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