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   1 /*
   2  * Kernel Debug Core
   3  *
   4  * Maintainer: Jason Wessel <jason.wessel@windriver.com>
   5  *
   6  * Copyright (C) 2000-2001 VERITAS Software Corporation.
   7  * Copyright (C) 2002-2004 Timesys Corporation
   8  * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
   9  * Copyright (C) 2004 Pavel Machek <pavel@suse.cz>
  10  * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
  11  * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
  12  * Copyright (C) 2005-2009 Wind River Systems, Inc.
  13  * Copyright (C) 2007 MontaVista Software, Inc.
  14  * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  15  *
  16  * Contributors at various stages not listed above:
  17  *  Jason Wessel ( jason.wessel@windriver.com )
  18  *  George Anzinger <george@mvista.com>
  19  *  Anurekh Saxena (anurekh.saxena@timesys.com)
  20  *  Lake Stevens Instrument Division (Glenn Engel)
  21  *  Jim Kingdon, Cygnus Support.
  22  *
  23  * Original KGDB stub: David Grothe <dave@gcom.com>,
  24  * Tigran Aivazian <tigran@sco.com>
  25  *
  26  * This file is licensed under the terms of the GNU General Public License
  27  * version 2. This program is licensed "as is" without any warranty of any
  28  * kind, whether express or implied.
  29  */
  30
  31 #include <linux/kernel.h>
  32 #include <linux/kgdb.h>
  33 #include <linux/kdb.h>
  34 #include <linux/reboot.h>
  35 #include <linux/uaccess.h>
  36 #include <asm/cacheflush.h>
  37 #include <asm/unaligned.h>
  38 #include "debug_core.h"
  39
  40 #define KGDB_MAX_THREAD_QUERY 17
  41
  42 /* Our I/O buffers. */
  43 static char                     remcom_in_buffer[BUFMAX];
  44 static char                     remcom_out_buffer[BUFMAX];
  45
  46 /* Storage for the registers, in GDB format. */
  47 static unsigned long            gdb_regs[(NUMREGBYTES +
  48                                         sizeof(unsigned long) - 1) /
  49                                         sizeof(unsigned long)];
  50
  51 /*
  52  * GDB remote protocol parser:
  53  */
  54
  55 static int hex(char ch)
  56 {
  57         if ((ch >= 'a') && (ch <= 'f'))
  58                 return ch - 'a' + 10;
  59         if ((ch >= '0') && (ch <= '9'))
  60                 return ch - '0';
  61         if ((ch >= 'A') && (ch <= 'F'))
  62                 return ch - 'A' + 10;
  63         return -1;
  64 }
  65
  66 #ifdef CONFIG_KGDB_KDB
  67 static int gdbstub_read_wait(void)
  68 {
  69         int ret = -1;
  70         int i;
  71
  72         /* poll any additional I/O interfaces that are defined */
  73         while (ret < 0)
  74                 for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
  75                         ret = kdb_poll_funcs[i]();
  76                         if (ret > 0)
  77                                 break;
  78                 }
  79         return ret;
  80 }
  81 #else
  82 static int gdbstub_read_wait(void)
  83 {
  84         int ret = dbg_io_ops->read_char();
  85         while (ret == NO_POLL_CHAR)
  86                 ret = dbg_io_ops->read_char();
  87         return ret;
  88 }
  89 #endif
  90 /* scan for the sequence $<data>#<checksum> */
  91 static void get_packet(char *buffer)
  92 {
  93         unsigned char checksum;
  94         unsigned char xmitcsum;
  95         int count;
  96         char ch;
  97
  98         do {
  99                 /*
 100                  * Spin and wait around for the start character, ignore all
 101                  * other characters:
 102                  */
 103                 while ((ch = (gdbstub_read_wait())) != '$')
 104                         /* nothing */;
 105
 106                 kgdb_connected = 1;
 107                 checksum = 0;
 108                 xmitcsum = -1;
 109
 110                 count = 0;
 111
 112                 /*
 113                  * now, read until a # or end of buffer is found:
 114                  */
 115                 while (count < (BUFMAX - 1)) {
 116                         ch = gdbstub_read_wait();
 117                         if (ch == '#')
 118                                 break;
 119                         checksum = checksum + ch;
 120                         buffer[count] = ch;
 121                         count = count + 1;
 122                 }
 123                 buffer[count] = 0;
 124
 125                 if (ch == '#') {
 126                         xmitcsum = hex(gdbstub_read_wait()) << 4;
 127                         xmitcsum += hex(gdbstub_read_wait());
 128
 129                         if (checksum != xmitcsum)
 130                                 /* failed checksum */
 131                                 dbg_io_ops->write_char('-');
 132                         else
 133                                 /* successful transfer */
 134                                 dbg_io_ops->write_char('+');
 135                         if (dbg_io_ops->flush)
 136                                 dbg_io_ops->flush();
 137                 }
 138         } while (checksum != xmitcsum);
 139 }
 140
 141 /*
 142  * Send the packet in buffer.
 143  * Check for gdb connection if asked for.
 144  */
 145 static void put_packet(char *buffer)
 146 {
 147         unsigned char checksum;
 148         int count;
 149         char ch;
 150
 151         /*
 152          * $<packet info>#<checksum>.
 153          */
 154         while (1) {
 155                 dbg_io_ops->write_char('$');
 156                 checksum = 0;
 157                 count = 0;
 158
 159                 while ((ch = buffer[count])) {
 160                         dbg_io_ops->write_char(ch);
 161                         checksum += ch;
 162                         count++;
 163                 }
 164
 165                 dbg_io_ops->write_char('#');
 166                 dbg_io_ops->write_char(hex_asc_hi(checksum));
 167                 dbg_io_ops->write_char(hex_asc_lo(checksum));
 168                 if (dbg_io_ops->flush)
 169                         dbg_io_ops->flush();
 170
 171                 /* Now see what we get in reply. */
 172                 ch = gdbstub_read_wait();
 173
 174                 if (ch == 3)
 175                         ch = gdbstub_read_wait();
 176
 177                 /* If we get an ACK, we are done. */
 178                 if (ch == '+')
 179                         return;
 180
 181                 /*
 182                  * If we get the start of another packet, this means
 183                  * that GDB is attempting to reconnect.  We will NAK
 184                  * the packet being sent, and stop trying to send this
 185                  * packet.
 186                  */
 187                 if (ch == '$') {
 188                         dbg_io_ops->write_char('-');
 189                         if (dbg_io_ops->flush)
 190                                 dbg_io_ops->flush();
 191                         return;
 192                 }
 193         }
 194 }
 195
 196 static char gdbmsgbuf[BUFMAX + 1];
 197
 198 void gdbstub_msg_write(const char *s, int len)
 199 {
 200         char *bufptr;
 201         int wcount;
 202         int i;
 203
 204         /* 'O'utput */
 205         gdbmsgbuf[0] = 'O';
 206
 207         /* Fill and send buffers... */
 208         while (len > 0) {
 209                 bufptr = gdbmsgbuf + 1;
 210
 211                 /* Calculate how many this time */
 212                 if ((len << 1) > (BUFMAX - 2))
 213                         wcount = (BUFMAX - 2) >> 1;
 214                 else
 215                         wcount = len;
 216
 217                 /* Pack in hex chars */
 218                 for (i = 0; i < wcount; i++)
 219                         bufptr = pack_hex_byte(bufptr, s[i]);
 220                 *bufptr = '\0';
 221
 222                 /* Move up */
 223                 s += wcount;
 224                 len -= wcount;
 225
 226                 /* Write packet */
 227                 put_packet(gdbmsgbuf);
 228         }
 229 }
 230
 231 /*
 232  * Convert the memory pointed to by mem into hex, placing result in
 233  * buf.  Return a pointer to the last char put in buf (null). May
 234  * return an error.
 235  */
 236 int kgdb_mem2hex(char *mem, char *buf, int count)
 237 {
 238         char *tmp;
 239         int err;
 240
 241         /*
 242          * We use the upper half of buf as an intermediate buffer for the
 243          * raw memory copy.  Hex conversion will work against this one.
 244          */
 245         tmp = buf + count;
 246
 247         err = probe_kernel_read(tmp, mem, count);
 248         if (!err) {
 249                 while (count > 0) {
 250                         buf = pack_hex_byte(buf, *tmp);
 251                         tmp++;
 252                         count--;
 253                 }
 254
 255                 *buf = 0;
 256         }
 257
 258         return err;
 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(*tmp_hex--);
 281                 *tmp_raw |= hex(*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(**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 /* Write memory due to an 'M' or 'X' packet. */
 340 static int write_mem_msg(int binary)
 341 {
 342         char *ptr = &remcom_in_buffer[1];
 343         unsigned long addr;
 344         unsigned long length;
 345         int err;
 346
 347         if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
 348             kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
 349                 if (binary)
 350                         err = kgdb_ebin2mem(ptr, (char *)addr, length);
 351                 else
 352                         err = kgdb_hex2mem(ptr, (char *)addr, length);
 353                 if (err)
 354                         return err;
 355                 if (CACHE_FLUSH_IS_SAFE)
 356                         flush_icache_range(addr, addr + length);
 357                 return 0;
 358         }
 359
 360         return -EINVAL;
 361 }
 362
 363 static void error_packet(char *pkt, int error)
 364 {
 365         error = -error;
 366         pkt[0] = 'E';
 367         pkt[1] = hex_asc[(error / 10)];
 368         pkt[2] = hex_asc[(error % 10)];
 369         pkt[3] = '\0';
 370 }
 371
 372 /*
 373  * Thread ID accessors. We represent a flat TID space to GDB, where
 374  * the per CPU idle threads (which under Linux all have PID 0) are
 375  * remapped to negative TIDs.
 376  */
 377
 378 #define BUF_THREAD_ID_SIZE      16
 379
 380 static char *pack_threadid(char *pkt, unsigned char *id)
 381 {
 382         char *limit;
 383
 384         limit = pkt + BUF_THREAD_ID_SIZE;
 385         while (pkt < limit)
 386                 pkt = pack_hex_byte(pkt, *id++);
 387
 388         return pkt;
 389 }
 390
 391 static void int_to_threadref(unsigned char *id, int value)
 392 {
 393         unsigned char *scan;
 394         int i = 4;
 395
 396         scan = (unsigned char *)id;
 397         while (i--)
 398                 *scan++ = 0;
 399         put_unaligned_be32(value, scan);
 400 }
 401
 402 static struct task_struct *getthread(struct pt_regs *regs, int tid)
 403 {
 404         /*
 405          * Non-positive TIDs are remapped to the cpu shadow information
 406          */
 407         if (tid == 0 || tid == -1)
 408                 tid = -atomic_read(&kgdb_active) - 2;
 409         if (tid < -1 && tid > -NR_CPUS - 2) {
 410                 if (kgdb_info[-tid - 2].task)
 411                         return kgdb_info[-tid - 2].task;
 412                 else
 413                         return idle_task(-tid - 2);
 414         }
 415         if (tid <= 0) {
 416                 printk(KERN_ERR "KGDB: Internal thread select error\n");
 417                 dump_stack();
 418                 return NULL;
 419         }
 420
 421         /*
 422          * find_task_by_pid_ns() does not take the tasklist lock anymore
 423          * but is nicely RCU locked - hence is a pretty resilient
 424          * thing to use:
 425          */
 426         return find_task_by_pid_ns(tid, &init_pid_ns);
 427 }
 428
 429
 430 /*
 431  * Remap normal tasks to their real PID,
 432  * CPU shadow threads are mapped to -CPU - 2
 433  */
 434 static inline int shadow_pid(int realpid)
 435 {
 436         if (realpid)
 437                 return realpid;
 438
 439         return -raw_smp_processor_id() - 2;
 440 }
 441
 442 /*
 443  * All the functions that start with gdb_cmd are the various
 444  * operations to implement the handlers for the gdbserial protocol
 445  * where KGDB is communicating with an external debugger
 446  */
 447
 448 /* Handle the '?' status packets */
 449 static void gdb_cmd_status(struct kgdb_state *ks)
 450 {
 451         /*
 452          * We know that this packet is only sent
 453          * during initial connect.  So to be safe,
 454          * we clear out our breakpoints now in case
 455          * GDB is reconnecting.
 456          */
 457         dbg_remove_all_break();
 458
 459         remcom_out_buffer[0] = 'S';
 460         pack_hex_byte(&remcom_out_buffer[1], ks->signo);
 461 }
 462
 463 /* Handle the 'g' get registers request */
 464 static void gdb_cmd_getregs(struct kgdb_state *ks)
 465 {
 466         struct task_struct *thread;
 467         void *local_debuggerinfo;
 468         int i;
 469
 470         thread = kgdb_usethread;
 471         if (!thread) {
 472                 thread = kgdb_info[ks->cpu].task;
 473                 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
 474         } else {
 475                 local_debuggerinfo = NULL;
 476                 for_each_online_cpu(i) {
 477                         /*
 478                          * Try to find the task on some other
 479                          * or possibly this node if we do not
 480                          * find the matching task then we try
 481                          * to approximate the results.
 482                          */
 483                         if (thread == kgdb_info[i].task)
 484                                 local_debuggerinfo = kgdb_info[i].debuggerinfo;
 485                 }
 486         }
 487
 488         /*
 489          * All threads that don't have debuggerinfo should be
 490          * in schedule() sleeping, since all other CPUs
 491          * are in kgdb_wait, and thus have debuggerinfo.
 492          */
 493         if (local_debuggerinfo) {
 494                 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
 495         } else {
 496                 /*
 497                  * Pull stuff saved during switch_to; nothing
 498                  * else is accessible (or even particularly
 499                  * relevant).
 500                  *
 501                  * This should be enough for a stack trace.
 502                  */
 503                 sleeping_thread_to_gdb_regs(gdb_regs, thread);
 504         }
 505         kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
 506 }
 507
 508 /* Handle the 'G' set registers request */
 509 static void gdb_cmd_setregs(struct kgdb_state *ks)
 510 {
 511         kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
 512
 513         if (kgdb_usethread && kgdb_usethread != current) {
 514                 error_packet(remcom_out_buffer, -EINVAL);
 515         } else {
 516                 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
 517                 strcpy(remcom_out_buffer, "OK");
 518         }
 519 }
 520
 521 /* Handle the 'm' memory read bytes */
 522 static void gdb_cmd_memread(struct kgdb_state *ks)
 523 {
 524         char *ptr = &remcom_in_buffer[1];
 525         unsigned long length;
 526         unsigned long addr;
 527         int err;
 528
 529         if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
 530                                         kgdb_hex2long(&ptr, &length) > 0) {
 531                 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
 532                 if (err)
 533                         error_packet(remcom_out_buffer, err);
 534         } else {
 535                 error_packet(remcom_out_buffer, -EINVAL);
 536         }
 537 }
 538
 539 /* Handle the 'M' memory write bytes */
 540 static void gdb_cmd_memwrite(struct kgdb_state *ks)
 541 {
 542         int err = write_mem_msg(0);
 543
 544         if (err)
 545                 error_packet(remcom_out_buffer, err);
 546         else
 547                 strcpy(remcom_out_buffer, "OK");
 548 }
 549
 550 /* Handle the 'X' memory binary write bytes */
 551 static void gdb_cmd_binwrite(struct kgdb_state *ks)
 552 {
 553         int err = write_mem_msg(1);
 554
 555         if (err)
 556                 error_packet(remcom_out_buffer, err);
 557         else
 558                 strcpy(remcom_out_buffer, "OK");
 559 }
 560
 561 /* Handle the 'D' or 'k', detach or kill packets */
 562 static void gdb_cmd_detachkill(struct kgdb_state *ks)
 563 {
 564         int error;
 565
 566         /* The detach case */
 567         if (remcom_in_buffer[0] == 'D') {
 568                 error = dbg_remove_all_break();
 569                 if (error < 0) {
 570                         error_packet(remcom_out_buffer, error);
 571                 } else {
 572                         strcpy(remcom_out_buffer, "OK");
 573                         kgdb_connected = 0;
 574                 }
 575                 put_packet(remcom_out_buffer);
 576         } else {
 577                 /*
 578                  * Assume the kill case, with no exit code checking,
 579                  * trying to force detach the debugger:
 580                  */
 581                 dbg_remove_all_break();
 582                 kgdb_connected = 0;
 583         }
 584 }
 585
 586 /* Handle the 'R' reboot packets */
 587 static int gdb_cmd_reboot(struct kgdb_state *ks)
 588 {
 589         /* For now, only honor R0 */
 590         if (strcmp(remcom_in_buffer, "R0") == 0) {
 591                 printk(KERN_CRIT "Executing emergency reboot\n");
 592                 strcpy(remcom_out_buffer, "OK");
 593                 put_packet(remcom_out_buffer);
 594
 595                 /*
 596                  * Execution should not return from
 597                  * machine_emergency_restart()
 598                  */
 599                 machine_emergency_restart();
 600                 kgdb_connected = 0;
 601
 602                 return 1;
 603         }
 604         return 0;
 605 }
 606
 607 /* Handle the 'q' query packets */
 608 static void gdb_cmd_query(struct kgdb_state *ks)
 609 {
 610         struct task_struct *g;
 611         struct task_struct *p;
 612         unsigned char thref[8];
 613         char *ptr;
 614         int i;
 615         int cpu;
 616         int finished = 0;
 617
 618         switch (remcom_in_buffer[1]) {
 619         case 's':
 620         case 'f':
 621                 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
 622                         error_packet(remcom_out_buffer, -EINVAL);
 623                         break;
 624                 }
 625
 626                 i = 0;
 627                 remcom_out_buffer[0] = 'm';
 628                 ptr = remcom_out_buffer + 1;
 629                 if (remcom_in_buffer[1] == 'f') {
 630                         /* Each cpu is a shadow thread */
 631                         for_each_online_cpu(cpu) {
 632                                 ks->thr_query = 0;
 633                                 int_to_threadref(thref, -cpu - 2);
 634                                 pack_threadid(ptr, thref);
 635                                 ptr += BUF_THREAD_ID_SIZE;
 636                                 *(ptr++) = ',';
 637                                 i++;
 638                         }
 639                 }
 640
 641                 do_each_thread(g, p) {
 642                         if (i >= ks->thr_query && !finished) {
 643                                 int_to_threadref(thref, p->pid);
 644                                 pack_threadid(ptr, thref);
 645                                 ptr += BUF_THREAD_ID_SIZE;
 646                                 *(ptr++) = ',';
 647                                 ks->thr_query++;
 648                                 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
 649                                         finished = 1;
 650                         }
 651                         i++;
 652                 } while_each_thread(g, p);
 653
 654                 *(--ptr) = '\0';
 655                 break;
 656
 657         case 'C':
 658                 /* Current thread id */
 659                 strcpy(remcom_out_buffer, "QC");
 660                 ks->threadid = shadow_pid(current->pid);
 661                 int_to_threadref(thref, ks->threadid);
 662                 pack_threadid(remcom_out_buffer + 2, thref);
 663                 break;
 664         case 'T':
 665                 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
 666                         error_packet(remcom_out_buffer, -EINVAL);
 667                         break;
 668                 }
 669                 ks->threadid = 0;
 670                 ptr = remcom_in_buffer + 17;
 671                 kgdb_hex2long(&ptr, &ks->threadid);
 672                 if (!getthread(ks->linux_regs, ks->threadid)) {
 673                         error_packet(remcom_out_buffer, -EINVAL);
 674                         break;
 675                 }
 676                 if ((int)ks->threadid > 0) {
 677                         kgdb_mem2hex(getthread(ks->linux_regs,
 678                                         ks->threadid)->comm,
 679                                         remcom_out_buffer, 16);
 680                 } else {
 681                         static char tmpstr[23 + BUF_THREAD_ID_SIZE];
 682
 683                         sprintf(tmpstr, "shadowCPU%d",
 684                                         (int)(-ks->threadid - 2));
 685                         kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
 686                 }
 687                 break;
 688         }
 689 }
 690
 691 /* Handle the 'H' task query packets */
 692 static void gdb_cmd_task(struct kgdb_state *ks)
 693 {
 694         struct task_struct *thread;
 695         char *ptr;
 696
 697         switch (remcom_in_buffer[1]) {
 698         case 'g':
 699                 ptr = &remcom_in_buffer[2];
 700                 kgdb_hex2long(&ptr, &ks->threadid);
 701                 thread = getthread(ks->linux_regs, ks->threadid);
 702                 if (!thread && ks->threadid > 0) {
 703                         error_packet(remcom_out_buffer, -EINVAL);
 704                         break;
 705                 }
 706                 kgdb_usethread = thread;
 707                 ks->kgdb_usethreadid = ks->threadid;
 708                 strcpy(remcom_out_buffer, "OK");
 709                 break;
 710         case 'c':
 711                 ptr = &remcom_in_buffer[2];
 712                 kgdb_hex2long(&ptr, &ks->threadid);
 713                 if (!ks->threadid) {
 714                         kgdb_contthread = NULL;
 715                 } else {
 716                         thread = getthread(ks->linux_regs, ks->threadid);
 717                         if (!thread && ks->threadid > 0) {
 718                                 error_packet(remcom_out_buffer, -EINVAL);
 719                                 break;
 720                         }
 721                         kgdb_contthread = thread;
 722                 }
 723                 strcpy(remcom_out_buffer, "OK");
 724                 break;
 725         }
 726 }
 727
 728 /* Handle the 'T' thread query packets */
 729 static void gdb_cmd_thread(struct kgdb_state *ks)
 730 {
 731         char *ptr = &remcom_in_buffer[1];
 732         struct task_struct *thread;
 733
 734         kgdb_hex2long(&ptr, &ks->threadid);
 735         thread = getthread(ks->linux_regs, ks->threadid);
 736         if (thread)
 737                 strcpy(remcom_out_buffer, "OK");
 738         else
 739                 error_packet(remcom_out_buffer, -EINVAL);
 740 }
 741
 742 /* Handle the 'z' or 'Z' breakpoint remove or set packets */
 743 static void gdb_cmd_break(struct kgdb_state *ks)
 744 {
 745         /*
 746          * Since GDB-5.3, it's been drafted that '0' is a software
 747          * breakpoint, '1' is a hardware breakpoint, so let's do that.
 748          */
 749         char *bpt_type = &remcom_in_buffer[1];
 750         char *ptr = &remcom_in_buffer[2];
 751         unsigned long addr;
 752         unsigned long length;
 753         int error = 0;
 754
 755         if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
 756                 /* Unsupported */
 757                 if (*bpt_type > '4')
 758                         return;
 759         } else {
 760                 if (*bpt_type != '0' && *bpt_type != '1')
 761                         /* Unsupported. */
 762                         return;
 763         }
 764
 765         /*
 766          * Test if this is a hardware breakpoint, and
 767          * if we support it:
 768          */
 769         if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
 770                 /* Unsupported. */
 771                 return;
 772
 773         if (*(ptr++) != ',') {
 774                 error_packet(remcom_out_buffer, -EINVAL);
 775                 return;
 776         }
 777         if (!kgdb_hex2long(&ptr, &addr)) {
 778                 error_packet(remcom_out_buffer, -EINVAL);
 779                 return;
 780         }
 781         if (*(ptr++) != ',' ||
 782                 !kgdb_hex2long(&ptr, &length)) {
 783                 error_packet(remcom_out_buffer, -EINVAL);
 784                 return;
 785         }
 786
 787         if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
 788                 error = dbg_set_sw_break(addr);
 789         else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
 790                 error = dbg_remove_sw_break(addr);
 791         else if (remcom_in_buffer[0] == 'Z')
 792                 error = arch_kgdb_ops.set_hw_breakpoint(addr,
 793                         (int)length, *bpt_type - '0');
 794         else if (remcom_in_buffer[0] == 'z')
 795                 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
 796                         (int) length, *bpt_type - '0');
 797
 798         if (error == 0)
 799                 strcpy(remcom_out_buffer, "OK");
 800         else
 801                 error_packet(remcom_out_buffer, error);
 802 }
 803
 804 /* Handle the 'C' signal / exception passing packets */
 805 static int gdb_cmd_exception_pass(struct kgdb_state *ks)
 806 {
 807         /* C09 == pass exception
 808          * C15 == detach kgdb, pass exception
 809          */
 810         if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
 811
 812                 ks->pass_exception = 1;
 813                 remcom_in_buffer[0] = 'c';
 814
 815         } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
 816
 817                 ks->pass_exception = 1;
 818                 remcom_in_buffer[0] = 'D';
 819                 dbg_remove_all_break();
 820                 kgdb_connected = 0;
 821                 return 1;
 822
 823         } else {
 824                 gdbstub_msg_write("KGDB only knows signal 9 (pass)"
 825                         " and 15 (pass and disconnect)\n"
 826                         "Executing a continue without signal passing\n", 0);
 827                 remcom_in_buffer[0] = 'c';
 828         }
 829
 830         /* Indicate fall through */
 831         return -1;
 832 }
 833
 834 /*
 835  * This function performs all gdbserial command procesing
 836  */
 837 int gdb_serial_stub(struct kgdb_state *ks)
 838 {
 839         int error = 0;
 840         int tmp;
 841
 842         /* Clear the out buffer. */
 843         memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
 844
 845         if (kgdb_connected) {
 846                 unsigned char thref[8];
 847                 char *ptr;
 848
 849                 /* Reply to host that an exception has occurred */
 850                 ptr = remcom_out_buffer;
 851                 *ptr++ = 'T';
 852                 ptr = pack_hex_byte(ptr, ks->signo);
 853                 ptr += strlen(strcpy(ptr, "thread:"));
 854                 int_to_threadref(thref, shadow_pid(current->pid));
 855                 ptr = pack_threadid(ptr, thref);
 856                 *ptr++ = ';';
 857                 put_packet(remcom_out_buffer);
 858         }
 859
 860         kgdb_usethread = kgdb_info[ks->cpu].task;
 861         ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
 862         ks->pass_exception = 0;
 863
 864         while (1) {
 865                 error = 0;
 866
 867                 /* Clear the out buffer. */
 868                 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
 869
 870                 get_packet(remcom_in_buffer);
 871
 872                 switch (remcom_in_buffer[0]) {
 873                 case '?': /* gdbserial status */
 874                         gdb_cmd_status(ks);
 875                         break;
 876                 case 'g': /* return the value of the CPU registers */
 877                         gdb_cmd_getregs(ks);
 878                         break;
 879                 case 'G': /* set the value of the CPU registers - return OK */
 880                         gdb_cmd_setregs(ks);
 881                         break;
 882                 case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
 883                         gdb_cmd_memread(ks);
 884                         break;
 885                 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
 886                         gdb_cmd_memwrite(ks);
 887                         break;
 888                 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
 889                         gdb_cmd_binwrite(ks);
 890                         break;
 891                         /* kill or detach. KGDB should treat this like a
 892                          * continue.
 893                          */
 894                 case 'D': /* Debugger detach */
 895                 case 'k': /* Debugger detach via kill */
 896                         gdb_cmd_detachkill(ks);
 897                         goto default_handle;
 898                 case 'R': /* Reboot */
 899                         if (gdb_cmd_reboot(ks))
 900                                 goto default_handle;
 901                         break;
 902                 case 'q': /* query command */
 903                         gdb_cmd_query(ks);
 904                         break;
 905                 case 'H': /* task related */
 906                         gdb_cmd_task(ks);
 907                         break;
 908                 case 'T': /* Query thread status */
 909                         gdb_cmd_thread(ks);
 910                         break;
 911                 case 'z': /* Break point remove */
 912                 case 'Z': /* Break point set */
 913                         gdb_cmd_break(ks);
 914                         break;
 915 #ifdef CONFIG_KGDB_KDB
 916                 case '3': /* Escape into back into kdb */
 917                         if (remcom_in_buffer[1] == '\0') {
 918                                 gdb_cmd_detachkill(ks);
 919                                 return DBG_PASS_EVENT;
 920                         }
 921 #endif
 922                 case 'C': /* Exception passing */
 923                         tmp = gdb_cmd_exception_pass(ks);
 924                         if (tmp > 0)
 925                                 goto default_handle;
 926                         if (tmp == 0)
 927                                 break;
 928                         /* Fall through on tmp < 0 */
 929                 case 'c': /* Continue packet */
 930                 case 's': /* Single step packet */
 931                         if (kgdb_contthread && kgdb_contthread != current) {
 932                                 /* Can't switch threads in kgdb */
 933                                 error_packet(remcom_out_buffer, -EINVAL);
 934                                 break;
 935                         }
 936                         dbg_activate_sw_breakpoints();
 937                         /* Fall through to default processing */
 938                 default:
 939 default_handle:
 940                         error = kgdb_arch_handle_exception(ks->ex_vector,
 941                                                 ks->signo,
 942                                                 ks->err_code,
 943                                                 remcom_in_buffer,
 944                                                 remcom_out_buffer,
 945                                                 ks->linux_regs);
 946                         /*
 947                          * Leave cmd processing on error, detach,
 948                          * kill, continue, or single step.
 949                          */
 950                         if (error >= 0 || remcom_in_buffer[0] == 'D' ||
 951                             remcom_in_buffer[0] == 'k') {
 952                                 error = 0;
 953                                 goto kgdb_exit;
 954                         }
 955
 956                 }
 957
 958                 /* reply to the request */
 959                 put_packet(remcom_out_buffer);
 960         }
 961
 962 kgdb_exit:
 963         if (ks->pass_exception)
 964                 error = 1;
 965         return error;
 966 }
 967
 968 int gdbstub_state(struct kgdb_state *ks, char *cmd)
 969 {
 970         int error;
 971
 972         switch (cmd[0]) {
 973         case 'e':
 974                 error = kgdb_arch_handle_exception(ks->ex_vector,
 975                                                    ks->signo,
 976                                                    ks->err_code,
 977                                                    remcom_in_buffer,
 978                                                    remcom_out_buffer,
 979                                                    ks->linux_regs);
 980                 return error;
 981         case 's':
 982         case 'c':
 983                 strcpy(remcom_in_buffer, cmd);
 984                 return 0;
 985         case '?':
 986                 gdb_cmd_status(ks);
 987                 break;
 988         case '\0':
 989                 strcpy(remcom_out_buffer, "");
 990                 break;
 991         }
 992         dbg_io_ops->write_char('+');
 993         put_packet(remcom_out_buffer);
 994         return 0;
 995 }