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/kdb.h>
  34 #include <linux/reboot.h>
  35 #include <linux/uaccess.h>
  36 #include <asm/cacheflush.h>
  37 #include <asm/unaligned.h>
  38 #include "debug_core.h"
  39
  40 #define KGDB_MAX_THREAD_QUERY 17
  41
  42 /* Our I/O buffers. */
  43 static char                     remcom_in_buffer[BUFMAX];
  44 static char                     remcom_out_buffer[BUFMAX];
  45
  46 /* Storage for the registers, in GDB format. */
  47 static unsigned long            gdb_regs[(NUMREGBYTES +
  48                                         sizeof(unsigned long) - 1) /
  49                                         sizeof(unsigned long)];
  50
  51 /*
  52  * GDB remote protocol parser:
  53  */
  54
  55 static int hex(char ch)
  56 {
  57         if ((ch >= 'a') && (ch <= 'f'))
  58                 return ch - 'a' + 10;
  59         if ((ch >= '0') && (ch <= '9'))
  60                 return ch - '0';
  61         if ((ch >= 'A') && (ch <= 'F'))
  62                 return ch - 'A' + 10;
  63         return -1;
  64 }
  65
  66 #ifdef CONFIG_KGDB_KDB
  67 static int gdbstub_read_wait(void)
  68 {
  69         int ret = -1;
  70         int i;
  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                 buffer[count] = 0;
 124
 125                 if (ch == '#') {
 126                         xmitcsum = hex(gdbstub_read_wait()) << 4;
 127                         xmitcsum += hex(gdbstub_read_wait());
 128
 129                         if (checksum != xmitcsum)
 130                                 /* failed checksum */
 131                                 dbg_io_ops->write_char('-');
 132                         else
 133                                 /* successful transfer */
 134                                 dbg_io_ops->write_char('+');
 135                         if (dbg_io_ops->flush)
 136                                 dbg_io_ops->flush();
 137                 }
 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 = pack_hex_byte(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 int 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                 while (count > 0) {
 253                         buf = pack_hex_byte(buf, *tmp);
 254                         tmp++;
 255                         count--;
 256                 }
 257
 258                 *buf = 0;
 259         }
 260
 261         return err;
 262 }
 263
 264 /*
 265  * Convert the hex array pointed to by buf into binary to be placed in
 266  * mem.  Return a pointer to the character AFTER the last byte
 267  * written.  May return an error.
 268  */
 269 int kgdb_hex2mem(char *buf, char *mem, int count)
 270 {
 271         char *tmp_raw;
 272         char *tmp_hex;
 273
 274         /*
 275          * We use the upper half of buf as an intermediate buffer for the
 276          * raw memory that is converted from hex.
 277          */
 278         tmp_raw = buf + count * 2;
 279
 280         tmp_hex = tmp_raw - 1;
 281         while (tmp_hex >= buf) {
 282                 tmp_raw--;
 283                 *tmp_raw = hex(*tmp_hex--);
 284                 *tmp_raw |= hex(*tmp_hex--) << 4;
 285         }
 286
 287         return probe_kernel_write(mem, tmp_raw, count);
 288 }
 289
 290 /*
 291  * While we find nice hex chars, build a long_val.
 292  * Return number of chars processed.
 293  */
 294 int kgdb_hex2long(char **ptr, unsigned long *long_val)
 295 {
 296         int hex_val;
 297         int num = 0;
 298         int negate = 0;
 299
 300         *long_val = 0;
 301
 302         if (**ptr == '-') {
 303                 negate = 1;
 304                 (*ptr)++;
 305         }
 306         while (**ptr) {
 307                 hex_val = hex(**ptr);
 308                 if (hex_val < 0)
 309                         break;
 310
 311                 *long_val = (*long_val << 4) | hex_val;
 312                 num++;
 313                 (*ptr)++;
 314         }
 315
 316         if (negate)
 317                 *long_val = -*long_val;
 318
 319         return num;
 320 }
 321
 322 /*
 323  * Copy the binary array pointed to by buf into mem.  Fix $, #, and
 324  * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success.
 325  * The input buf is overwitten with the result to write to mem.
 326  */
 327 static int kgdb_ebin2mem(char *buf, char *mem, int count)
 328 {
 329         int size = 0;
 330         char *c = buf;
 331
 332         while (count-- > 0) {
 333                 c[size] = *buf++;
 334                 if (c[size] == 0x7d)
 335                         c[size] = *buf++ ^ 0x20;
 336                 size++;
 337         }
 338
 339         return probe_kernel_write(mem, c, size);
 340 }
 341
 342 /* Write memory due to an 'M' or 'X' packet. */
 343 static int write_mem_msg(int binary)
 344 {
 345         char *ptr = &remcom_in_buffer[1];
 346         unsigned long addr;
 347         unsigned long length;
 348         int err;
 349
 350         if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
 351             kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
 352                 if (binary)
 353                         err = kgdb_ebin2mem(ptr, (char *)addr, length);
 354                 else
 355                         err = kgdb_hex2mem(ptr, (char *)addr, length);
 356                 if (err)
 357                         return err;
 358                 if (CACHE_FLUSH_IS_SAFE)
 359                         flush_icache_range(addr, addr + length);
 360                 return 0;
 361         }
 362
 363         return -EINVAL;
 364 }
 365
 366 static void error_packet(char *pkt, int error)
 367 {
 368         error = -error;
 369         pkt[0] = 'E';
 370         pkt[1] = hex_asc[(error / 10)];
 371         pkt[2] = hex_asc[(error % 10)];
 372         pkt[3] = '\0';
 373 }
 374
 375 /*
 376  * Thread ID accessors. We represent a flat TID space to GDB, where
 377  * the per CPU idle threads (which under Linux all have PID 0) are
 378  * remapped to negative TIDs.
 379  */
 380
 381 #define BUF_THREAD_ID_SIZE      16
 382
 383 static char *pack_threadid(char *pkt, unsigned char *id)
 384 {
 385         char *limit;
 386
 387         limit = pkt + BUF_THREAD_ID_SIZE;
 388         while (pkt < limit)
 389                 pkt = pack_hex_byte(pkt, *id++);
 390
 391         return pkt;
 392 }
 393
 394 static void int_to_threadref(unsigned char *id, int value)
 395 {
 396         unsigned char *scan;
 397         int i = 4;
 398
 399         scan = (unsigned char *)id;
 400         while (i--)
 401                 *scan++ = 0;
 402         put_unaligned_be32(value, scan);
 403 }
 404
 405 static struct task_struct *getthread(struct pt_regs *regs, int tid)
 406 {
 407         /*
 408          * Non-positive TIDs are remapped to the cpu shadow information
 409          */
 410         if (tid == 0 || tid == -1)
 411                 tid = -atomic_read(&kgdb_active) - 2;
 412         if (tid < -1 && tid > -NR_CPUS - 2) {
 413                 if (kgdb_info[-tid - 2].task)
 414                         return kgdb_info[-tid - 2].task;
 415                 else
 416                         return idle_task(-tid - 2);
 417         }
 418         if (tid <= 0) {
 419                 printk(KERN_ERR "KGDB: Internal thread select error\n");
 420                 dump_stack();
 421                 return NULL;
 422         }
 423
 424         /*
 425          * find_task_by_pid_ns() does not take the tasklist lock anymore
 426          * but is nicely RCU locked - hence is a pretty resilient
 427          * thing to use:
 428          */
 429         return find_task_by_pid_ns(tid, &init_pid_ns);
 430 }
 431
 432
 433 /*
 434  * Remap normal tasks to their real PID,
 435  * CPU shadow threads are mapped to -CPU - 2
 436  */
 437 static inline int shadow_pid(int realpid)
 438 {
 439         if (realpid)
 440                 return realpid;
 441
 442         return -raw_smp_processor_id() - 2;
 443 }
 444
 445 /*
 446  * All the functions that start with gdb_cmd are the various
 447  * operations to implement the handlers for the gdbserial protocol
 448  * where KGDB is communicating with an external debugger
 449  */
 450
 451 /* Handle the '?' status packets */
 452 static void gdb_cmd_status(struct kgdb_state *ks)
 453 {
 454         /*
 455          * We know that this packet is only sent
 456          * during initial connect.  So to be safe,
 457          * we clear out our breakpoints now in case
 458          * GDB is reconnecting.
 459          */
 460         dbg_remove_all_break();
 461
 462         remcom_out_buffer[0] = 'S';
 463         pack_hex_byte(&remcom_out_buffer[1], ks->signo);
 464 }
 465
 466 /* Handle the 'g' get registers request */
 467 static void gdb_cmd_getregs(struct kgdb_state *ks)
 468 {
 469         struct task_struct *thread;
 470         void *local_debuggerinfo;
 471         int i;
 472
 473         thread = kgdb_usethread;
 474         if (!thread) {
 475                 thread = kgdb_info[ks->cpu].task;
 476                 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
 477         } else {
 478                 local_debuggerinfo = NULL;
 479                 for_each_online_cpu(i) {
 480                         /*
 481                          * Try to find the task on some other
 482                          * or possibly this node if we do not
 483                          * find the matching task then we try
 484                          * to approximate the results.
 485                          */
 486                         if (thread == kgdb_info[i].task)
 487                                 local_debuggerinfo = kgdb_info[i].debuggerinfo;
 488                 }
 489         }
 490
 491         /*
 492          * All threads that don't have debuggerinfo should be
 493          * in schedule() sleeping, since all other CPUs
 494          * are in kgdb_wait, and thus have debuggerinfo.
 495          */
 496         if (local_debuggerinfo) {
 497                 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
 498         } else {
 499                 /*
 500                  * Pull stuff saved during switch_to; nothing
 501                  * else is accessible (or even particularly
 502                  * relevant).
 503                  *
 504                  * This should be enough for a stack trace.
 505                  */
 506                 sleeping_thread_to_gdb_regs(gdb_regs, thread);
 507         }
 508         kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
 509 }
 510
 511 /* Handle the 'G' set registers request */
 512 static void gdb_cmd_setregs(struct kgdb_state *ks)
 513 {
 514         kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
 515
 516         if (kgdb_usethread && kgdb_usethread != current) {
 517                 error_packet(remcom_out_buffer, -EINVAL);
 518         } else {
 519                 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
 520                 strcpy(remcom_out_buffer, "OK");
 521         }
 522 }
 523
 524 /* Handle the 'm' memory read bytes */
 525 static void gdb_cmd_memread(struct kgdb_state *ks)
 526 {
 527         char *ptr = &remcom_in_buffer[1];
 528         unsigned long length;
 529         unsigned long addr;
 530         int err;
 531
 532         if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
 533                                         kgdb_hex2long(&ptr, &length) > 0) {
 534                 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
 535                 if (err)
 536                         error_packet(remcom_out_buffer, err);
 537         } else {
 538                 error_packet(remcom_out_buffer, -EINVAL);
 539         }
 540 }
 541
 542 /* Handle the 'M' memory write bytes */
 543 static void gdb_cmd_memwrite(struct kgdb_state *ks)
 544 {
 545         int err = write_mem_msg(0);
 546
 547         if (err)
 548                 error_packet(remcom_out_buffer, err);
 549         else
 550                 strcpy(remcom_out_buffer, "OK");
 551 }
 552
 553 /* Handle the 'X' memory binary write bytes */
 554 static void gdb_cmd_binwrite(struct kgdb_state *ks)
 555 {
 556         int err = write_mem_msg(1);
 557
 558         if (err)
 559                 error_packet(remcom_out_buffer, err);
 560         else
 561                 strcpy(remcom_out_buffer, "OK");
 562 }
 563
 564 /* Handle the 'D' or 'k', detach or kill packets */
 565 static void gdb_cmd_detachkill(struct kgdb_state *ks)
 566 {
 567         int error;
 568
 569         /* The detach case */
 570         if (remcom_in_buffer[0] == 'D') {
 571                 error = dbg_remove_all_break();
 572                 if (error < 0) {
 573                         error_packet(remcom_out_buffer, error);
 574                 } else {
 575                         strcpy(remcom_out_buffer, "OK");
 576                         kgdb_connected = 0;
 577                 }
 578                 put_packet(remcom_out_buffer);
 579         } else {
 580                 /*
 581                  * Assume the kill case, with no exit code checking,
 582                  * trying to force detach the debugger:
 583                  */
 584                 dbg_remove_all_break();
 585                 kgdb_connected = 0;
 586         }
 587 }
 588
 589 /* Handle the 'R' reboot packets */
 590 static int gdb_cmd_reboot(struct kgdb_state *ks)
 591 {
 592         /* For now, only honor R0 */
 593         if (strcmp(remcom_in_buffer, "R0") == 0) {
 594                 printk(KERN_CRIT "Executing emergency reboot\n");
 595                 strcpy(remcom_out_buffer, "OK");
 596                 put_packet(remcom_out_buffer);
 597
 598                 /*
 599                  * Execution should not return from
 600                  * machine_emergency_restart()
 601                  */
 602                 machine_emergency_restart();
 603                 kgdb_connected = 0;
 604
 605                 return 1;
 606         }
 607         return 0;
 608 }
 609
 610 /* Handle the 'q' query packets */
 611 static void gdb_cmd_query(struct kgdb_state *ks)
 612 {
 613         struct task_struct *g;
 614         struct task_struct *p;
 615         unsigned char thref[8];
 616         char *ptr;
 617         int i;
 618         int cpu;
 619         int finished = 0;
 620
 621         switch (remcom_in_buffer[1]) {
 622         case 's':
 623         case 'f':
 624                 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
 625                         error_packet(remcom_out_buffer, -EINVAL);
 626                         break;
 627                 }
 628
 629                 i = 0;
 630                 remcom_out_buffer[0] = 'm';
 631                 ptr = remcom_out_buffer + 1;
 632                 if (remcom_in_buffer[1] == 'f') {
 633                         /* Each cpu is a shadow thread */
 634                         for_each_online_cpu(cpu) {
 635                                 ks->thr_query = 0;
 636                                 int_to_threadref(thref, -cpu - 2);
 637                                 pack_threadid(ptr, thref);
 638                                 ptr += BUF_THREAD_ID_SIZE;
 639                                 *(ptr++) = ',';
 640                                 i++;
 641                         }
 642                 }
 643
 644                 do_each_thread(g, p) {
 645                         if (i >= ks->thr_query && !finished) {
 646                                 int_to_threadref(thref, p->pid);
 647                                 pack_threadid(ptr, thref);
 648                                 ptr += BUF_THREAD_ID_SIZE;
 649                                 *(ptr++) = ',';
 650                                 ks->thr_query++;
 651                                 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
 652                                         finished = 1;
 653                         }
 654                         i++;
 655                 } while_each_thread(g, p);
 656
 657                 *(--ptr) = '\0';
 658                 break;
 659
 660         case 'C':
 661                 /* Current thread id */
 662                 strcpy(remcom_out_buffer, "QC");
 663                 ks->threadid = shadow_pid(current->pid);
 664                 int_to_threadref(thref, ks->threadid);
 665                 pack_threadid(remcom_out_buffer + 2, thref);
 666                 break;
 667         case 'T':
 668                 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
 669                         error_packet(remcom_out_buffer, -EINVAL);
 670                         break;
 671                 }
 672                 ks->threadid = 0;
 673                 ptr = remcom_in_buffer + 17;
 674                 kgdb_hex2long(&ptr, &ks->threadid);
 675                 if (!getthread(ks->linux_regs, ks->threadid)) {
 676                         error_packet(remcom_out_buffer, -EINVAL);
 677                         break;
 678                 }
 679                 if ((int)ks->threadid > 0) {
 680                         kgdb_mem2hex(getthread(ks->linux_regs,
 681                                         ks->threadid)->comm,
 682                                         remcom_out_buffer, 16);
 683                 } else {
 684                         static char tmpstr[23 + BUF_THREAD_ID_SIZE];
 685
 686                         sprintf(tmpstr, "shadowCPU%d",
 687                                         (int)(-ks->threadid - 2));
 688                         kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
 689                 }
 690                 break;
 691 #ifdef CONFIG_KGDB_KDB
 692         case 'R':
 693                 if (strncmp(remcom_in_buffer, "qRcmd,", 6) == 0) {
 694                         int len = strlen(remcom_in_buffer + 6);
 695
 696                         if ((len % 2) != 0) {
 697                                 strcpy(remcom_out_buffer, "E01");
 698                                 break;
 699                         }
 700                         kgdb_hex2mem(remcom_in_buffer + 6,
 701                                      remcom_out_buffer, len);
 702                         len = len / 2;
 703                         remcom_out_buffer[len++] = 0;
 704
 705                         kdb_parse(remcom_out_buffer);
 706                         strcpy(remcom_out_buffer, "OK");
 707                 }
 708                 break;
 709 #endif
 710         }
 711 }
 712
 713 /* Handle the 'H' task query packets */
 714 static void gdb_cmd_task(struct kgdb_state *ks)
 715 {
 716         struct task_struct *thread;
 717         char *ptr;
 718
 719         switch (remcom_in_buffer[1]) {
 720         case 'g':
 721                 ptr = &remcom_in_buffer[2];
 722                 kgdb_hex2long(&ptr, &ks->threadid);
 723                 thread = getthread(ks->linux_regs, ks->threadid);
 724                 if (!thread && ks->threadid > 0) {
 725                         error_packet(remcom_out_buffer, -EINVAL);
 726                         break;
 727                 }
 728                 kgdb_usethread = thread;
 729                 ks->kgdb_usethreadid = ks->threadid;
 730                 strcpy(remcom_out_buffer, "OK");
 731                 break;
 732         case 'c':
 733                 ptr = &remcom_in_buffer[2];
 734                 kgdb_hex2long(&ptr, &ks->threadid);
 735                 if (!ks->threadid) {
 736                         kgdb_contthread = NULL;
 737                 } else {
 738                         thread = getthread(ks->linux_regs, ks->threadid);
 739                         if (!thread && ks->threadid > 0) {
 740                                 error_packet(remcom_out_buffer, -EINVAL);
 741                                 break;
 742                         }
 743                         kgdb_contthread = thread;
 744                 }
 745                 strcpy(remcom_out_buffer, "OK");
 746                 break;
 747         }
 748 }
 749
 750 /* Handle the 'T' thread query packets */
 751 static void gdb_cmd_thread(struct kgdb_state *ks)
 752 {
 753         char *ptr = &remcom_in_buffer[1];
 754         struct task_struct *thread;
 755
 756         kgdb_hex2long(&ptr, &ks->threadid);
 757         thread = getthread(ks->linux_regs, ks->threadid);
 758         if (thread)
 759                 strcpy(remcom_out_buffer, "OK");
 760         else
 761                 error_packet(remcom_out_buffer, -EINVAL);
 762 }
 763
 764 /* Handle the 'z' or 'Z' breakpoint remove or set packets */
 765 static void gdb_cmd_break(struct kgdb_state *ks)
 766 {
 767         /*
 768          * Since GDB-5.3, it's been drafted that '0' is a software
 769          * breakpoint, '1' is a hardware breakpoint, so let's do that.
 770          */
 771         char *bpt_type = &remcom_in_buffer[1];
 772         char *ptr = &remcom_in_buffer[2];
 773         unsigned long addr;
 774         unsigned long length;
 775         int error = 0;
 776
 777         if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
 778                 /* Unsupported */
 779                 if (*bpt_type > '4')
 780                         return;
 781         } else {
 782                 if (*bpt_type != '0' && *bpt_type != '1')
 783                         /* Unsupported. */
 784                         return;
 785         }
 786
 787         /*
 788          * Test if this is a hardware breakpoint, and
 789          * if we support it:
 790          */
 791         if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
 792                 /* Unsupported. */
 793                 return;
 794
 795         if (*(ptr++) != ',') {
 796                 error_packet(remcom_out_buffer, -EINVAL);
 797                 return;
 798         }
 799         if (!kgdb_hex2long(&ptr, &addr)) {
 800                 error_packet(remcom_out_buffer, -EINVAL);
 801                 return;
 802         }
 803         if (*(ptr++) != ',' ||
 804                 !kgdb_hex2long(&ptr, &length)) {
 805                 error_packet(remcom_out_buffer, -EINVAL);
 806                 return;
 807         }
 808
 809         if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
 810                 error = dbg_set_sw_break(addr);
 811         else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
 812                 error = dbg_remove_sw_break(addr);
 813         else if (remcom_in_buffer[0] == 'Z')
 814                 error = arch_kgdb_ops.set_hw_breakpoint(addr,
 815                         (int)length, *bpt_type - '0');
 816         else if (remcom_in_buffer[0] == 'z')
 817                 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
 818                         (int) length, *bpt_type - '0');
 819
 820         if (error == 0)
 821                 strcpy(remcom_out_buffer, "OK");
 822         else
 823                 error_packet(remcom_out_buffer, error);
 824 }
 825
 826 /* Handle the 'C' signal / exception passing packets */
 827 static int gdb_cmd_exception_pass(struct kgdb_state *ks)
 828 {
 829         /* C09 == pass exception
 830          * C15 == detach kgdb, pass exception
 831          */
 832         if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
 833
 834                 ks->pass_exception = 1;
 835                 remcom_in_buffer[0] = 'c';
 836
 837         } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
 838
 839                 ks->pass_exception = 1;
 840                 remcom_in_buffer[0] = 'D';
 841                 dbg_remove_all_break();
 842                 kgdb_connected = 0;
 843                 return 1;
 844
 845         } else {
 846                 gdbstub_msg_write("KGDB only knows signal 9 (pass)"
 847                         " and 15 (pass and disconnect)\n"
 848                         "Executing a continue without signal passing\n", 0);
 849                 remcom_in_buffer[0] = 'c';
 850         }
 851
 852         /* Indicate fall through */
 853         return -1;
 854 }
 855
 856 /*
 857  * This function performs all gdbserial command procesing
 858  */
 859 int gdb_serial_stub(struct kgdb_state *ks)
 860 {
 861         int error = 0;
 862         int tmp;
 863
 864         /* Clear the out buffer. */
 865         memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
 866
 867         if (kgdb_connected) {
 868                 unsigned char thref[8];
 869                 char *ptr;
 870
 871                 /* Reply to host that an exception has occurred */
 872                 ptr = remcom_out_buffer;
 873                 *ptr++ = 'T';
 874                 ptr = pack_hex_byte(ptr, ks->signo);
 875                 ptr += strlen(strcpy(ptr, "thread:"));
 876                 int_to_threadref(thref, shadow_pid(current->pid));
 877                 ptr = pack_threadid(ptr, thref);
 878                 *ptr++ = ';';
 879                 put_packet(remcom_out_buffer);
 880         }
 881
 882         kgdb_usethread = kgdb_info[ks->cpu].task;
 883         ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
 884         ks->pass_exception = 0;
 885
 886         while (1) {
 887                 error = 0;
 888
 889                 /* Clear the out buffer. */
 890                 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
 891
 892                 get_packet(remcom_in_buffer);
 893
 894                 switch (remcom_in_buffer[0]) {
 895                 case '?': /* gdbserial status */
 896                         gdb_cmd_status(ks);
 897                         break;
 898                 case 'g': /* return the value of the CPU registers */
 899                         gdb_cmd_getregs(ks);
 900                         break;
 901                 case 'G': /* set the value of the CPU registers - return OK */
 902                         gdb_cmd_setregs(ks);
 903                         break;
 904                 case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
 905                         gdb_cmd_memread(ks);
 906                         break;
 907                 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
 908                         gdb_cmd_memwrite(ks);
 909                         break;
 910                 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
 911                         gdb_cmd_binwrite(ks);
 912                         break;
 913                         /* kill or detach. KGDB should treat this like a
 914                          * continue.
 915                          */
 916                 case 'D': /* Debugger detach */
 917                 case 'k': /* Debugger detach via kill */
 918                         gdb_cmd_detachkill(ks);
 919                         goto default_handle;
 920                 case 'R': /* Reboot */
 921                         if (gdb_cmd_reboot(ks))
 922                                 goto default_handle;
 923                         break;
 924                 case 'q': /* query command */
 925                         gdb_cmd_query(ks);
 926                         break;
 927                 case 'H': /* task related */
 928                         gdb_cmd_task(ks);
 929                         break;
 930                 case 'T': /* Query thread status */
 931                         gdb_cmd_thread(ks);
 932                         break;
 933                 case 'z': /* Break point remove */
 934                 case 'Z': /* Break point set */
 935                         gdb_cmd_break(ks);
 936                         break;
 937 #ifdef CONFIG_KGDB_KDB
 938                 case '3': /* Escape into back into kdb */
 939                         if (remcom_in_buffer[1] == '\0') {
 940                                 gdb_cmd_detachkill(ks);
 941                                 return DBG_PASS_EVENT;
 942                         }
 943 #endif
 944                 case 'C': /* Exception passing */
 945                         tmp = gdb_cmd_exception_pass(ks);
 946                         if (tmp > 0)
 947                                 goto default_handle;
 948                         if (tmp == 0)
 949                                 break;
 950                         /* Fall through on tmp < 0 */
 951                 case 'c': /* Continue packet */
 952                 case 's': /* Single step packet */
 953                         if (kgdb_contthread && kgdb_contthread != current) {
 954                                 /* Can't switch threads in kgdb */
 955                                 error_packet(remcom_out_buffer, -EINVAL);
 956                                 break;
 957                         }
 958                         dbg_activate_sw_breakpoints();
 959                         /* Fall through to default processing */
 960                 default:
 961 default_handle:
 962                         error = kgdb_arch_handle_exception(ks->ex_vector,
 963                                                 ks->signo,
 964                                                 ks->err_code,
 965                                                 remcom_in_buffer,
 966                                                 remcom_out_buffer,
 967                                                 ks->linux_regs);
 968                         /*
 969                          * Leave cmd processing on error, detach,
 970                          * kill, continue, or single step.
 971                          */
 972                         if (error >= 0 || remcom_in_buffer[0] == 'D' ||
 973                             remcom_in_buffer[0] == 'k') {
 974                                 error = 0;
 975                                 goto kgdb_exit;
 976                         }
 977
 978                 }
 979
 980                 /* reply to the request */
 981                 put_packet(remcom_out_buffer);
 982         }
 983
 984 kgdb_exit:
 985         if (ks->pass_exception)
 986                 error = 1;
 987         return error;
 988 }
 989
 990 int gdbstub_state(struct kgdb_state *ks, char *cmd)
 991 {
 992         int error;
 993
 994         switch (cmd[0]) {
 995         case 'e':
 996                 error = kgdb_arch_handle_exception(ks->ex_vector,
 997                                                    ks->signo,
 998                                                    ks->err_code,
 999                                                    remcom_in_buffer,
1000                                                    remcom_out_buffer,
1001                                                    ks->linux_regs);
1002                 return error;
1003         case 's':
1004         case 'c':
1005                 strcpy(remcom_in_buffer, cmd);
1006                 return 0;
1007         case '?':
1008                 gdb_cmd_status(ks);
1009                 break;
1010         case '\0':
1011                 strcpy(remcom_out_buffer, "");
1012                 break;
1013         }
1014         dbg_io_ops->write_char('+');
1015         put_packet(remcom_out_buffer);
1016         return 0;
1017 }