Separate the gdbstub from the debug core
[sfrench/cifs-2.6.git] / kernel / debug / gdbstub.c
1 /*
2  * Kernel Debug Core
3  *
4  * Maintainer: Jason Wessel <jason.wessel@windriver.com>
5  *
6  * Copyright (C) 2000-2001 VERITAS Software Corporation.
7  * Copyright (C) 2002-2004 Timesys Corporation
8  * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
9  * Copyright (C) 2004 Pavel Machek <pavel@suse.cz>
10  * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
11  * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
12  * Copyright (C) 2005-2009 Wind River Systems, Inc.
13  * Copyright (C) 2007 MontaVista Software, Inc.
14  * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
15  *
16  * Contributors at various stages not listed above:
17  *  Jason Wessel ( jason.wessel@windriver.com )
18  *  George Anzinger <george@mvista.com>
19  *  Anurekh Saxena (anurekh.saxena@timesys.com)
20  *  Lake Stevens Instrument Division (Glenn Engel)
21  *  Jim Kingdon, Cygnus Support.
22  *
23  * Original KGDB stub: David Grothe <dave@gcom.com>,
24  * Tigran Aivazian <tigran@sco.com>
25  *
26  * This file is licensed under the terms of the GNU General Public License
27  * version 2. This program is licensed "as is" without any warranty of any
28  * kind, whether express or implied.
29  */
30
31 #include <linux/kernel.h>
32 #include <linux/kgdb.h>
33 #include <linux/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
45 /* Storage for the registers, in GDB format. */
46 static unsigned long            gdb_regs[(NUMREGBYTES +
47                                         sizeof(unsigned long) - 1) /
48                                         sizeof(unsigned long)];
49
50 /*
51  * GDB remote protocol parser:
52  */
53
54 static int hex(char ch)
55 {
56         if ((ch >= 'a') && (ch <= 'f'))
57                 return ch - 'a' + 10;
58         if ((ch >= '0') && (ch <= '9'))
59                 return ch - '0';
60         if ((ch >= 'A') && (ch <= 'F'))
61                 return ch - 'A' + 10;
62         return -1;
63 }
64
65 /* scan for the sequence $<data>#<checksum> */
66 static void get_packet(char *buffer)
67 {
68         unsigned char checksum;
69         unsigned char xmitcsum;
70         int count;
71         char ch;
72
73         do {
74                 /*
75                  * Spin and wait around for the start character, ignore all
76                  * other characters:
77                  */
78                 while ((ch = (dbg_io_ops->read_char())) != '$')
79                         /* nothing */;
80
81                 kgdb_connected = 1;
82                 checksum = 0;
83                 xmitcsum = -1;
84
85                 count = 0;
86
87                 /*
88                  * now, read until a # or end of buffer is found:
89                  */
90                 while (count < (BUFMAX - 1)) {
91                         ch = dbg_io_ops->read_char();
92                         if (ch == '#')
93                                 break;
94                         checksum = checksum + ch;
95                         buffer[count] = ch;
96                         count = count + 1;
97                 }
98                 buffer[count] = 0;
99
100                 if (ch == '#') {
101                         xmitcsum = hex(dbg_io_ops->read_char()) << 4;
102                         xmitcsum += hex(dbg_io_ops->read_char());
103
104                         if (checksum != xmitcsum)
105                                 /* failed checksum */
106                                 dbg_io_ops->write_char('-');
107                         else
108                                 /* successful transfer */
109                                 dbg_io_ops->write_char('+');
110                         if (dbg_io_ops->flush)
111                                 dbg_io_ops->flush();
112                 }
113         } while (checksum != xmitcsum);
114 }
115
116 /*
117  * Send the packet in buffer.
118  * Check for gdb connection if asked for.
119  */
120 static void put_packet(char *buffer)
121 {
122         unsigned char checksum;
123         int count;
124         char ch;
125
126         /*
127          * $<packet info>#<checksum>.
128          */
129         while (1) {
130                 dbg_io_ops->write_char('$');
131                 checksum = 0;
132                 count = 0;
133
134                 while ((ch = buffer[count])) {
135                         dbg_io_ops->write_char(ch);
136                         checksum += ch;
137                         count++;
138                 }
139
140                 dbg_io_ops->write_char('#');
141                 dbg_io_ops->write_char(hex_asc_hi(checksum));
142                 dbg_io_ops->write_char(hex_asc_lo(checksum));
143                 if (dbg_io_ops->flush)
144                         dbg_io_ops->flush();
145
146                 /* Now see what we get in reply. */
147                 ch = dbg_io_ops->read_char();
148
149                 if (ch == 3)
150                         ch = dbg_io_ops->read_char();
151
152                 /* If we get an ACK, we are done. */
153                 if (ch == '+')
154                         return;
155
156                 /*
157                  * If we get the start of another packet, this means
158                  * that GDB is attempting to reconnect.  We will NAK
159                  * the packet being sent, and stop trying to send this
160                  * packet.
161                  */
162                 if (ch == '$') {
163                         dbg_io_ops->write_char('-');
164                         if (dbg_io_ops->flush)
165                                 dbg_io_ops->flush();
166                         return;
167                 }
168         }
169 }
170
171 static char gdbmsgbuf[BUFMAX + 1];
172
173 void gdbstub_msg_write(const char *s, int len)
174 {
175         char *bufptr;
176         int wcount;
177         int i;
178
179         /* 'O'utput */
180         gdbmsgbuf[0] = 'O';
181
182         /* Fill and send buffers... */
183         while (len > 0) {
184                 bufptr = gdbmsgbuf + 1;
185
186                 /* Calculate how many this time */
187                 if ((len << 1) > (BUFMAX - 2))
188                         wcount = (BUFMAX - 2) >> 1;
189                 else
190                         wcount = len;
191
192                 /* Pack in hex chars */
193                 for (i = 0; i < wcount; i++)
194                         bufptr = pack_hex_byte(bufptr, s[i]);
195                 *bufptr = '\0';
196
197                 /* Move up */
198                 s += wcount;
199                 len -= wcount;
200
201                 /* Write packet */
202                 put_packet(gdbmsgbuf);
203         }
204 }
205
206 /*
207  * Convert the memory pointed to by mem into hex, placing result in
208  * buf.  Return a pointer to the last char put in buf (null). May
209  * return an error.
210  */
211 int kgdb_mem2hex(char *mem, char *buf, int count)
212 {
213         char *tmp;
214         int err;
215
216         /*
217          * We use the upper half of buf as an intermediate buffer for the
218          * raw memory copy.  Hex conversion will work against this one.
219          */
220         tmp = buf + count;
221
222         err = probe_kernel_read(tmp, mem, count);
223         if (!err) {
224                 while (count > 0) {
225                         buf = pack_hex_byte(buf, *tmp);
226                         tmp++;
227                         count--;
228                 }
229
230                 *buf = 0;
231         }
232
233         return err;
234 }
235
236 /*
237  * Convert the hex array pointed to by buf into binary to be placed in
238  * mem.  Return a pointer to the character AFTER the last byte
239  * written.  May return an error.
240  */
241 int kgdb_hex2mem(char *buf, char *mem, int count)
242 {
243         char *tmp_raw;
244         char *tmp_hex;
245
246         /*
247          * We use the upper half of buf as an intermediate buffer for the
248          * raw memory that is converted from hex.
249          */
250         tmp_raw = buf + count * 2;
251
252         tmp_hex = tmp_raw - 1;
253         while (tmp_hex >= buf) {
254                 tmp_raw--;
255                 *tmp_raw = hex(*tmp_hex--);
256                 *tmp_raw |= hex(*tmp_hex--) << 4;
257         }
258
259         return probe_kernel_write(mem, tmp_raw, count);
260 }
261
262 /*
263  * While we find nice hex chars, build a long_val.
264  * Return number of chars processed.
265  */
266 int kgdb_hex2long(char **ptr, unsigned long *long_val)
267 {
268         int hex_val;
269         int num = 0;
270         int negate = 0;
271
272         *long_val = 0;
273
274         if (**ptr == '-') {
275                 negate = 1;
276                 (*ptr)++;
277         }
278         while (**ptr) {
279                 hex_val = hex(**ptr);
280                 if (hex_val < 0)
281                         break;
282
283                 *long_val = (*long_val << 4) | hex_val;
284                 num++;
285                 (*ptr)++;
286         }
287
288         if (negate)
289                 *long_val = -*long_val;
290
291         return num;
292 }
293
294 /*
295  * Copy the binary array pointed to by buf into mem.  Fix $, #, and
296  * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success.
297  * The input buf is overwitten with the result to write to mem.
298  */
299 static int kgdb_ebin2mem(char *buf, char *mem, int count)
300 {
301         int size = 0;
302         char *c = buf;
303
304         while (count-- > 0) {
305                 c[size] = *buf++;
306                 if (c[size] == 0x7d)
307                         c[size] = *buf++ ^ 0x20;
308                 size++;
309         }
310
311         return probe_kernel_write(mem, c, size);
312 }
313
314 /* Write memory due to an 'M' or 'X' packet. */
315 static int write_mem_msg(int binary)
316 {
317         char *ptr = &remcom_in_buffer[1];
318         unsigned long addr;
319         unsigned long length;
320         int err;
321
322         if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
323             kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
324                 if (binary)
325                         err = kgdb_ebin2mem(ptr, (char *)addr, length);
326                 else
327                         err = kgdb_hex2mem(ptr, (char *)addr, length);
328                 if (err)
329                         return err;
330                 if (CACHE_FLUSH_IS_SAFE)
331                         flush_icache_range(addr, addr + length);
332                 return 0;
333         }
334
335         return -EINVAL;
336 }
337
338 static void error_packet(char *pkt, int error)
339 {
340         error = -error;
341         pkt[0] = 'E';
342         pkt[1] = hex_asc[(error / 10)];
343         pkt[2] = hex_asc[(error % 10)];
344         pkt[3] = '\0';
345 }
346
347 /*
348  * Thread ID accessors. We represent a flat TID space to GDB, where
349  * the per CPU idle threads (which under Linux all have PID 0) are
350  * remapped to negative TIDs.
351  */
352
353 #define BUF_THREAD_ID_SIZE      16
354
355 static char *pack_threadid(char *pkt, unsigned char *id)
356 {
357         char *limit;
358
359         limit = pkt + BUF_THREAD_ID_SIZE;
360         while (pkt < limit)
361                 pkt = pack_hex_byte(pkt, *id++);
362
363         return pkt;
364 }
365
366 static void int_to_threadref(unsigned char *id, int value)
367 {
368         unsigned char *scan;
369         int i = 4;
370
371         scan = (unsigned char *)id;
372         while (i--)
373                 *scan++ = 0;
374         put_unaligned_be32(value, scan);
375 }
376
377 static struct task_struct *getthread(struct pt_regs *regs, int tid)
378 {
379         /*
380          * Non-positive TIDs are remapped to the cpu shadow information
381          */
382         if (tid == 0 || tid == -1)
383                 tid = -atomic_read(&kgdb_active) - 2;
384         if (tid < -1 && tid > -NR_CPUS - 2) {
385                 if (kgdb_info[-tid - 2].task)
386                         return kgdb_info[-tid - 2].task;
387                 else
388                         return idle_task(-tid - 2);
389         }
390         if (tid <= 0) {
391                 printk(KERN_ERR "KGDB: Internal thread select error\n");
392                 dump_stack();
393                 return NULL;
394         }
395
396         /*
397          * find_task_by_pid_ns() does not take the tasklist lock anymore
398          * but is nicely RCU locked - hence is a pretty resilient
399          * thing to use:
400          */
401         return find_task_by_pid_ns(tid, &init_pid_ns);
402 }
403
404
405 /*
406  * Remap normal tasks to their real PID,
407  * CPU shadow threads are mapped to -CPU - 2
408  */
409 static inline int shadow_pid(int realpid)
410 {
411         if (realpid)
412                 return realpid;
413
414         return -raw_smp_processor_id() - 2;
415 }
416
417 /*
418  * All the functions that start with gdb_cmd are the various
419  * operations to implement the handlers for the gdbserial protocol
420  * where KGDB is communicating with an external debugger
421  */
422
423 /* Handle the '?' status packets */
424 static void gdb_cmd_status(struct kgdb_state *ks)
425 {
426         /*
427          * We know that this packet is only sent
428          * during initial connect.  So to be safe,
429          * we clear out our breakpoints now in case
430          * GDB is reconnecting.
431          */
432         dbg_remove_all_break();
433
434         remcom_out_buffer[0] = 'S';
435         pack_hex_byte(&remcom_out_buffer[1], ks->signo);
436 }
437
438 /* Handle the 'g' get registers request */
439 static void gdb_cmd_getregs(struct kgdb_state *ks)
440 {
441         struct task_struct *thread;
442         void *local_debuggerinfo;
443         int i;
444
445         thread = kgdb_usethread;
446         if (!thread) {
447                 thread = kgdb_info[ks->cpu].task;
448                 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
449         } else {
450                 local_debuggerinfo = NULL;
451                 for_each_online_cpu(i) {
452                         /*
453                          * Try to find the task on some other
454                          * or possibly this node if we do not
455                          * find the matching task then we try
456                          * to approximate the results.
457                          */
458                         if (thread == kgdb_info[i].task)
459                                 local_debuggerinfo = kgdb_info[i].debuggerinfo;
460                 }
461         }
462
463         /*
464          * All threads that don't have debuggerinfo should be
465          * in schedule() sleeping, since all other CPUs
466          * are in kgdb_wait, and thus have debuggerinfo.
467          */
468         if (local_debuggerinfo) {
469                 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
470         } else {
471                 /*
472                  * Pull stuff saved during switch_to; nothing
473                  * else is accessible (or even particularly
474                  * relevant).
475                  *
476                  * This should be enough for a stack trace.
477                  */
478                 sleeping_thread_to_gdb_regs(gdb_regs, thread);
479         }
480         kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
481 }
482
483 /* Handle the 'G' set registers request */
484 static void gdb_cmd_setregs(struct kgdb_state *ks)
485 {
486         kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
487
488         if (kgdb_usethread && kgdb_usethread != current) {
489                 error_packet(remcom_out_buffer, -EINVAL);
490         } else {
491                 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
492                 strcpy(remcom_out_buffer, "OK");
493         }
494 }
495
496 /* Handle the 'm' memory read bytes */
497 static void gdb_cmd_memread(struct kgdb_state *ks)
498 {
499         char *ptr = &remcom_in_buffer[1];
500         unsigned long length;
501         unsigned long addr;
502         int err;
503
504         if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
505                                         kgdb_hex2long(&ptr, &length) > 0) {
506                 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
507                 if (err)
508                         error_packet(remcom_out_buffer, err);
509         } else {
510                 error_packet(remcom_out_buffer, -EINVAL);
511         }
512 }
513
514 /* Handle the 'M' memory write bytes */
515 static void gdb_cmd_memwrite(struct kgdb_state *ks)
516 {
517         int err = write_mem_msg(0);
518
519         if (err)
520                 error_packet(remcom_out_buffer, err);
521         else
522                 strcpy(remcom_out_buffer, "OK");
523 }
524
525 /* Handle the 'X' memory binary write bytes */
526 static void gdb_cmd_binwrite(struct kgdb_state *ks)
527 {
528         int err = write_mem_msg(1);
529
530         if (err)
531                 error_packet(remcom_out_buffer, err);
532         else
533                 strcpy(remcom_out_buffer, "OK");
534 }
535
536 /* Handle the 'D' or 'k', detach or kill packets */
537 static void gdb_cmd_detachkill(struct kgdb_state *ks)
538 {
539         int error;
540
541         /* The detach case */
542         if (remcom_in_buffer[0] == 'D') {
543                 error = dbg_remove_all_break();
544                 if (error < 0) {
545                         error_packet(remcom_out_buffer, error);
546                 } else {
547                         strcpy(remcom_out_buffer, "OK");
548                         kgdb_connected = 0;
549                 }
550                 put_packet(remcom_out_buffer);
551         } else {
552                 /*
553                  * Assume the kill case, with no exit code checking,
554                  * trying to force detach the debugger:
555                  */
556                 dbg_remove_all_break();
557                 kgdb_connected = 0;
558         }
559 }
560
561 /* Handle the 'R' reboot packets */
562 static int gdb_cmd_reboot(struct kgdb_state *ks)
563 {
564         /* For now, only honor R0 */
565         if (strcmp(remcom_in_buffer, "R0") == 0) {
566                 printk(KERN_CRIT "Executing emergency reboot\n");
567                 strcpy(remcom_out_buffer, "OK");
568                 put_packet(remcom_out_buffer);
569
570                 /*
571                  * Execution should not return from
572                  * machine_emergency_restart()
573                  */
574                 machine_emergency_restart();
575                 kgdb_connected = 0;
576
577                 return 1;
578         }
579         return 0;
580 }
581
582 /* Handle the 'q' query packets */
583 static void gdb_cmd_query(struct kgdb_state *ks)
584 {
585         struct task_struct *g;
586         struct task_struct *p;
587         unsigned char thref[8];
588         char *ptr;
589         int i;
590         int cpu;
591         int finished = 0;
592
593         switch (remcom_in_buffer[1]) {
594         case 's':
595         case 'f':
596                 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
597                         error_packet(remcom_out_buffer, -EINVAL);
598                         break;
599                 }
600
601                 i = 0;
602                 remcom_out_buffer[0] = 'm';
603                 ptr = remcom_out_buffer + 1;
604                 if (remcom_in_buffer[1] == 'f') {
605                         /* Each cpu is a shadow thread */
606                         for_each_online_cpu(cpu) {
607                                 ks->thr_query = 0;
608                                 int_to_threadref(thref, -cpu - 2);
609                                 pack_threadid(ptr, thref);
610                                 ptr += BUF_THREAD_ID_SIZE;
611                                 *(ptr++) = ',';
612                                 i++;
613                         }
614                 }
615
616                 do_each_thread(g, p) {
617                         if (i >= ks->thr_query && !finished) {
618                                 int_to_threadref(thref, p->pid);
619                                 pack_threadid(ptr, thref);
620                                 ptr += BUF_THREAD_ID_SIZE;
621                                 *(ptr++) = ',';
622                                 ks->thr_query++;
623                                 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
624                                         finished = 1;
625                         }
626                         i++;
627                 } while_each_thread(g, p);
628
629                 *(--ptr) = '\0';
630                 break;
631
632         case 'C':
633                 /* Current thread id */
634                 strcpy(remcom_out_buffer, "QC");
635                 ks->threadid = shadow_pid(current->pid);
636                 int_to_threadref(thref, ks->threadid);
637                 pack_threadid(remcom_out_buffer + 2, thref);
638                 break;
639         case 'T':
640                 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
641                         error_packet(remcom_out_buffer, -EINVAL);
642                         break;
643                 }
644                 ks->threadid = 0;
645                 ptr = remcom_in_buffer + 17;
646                 kgdb_hex2long(&ptr, &ks->threadid);
647                 if (!getthread(ks->linux_regs, ks->threadid)) {
648                         error_packet(remcom_out_buffer, -EINVAL);
649                         break;
650                 }
651                 if ((int)ks->threadid > 0) {
652                         kgdb_mem2hex(getthread(ks->linux_regs,
653                                         ks->threadid)->comm,
654                                         remcom_out_buffer, 16);
655                 } else {
656                         static char tmpstr[23 + BUF_THREAD_ID_SIZE];
657
658                         sprintf(tmpstr, "shadowCPU%d",
659                                         (int)(-ks->threadid - 2));
660                         kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
661                 }
662                 break;
663         }
664 }
665
666 /* Handle the 'H' task query packets */
667 static void gdb_cmd_task(struct kgdb_state *ks)
668 {
669         struct task_struct *thread;
670         char *ptr;
671
672         switch (remcom_in_buffer[1]) {
673         case 'g':
674                 ptr = &remcom_in_buffer[2];
675                 kgdb_hex2long(&ptr, &ks->threadid);
676                 thread = getthread(ks->linux_regs, ks->threadid);
677                 if (!thread && ks->threadid > 0) {
678                         error_packet(remcom_out_buffer, -EINVAL);
679                         break;
680                 }
681                 kgdb_usethread = thread;
682                 ks->kgdb_usethreadid = ks->threadid;
683                 strcpy(remcom_out_buffer, "OK");
684                 break;
685         case 'c':
686                 ptr = &remcom_in_buffer[2];
687                 kgdb_hex2long(&ptr, &ks->threadid);
688                 if (!ks->threadid) {
689                         kgdb_contthread = NULL;
690                 } else {
691                         thread = getthread(ks->linux_regs, ks->threadid);
692                         if (!thread && ks->threadid > 0) {
693                                 error_packet(remcom_out_buffer, -EINVAL);
694                                 break;
695                         }
696                         kgdb_contthread = thread;
697                 }
698                 strcpy(remcom_out_buffer, "OK");
699                 break;
700         }
701 }
702
703 /* Handle the 'T' thread query packets */
704 static void gdb_cmd_thread(struct kgdb_state *ks)
705 {
706         char *ptr = &remcom_in_buffer[1];
707         struct task_struct *thread;
708
709         kgdb_hex2long(&ptr, &ks->threadid);
710         thread = getthread(ks->linux_regs, ks->threadid);
711         if (thread)
712                 strcpy(remcom_out_buffer, "OK");
713         else
714                 error_packet(remcom_out_buffer, -EINVAL);
715 }
716
717 /* Handle the 'z' or 'Z' breakpoint remove or set packets */
718 static void gdb_cmd_break(struct kgdb_state *ks)
719 {
720         /*
721          * Since GDB-5.3, it's been drafted that '0' is a software
722          * breakpoint, '1' is a hardware breakpoint, so let's do that.
723          */
724         char *bpt_type = &remcom_in_buffer[1];
725         char *ptr = &remcom_in_buffer[2];
726         unsigned long addr;
727         unsigned long length;
728         int error = 0;
729
730         if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
731                 /* Unsupported */
732                 if (*bpt_type > '4')
733                         return;
734         } else {
735                 if (*bpt_type != '0' && *bpt_type != '1')
736                         /* Unsupported. */
737                         return;
738         }
739
740         /*
741          * Test if this is a hardware breakpoint, and
742          * if we support it:
743          */
744         if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
745                 /* Unsupported. */
746                 return;
747
748         if (*(ptr++) != ',') {
749                 error_packet(remcom_out_buffer, -EINVAL);
750                 return;
751         }
752         if (!kgdb_hex2long(&ptr, &addr)) {
753                 error_packet(remcom_out_buffer, -EINVAL);
754                 return;
755         }
756         if (*(ptr++) != ',' ||
757                 !kgdb_hex2long(&ptr, &length)) {
758                 error_packet(remcom_out_buffer, -EINVAL);
759                 return;
760         }
761
762         if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
763                 error = dbg_set_sw_break(addr);
764         else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
765                 error = dbg_remove_sw_break(addr);
766         else if (remcom_in_buffer[0] == 'Z')
767                 error = arch_kgdb_ops.set_hw_breakpoint(addr,
768                         (int)length, *bpt_type - '0');
769         else if (remcom_in_buffer[0] == 'z')
770                 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
771                         (int) length, *bpt_type - '0');
772
773         if (error == 0)
774                 strcpy(remcom_out_buffer, "OK");
775         else
776                 error_packet(remcom_out_buffer, error);
777 }
778
779 /* Handle the 'C' signal / exception passing packets */
780 static int gdb_cmd_exception_pass(struct kgdb_state *ks)
781 {
782         /* C09 == pass exception
783          * C15 == detach kgdb, pass exception
784          */
785         if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
786
787                 ks->pass_exception = 1;
788                 remcom_in_buffer[0] = 'c';
789
790         } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
791
792                 ks->pass_exception = 1;
793                 remcom_in_buffer[0] = 'D';
794                 dbg_remove_all_break();
795                 kgdb_connected = 0;
796                 return 1;
797
798         } else {
799                 gdbstub_msg_write("KGDB only knows signal 9 (pass)"
800                         " and 15 (pass and disconnect)\n"
801                         "Executing a continue without signal passing\n", 0);
802                 remcom_in_buffer[0] = 'c';
803         }
804
805         /* Indicate fall through */
806         return -1;
807 }
808
809 /*
810  * This function performs all gdbserial command procesing
811  */
812 int gdb_serial_stub(struct kgdb_state *ks)
813 {
814         int error = 0;
815         int tmp;
816
817         /* Clear the out buffer. */
818         memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
819
820         if (kgdb_connected) {
821                 unsigned char thref[8];
822                 char *ptr;
823
824                 /* Reply to host that an exception has occurred */
825                 ptr = remcom_out_buffer;
826                 *ptr++ = 'T';
827                 ptr = pack_hex_byte(ptr, ks->signo);
828                 ptr += strlen(strcpy(ptr, "thread:"));
829                 int_to_threadref(thref, shadow_pid(current->pid));
830                 ptr = pack_threadid(ptr, thref);
831                 *ptr++ = ';';
832                 put_packet(remcom_out_buffer);
833         }
834
835         kgdb_usethread = kgdb_info[ks->cpu].task;
836         ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
837         ks->pass_exception = 0;
838
839         while (1) {
840                 error = 0;
841
842                 /* Clear the out buffer. */
843                 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
844
845                 get_packet(remcom_in_buffer);
846
847                 switch (remcom_in_buffer[0]) {
848                 case '?': /* gdbserial status */
849                         gdb_cmd_status(ks);
850                         break;
851                 case 'g': /* return the value of the CPU registers */
852                         gdb_cmd_getregs(ks);
853                         break;
854                 case 'G': /* set the value of the CPU registers - return OK */
855                         gdb_cmd_setregs(ks);
856                         break;
857                 case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
858                         gdb_cmd_memread(ks);
859                         break;
860                 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
861                         gdb_cmd_memwrite(ks);
862                         break;
863                 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
864                         gdb_cmd_binwrite(ks);
865                         break;
866                         /* kill or detach. KGDB should treat this like a
867                          * continue.
868                          */
869                 case 'D': /* Debugger detach */
870                 case 'k': /* Debugger detach via kill */
871                         gdb_cmd_detachkill(ks);
872                         goto default_handle;
873                 case 'R': /* Reboot */
874                         if (gdb_cmd_reboot(ks))
875                                 goto default_handle;
876                         break;
877                 case 'q': /* query command */
878                         gdb_cmd_query(ks);
879                         break;
880                 case 'H': /* task related */
881                         gdb_cmd_task(ks);
882                         break;
883                 case 'T': /* Query thread status */
884                         gdb_cmd_thread(ks);
885                         break;
886                 case 'z': /* Break point remove */
887                 case 'Z': /* Break point set */
888                         gdb_cmd_break(ks);
889                         break;
890                 case 'C': /* Exception passing */
891                         tmp = gdb_cmd_exception_pass(ks);
892                         if (tmp > 0)
893                                 goto default_handle;
894                         if (tmp == 0)
895                                 break;
896                         /* Fall through on tmp < 0 */
897                 case 'c': /* Continue packet */
898                 case 's': /* Single step packet */
899                         if (kgdb_contthread && kgdb_contthread != current) {
900                                 /* Can't switch threads in kgdb */
901                                 error_packet(remcom_out_buffer, -EINVAL);
902                                 break;
903                         }
904                         dbg_activate_sw_breakpoints();
905                         /* Fall through to default processing */
906                 default:
907 default_handle:
908                         error = kgdb_arch_handle_exception(ks->ex_vector,
909                                                 ks->signo,
910                                                 ks->err_code,
911                                                 remcom_in_buffer,
912                                                 remcom_out_buffer,
913                                                 ks->linux_regs);
914                         /*
915                          * Leave cmd processing on error, detach,
916                          * kill, continue, or single step.
917                          */
918                         if (error >= 0 || remcom_in_buffer[0] == 'D' ||
919                             remcom_in_buffer[0] == 'k') {
920                                 error = 0;
921                                 goto kgdb_exit;
922                         }
923
924                 }
925
926                 /* reply to the request */
927                 put_packet(remcom_out_buffer);
928         }
929
930 kgdb_exit:
931         if (ks->pass_exception)
932                 error = 1;
933         return error;
934 }