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

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