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