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Linux/kernel/debug/gdbstub.c

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  1 /*
  2  * Kernel Debug Core
  3  *
  4  * Maintainer: Jason Wessel <jason.wessel@windriver.com>
  5  *
  6  * Copyright (C) 2000-2001 VERITAS Software Corporation.
  7  * Copyright (C) 2002-2004 Timesys Corporation
  8  * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
  9  * Copyright (C) 2004 Pavel Machek <pavel@ucw.cz>
 10  * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
 11  * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
 12  * Copyright (C) 2005-2009 Wind River Systems, Inc.
 13  * Copyright (C) 2007 MontaVista Software, Inc.
 14  * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 15  *
 16  * Contributors at various stages not listed above:
 17  *  Jason Wessel ( jason.wessel@windriver.com )
 18  *  George Anzinger <george@mvista.com>
 19  *  Anurekh Saxena (anurekh.saxena@timesys.com)
 20  *  Lake Stevens Instrument Division (Glenn Engel)
 21  *  Jim Kingdon, Cygnus Support.
 22  *
 23  * Original KGDB stub: David Grothe <dave@gcom.com>,
 24  * Tigran Aivazian <tigran@sco.com>
 25  *
 26  * This file is licensed under the terms of the GNU General Public License
 27  * version 2. This program is licensed "as is" without any warranty of any
 28  * kind, whether express or implied.
 29  */
 30 
 31 #include <linux/kernel.h>
 32 #include <linux/kgdb.h>
 33 #include <linux/kdb.h>
 34 #include <linux/serial_core.h>
 35 #include <linux/reboot.h>
 36 #include <linux/uaccess.h>
 37 #include <asm/cacheflush.h>
 38 #include <asm/unaligned.h>
 39 #include "debug_core.h"
 40 
 41 #define KGDB_MAX_THREAD_QUERY 17
 42 
 43 /* Our I/O buffers. */
 44 static char                     remcom_in_buffer[BUFMAX];
 45 static char                     remcom_out_buffer[BUFMAX];
 46 static int                      gdbstub_use_prev_in_buf;
 47 static int                      gdbstub_prev_in_buf_pos;
 48 
 49 /* Storage for the registers, in GDB format. */
 50 static unsigned long            gdb_regs[(NUMREGBYTES +
 51                                         sizeof(unsigned long) - 1) /
 52                                         sizeof(unsigned long)];
 53 
 54 /*
 55  * GDB remote protocol parser:
 56  */
 57 
 58 #ifdef CONFIG_KGDB_KDB
 59 static int gdbstub_read_wait(void)
 60 {
 61         int ret = -1;
 62         int i;
 63 
 64         if (unlikely(gdbstub_use_prev_in_buf)) {
 65                 if (gdbstub_prev_in_buf_pos < gdbstub_use_prev_in_buf)
 66                         return remcom_in_buffer[gdbstub_prev_in_buf_pos++];
 67                 else
 68                         gdbstub_use_prev_in_buf = 0;
 69         }
 70 
 71         /* poll any additional I/O interfaces that are defined */
 72         while (ret < 0)
 73                 for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
 74                         ret = kdb_poll_funcs[i]();
 75                         if (ret > 0)
 76                                 break;
 77                 }
 78         return ret;
 79 }
 80 #else
 81 static int gdbstub_read_wait(void)
 82 {
 83         int ret = dbg_io_ops->read_char();
 84         while (ret == NO_POLL_CHAR)
 85                 ret = dbg_io_ops->read_char();
 86         return ret;
 87 }
 88 #endif
 89 /* scan for the sequence $<data>#<checksum> */
 90 static void get_packet(char *buffer)
 91 {
 92         unsigned char checksum;
 93         unsigned char xmitcsum;
 94         int count;
 95         char ch;
 96 
 97         do {
 98                 /*
 99                  * Spin and wait around for the start character, ignore all
100                  * other characters:
101                  */
102                 while ((ch = (gdbstub_read_wait())) != '$')
103                         /* nothing */;
104 
105                 kgdb_connected = 1;
106                 checksum = 0;
107                 xmitcsum = -1;
108 
109                 count = 0;
110 
111                 /*
112                  * now, read until a # or end of buffer is found:
113                  */
114                 while (count < (BUFMAX - 1)) {
115                         ch = gdbstub_read_wait();
116                         if (ch == '#')
117                                 break;
118                         checksum = checksum + ch;
119                         buffer[count] = ch;
120                         count = count + 1;
121                 }
122 
123                 if (ch == '#') {
124                         xmitcsum = hex_to_bin(gdbstub_read_wait()) << 4;
125                         xmitcsum += hex_to_bin(gdbstub_read_wait());
126 
127                         if (checksum != xmitcsum)
128                                 /* failed checksum */
129                                 dbg_io_ops->write_char('-');
130                         else
131                                 /* successful transfer */
132                                 dbg_io_ops->write_char('+');
133                         if (dbg_io_ops->flush)
134                                 dbg_io_ops->flush();
135                 }
136                 buffer[count] = 0;
137         } while (checksum != xmitcsum);
138 }
139 
140 /*
141  * Send the packet in buffer.
142  * Check for gdb connection if asked for.
143  */
144 static void put_packet(char *buffer)
145 {
146         unsigned char checksum;
147         int count;
148         char ch;
149 
150         /*
151          * $<packet info>#<checksum>.
152          */
153         while (1) {
154                 dbg_io_ops->write_char('$');
155                 checksum = 0;
156                 count = 0;
157 
158                 while ((ch = buffer[count])) {
159                         dbg_io_ops->write_char(ch);
160                         checksum += ch;
161                         count++;
162                 }
163 
164                 dbg_io_ops->write_char('#');
165                 dbg_io_ops->write_char(hex_asc_hi(checksum));
166                 dbg_io_ops->write_char(hex_asc_lo(checksum));
167                 if (dbg_io_ops->flush)
168                         dbg_io_ops->flush();
169 
170                 /* Now see what we get in reply. */
171                 ch = gdbstub_read_wait();
172 
173                 if (ch == 3)
174                         ch = gdbstub_read_wait();
175 
176                 /* If we get an ACK, we are done. */
177                 if (ch == '+')
178                         return;
179 
180                 /*
181                  * If we get the start of another packet, this means
182                  * that GDB is attempting to reconnect.  We will NAK
183                  * the packet being sent, and stop trying to send this
184                  * packet.
185                  */
186                 if (ch == '$') {
187                         dbg_io_ops->write_char('-');
188                         if (dbg_io_ops->flush)
189                                 dbg_io_ops->flush();
190                         return;
191                 }
192         }
193 }
194 
195 static char gdbmsgbuf[BUFMAX + 1];
196 
197 void gdbstub_msg_write(const char *s, int len)
198 {
199         char *bufptr;
200         int wcount;
201         int i;
202 
203         if (len == 0)
204                 len = strlen(s);
205 
206         /* 'O'utput */
207         gdbmsgbuf[0] = 'O';
208 
209         /* Fill and send buffers... */
210         while (len > 0) {
211                 bufptr = gdbmsgbuf + 1;
212 
213                 /* Calculate how many this time */
214                 if ((len << 1) > (BUFMAX - 2))
215                         wcount = (BUFMAX - 2) >> 1;
216                 else
217                         wcount = len;
218 
219                 /* Pack in hex chars */
220                 for (i = 0; i < wcount; i++)
221                         bufptr = hex_byte_pack(bufptr, s[i]);
222                 *bufptr = '\0';
223 
224                 /* Move up */
225                 s += wcount;
226                 len -= wcount;
227 
228                 /* Write packet */
229                 put_packet(gdbmsgbuf);
230         }
231 }
232 
233 /*
234  * Convert the memory pointed to by mem into hex, placing result in
235  * buf.  Return a pointer to the last char put in buf (null). May
236  * return an error.
237  */
238 char *kgdb_mem2hex(char *mem, char *buf, int count)
239 {
240         char *tmp;
241         int err;
242 
243         /*
244          * We use the upper half of buf as an intermediate buffer for the
245          * raw memory copy.  Hex conversion will work against this one.
246          */
247         tmp = buf + count;
248 
249         err = probe_kernel_read(tmp, mem, count);
250         if (err)
251                 return NULL;
252         while (count > 0) {
253                 buf = hex_byte_pack(buf, *tmp);
254                 tmp++;
255                 count--;
256         }
257         *buf = 0;
258 
259         return buf;
260 }
261 
262 /*
263  * Convert the hex array pointed to by buf into binary to be placed in
264  * mem.  Return a pointer to the character AFTER the last byte
265  * written.  May return an error.
266  */
267 int kgdb_hex2mem(char *buf, char *mem, int count)
268 {
269         char *tmp_raw;
270         char *tmp_hex;
271 
272         /*
273          * We use the upper half of buf as an intermediate buffer for the
274          * raw memory that is converted from hex.
275          */
276         tmp_raw = buf + count * 2;
277 
278         tmp_hex = tmp_raw - 1;
279         while (tmp_hex >= buf) {
280                 tmp_raw--;
281                 *tmp_raw = hex_to_bin(*tmp_hex--);
282                 *tmp_raw |= hex_to_bin(*tmp_hex--) << 4;
283         }
284 
285         return probe_kernel_write(mem, tmp_raw, count);
286 }
287 
288 /*
289  * While we find nice hex chars, build a long_val.
290  * Return number of chars processed.
291  */
292 int kgdb_hex2long(char **ptr, unsigned long *long_val)
293 {
294         int hex_val;
295         int num = 0;
296         int negate = 0;
297 
298         *long_val = 0;
299 
300         if (**ptr == '-') {
301                 negate = 1;
302                 (*ptr)++;
303         }
304         while (**ptr) {
305                 hex_val = hex_to_bin(**ptr);
306                 if (hex_val < 0)
307                         break;
308 
309                 *long_val = (*long_val << 4) | hex_val;
310                 num++;
311                 (*ptr)++;
312         }
313 
314         if (negate)
315                 *long_val = -*long_val;
316 
317         return num;
318 }
319 
320 /*
321  * Copy the binary array pointed to by buf into mem.  Fix $, #, and
322  * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success.
323  * The input buf is overwitten with the result to write to mem.
324  */
325 static int kgdb_ebin2mem(char *buf, char *mem, int count)
326 {
327         int size = 0;
328         char *c = buf;
329 
330         while (count-- > 0) {
331                 c[size] = *buf++;
332                 if (c[size] == 0x7d)
333                         c[size] = *buf++ ^ 0x20;
334                 size++;
335         }
336 
337         return probe_kernel_write(mem, c, size);
338 }
339 
340 #if DBG_MAX_REG_NUM > 0
341 void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
342 {
343         int i;
344         int idx = 0;
345         char *ptr = (char *)gdb_regs;
346 
347         for (i = 0; i < DBG_MAX_REG_NUM; i++) {
348                 dbg_get_reg(i, ptr + idx, regs);
349                 idx += dbg_reg_def[i].size;
350         }
351 }
352 
353 void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
354 {
355         int i;
356         int idx = 0;
357         char *ptr = (char *)gdb_regs;
358 
359         for (i = 0; i < DBG_MAX_REG_NUM; i++) {
360                 dbg_set_reg(i, ptr + idx, regs);
361                 idx += dbg_reg_def[i].size;
362         }
363 }
364 #endif /* DBG_MAX_REG_NUM > 0 */
365 
366 /* Write memory due to an 'M' or 'X' packet. */
367 static int write_mem_msg(int binary)
368 {
369         char *ptr = &remcom_in_buffer[1];
370         unsigned long addr;
371         unsigned long length;
372         int err;
373 
374         if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
375             kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
376                 if (binary)
377                         err = kgdb_ebin2mem(ptr, (char *)addr, length);
378                 else
379                         err = kgdb_hex2mem(ptr, (char *)addr, length);
380                 if (err)
381                         return err;
382                 if (CACHE_FLUSH_IS_SAFE)
383                         flush_icache_range(addr, addr + length);
384                 return 0;
385         }
386 
387         return -EINVAL;
388 }
389 
390 static void error_packet(char *pkt, int error)
391 {
392         error = -error;
393         pkt[0] = 'E';
394         pkt[1] = hex_asc[(error / 10)];
395         pkt[2] = hex_asc[(error % 10)];
396         pkt[3] = '\0';
397 }
398 
399 /*
400  * Thread ID accessors. We represent a flat TID space to GDB, where
401  * the per CPU idle threads (which under Linux all have PID 0) are
402  * remapped to negative TIDs.
403  */
404 
405 #define BUF_THREAD_ID_SIZE      8
406 
407 static char *pack_threadid(char *pkt, unsigned char *id)
408 {
409         unsigned char *limit;
410         int lzero = 1;
411 
412         limit = id + (BUF_THREAD_ID_SIZE / 2);
413         while (id < limit) {
414                 if (!lzero || *id != 0) {
415                         pkt = hex_byte_pack(pkt, *id);
416                         lzero = 0;
417                 }
418                 id++;
419         }
420 
421         if (lzero)
422                 pkt = hex_byte_pack(pkt, 0);
423 
424         return pkt;
425 }
426 
427 static void int_to_threadref(unsigned char *id, int value)
428 {
429         put_unaligned_be32(value, id);
430 }
431 
432 static struct task_struct *getthread(struct pt_regs *regs, int tid)
433 {
434         /*
435          * Non-positive TIDs are remapped to the cpu shadow information
436          */
437         if (tid == 0 || tid == -1)
438                 tid = -atomic_read(&kgdb_active) - 2;
439         if (tid < -1 && tid > -NR_CPUS - 2) {
440                 if (kgdb_info[-tid - 2].task)
441                         return kgdb_info[-tid - 2].task;
442                 else
443                         return idle_task(-tid - 2);
444         }
445         if (tid <= 0) {
446                 printk(KERN_ERR "KGDB: Internal thread select error\n");
447                 dump_stack();
448                 return NULL;
449         }
450 
451         /*
452          * find_task_by_pid_ns() does not take the tasklist lock anymore
453          * but is nicely RCU locked - hence is a pretty resilient
454          * thing to use:
455          */
456         return find_task_by_pid_ns(tid, &init_pid_ns);
457 }
458 
459 
460 /*
461  * Remap normal tasks to their real PID,
462  * CPU shadow threads are mapped to -CPU - 2
463  */
464 static inline int shadow_pid(int realpid)
465 {
466         if (realpid)
467                 return realpid;
468 
469         return -raw_smp_processor_id() - 2;
470 }
471 
472 /*
473  * All the functions that start with gdb_cmd are the various
474  * operations to implement the handlers for the gdbserial protocol
475  * where KGDB is communicating with an external debugger
476  */
477 
478 /* Handle the '?' status packets */
479 static void gdb_cmd_status(struct kgdb_state *ks)
480 {
481         /*
482          * We know that this packet is only sent
483          * during initial connect.  So to be safe,
484          * we clear out our breakpoints now in case
485          * GDB is reconnecting.
486          */
487         dbg_remove_all_break();
488 
489         remcom_out_buffer[0] = 'S';
490         hex_byte_pack(&remcom_out_buffer[1], ks->signo);
491 }
492 
493 static void gdb_get_regs_helper(struct kgdb_state *ks)
494 {
495         struct task_struct *thread;
496         void *local_debuggerinfo;
497         int i;
498 
499         thread = kgdb_usethread;
500         if (!thread) {
501                 thread = kgdb_info[ks->cpu].task;
502                 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
503         } else {
504                 local_debuggerinfo = NULL;
505                 for_each_online_cpu(i) {
506                         /*
507                          * Try to find the task on some other
508                          * or possibly this node if we do not
509                          * find the matching task then we try
510                          * to approximate the results.
511                          */
512                         if (thread == kgdb_info[i].task)
513                                 local_debuggerinfo = kgdb_info[i].debuggerinfo;
514                 }
515         }
516 
517         /*
518          * All threads that don't have debuggerinfo should be
519          * in schedule() sleeping, since all other CPUs
520          * are in kgdb_wait, and thus have debuggerinfo.
521          */
522         if (local_debuggerinfo) {
523                 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
524         } else {
525                 /*
526                  * Pull stuff saved during switch_to; nothing
527                  * else is accessible (or even particularly
528                  * relevant).
529                  *
530                  * This should be enough for a stack trace.
531                  */
532                 sleeping_thread_to_gdb_regs(gdb_regs, thread);
533         }
534 }
535 
536 /* Handle the 'g' get registers request */
537 static void gdb_cmd_getregs(struct kgdb_state *ks)
538 {
539         gdb_get_regs_helper(ks);
540         kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
541 }
542 
543 /* Handle the 'G' set registers request */
544 static void gdb_cmd_setregs(struct kgdb_state *ks)
545 {
546         kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
547 
548         if (kgdb_usethread && kgdb_usethread != current) {
549                 error_packet(remcom_out_buffer, -EINVAL);
550         } else {
551                 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
552                 strcpy(remcom_out_buffer, "OK");
553         }
554 }
555 
556 /* Handle the 'm' memory read bytes */
557 static void gdb_cmd_memread(struct kgdb_state *ks)
558 {
559         char *ptr = &remcom_in_buffer[1];
560         unsigned long length;
561         unsigned long addr;
562         char *err;
563 
564         if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
565                                         kgdb_hex2long(&ptr, &length) > 0) {
566                 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
567                 if (!err)
568                         error_packet(remcom_out_buffer, -EINVAL);
569         } else {
570                 error_packet(remcom_out_buffer, -EINVAL);
571         }
572 }
573 
574 /* Handle the 'M' memory write bytes */
575 static void gdb_cmd_memwrite(struct kgdb_state *ks)
576 {
577         int err = write_mem_msg(0);
578 
579         if (err)
580                 error_packet(remcom_out_buffer, err);
581         else
582                 strcpy(remcom_out_buffer, "OK");
583 }
584 
585 #if DBG_MAX_REG_NUM > 0
586 static char *gdb_hex_reg_helper(int regnum, char *out)
587 {
588         int i;
589         int offset = 0;
590 
591         for (i = 0; i < regnum; i++)
592                 offset += dbg_reg_def[i].size;
593         return kgdb_mem2hex((char *)gdb_regs + offset, out,
594                             dbg_reg_def[i].size);
595 }
596 
597 /* Handle the 'p' individual regster get */
598 static void gdb_cmd_reg_get(struct kgdb_state *ks)
599 {
600         unsigned long regnum;
601         char *ptr = &remcom_in_buffer[1];
602 
603         kgdb_hex2long(&ptr, &regnum);
604         if (regnum >= DBG_MAX_REG_NUM) {
605                 error_packet(remcom_out_buffer, -EINVAL);
606                 return;
607         }
608         gdb_get_regs_helper(ks);
609         gdb_hex_reg_helper(regnum, remcom_out_buffer);
610 }
611 
612 /* Handle the 'P' individual regster set */
613 static void gdb_cmd_reg_set(struct kgdb_state *ks)
614 {
615         unsigned long regnum;
616         char *ptr = &remcom_in_buffer[1];
617         int i = 0;
618 
619         kgdb_hex2long(&ptr, &regnum);
620         if (*ptr++ != '=' ||
621             !(!kgdb_usethread || kgdb_usethread == current) ||
622             !dbg_get_reg(regnum, gdb_regs, ks->linux_regs)) {
623                 error_packet(remcom_out_buffer, -EINVAL);
624                 return;
625         }
626         memset(gdb_regs, 0, sizeof(gdb_regs));
627         while (i < sizeof(gdb_regs) * 2)
628                 if (hex_to_bin(ptr[i]) >= 0)
629                         i++;
630                 else
631                         break;
632         i = i / 2;
633         kgdb_hex2mem(ptr, (char *)gdb_regs, i);
634         dbg_set_reg(regnum, gdb_regs, ks->linux_regs);
635         strcpy(remcom_out_buffer, "OK");
636 }
637 #endif /* DBG_MAX_REG_NUM > 0 */
638 
639 /* Handle the 'X' memory binary write bytes */
640 static void gdb_cmd_binwrite(struct kgdb_state *ks)
641 {
642         int err = write_mem_msg(1);
643 
644         if (err)
645                 error_packet(remcom_out_buffer, err);
646         else
647                 strcpy(remcom_out_buffer, "OK");
648 }
649 
650 /* Handle the 'D' or 'k', detach or kill packets */
651 static void gdb_cmd_detachkill(struct kgdb_state *ks)
652 {
653         int error;
654 
655         /* The detach case */
656         if (remcom_in_buffer[0] == 'D') {
657                 error = dbg_remove_all_break();
658                 if (error < 0) {
659                         error_packet(remcom_out_buffer, error);
660                 } else {
661                         strcpy(remcom_out_buffer, "OK");
662                         kgdb_connected = 0;
663                 }
664                 put_packet(remcom_out_buffer);
665         } else {
666                 /*
667                  * Assume the kill case, with no exit code checking,
668                  * trying to force detach the debugger:
669                  */
670                 dbg_remove_all_break();
671                 kgdb_connected = 0;
672         }
673 }
674 
675 /* Handle the 'R' reboot packets */
676 static int gdb_cmd_reboot(struct kgdb_state *ks)
677 {
678         /* For now, only honor R0 */
679         if (strcmp(remcom_in_buffer, "R0") == 0) {
680                 printk(KERN_CRIT "Executing emergency reboot\n");
681                 strcpy(remcom_out_buffer, "OK");
682                 put_packet(remcom_out_buffer);
683 
684                 /*
685                  * Execution should not return from
686                  * machine_emergency_restart()
687                  */
688                 machine_emergency_restart();
689                 kgdb_connected = 0;
690 
691                 return 1;
692         }
693         return 0;
694 }
695 
696 /* Handle the 'q' query packets */
697 static void gdb_cmd_query(struct kgdb_state *ks)
698 {
699         struct task_struct *g;
700         struct task_struct *p;
701         unsigned char thref[BUF_THREAD_ID_SIZE];
702         char *ptr;
703         int i;
704         int cpu;
705         int finished = 0;
706 
707         switch (remcom_in_buffer[1]) {
708         case 's':
709         case 'f':
710                 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10))
711                         break;
712 
713                 i = 0;
714                 remcom_out_buffer[0] = 'm';
715                 ptr = remcom_out_buffer + 1;
716                 if (remcom_in_buffer[1] == 'f') {
717                         /* Each cpu is a shadow thread */
718                         for_each_online_cpu(cpu) {
719                                 ks->thr_query = 0;
720                                 int_to_threadref(thref, -cpu - 2);
721                                 ptr = pack_threadid(ptr, thref);
722                                 *(ptr++) = ',';
723                                 i++;
724                         }
725                 }
726 
727                 do_each_thread(g, p) {
728                         if (i >= ks->thr_query && !finished) {
729                                 int_to_threadref(thref, p->pid);
730                                 ptr = pack_threadid(ptr, thref);
731                                 *(ptr++) = ',';
732                                 ks->thr_query++;
733                                 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
734                                         finished = 1;
735                         }
736                         i++;
737                 } while_each_thread(g, p);
738 
739                 *(--ptr) = '\0';
740                 break;
741 
742         case 'C':
743                 /* Current thread id */
744                 strcpy(remcom_out_buffer, "QC");
745                 ks->threadid = shadow_pid(current->pid);
746                 int_to_threadref(thref, ks->threadid);
747                 pack_threadid(remcom_out_buffer + 2, thref);
748                 break;
749         case 'T':
750                 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16))
751                         break;
752 
753                 ks->threadid = 0;
754                 ptr = remcom_in_buffer + 17;
755                 kgdb_hex2long(&ptr, &ks->threadid);
756                 if (!getthread(ks->linux_regs, ks->threadid)) {
757                         error_packet(remcom_out_buffer, -EINVAL);
758                         break;
759                 }
760                 if ((int)ks->threadid > 0) {
761                         kgdb_mem2hex(getthread(ks->linux_regs,
762                                         ks->threadid)->comm,
763                                         remcom_out_buffer, 16);
764                 } else {
765                         static char tmpstr[23 + BUF_THREAD_ID_SIZE];
766 
767                         sprintf(tmpstr, "shadowCPU%d",
768                                         (int)(-ks->threadid - 2));
769                         kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
770                 }
771                 break;
772 #ifdef CONFIG_KGDB_KDB
773         case 'R':
774                 if (strncmp(remcom_in_buffer, "qRcmd,", 6) == 0) {
775                         int len = strlen(remcom_in_buffer + 6);
776 
777                         if ((len % 2) != 0) {
778                                 strcpy(remcom_out_buffer, "E01");
779                                 break;
780                         }
781                         kgdb_hex2mem(remcom_in_buffer + 6,
782                                      remcom_out_buffer, len);
783                         len = len / 2;
784                         remcom_out_buffer[len++] = 0;
785 
786                         kdb_common_init_state(ks);
787                         kdb_parse(remcom_out_buffer);
788                         kdb_common_deinit_state();
789 
790                         strcpy(remcom_out_buffer, "OK");
791                 }
792                 break;
793 #endif
794         }
795 }
796 
797 /* Handle the 'H' task query packets */
798 static void gdb_cmd_task(struct kgdb_state *ks)
799 {
800         struct task_struct *thread;
801         char *ptr;
802 
803         switch (remcom_in_buffer[1]) {
804         case 'g':
805                 ptr = &remcom_in_buffer[2];
806                 kgdb_hex2long(&ptr, &ks->threadid);
807                 thread = getthread(ks->linux_regs, ks->threadid);
808                 if (!thread && ks->threadid > 0) {
809                         error_packet(remcom_out_buffer, -EINVAL);
810                         break;
811                 }
812                 kgdb_usethread = thread;
813                 ks->kgdb_usethreadid = ks->threadid;
814                 strcpy(remcom_out_buffer, "OK");
815                 break;
816         case 'c':
817                 ptr = &remcom_in_buffer[2];
818                 kgdb_hex2long(&ptr, &ks->threadid);
819                 if (!ks->threadid) {
820                         kgdb_contthread = NULL;
821                 } else {
822                         thread = getthread(ks->linux_regs, ks->threadid);
823                         if (!thread && ks->threadid > 0) {
824                                 error_packet(remcom_out_buffer, -EINVAL);
825                                 break;
826                         }
827                         kgdb_contthread = thread;
828                 }
829                 strcpy(remcom_out_buffer, "OK");
830                 break;
831         }
832 }
833 
834 /* Handle the 'T' thread query packets */
835 static void gdb_cmd_thread(struct kgdb_state *ks)
836 {
837         char *ptr = &remcom_in_buffer[1];
838         struct task_struct *thread;
839 
840         kgdb_hex2long(&ptr, &ks->threadid);
841         thread = getthread(ks->linux_regs, ks->threadid);
842         if (thread)
843                 strcpy(remcom_out_buffer, "OK");
844         else
845                 error_packet(remcom_out_buffer, -EINVAL);
846 }
847 
848 /* Handle the 'z' or 'Z' breakpoint remove or set packets */
849 static void gdb_cmd_break(struct kgdb_state *ks)
850 {
851         /*
852          * Since GDB-5.3, it's been drafted that '' is a software
853          * breakpoint, '1' is a hardware breakpoint, so let's do that.
854          */
855         char *bpt_type = &remcom_in_buffer[1];
856         char *ptr = &remcom_in_buffer[2];
857         unsigned long addr;
858         unsigned long length;
859         int error = 0;
860 
861         if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
862                 /* Unsupported */
863                 if (*bpt_type > '4')
864                         return;
865         } else {
866                 if (*bpt_type != '' && *bpt_type != '1')
867                         /* Unsupported. */
868                         return;
869         }
870 
871         /*
872          * Test if this is a hardware breakpoint, and
873          * if we support it:
874          */
875         if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
876                 /* Unsupported. */
877                 return;
878 
879         if (*(ptr++) != ',') {
880                 error_packet(remcom_out_buffer, -EINVAL);
881                 return;
882         }
883         if (!kgdb_hex2long(&ptr, &addr)) {
884                 error_packet(remcom_out_buffer, -EINVAL);
885                 return;
886         }
887         if (*(ptr++) != ',' ||
888                 !kgdb_hex2long(&ptr, &length)) {
889                 error_packet(remcom_out_buffer, -EINVAL);
890                 return;
891         }
892 
893         if (remcom_in_buffer[0] == 'Z' && *bpt_type == '')
894                 error = dbg_set_sw_break(addr);
895         else if (remcom_in_buffer[0] == 'z' && *bpt_type == '')
896                 error = dbg_remove_sw_break(addr);
897         else if (remcom_in_buffer[0] == 'Z')
898                 error = arch_kgdb_ops.set_hw_breakpoint(addr,
899                         (int)length, *bpt_type - '');
900         else if (remcom_in_buffer[0] == 'z')
901                 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
902                         (int) length, *bpt_type - '');
903 
904         if (error == 0)
905                 strcpy(remcom_out_buffer, "OK");
906         else
907                 error_packet(remcom_out_buffer, error);
908 }
909 
910 /* Handle the 'C' signal / exception passing packets */
911 static int gdb_cmd_exception_pass(struct kgdb_state *ks)
912 {
913         /* C09 == pass exception
914          * C15 == detach kgdb, pass exception
915          */
916         if (remcom_in_buffer[1] == '' && remcom_in_buffer[2] == '9') {
917 
918                 ks->pass_exception = 1;
919                 remcom_in_buffer[0] = 'c';
920 
921         } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
922 
923                 ks->pass_exception = 1;
924                 remcom_in_buffer[0] = 'D';
925                 dbg_remove_all_break();
926                 kgdb_connected = 0;
927                 return 1;
928 
929         } else {
930                 gdbstub_msg_write("KGDB only knows signal 9 (pass)"
931                         " and 15 (pass and disconnect)\n"
932                         "Executing a continue without signal passing\n", 0);
933                 remcom_in_buffer[0] = 'c';
934         }
935 
936         /* Indicate fall through */
937         return -1;
938 }
939 
940 /*
941  * This function performs all gdbserial command procesing
942  */
943 int gdb_serial_stub(struct kgdb_state *ks)
944 {
945         int error = 0;
946         int tmp;
947 
948         /* Initialize comm buffer and globals. */
949         memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
950         kgdb_usethread = kgdb_info[ks->cpu].task;
951         ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
952         ks->pass_exception = 0;
953 
954         if (kgdb_connected) {
955                 unsigned char thref[BUF_THREAD_ID_SIZE];
956                 char *ptr;
957 
958                 /* Reply to host that an exception has occurred */
959                 ptr = remcom_out_buffer;
960                 *ptr++ = 'T';
961                 ptr = hex_byte_pack(ptr, ks->signo);
962                 ptr += strlen(strcpy(ptr, "thread:"));
963                 int_to_threadref(thref, shadow_pid(current->pid));
964                 ptr = pack_threadid(ptr, thref);
965                 *ptr++ = ';';
966                 put_packet(remcom_out_buffer);
967         }
968 
969         while (1) {
970                 error = 0;
971 
972                 /* Clear the out buffer. */
973                 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
974 
975                 get_packet(remcom_in_buffer);
976 
977                 switch (remcom_in_buffer[0]) {
978                 case '?': /* gdbserial status */
979                         gdb_cmd_status(ks);
980                         break;
981                 case 'g': /* return the value of the CPU registers */
982                         gdb_cmd_getregs(ks);
983                         break;
984                 case 'G': /* set the value of the CPU registers - return OK */
985                         gdb_cmd_setregs(ks);
986                         break;
987                 case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
988                         gdb_cmd_memread(ks);
989                         break;
990                 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
991                         gdb_cmd_memwrite(ks);
992                         break;
993 #if DBG_MAX_REG_NUM > 0
994                 case 'p': /* pXX Return gdb register XX (in hex) */
995                         gdb_cmd_reg_get(ks);
996                         break;
997                 case 'P': /* PXX=aaaa Set gdb register XX to aaaa (in hex) */
998                         gdb_cmd_reg_set(ks);
999                         break;
1000 #endif /* DBG_MAX_REG_NUM > 0 */
1001                 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1002                         gdb_cmd_binwrite(ks);
1003                         break;
1004                         /* kill or detach. KGDB should treat this like a
1005                          * continue.
1006                          */
1007                 case 'D': /* Debugger detach */
1008                 case 'k': /* Debugger detach via kill */
1009                         gdb_cmd_detachkill(ks);
1010                         goto default_handle;
1011                 case 'R': /* Reboot */
1012                         if (gdb_cmd_reboot(ks))
1013                                 goto default_handle;
1014                         break;
1015                 case 'q': /* query command */
1016                         gdb_cmd_query(ks);
1017                         break;
1018                 case 'H': /* task related */
1019                         gdb_cmd_task(ks);
1020                         break;
1021                 case 'T': /* Query thread status */
1022                         gdb_cmd_thread(ks);
1023                         break;
1024                 case 'z': /* Break point remove */
1025                 case 'Z': /* Break point set */
1026                         gdb_cmd_break(ks);
1027                         break;
1028 #ifdef CONFIG_KGDB_KDB
1029                 case '3': /* Escape into back into kdb */
1030                         if (remcom_in_buffer[1] == '\0') {
1031                                 gdb_cmd_detachkill(ks);
1032                                 return DBG_PASS_EVENT;
1033                         }
1034 #endif
1035                 case 'C': /* Exception passing */
1036                         tmp = gdb_cmd_exception_pass(ks);
1037                         if (tmp > 0)
1038                                 goto default_handle;
1039                         if (tmp == 0)
1040                                 break;
1041                         /* Fall through on tmp < 0 */
1042                 case 'c': /* Continue packet */
1043                 case 's': /* Single step packet */
1044                         if (kgdb_contthread && kgdb_contthread != current) {
1045                                 /* Can't switch threads in kgdb */
1046                                 error_packet(remcom_out_buffer, -EINVAL);
1047                                 break;
1048                         }
1049                         dbg_activate_sw_breakpoints();
1050                         /* Fall through to default processing */
1051                 default:
1052 default_handle:
1053                         error = kgdb_arch_handle_exception(ks->ex_vector,
1054                                                 ks->signo,
1055                                                 ks->err_code,
1056                                                 remcom_in_buffer,
1057                                                 remcom_out_buffer,
1058                                                 ks->linux_regs);
1059                         /*
1060                          * Leave cmd processing on error, detach,
1061                          * kill, continue, or single step.
1062                          */
1063                         if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1064                             remcom_in_buffer[0] == 'k') {
1065                                 error = 0;
1066                                 goto kgdb_exit;
1067                         }
1068 
1069                 }
1070 
1071                 /* reply to the request */
1072                 put_packet(remcom_out_buffer);
1073         }
1074 
1075 kgdb_exit:
1076         if (ks->pass_exception)
1077                 error = 1;
1078         return error;
1079 }
1080 
1081 int gdbstub_state(struct kgdb_state *ks, char *cmd)
1082 {
1083         int error;
1084 
1085         switch (cmd[0]) {
1086         case 'e':
1087                 error = kgdb_arch_handle_exception(ks->ex_vector,
1088                                                    ks->signo,
1089                                                    ks->err_code,
1090                                                    remcom_in_buffer,
1091                                                    remcom_out_buffer,
1092                                                    ks->linux_regs);
1093                 return error;
1094         case 's':
1095         case 'c':
1096                 strcpy(remcom_in_buffer, cmd);
1097                 return 0;
1098         case '$':
1099                 strcpy(remcom_in_buffer, cmd);
1100                 gdbstub_use_prev_in_buf = strlen(remcom_in_buffer);
1101                 gdbstub_prev_in_buf_pos = 0;
1102                 return 0;
1103         }
1104         dbg_io_ops->write_char('+');
1105         put_packet(remcom_out_buffer);
1106         return 0;
1107 }
1108 
1109 /**
1110  * gdbstub_exit - Send an exit message to GDB
1111  * @status: The exit code to report.
1112  */
1113 void gdbstub_exit(int status)
1114 {
1115         unsigned char checksum, ch, buffer[3];
1116         int loop;
1117 
1118         if (!kgdb_connected)
1119                 return;
1120         kgdb_connected = 0;
1121 
1122         if (!dbg_io_ops || dbg_kdb_mode)
1123                 return;
1124 
1125         buffer[0] = 'W';
1126         buffer[1] = hex_asc_hi(status);
1127         buffer[2] = hex_asc_lo(status);
1128 
1129         dbg_io_ops->write_char('$');
1130         checksum = 0;
1131 
1132         for (loop = 0; loop < 3; loop++) {
1133                 ch = buffer[loop];
1134                 checksum += ch;
1135                 dbg_io_ops->write_char(ch);
1136         }
1137 
1138         dbg_io_ops->write_char('#');
1139         dbg_io_ops->write_char(hex_asc_hi(checksum));
1140         dbg_io_ops->write_char(hex_asc_lo(checksum));
1141 
1142         /* make sure the output is flushed, lest the bootloader clobber it */
1143         if (dbg_io_ops->flush)
1144                 dbg_io_ops->flush();
1145 }
1146 

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