kernel/debug/gdbstub.c

   1 /*
   2  * Kernel Debug Core
   3  *
   4  * Maintainer: Jason Wessel <jason.wessel@windriver.com>
   5  *
   6  * Copyright (C) 2000-2001 VERITAS Software Corporation.
   7  * Copyright (C) 2002-2004 Timesys Corporation
   8  * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
   9  * Copyright (C) 2004 Pavel Machek <pavel@suse.cz>
  10  * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
  11  * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
  12  * Copyright (C) 2005-2009 Wind River Systems, Inc.
  13  * Copyright (C) 2007 MontaVista Software, Inc.
  14  * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  15  *
  16  * Contributors at various stages not listed above:
  17  *  Jason Wessel ( jason.wessel@windriver.com )
  18  *  George Anzinger <george@mvista.com>
  19  *  Anurekh Saxena (anurekh.saxena@timesys.com)
  20  *  Lake Stevens Instrument Division (Glenn Engel)
  21  *  Jim Kingdon, Cygnus Support.
  22  *
  23  * Original KGDB stub: David Grothe <dave@gcom.com>,
  24  * Tigran Aivazian <tigran@sco.com>
  25  *
  26  * This file is licensed under the terms of the GNU General Public License
  27  * version 2. This program is licensed "as is" without any warranty of any
  28  * kind, whether express or implied.
  29  */
  30
  31 #include <linux/kernel.h>
  32 #include <linux/kgdb.h>
  33 #include <linux/kdb.h>
  34 #include <linux/reboot.h>
  35 #include <linux/uaccess.h>
  36 #include <asm/cacheflush.h>
  37 #include <asm/unaligned.h>
  38 #include "debug_core.h"
  39
  40 #define KGDB_MAX_THREAD_QUERY 17
  41
  42 /* Our I/O buffers. */
  43 static char                     remcom_in_buffer[BUFMAX];
  44 static char                     remcom_out_buffer[BUFMAX];
  45
  46 /* Storage for the registers, in GDB format. */
  47 static unsigned long            gdb_regs[(NUMREGBYTES +
  48                                         sizeof(unsigned long) - 1) /
  49                                         sizeof(unsigned long)];
  50
  51 /*
  52  * GDB remote protocol parser:
  53  */
  54
  55 #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 int 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                 while (count > 0) {
 242                         buf = pack_hex_byte(buf, *tmp);
 243                         tmp++;
 244                         count--;
 245                 }
 246
 247                 *buf = 0;
 248         }
 249
 250         return err;
 251 }
 252
 253 /*
 254  * Convert the hex array pointed to by buf into binary to be placed in
 255  * mem.  Return a pointer to the character AFTER the last byte
 256  * written.  May return an error.
 257  */
 258 int kgdb_hex2mem(char *buf, char *mem, int count)
 259 {
 260         char *tmp_raw;
 261         char *tmp_hex;
 262
 263         /*
 264          * We use the upper half of buf as an intermediate buffer for the
 265          * raw memory that is converted from hex.
 266          */
 267         tmp_raw = buf + count * 2;
 268
 269         tmp_hex = tmp_raw - 1;
 270         while (tmp_hex >= buf) {
 271                 tmp_raw--;
 272                 *tmp_raw = hex_to_bin(*tmp_hex--);
 273                 *tmp_raw |= hex_to_bin(*tmp_hex--) << 4;
 274         }
 275
 276         return probe_kernel_write(mem, tmp_raw, count);
 277 }
 278
 279 /*
 280  * While we find nice hex chars, build a long_val.
 281  * Return number of chars processed.
 282  */
 283 int kgdb_hex2long(char **ptr, unsigned long *long_val)
 284 {
 285         int hex_val;
 286         int num = 0;
 287         int negate = 0;
 288
 289         *long_val = 0;
 290
 291         if (**ptr == '-') {
 292                 negate = 1;
 293                 (*ptr)++;
 294         }
 295         while (**ptr) {
 296                 hex_val = hex_to_bin(**ptr);
 297                 if (hex_val < 0)
 298                         break;
 299
 300                 *long_val = (*long_val << 4) | hex_val;
 301                 num++;
 302                 (*ptr)++;
 303         }
 304
 305         if (negate)
 306                 *long_val = -*long_val;
 307
 308         return num;
 309 }
 310
 311 /*
 312  * Copy the binary array pointed to by buf into mem.  Fix $, #, and
 313  * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success.
 314  * The input buf is overwitten with the result to write to mem.
 315  */
 316 static int kgdb_ebin2mem(char *buf, char *mem, int count)
 317 {
 318         int size = 0;
 319         char *c = buf;
 320
 321         while (count-- > 0) {
 322                 c[size] = *buf++;
 323                 if (c[size] == 0x7d)
 324                         c[size] = *buf++ ^ 0x20;
 325                 size++;
 326         }
 327
 328         return probe_kernel_write(mem, c, size);
 329 }
 330
 331 /* Write memory due to an 'M' or 'X' packet. */
 332 static int write_mem_msg(int binary)
 333 {
 334         char *ptr = &remcom_in_buffer[1];
 335         unsigned long addr;
 336         unsigned long length;
 337         int err;
 338
 339         if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
 340             kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
 341                 if (binary)
 342                         err = kgdb_ebin2mem(ptr, (char *)addr, length);
 343                 else
 344                         err = kgdb_hex2mem(ptr, (char *)addr, length);
 345                 if (err)
 346                         return err;
 347                 if (CACHE_FLUSH_IS_SAFE)
 348                         flush_icache_range(addr, addr + length);
 349                 return 0;
 350         }
 351
 352         return -EINVAL;
 353 }
 354
 355 static void error_packet(char *pkt, int error)
 356 {
 357         error = -error;
 358         pkt[0] = 'E';
 359         pkt[1] = hex_asc[(error / 10)];
 360         pkt[2] = hex_asc[(error % 10)];
 361         pkt[3] = '\0';
 362 }
 363
 364 /*
 365  * Thread ID accessors. We represent a flat TID space to GDB, where
 366  * the per CPU idle threads (which under Linux all have PID 0) are
 367  * remapped to negative TIDs.
 368  */
 369
 370 #define BUF_THREAD_ID_SIZE      8
 371
 372 static char *pack_threadid(char *pkt, unsigned char *id)
 373 {
 374         unsigned char *limit;
 375         int lzero = 1;
 376
 377         limit = id + (BUF_THREAD_ID_SIZE / 2);
 378         while (id < limit) {
 379                 if (!lzero || *id != 0) {
 380                         pkt = pack_hex_byte(pkt, *id);
 381                         lzero = 0;
 382                 }
 383                 id++;
 384         }
 385
 386         if (lzero)
 387                 pkt = pack_hex_byte(pkt, 0);
 388
 389         return pkt;
 390 }
 391
 392 static void int_to_threadref(unsigned char *id, int value)
 393 {
 394         put_unaligned_be32(value, id);
 395 }
 396
 397 static struct task_struct *getthread(struct pt_regs *regs, int tid)
 398 {
 399         /*
 400          * Non-positive TIDs are remapped to the cpu shadow information
 401          */
 402         if (tid == 0 || tid == -1)
 403                 tid = -atomic_read(&kgdb_active) - 2;
 404         if (tid < -1 && tid > -NR_CPUS - 2) {
 405                 if (kgdb_info[-tid - 2].task)
 406                         return kgdb_info[-tid - 2].task;
 407                 else
 408                         return idle_task(-tid - 2);
 409         }
 410         if (tid <= 0) {
 411                 printk(KERN_ERR "KGDB: Internal thread select error\n");
 412                 dump_stack();
 413                 return NULL;
 414         }
 415
 416         /*
 417          * find_task_by_pid_ns() does not take the tasklist lock anymore
 418          * but is nicely RCU locked - hence is a pretty resilient
 419          * thing to use:
 420          */
 421         return find_task_by_pid_ns(tid, &init_pid_ns);
 422 }
 423
 424
 425 /*
 426  * Remap normal tasks to their real PID,
 427  * CPU shadow threads are mapped to -CPU - 2
 428  */
 429 static inline int shadow_pid(int realpid)
 430 {
 431         if (realpid)
 432                 return realpid;
 433
 434         return -raw_smp_processor_id() - 2;
 435 }
 436
 437 /*
 438  * All the functions that start with gdb_cmd are the various
 439  * operations to implement the handlers for the gdbserial protocol
 440  * where KGDB is communicating with an external debugger
 441  */
 442
 443 /* Handle the '?' status packets */
 444 static void gdb_cmd_status(struct kgdb_state *ks)
 445 {
 446         /*
 447          * We know that this packet is only sent
 448          * during initial connect.  So to be safe,
 449          * we clear out our breakpoints now in case
 450          * GDB is reconnecting.
 451          */
 452         dbg_remove_all_break();
 453
 454         remcom_out_buffer[0] = 'S';
 455         pack_hex_byte(&remcom_out_buffer[1], ks->signo);
 456 }
 457
 458 /* Handle the 'g' get registers request */
 459 static void gdb_cmd_getregs(struct kgdb_state *ks)
 460 {
 461         struct task_struct *thread;
 462         void *local_debuggerinfo;
 463         int i;
 464
 465         thread = kgdb_usethread;
 466         if (!thread) {
 467                 thread = kgdb_info[ks->cpu].task;
 468                 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
 469         } else {
 470                 local_debuggerinfo = NULL;
 471                 for_each_online_cpu(i) {
 472                         /*
 473                          * Try to find the task on some other
 474                          * or possibly this node if we do not
 475                          * find the matching task then we try
 476                          * to approximate the results.
 477                          */
 478                         if (thread == kgdb_info[i].task)
 479                                 local_debuggerinfo = kgdb_info[i].debuggerinfo;
 480                 }
 481         }
 482
 483         /*
 484          * All threads that don't have debuggerinfo should be
 485          * in schedule() sleeping, since all other CPUs
 486          * are in kgdb_wait, and thus have debuggerinfo.
 487          */
 488         if (local_debuggerinfo) {
 489                 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
 490         } else {
 491                 /*
 492                  * Pull stuff saved during switch_to; nothing
 493                  * else is accessible (or even particularly
 494                  * relevant).
 495                  *
 496                  * This should be enough for a stack trace.
 497                  */
 498                 sleeping_thread_to_gdb_regs(gdb_regs, thread);
 499         }
 500         kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
 501 }
 502
 503 /* Handle the 'G' set registers request */
 504 static void gdb_cmd_setregs(struct kgdb_state *ks)
 505 {
 506         kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
 507
 508         if (kgdb_usethread && kgdb_usethread != current) {
 509                 error_packet(remcom_out_buffer, -EINVAL);
 510         } else {
 511                 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
 512                 strcpy(remcom_out_buffer, "OK");
 513         }
 514 }
 515
 516 /* Handle the 'm' memory read bytes */
 517 static void gdb_cmd_memread(struct kgdb_state *ks)
 518 {
 519         char *ptr = &remcom_in_buffer[1];
 520         unsigned long length;
 521         unsigned long addr;
 522         int err;
 523
 524         if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
 525                                         kgdb_hex2long(&ptr, &length) > 0) {
 526                 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
 527                 if (err)
 528                         error_packet(remcom_out_buffer, err);
 529         } else {
 530                 error_packet(remcom_out_buffer, -EINVAL);
 531         }
 532 }
 533
 534 /* Handle the 'M' memory write bytes */
 535 static void gdb_cmd_memwrite(struct kgdb_state *ks)
 536 {
 537         int err = write_mem_msg(0);
 538
 539         if (err)
 540                 error_packet(remcom_out_buffer, err);
 541         else
 542                 strcpy(remcom_out_buffer, "OK");
 543 }
 544
 545 /* Handle the 'X' memory binary write bytes */
 546 static void gdb_cmd_binwrite(struct kgdb_state *ks)
 547 {
 548         int err = write_mem_msg(1);
 549
 550         if (err)
 551                 error_packet(remcom_out_buffer, err);
 552         else
 553                 strcpy(remcom_out_buffer, "OK");
 554 }
 555
 556 /* Handle the 'D' or 'k', detach or kill packets */
 557 static void gdb_cmd_detachkill(struct kgdb_state *ks)
 558 {
 559         int error;
 560
 561         /* The detach case */
 562         if (remcom_in_buffer[0] == 'D') {
 563                 error = dbg_remove_all_break();
 564                 if (error < 0) {
 565                         error_packet(remcom_out_buffer, error);
 566                 } else {
 567                         strcpy(remcom_out_buffer, "OK");
 568                         kgdb_connected = 0;
 569                 }
 570                 put_packet(remcom_out_buffer);
 571         } else {
 572                 /*
 573                  * Assume the kill case, with no exit code checking,
 574                  * trying to force detach the debugger:
 575                  */
 576                 dbg_remove_all_break();
 577                 kgdb_connected = 0;
 578         }
 579 }
 580
 581 /* Handle the 'R' reboot packets */
 582 static int gdb_cmd_reboot(struct kgdb_state *ks)
 583 {
 584         /* For now, only honor R0 */
 585         if (strcmp(remcom_in_buffer, "R0") == 0) {
 586                 printk(KERN_CRIT "Executing emergency reboot\n");
 587                 strcpy(remcom_out_buffer, "OK");
 588                 put_packet(remcom_out_buffer);
 589
 590                 /*
 591                  * Execution should not return from
 592                  * machine_emergency_restart()
 593                  */
 594                 machine_emergency_restart();
 595                 kgdb_connected = 0;
 596
 597                 return 1;
 598         }
 599         return 0;
 600 }
 601
 602 /* Handle the 'q' query packets */
 603 static void gdb_cmd_query(struct kgdb_state *ks)
 604 {
 605         struct task_struct *g;
 606         struct task_struct *p;
 607         unsigned char thref[BUF_THREAD_ID_SIZE];
 608         char *ptr;
 609         int i;
 610         int cpu;
 611         int finished = 0;
 612
 613         switch (remcom_in_buffer[1]) {
 614         case 's':
 615         case 'f':
 616                 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10))
 617                         break;
 618
 619                 i = 0;
 620                 remcom_out_buffer[0] = 'm';
 621                 ptr = remcom_out_buffer + 1;
 622                 if (remcom_in_buffer[1] == 'f') {
 623                         /* Each cpu is a shadow thread */
 624                         for_each_online_cpu(cpu) {
 625                                 ks->thr_query = 0;
 626                                 int_to_threadref(thref, -cpu - 2);
 627                                 ptr = pack_threadid(ptr, thref);
 628                                 *(ptr++) = ',';
 629                                 i++;
 630                         }
 631                 }
 632
 633                 do_each_thread(g, p) {
 634                         if (i >= ks->thr_query && !finished) {
 635                                 int_to_threadref(thref, p->pid);
 636                                 ptr = pack_threadid(ptr, thref);
 637                                 *(ptr++) = ',';
 638                                 ks->thr_query++;
 639                                 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
 640                                         finished = 1;
 641                         }
 642                         i++;
 643                 } while_each_thread(g, p);
 644
 645                 *(--ptr) = '\0';
 646                 break;
 647
 648         case 'C':
 649                 /* Current thread id */
 650                 strcpy(remcom_out_buffer, "QC");
 651                 ks->threadid = shadow_pid(current->pid);
 652                 int_to_threadref(thref, ks->threadid);
 653                 pack_threadid(remcom_out_buffer + 2, thref);
 654                 break;
 655         case 'T':
 656                 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16))
 657                         break;
 658
 659                 ks->threadid = 0;
 660                 ptr = remcom_in_buffer + 17;
 661                 kgdb_hex2long(&ptr, &ks->threadid);
 662                 if (!getthread(ks->linux_regs, ks->threadid)) {
 663                         error_packet(remcom_out_buffer, -EINVAL);
 664                         break;
 665                 }
 666                 if ((int)ks->threadid > 0) {
 667                         kgdb_mem2hex(getthread(ks->linux_regs,
 668                                         ks->threadid)->comm,
 669                                         remcom_out_buffer, 16);
 670                 } else {
 671                         static char tmpstr[23 + BUF_THREAD_ID_SIZE];
 672
 673                         sprintf(tmpstr, "shadowCPU%d",
 674                                         (int)(-ks->threadid - 2));
 675                         kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
 676                 }
 677                 break;
 678 #ifdef CONFIG_KGDB_KDB
 679         case 'R':
 680                 if (strncmp(remcom_in_buffer, "qRcmd,", 6) == 0) {
 681                         int len = strlen(remcom_in_buffer + 6);
 682
 683                         if ((len % 2) != 0) {
 684                                 strcpy(remcom_out_buffer, "E01");
 685                                 break;
 686                         }
 687                         kgdb_hex2mem(remcom_in_buffer + 6,
 688                                      remcom_out_buffer, len);
 689                         len = len / 2;
 690                         remcom_out_buffer[len++] = 0;
 691
 692                         kdb_parse(remcom_out_buffer);
 693                         strcpy(remcom_out_buffer, "OK");
 694                 }
 695                 break;
 696 #endif
 697         }
 698 }
 699
 700 /* Handle the 'H' task query packets */
 701 static void gdb_cmd_task(struct kgdb_state *ks)
 702 {
 703         struct task_struct *thread;
 704         char *ptr;
 705
 706         switch (remcom_in_buffer[1]) {
 707         case 'g':
 708                 ptr = &remcom_in_buffer[2];
 709                 kgdb_hex2long(&ptr, &ks->threadid);
 710                 thread = getthread(ks->linux_regs, ks->threadid);
 711                 if (!thread && ks->threadid > 0) {
 712                         error_packet(remcom_out_buffer, -EINVAL);
 713                         break;
 714                 }
 715                 kgdb_usethread = thread;
 716                 ks->kgdb_usethreadid = ks->threadid;
 717                 strcpy(remcom_out_buffer, "OK");
 718                 break;
 719         case 'c':
 720                 ptr = &remcom_in_buffer[2];
 721                 kgdb_hex2long(&ptr, &ks->threadid);
 722                 if (!ks->threadid) {
 723                         kgdb_contthread = NULL;
 724                 } else {
 725                         thread = getthread(ks->linux_regs, ks->threadid);
 726                         if (!thread && ks->threadid > 0) {
 727                                 error_packet(remcom_out_buffer, -EINVAL);
 728                                 break;
 729                         }
 730                         kgdb_contthread = thread;
 731                 }
 732                 strcpy(remcom_out_buffer, "OK");
 733                 break;
 734         }
 735 }
 736
 737 /* Handle the 'T' thread query packets */
 738 static void gdb_cmd_thread(struct kgdb_state *ks)
 739 {
 740         char *ptr = &remcom_in_buffer[1];
 741         struct task_struct *thread;
 742
 743         kgdb_hex2long(&ptr, &ks->threadid);
 744         thread = getthread(ks->linux_regs, ks->threadid);
 745         if (thread)
 746                 strcpy(remcom_out_buffer, "OK");
 747         else
 748                 error_packet(remcom_out_buffer, -EINVAL);
 749 }
 750
 751 /* Handle the 'z' or 'Z' breakpoint remove or set packets */
 752 static void gdb_cmd_break(struct kgdb_state *ks)
 753 {
 754         /*
 755          * Since GDB-5.3, it's been drafted that '0' is a software
 756          * breakpoint, '1' is a hardware breakpoint, so let's do that.
 757          */
 758         char *bpt_type = &remcom_in_buffer[1];
 759         char *ptr = &remcom_in_buffer[2];
 760         unsigned long addr;
 761         unsigned long length;
 762         int error = 0;
 763
 764         if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
 765                 /* Unsupported */
 766                 if (*bpt_type > '4')
 767                         return;
 768         } else {
 769                 if (*bpt_type != '0' && *bpt_type != '1')
 770                         /* Unsupported. */
 771                         return;
 772         }
 773
 774         /*
 775          * Test if this is a hardware breakpoint, and
 776          * if we support it:
 777          */
 778         if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
 779                 /* Unsupported. */
 780                 return;
 781
 782         if (*(ptr++) != ',') {
 783                 error_packet(remcom_out_buffer, -EINVAL);
 784                 return;
 785         }
 786         if (!kgdb_hex2long(&ptr, &addr)) {
 787                 error_packet(remcom_out_buffer, -EINVAL);
 788                 return;
 789         }
 790         if (*(ptr++) != ',' ||
 791                 !kgdb_hex2long(&ptr, &length)) {
 792                 error_packet(remcom_out_buffer, -EINVAL);
 793                 return;
 794         }
 795
 796         if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
 797                 error = dbg_set_sw_break(addr);
 798         else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
 799                 error = dbg_remove_sw_break(addr);
 800         else if (remcom_in_buffer[0] == 'Z')
 801                 error = arch_kgdb_ops.set_hw_breakpoint(addr,
 802                         (int)length, *bpt_type - '0');
 803         else if (remcom_in_buffer[0] == 'z')
 804                 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
 805                         (int) length, *bpt_type - '0');
 806
 807         if (error == 0)
 808                 strcpy(remcom_out_buffer, "OK");
 809         else
 810                 error_packet(remcom_out_buffer, error);
 811 }
 812
 813 /* Handle the 'C' signal / exception passing packets */
 814 static int gdb_cmd_exception_pass(struct kgdb_state *ks)
 815 {
 816         /* C09 == pass exception
 817          * C15 == detach kgdb, pass exception
 818          */
 819         if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
 820
 821                 ks->pass_exception = 1;
 822                 remcom_in_buffer[0] = 'c';
 823
 824         } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
 825
 826                 ks->pass_exception = 1;
 827                 remcom_in_buffer[0] = 'D';
 828                 dbg_remove_all_break();
 829                 kgdb_connected = 0;
 830                 return 1;
 831
 832         } else {
 833                 gdbstub_msg_write("KGDB only knows signal 9 (pass)"
 834                         " and 15 (pass and disconnect)\n"
 835                         "Executing a continue without signal passing\n", 0);
 836                 remcom_in_buffer[0] = 'c';
 837         }
 838
 839         /* Indicate fall through */
 840         return -1;
 841 }
 842
 843 /*
 844  * This function performs all gdbserial command procesing
 845  */
 846 int gdb_serial_stub(struct kgdb_state *ks)
 847 {
 848         int error = 0;
 849         int tmp;
 850
 851         /* Clear the out buffer. */
 852         memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
 853
 854         if (kgdb_connected) {
 855                 unsigned char thref[BUF_THREAD_ID_SIZE];
 856                 char *ptr;
 857
 858                 /* Reply to host that an exception has occurred */
 859                 ptr = remcom_out_buffer;
 860                 *ptr++ = 'T';
 861                 ptr = pack_hex_byte(ptr, ks->signo);
 862                 ptr += strlen(strcpy(ptr, "thread:"));
 863                 int_to_threadref(thref, shadow_pid(current->pid));
 864                 ptr = pack_threadid(ptr, thref);
 865                 *ptr++ = ';';
 866                 put_packet(remcom_out_buffer);
 867         }
 868
 869         kgdb_usethread = kgdb_info[ks->cpu].task;
 870         ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
 871         ks->pass_exception = 0;
 872
 873         while (1) {
 874                 error = 0;
 875
 876                 /* Clear the out buffer. */
 877                 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
 878
 879                 get_packet(remcom_in_buffer);
 880
 881                 switch (remcom_in_buffer[0]) {
 882                 case '?': /* gdbserial status */
 883                         gdb_cmd_status(ks);
 884                         break;
 885                 case 'g': /* return the value of the CPU registers */
 886                         gdb_cmd_getregs(ks);
 887                         break;
 888                 case 'G': /* set the value of the CPU registers - return OK */
 889                         gdb_cmd_setregs(ks);
 890                         break;
 891                 case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
 892                         gdb_cmd_memread(ks);
 893                         break;
 894                 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
 895                         gdb_cmd_memwrite(ks);
 896                         break;
 897                 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
 898                         gdb_cmd_binwrite(ks);
 899                         break;
 900                         /* kill or detach. KGDB should treat this like a
 901                          * continue.
 902                          */
 903                 case 'D': /* Debugger detach */
 904                 case 'k': /* Debugger detach via kill */
 905                         gdb_cmd_detachkill(ks);
 906                         goto default_handle;
 907                 case 'R': /* Reboot */
 908                         if (gdb_cmd_reboot(ks))
 909                                 goto default_handle;
 910                         break;
 911                 case 'q': /* query command */
 912                         gdb_cmd_query(ks);
 913                         break;
 914                 case 'H': /* task related */
 915                         gdb_cmd_task(ks);
 916                         break;
 917                 case 'T': /* Query thread status */
 918                         gdb_cmd_thread(ks);
 919                         break;
 920                 case 'z': /* Break point remove */
 921                 case 'Z': /* Break point set */
 922                         gdb_cmd_break(ks);
 923                         break;
 924 #ifdef CONFIG_KGDB_KDB
 925                 case '3': /* Escape into back into kdb */
 926                         if (remcom_in_buffer[1] == '\0') {
 927                                 gdb_cmd_detachkill(ks);
 928                                 return DBG_PASS_EVENT;
 929                         }
 930 #endif
 931                 case 'C': /* Exception passing */
 932                         tmp = gdb_cmd_exception_pass(ks);
 933                         if (tmp > 0)
 934                                 goto default_handle;
 935                         if (tmp == 0)
 936                                 break;
 937                         /* Fall through on tmp < 0 */
 938                 case 'c': /* Continue packet */
 939                 case 's': /* Single step packet */
 940                         if (kgdb_contthread && kgdb_contthread != current) {
 941                                 /* Can't switch threads in kgdb */
 942                                 error_packet(remcom_out_buffer, -EINVAL);
 943                                 break;
 944                         }
 945                         dbg_activate_sw_breakpoints();
 946                         /* Fall through to default processing */
 947                 default:
 948 default_handle:
 949                         error = kgdb_arch_handle_exception(ks->ex_vector,
 950                                                 ks->signo,
 951                                                 ks->err_code,
 952                                                 remcom_in_buffer,
 953                                                 remcom_out_buffer,
 954                                                 ks->linux_regs);
 955                         /*
 956                          * Leave cmd processing on error, detach,
 957                          * kill, continue, or single step.
 958                          */
 959                         if (error >= 0 || remcom_in_buffer[0] == 'D' ||
 960                             remcom_in_buffer[0] == 'k') {
 961                                 error = 0;
 962                                 goto kgdb_exit;
 963                         }
 964
 965                 }
 966
 967                 /* reply to the request */
 968                 put_packet(remcom_out_buffer);
 969         }
 970
 971 kgdb_exit:
 972         if (ks->pass_exception)
 973                 error = 1;
 974         return error;
 975 }
 976
 977 int gdbstub_state(struct kgdb_state *ks, char *cmd)
 978 {
 979         int error;
 980
 981         switch (cmd[0]) {
 982         case 'e':
 983                 error = kgdb_arch_handle_exception(ks->ex_vector,
 984                                                    ks->signo,
 985                                                    ks->err_code,
 986                                                    remcom_in_buffer,
 987                                                    remcom_out_buffer,
 988                                                    ks->linux_regs);
 989                 return error;
 990         case 's':
 991         case 'c':
 992                 strcpy(remcom_in_buffer, cmd);
 993                 return 0;
 994         case '?':
 995                 gdb_cmd_status(ks);
 996                 break;
 997         case '\0':
 998                 strcpy(remcom_out_buffer, "");
 999                 break;
1000         }
1001         dbg_io_ops->write_char('+');
1002         put_packet(remcom_out_buffer);
1003         return 0;
1004 }