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