Merge tag 'iommu-updates-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/joro...
[linux-2.6-microblaze.git] / kernel / debug / gdbstub.c
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
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
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 $<data>#<checksum> */
88 static void get_packet(char *buffer)
89 {
90         unsigned char checksum;
91         unsigned char xmitcsum;
92         int count;
93         char ch;
94
95         do {
96                 /*
97                  * Spin and wait around for the start character, ignore all
98                  * other characters:
99                  */
100                 while ((ch = (gdbstub_read_wait())) != '$')
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  */
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
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  */
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  */
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  */
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  */
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
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
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. */
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
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
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
425 static void int_to_threadref(unsigned char *id, int value)
426 {
427         put_unaligned_be32(value, id);
428 }
429
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  */
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 */
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
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 */
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 */
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 */
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 */
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
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 */
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, &regnum);
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 */
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, &regnum);
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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  */
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
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  */
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 }