') {
715 /* Each cpu is a shadow thread */
716 for_each_online_cpu(cpu) {
717 ks->thr_query = 0;
718 int_to_threadref(thref, -cpu - 2);
719 ptr = pack_threadid(ptr, thref);
720 *(ptr++) = ',';
721 i++;
722 }
723 }
724
725 for_each_process_thread(g, p) {
726 if (i >= ks->thr_query && !finished) {
727 int_to_threadref(thref, p->pid);
728 ptr = pack_threadid(ptr, thref);
729 *(ptr++) = ',';
730 ks->thr_query++;
731 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
732 finished = 1;
733 }
734 i++;
735 }
736
737 *(--ptr) = '\0';
738 break;
739
740 case 'C':
741 /* Current thread id */
742 strcpy(remcom_out_buffer, "QC");
743 ks->threadid = shadow_pid(current->pid);
744 int_to_threadref(thref, ks->threadid);
745 pack_threadid(remcom_out_buffer + 2, thref);
746 break;
747 case 'T':
748 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16))
749 break;
750
751 ks->threadid = 0;
752 ptr = remcom_in_buffer + 17;
753 kgdb_hex2long(&ptr, &ks->threadid);
754 if (!getthread(ks->linux_regs, ks->threadid)) {
755 error_packet(remcom_out_buffer, -EINVAL);
756 break;
757 }
758 if ((int)ks->threadid > 0) {
759 kgdb_mem2hex(getthread(ks->linux_regs,
760 ks->threadid)->comm,
761 remcom_out_buffer, 16);
762 } else {
763 static char tmpstr[23 + BUF_THREAD_ID_SIZE];
764
765 sprintf(tmpstr, "shadowCPU%d",
766 (int)(-ks->threadid - 2));
767 kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
768 }
769 break;
770 #ifdef CONFIG_KGDB_KDB
771 case 'R':
772 if (strncmp(remcom_in_buffer, "qRcmd,", 6) == 0) {
773 int len = strlen(remcom_in_buffer + 6);
774
775 if ((len % 2) != 0) {
776 strcpy(remcom_out_buffer, "E01");
777 break;
778 }
779 kgdb_hex2mem(remcom_in_buffer + 6,
780 remcom_out_buffer, len);
781 len = len / 2;
782 remcom_out_buffer[len++] = 0;
783
784 kdb_common_init_state(ks);
785 kdb_parse(remcom_out_buffer);
786 kdb_common_deinit_state();
787
788 strcpy(remcom_out_buffer, "OK");
789 }
790 break;
791 #endif
792 #ifdef CONFIG_HAVE_ARCH_KGDB_QXFER_PKT
793 case 'S':
794 if (!strncmp(remcom_in_buffer, "qSupported:", 11))
795 strcpy(remcom_out_buffer, kgdb_arch_gdb_stub_feature);
796 break;
797 case 'X':
798 if (!strncmp(remcom_in_buffer, "qXfer:", 6))
799 kgdb_arch_handle_qxfer_pkt(remcom_in_buffer,
800 remcom_out_buffer);
801 break;
802 #endif
803 default:
804 break;
805 }
806 }
807
808 /* Handle the 'H' task query packets */
gdb_cmd_task(struct kgdb_state * ks)809 static void gdb_cmd_task(struct kgdb_state *ks)
810 {
811 struct task_struct *thread;
812 char *ptr;
813
814 switch (remcom_in_buffer[1]) {
815 case 'g':
816 ptr = &remcom_in_buffer[2];
817 kgdb_hex2long(&ptr, &ks->threadid);
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_usethread = thread;
824 ks->kgdb_usethreadid = ks->threadid;
825 strcpy(remcom_out_buffer, "OK");
826 break;
827 case 'c':
828 ptr = &remcom_in_buffer[2];
829 kgdb_hex2long(&ptr, &ks->threadid);
830 if (!ks->threadid) {
831 kgdb_contthread = NULL;
832 } else {
833 thread = getthread(ks->linux_regs, ks->threadid);
834 if (!thread && ks->threadid > 0) {
835 error_packet(remcom_out_buffer, -EINVAL);
836 break;
837 }
838 kgdb_contthread = thread;
839 }
840 strcpy(remcom_out_buffer, "OK");
841 break;
842 }
843 }
844
845 /* Handle the 'T' thread query packets */
gdb_cmd_thread(struct kgdb_state * ks)846 static void gdb_cmd_thread(struct kgdb_state *ks)
847 {
848 char *ptr = &remcom_in_buffer[1];
849 struct task_struct *thread;
850
851 kgdb_hex2long(&ptr, &ks->threadid);
852 thread = getthread(ks->linux_regs, ks->threadid);
853 if (thread)
854 strcpy(remcom_out_buffer, "OK");
855 else
856 error_packet(remcom_out_buffer, -EINVAL);
857 }
858
859 /* Handle the 'z' or 'Z' breakpoint remove or set packets */
gdb_cmd_break(struct kgdb_state * ks)860 static void gdb_cmd_break(struct kgdb_state *ks)
861 {
862 /*
863 * Since GDB-5.3, it's been drafted that '0' is a software
864 * breakpoint, '1' is a hardware breakpoint, so let's do that.
865 */
866 char *bpt_type = &remcom_in_buffer[1];
867 char *ptr = &remcom_in_buffer[2];
868 unsigned long addr;
869 unsigned long length;
870 int error = 0;
871
872 if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
873 /* Unsupported */
874 if (*bpt_type > '4')
875 return;
876 } else {
877 if (*bpt_type != '0' && *bpt_type != '1')
878 /* Unsupported. */
879 return;
880 }
881
882 /*
883 * Test if this is a hardware breakpoint, and
884 * if we support it:
885 */
886 if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
887 /* Unsupported. */
888 return;
889
890 if (*(ptr++) != ',') {
891 error_packet(remcom_out_buffer, -EINVAL);
892 return;
893 }
894 if (!kgdb_hex2long(&ptr, &addr)) {
895 error_packet(remcom_out_buffer, -EINVAL);
896 return;
897 }
898 if (*(ptr++) != ',' ||
899 !kgdb_hex2long(&ptr, &length)) {
900 error_packet(remcom_out_buffer, -EINVAL);
901 return;
902 }
903
904 if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
905 error = dbg_set_sw_break(addr);
906 else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
907 error = dbg_remove_sw_break(addr);
908 else if (remcom_in_buffer[0] == 'Z')
909 error = arch_kgdb_ops.set_hw_breakpoint(addr,
910 (int)length, *bpt_type - '0');
911 else if (remcom_in_buffer[0] == 'z')
912 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
913 (int) length, *bpt_type - '0');
914
915 if (error == 0)
916 strcpy(remcom_out_buffer, "OK");
917 else
918 error_packet(remcom_out_buffer, error);
919 }
920
921 /* Handle the 'C' signal / exception passing packets */
gdb_cmd_exception_pass(struct kgdb_state * ks)922 static int gdb_cmd_exception_pass(struct kgdb_state *ks)
923 {
924 /* C09 == pass exception
925 * C15 == detach kgdb, pass exception
926 */
927 if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
928
929 ks->pass_exception = 1;
930 remcom_in_buffer[0] = 'c';
931
932 } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
933
934 ks->pass_exception = 1;
935 remcom_in_buffer[0] = 'D';
936 dbg_remove_all_break();
937 kgdb_connected = 0;
938 return 1;
939
940 } else {
941 gdbstub_msg_write("KGDB only knows signal 9 (pass)"
942 " and 15 (pass and disconnect)\n"
943 "Executing a continue without signal passing\n", 0);
944 remcom_in_buffer[0] = 'c';
945 }
946
947 /* Indicate fall through */
948 return -1;
949 }
950
951 /*
952 * This function performs all gdbserial command processing
953 */
gdb_serial_stub(struct kgdb_state * ks)954 int gdb_serial_stub(struct kgdb_state *ks)
955 {
956 int error = 0;
957 int tmp;
958
959 /* Initialize comm buffer and globals. */
960 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
961 kgdb_usethread = kgdb_info[ks->cpu].task;
962 ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
963 ks->pass_exception = 0;
964
965 if (kgdb_connected) {
966 unsigned char thref[BUF_THREAD_ID_SIZE];
967 char *ptr;
968
969 /* Reply to host that an exception has occurred */
970 ptr = remcom_out_buffer;
971 *ptr++ = 'T';
972 ptr = hex_byte_pack(ptr, ks->signo);
973 ptr += strlen(strcpy(ptr, "thread:"));
974 int_to_threadref(thref, shadow_pid(current->pid));
975 ptr = pack_threadid(ptr, thref);
976 *ptr++ = ';';
977 put_packet(remcom_out_buffer);
978 }
979
980 while (1) {
981 error = 0;
982
983 /* Clear the out buffer. */
984 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
985
986 get_packet(remcom_in_buffer);
987
988 switch (remcom_in_buffer[0]) {
989 case '?': /* gdbserial status */
990 gdb_cmd_status(ks);
991 break;
992 case 'g': /* return the value of the CPU registers */
993 gdb_cmd_getregs(ks);
994 break;
995 case 'G': /* set the value of the CPU registers - return OK */
996 gdb_cmd_setregs(ks);
997 break;
998 case 'm': /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */
999 gdb_cmd_memread(ks);
1000 break;
1001 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1002 gdb_cmd_memwrite(ks);
1003 break;
1004 #if DBG_MAX_REG_NUM > 0
1005 case 'p': /* pXX Return gdb register XX (in hex) */
1006 gdb_cmd_reg_get(ks);
1007 break;
1008 case 'P': /* PXX=aaaa Set gdb register XX to aaaa (in hex) */
1009 gdb_cmd_reg_set(ks);
1010 break;
1011 #endif /* DBG_MAX_REG_NUM > 0 */
1012 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1013 gdb_cmd_binwrite(ks);
1014 break;
1015 /* kill or detach. KGDB should treat this like a
1016 * continue.
1017 */
1018 case 'D': /* Debugger detach */
1019 case 'k': /* Debugger detach via kill */
1020 gdb_cmd_detachkill(ks);
1021 goto default_handle;
1022 case 'R': /* Reboot */
1023 if (gdb_cmd_reboot(ks))
1024 goto default_handle;
1025 break;
1026 case 'q': /* query command */
1027 gdb_cmd_query(ks);
1028 break;
1029 case 'H': /* task related */
1030 gdb_cmd_task(ks);
1031 break;
1032 case 'T': /* Query thread status */
1033 gdb_cmd_thread(ks);
1034 break;
1035 case 'z': /* Break point remove */
1036 case 'Z': /* Break point set */
1037 gdb_cmd_break(ks);
1038 break;
1039 #ifdef CONFIG_KGDB_KDB
1040 case '3': /* Escape into back into kdb */
1041 if (remcom_in_buffer[1] == '\0') {
1042 gdb_cmd_detachkill(ks);
1043 return DBG_PASS_EVENT;
1044 }
1045 fallthrough;
1046 #endif
1047 case 'C': /* Exception passing */
1048 tmp = gdb_cmd_exception_pass(ks);
1049 if (tmp > 0)
1050 goto default_handle;
1051 if (tmp == 0)
1052 break;
1053 fallthrough; /* on tmp < 0 */
1054 case 'c': /* Continue packet */
1055 case 's': /* Single step packet */
1056 if (kgdb_contthread && kgdb_contthread != current) {
1057 /* Can't switch threads in kgdb */
1058 error_packet(remcom_out_buffer, -EINVAL);
1059 break;
1060 }
1061 fallthrough; /* to default processing */
1062 default:
1063 default_handle:
1064 error = kgdb_arch_handle_exception(ks->ex_vector,
1065 ks->signo,
1066 ks->err_code,
1067 remcom_in_buffer,
1068 remcom_out_buffer,
1069 ks->linux_regs);
1070 /*
1071 * Leave cmd processing on error, detach,
1072 * kill, continue, or single step.
1073 */
1074 if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1075 remcom_in_buffer[0] == 'k') {
1076 error = 0;
1077 goto kgdb_exit;
1078 }
1079
1080 }
1081
1082 /* reply to the request */
1083 put_packet(remcom_out_buffer);
1084 }
1085
1086 kgdb_exit:
1087 if (ks->pass_exception)
1088 error = 1;
1089 return error;
1090 }
1091
gdbstub_state(struct kgdb_state * ks,char * cmd)1092 int gdbstub_state(struct kgdb_state *ks, char *cmd)
1093 {
1094 int error;
1095
1096 switch (cmd[0]) {
1097 case 'e':
1098 error = kgdb_arch_handle_exception(ks->ex_vector,
1099 ks->signo,
1100 ks->err_code,
1101 remcom_in_buffer,
1102 remcom_out_buffer,
1103 ks->linux_regs);
1104 return error;
1105 case 's':
1106 case 'c':
1107 strscpy(remcom_in_buffer, cmd, sizeof(remcom_in_buffer));
1108 return 0;
1109 case '$':
1110 strscpy(remcom_in_buffer, cmd, sizeof(remcom_in_buffer));
1111 gdbstub_use_prev_in_buf = strlen(remcom_in_buffer);
1112 gdbstub_prev_in_buf_pos = 0;
1113 return 0;
1114 }
1115 dbg_io_ops->write_char('+');
1116 put_packet(remcom_out_buffer);
1117 return 0;
1118 }
1119
1120 /**
1121 * gdbstub_exit - Send an exit message to GDB
1122 * @status: The exit code to report.
1123 */
gdbstub_exit(int status)1124 void gdbstub_exit(int status)
1125 {
1126 unsigned char checksum, ch, buffer[3];
1127 int loop;
1128
1129 if (!kgdb_connected)
1130 return;
1131 kgdb_connected = 0;
1132
1133 if (!dbg_io_ops || dbg_kdb_mode)
1134 return;
1135
1136 buffer[0] = 'W';
1137 buffer[1] = hex_asc_hi(status);
1138 buffer[2] = hex_asc_lo(status);
1139
1140 dbg_io_ops->write_char('$');
1141 checksum = 0;
1142
1143 for (loop = 0; loop < 3; loop++) {
1144 ch = buffer[loop];
1145 checksum += ch;
1146 dbg_io_ops->write_char(ch);
1147 }
1148
1149 dbg_io_ops->write_char('#');
1150 dbg_io_ops->write_char(hex_asc_hi(checksum));
1151 dbg_io_ops->write_char(hex_asc_lo(checksum));
1152
1153 /* make sure the output is flushed, lest the bootloader clobber it */
1154 if (dbg_io_ops->flush)
1155 dbg_io_ops->flush();
1156 }
1157