kernel/kgdb.c

   1 /*
   2  * KGDB stub.
   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) 2005-2008 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 #include <linux/pid_namespace.h>
  31 #include <linux/clocksource.h>
  32 #include <linux/interrupt.h>
  33 #include <linux/spinlock.h>
  34 #include <linux/console.h>
  35 #include <linux/threads.h>
  36 #include <linux/uaccess.h>
  37 #include <linux/kernel.h>
  38 #include <linux/module.h>
  39 #include <linux/ptrace.h>
  40 #include <linux/reboot.h>
  41 #include <linux/string.h>
  42 #include <linux/delay.h>
  43 #include <linux/sched.h>
  44 #include <linux/sysrq.h>
  45 #include <linux/init.h>
  46 #include <linux/kgdb.h>
  47 #include <linux/pid.h>
  48 #include <linux/smp.h>
  49 #include <linux/mm.h>
  50
  51 #include <asm/cacheflush.h>
  52 #include <asm/byteorder.h>
  53 #include <asm/atomic.h>
  54 #include <asm/system.h>
  55
  56 static int kgdb_break_asap;
  57
  58 struct kgdb_state {
  59         int                     ex_vector;
  60         int                     signo;
  61         int                     err_code;
  62         int                     cpu;
  63         int                     pass_exception;
  64         unsigned long           threadid;
  65         long                    kgdb_usethreadid;
  66         struct pt_regs          *linux_regs;
  67 };
  68
  69 static struct debuggerinfo_struct {
  70         void                    *debuggerinfo;
  71         struct task_struct      *task;
  72 } kgdb_info[NR_CPUS];
  73
  74 /**
  75  * kgdb_connected - Is a host GDB connected to us?
  76  */
  77 int                             kgdb_connected;
  78 EXPORT_SYMBOL_GPL(kgdb_connected);
  79
  80 /* All the KGDB handlers are installed */
  81 static int                      kgdb_io_module_registered;
  82
  83 /* Guard for recursive entry */
  84 static int                      exception_level;
  85
  86 static struct kgdb_io           *kgdb_io_ops;
  87 static DEFINE_SPINLOCK(kgdb_registration_lock);
  88
  89 /* kgdb console driver is loaded */
  90 static int kgdb_con_registered;
  91 /* determine if kgdb console output should be used */
  92 static int kgdb_use_con;
  93
  94 static int __init opt_kgdb_con(char *str)
  95 {
  96         kgdb_use_con = 1;
  97         return 0;
  98 }
  99
 100 early_param("kgdbcon", opt_kgdb_con);
 101
 102 module_param(kgdb_use_con, int, 0644);
 103
 104 /*
 105  * Holds information about breakpoints in a kernel. These breakpoints are
 106  * added and removed by gdb.
 107  */
 108 static struct kgdb_bkpt         kgdb_break[KGDB_MAX_BREAKPOINTS] = {
 109         [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
 110 };
 111
 112 /*
 113  * The CPU# of the active CPU, or -1 if none:
 114  */
 115 atomic_t                        kgdb_active = ATOMIC_INIT(-1);
 116
 117 /*
 118  * We use NR_CPUs not PERCPU, in case kgdb is used to debug early
 119  * bootup code (which might not have percpu set up yet):
 120  */
 121 static atomic_t                 passive_cpu_wait[NR_CPUS];
 122 static atomic_t                 cpu_in_kgdb[NR_CPUS];
 123 atomic_t                        kgdb_setting_breakpoint;
 124
 125 struct task_struct              *kgdb_usethread;
 126 struct task_struct              *kgdb_contthread;
 127
 128 int                             kgdb_single_step;
 129
 130 /* Our I/O buffers. */
 131 static char                     remcom_in_buffer[BUFMAX];
 132 static char                     remcom_out_buffer[BUFMAX];
 133
 134 /* Storage for the registers, in GDB format. */
 135 static unsigned long            gdb_regs[(NUMREGBYTES +
 136                                         sizeof(unsigned long) - 1) /
 137                                         sizeof(unsigned long)];
 138
 139 /* to keep track of the CPU which is doing the single stepping*/
 140 atomic_t                        kgdb_cpu_doing_single_step = ATOMIC_INIT(-1);
 141
 142 /*
 143  * If you are debugging a problem where roundup (the collection of
 144  * all other CPUs) is a problem [this should be extremely rare],
 145  * then use the nokgdbroundup option to avoid roundup. In that case
 146  * the other CPUs might interfere with your debugging context, so
 147  * use this with care:
 148  */
 149 static int kgdb_do_roundup = 1;
 150
 151 static int __init opt_nokgdbroundup(char *str)
 152 {
 153         kgdb_do_roundup = 0;
 154
 155         return 0;
 156 }
 157
 158 early_param("nokgdbroundup", opt_nokgdbroundup);
 159
 160 /*
 161  * Finally, some KGDB code :-)
 162  */
 163
 164 /*
 165  * Weak aliases for breakpoint management,
 166  * can be overriden by architectures when needed:
 167  */
 168 int __weak kgdb_validate_break_address(unsigned long addr)
 169 {
 170         char tmp_variable[BREAK_INSTR_SIZE];
 171
 172         return probe_kernel_read(tmp_variable, (char *)addr, BREAK_INSTR_SIZE);
 173 }
 174
 175 int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr)
 176 {
 177         int err;
 178
 179         err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE);
 180         if (err)
 181                 return err;
 182
 183         return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr,
 184                                   BREAK_INSTR_SIZE);
 185 }
 186
 187 int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle)
 188 {
 189         return probe_kernel_write((char *)addr,
 190                                   (char *)bundle, BREAK_INSTR_SIZE);
 191 }
 192
 193 unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
 194 {
 195         return instruction_pointer(regs);
 196 }
 197
 198 int __weak kgdb_arch_init(void)
 199 {
 200         return 0;
 201 }
 202
 203 int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
 204 {
 205         return 0;
 206 }
 207
 208 void __weak
 209 kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
 210 {
 211         return;
 212 }
 213
 214 /**
 215  *      kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
 216  *      @regs: Current &struct pt_regs.
 217  *
 218  *      This function will be called if the particular architecture must
 219  *      disable hardware debugging while it is processing gdb packets or
 220  *      handling exception.
 221  */
 222 void __weak kgdb_disable_hw_debug(struct pt_regs *regs)
 223 {
 224 }
 225
 226 /*
 227  * GDB remote protocol parser:
 228  */
 229
 230 static const char       hexchars[] = "0123456789abcdef";
 231
 232 static int hex(char ch)
 233 {
 234         if ((ch >= 'a') && (ch <= 'f'))
 235                 return ch - 'a' + 10;
 236         if ((ch >= '0') && (ch <= '9'))
 237                 return ch - '0';
 238         if ((ch >= 'A') && (ch <= 'F'))
 239                 return ch - 'A' + 10;
 240         return -1;
 241 }
 242
 243 /* scan for the sequence $<data>#<checksum> */
 244 static void get_packet(char *buffer)
 245 {
 246         unsigned char checksum;
 247         unsigned char xmitcsum;
 248         int count;
 249         char ch;
 250
 251         do {
 252                 /*
 253                  * Spin and wait around for the start character, ignore all
 254                  * other characters:
 255                  */
 256                 while ((ch = (kgdb_io_ops->read_char())) != '$')
 257                         /* nothing */;
 258
 259                 kgdb_connected = 1;
 260                 checksum = 0;
 261                 xmitcsum = -1;
 262
 263                 count = 0;
 264
 265                 /*
 266                  * now, read until a # or end of buffer is found:
 267                  */
 268                 while (count < (BUFMAX - 1)) {
 269                         ch = kgdb_io_ops->read_char();
 270                         if (ch == '#')
 271                                 break;
 272                         checksum = checksum + ch;
 273                         buffer[count] = ch;
 274                         count = count + 1;
 275                 }
 276                 buffer[count] = 0;
 277
 278                 if (ch == '#') {
 279                         xmitcsum = hex(kgdb_io_ops->read_char()) << 4;
 280                         xmitcsum += hex(kgdb_io_ops->read_char());
 281
 282                         if (checksum != xmitcsum)
 283                                 /* failed checksum */
 284                                 kgdb_io_ops->write_char('-');
 285                         else
 286                                 /* successful transfer */
 287                                 kgdb_io_ops->write_char('+');
 288                         if (kgdb_io_ops->flush)
 289                                 kgdb_io_ops->flush();
 290                 }
 291         } while (checksum != xmitcsum);
 292 }
 293
 294 /*
 295  * Send the packet in buffer.
 296  * Check for gdb connection if asked for.
 297  */
 298 static void put_packet(char *buffer)
 299 {
 300         unsigned char checksum;
 301         int count;
 302         char ch;
 303
 304         /*
 305          * $<packet info>#<checksum>.
 306          */
 307         while (1) {
 308                 kgdb_io_ops->write_char('$');
 309                 checksum = 0;
 310                 count = 0;
 311
 312                 while ((ch = buffer[count])) {
 313                         kgdb_io_ops->write_char(ch);
 314                         checksum += ch;
 315                         count++;
 316                 }
 317
 318                 kgdb_io_ops->write_char('#');
 319                 kgdb_io_ops->write_char(hexchars[checksum >> 4]);
 320                 kgdb_io_ops->write_char(hexchars[checksum & 0xf]);
 321                 if (kgdb_io_ops->flush)
 322                         kgdb_io_ops->flush();
 323
 324                 /* Now see what we get in reply. */
 325                 ch = kgdb_io_ops->read_char();
 326
 327                 if (ch == 3)
 328                         ch = kgdb_io_ops->read_char();
 329
 330                 /* If we get an ACK, we are done. */
 331                 if (ch == '+')
 332                         return;
 333
 334                 /*
 335                  * If we get the start of another packet, this means
 336                  * that GDB is attempting to reconnect.  We will NAK
 337                  * the packet being sent, and stop trying to send this
 338                  * packet.
 339                  */
 340                 if (ch == '$') {
 341                         kgdb_io_ops->write_char('-');
 342                         if (kgdb_io_ops->flush)
 343                                 kgdb_io_ops->flush();
 344                         return;
 345                 }
 346         }
 347 }
 348
 349 /*
 350  * Convert the memory pointed to by mem into hex, placing result in buf.
 351  * Return a pointer to the last char put in buf (null). May return an error.
 352  */
 353 int kgdb_mem2hex(char *mem, char *buf, int count)
 354 {
 355         char *tmp;
 356         int err;
 357
 358         /*
 359          * We use the upper half of buf as an intermediate buffer for the
 360          * raw memory copy.  Hex conversion will work against this one.
 361          */
 362         tmp = buf + count;
 363
 364         err = probe_kernel_read(tmp, mem, count);
 365         if (!err) {
 366                 while (count > 0) {
 367                         buf = pack_hex_byte(buf, *tmp);
 368                         tmp++;
 369                         count--;
 370                 }
 371
 372                 *buf = 0;
 373         }
 374
 375         return err;
 376 }
 377
 378 /*
 379  * Copy the binary array pointed to by buf into mem.  Fix $, #, and
 380  * 0x7d escaped with 0x7d.  Return a pointer to the character after
 381  * the last byte written.
 382  */
 383 static int kgdb_ebin2mem(char *buf, char *mem, int count)
 384 {
 385         int err = 0;
 386         char c;
 387
 388         while (count-- > 0) {
 389                 c = *buf++;
 390                 if (c == 0x7d)
 391                         c = *buf++ ^ 0x20;
 392
 393                 err = probe_kernel_write(mem, &c, 1);
 394                 if (err)
 395                         break;
 396
 397                 mem++;
 398         }
 399
 400         return err;
 401 }
 402
 403 /*
 404  * Convert the hex array pointed to by buf into binary to be placed in mem.
 405  * Return a pointer to the character AFTER the last byte written.
 406  * May return an error.
 407  */
 408 int kgdb_hex2mem(char *buf, char *mem, int count)
 409 {
 410         char *tmp_raw;
 411         char *tmp_hex;
 412
 413         /*
 414          * We use the upper half of buf as an intermediate buffer for the
 415          * raw memory that is converted from hex.
 416          */
 417         tmp_raw = buf + count * 2;
 418
 419         tmp_hex = tmp_raw - 1;
 420         while (tmp_hex >= buf) {
 421                 tmp_raw--;
 422                 *tmp_raw = hex(*tmp_hex--);
 423                 *tmp_raw |= hex(*tmp_hex--) << 4;
 424         }
 425
 426         return probe_kernel_write(mem, tmp_raw, count);
 427 }
 428
 429 /*
 430  * While we find nice hex chars, build a long_val.
 431  * Return number of chars processed.
 432  */
 433 int kgdb_hex2long(char **ptr, unsigned long *long_val)
 434 {
 435         int hex_val;
 436         int num = 0;
 437
 438         *long_val = 0;
 439
 440         while (**ptr) {
 441                 hex_val = hex(**ptr);
 442                 if (hex_val < 0)
 443                         break;
 444
 445                 *long_val = (*long_val << 4) | hex_val;
 446                 num++;
 447                 (*ptr)++;
 448         }
 449
 450         return num;
 451 }
 452
 453 /* Write memory due to an 'M' or 'X' packet. */
 454 static int write_mem_msg(int binary)
 455 {
 456         char *ptr = &remcom_in_buffer[1];
 457         unsigned long addr;
 458         unsigned long length;
 459         int err;
 460
 461         if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
 462             kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
 463                 if (binary)
 464                         err = kgdb_ebin2mem(ptr, (char *)addr, length);
 465                 else
 466                         err = kgdb_hex2mem(ptr, (char *)addr, length);
 467                 if (err)
 468                         return err;
 469                 if (CACHE_FLUSH_IS_SAFE)
 470                         flush_icache_range(addr, addr + length + 1);
 471                 return 0;
 472         }
 473
 474         return -EINVAL;
 475 }
 476
 477 static void error_packet(char *pkt, int error)
 478 {
 479         error = -error;
 480         pkt[0] = 'E';
 481         pkt[1] = hexchars[(error / 10)];
 482         pkt[2] = hexchars[(error % 10)];
 483         pkt[3] = '\0';
 484 }
 485
 486 /*
 487  * Thread ID accessors. We represent a flat TID space to GDB, where
 488  * the per CPU idle threads (which under Linux all have PID 0) are
 489  * remapped to negative TIDs.
 490  */
 491
 492 #define BUF_THREAD_ID_SIZE      16
 493
 494 static char *pack_threadid(char *pkt, unsigned char *id)
 495 {
 496         char *limit;
 497
 498         limit = pkt + BUF_THREAD_ID_SIZE;
 499         while (pkt < limit)
 500                 pkt = pack_hex_byte(pkt, *id++);
 501
 502         return pkt;
 503 }
 504
 505 static void int_to_threadref(unsigned char *id, int value)
 506 {
 507         unsigned char *scan;
 508         int i = 4;
 509
 510         scan = (unsigned char *)id;
 511         while (i--)
 512                 *scan++ = 0;
 513         *scan++ = (value >> 24) & 0xff;
 514         *scan++ = (value >> 16) & 0xff;
 515         *scan++ = (value >> 8) & 0xff;
 516         *scan++ = (value & 0xff);
 517 }
 518
 519 static struct task_struct *getthread(struct pt_regs *regs, int tid)
 520 {
 521         /*
 522          * Non-positive TIDs are remapped idle tasks:
 523          */
 524         if (tid <= 0)
 525                 return idle_task(-tid);
 526
 527         /*
 528          * find_task_by_pid_ns() does not take the tasklist lock anymore
 529          * but is nicely RCU locked - hence is a pretty resilient
 530          * thing to use:
 531          */
 532         return find_task_by_pid_ns(tid, &init_pid_ns);
 533 }
 534
 535 /*
 536  * CPU debug state control:
 537  */
 538
 539 #ifdef CONFIG_SMP
 540 static void kgdb_wait(struct pt_regs *regs)
 541 {
 542         unsigned long flags;
 543         int cpu;
 544
 545         local_irq_save(flags);
 546         cpu = raw_smp_processor_id();
 547         kgdb_info[cpu].debuggerinfo = regs;
 548         kgdb_info[cpu].task = current;
 549         /*
 550          * Make sure the above info reaches the primary CPU before
 551          * our cpu_in_kgdb[] flag setting does:
 552          */
 553         smp_wmb();
 554         atomic_set(&cpu_in_kgdb[cpu], 1);
 555
 556         /* Wait till primary CPU is done with debugging */
 557         while (atomic_read(&passive_cpu_wait[cpu]))
 558                 cpu_relax();
 559
 560         kgdb_info[cpu].debuggerinfo = NULL;
 561         kgdb_info[cpu].task = NULL;
 562
 563         /* fix up hardware debug registers on local cpu */
 564         if (arch_kgdb_ops.correct_hw_break)
 565                 arch_kgdb_ops.correct_hw_break();
 566
 567         /* Signal the primary CPU that we are done: */
 568         atomic_set(&cpu_in_kgdb[cpu], 0);
 569         clocksource_touch_watchdog();
 570         local_irq_restore(flags);
 571 }
 572 #endif
 573
 574 /*
 575  * Some architectures need cache flushes when we set/clear a
 576  * breakpoint:
 577  */
 578 static void kgdb_flush_swbreak_addr(unsigned long addr)
 579 {
 580         if (!CACHE_FLUSH_IS_SAFE)
 581                 return;
 582
 583         if (current->mm && current->mm->mmap_cache) {
 584                 flush_cache_range(current->mm->mmap_cache,
 585                                   addr, addr + BREAK_INSTR_SIZE);
 586         }
 587         /* Force flush instruction cache if it was outside the mm */
 588         flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
 589 }
 590
 591 /*
 592  * SW breakpoint management:
 593  */
 594 static int kgdb_activate_sw_breakpoints(void)
 595 {
 596         unsigned long addr;
 597         int error = 0;
 598         int i;
 599
 600         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 601                 if (kgdb_break[i].state != BP_SET)
 602                         continue;
 603
 604                 addr = kgdb_break[i].bpt_addr;
 605                 error = kgdb_arch_set_breakpoint(addr,
 606                                 kgdb_break[i].saved_instr);
 607                 if (error)
 608                         return error;
 609
 610                 kgdb_flush_swbreak_addr(addr);
 611                 kgdb_break[i].state = BP_ACTIVE;
 612         }
 613         return 0;
 614 }
 615
 616 static int kgdb_set_sw_break(unsigned long addr)
 617 {
 618         int err = kgdb_validate_break_address(addr);
 619         int breakno = -1;
 620         int i;
 621
 622         if (err)
 623                 return err;
 624
 625         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 626                 if ((kgdb_break[i].state == BP_SET) &&
 627                                         (kgdb_break[i].bpt_addr == addr))
 628                         return -EEXIST;
 629         }
 630         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 631                 if (kgdb_break[i].state == BP_REMOVED &&
 632                                         kgdb_break[i].bpt_addr == addr) {
 633                         breakno = i;
 634                         break;
 635                 }
 636         }
 637
 638         if (breakno == -1) {
 639                 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 640                         if (kgdb_break[i].state == BP_UNDEFINED) {
 641                                 breakno = i;
 642                                 break;
 643                         }
 644                 }
 645         }
 646
 647         if (breakno == -1)
 648                 return -E2BIG;
 649
 650         kgdb_break[breakno].state = BP_SET;
 651         kgdb_break[breakno].type = BP_BREAKPOINT;
 652         kgdb_break[breakno].bpt_addr = addr;
 653
 654         return 0;
 655 }
 656
 657 static int kgdb_deactivate_sw_breakpoints(void)
 658 {
 659         unsigned long addr;
 660         int error = 0;
 661         int i;
 662
 663         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 664                 if (kgdb_break[i].state != BP_ACTIVE)
 665                         continue;
 666                 addr = kgdb_break[i].bpt_addr;
 667                 error = kgdb_arch_remove_breakpoint(addr,
 668                                         kgdb_break[i].saved_instr);
 669                 if (error)
 670                         return error;
 671
 672                 kgdb_flush_swbreak_addr(addr);
 673                 kgdb_break[i].state = BP_SET;
 674         }
 675         return 0;
 676 }
 677
 678 static int kgdb_remove_sw_break(unsigned long addr)
 679 {
 680         int i;
 681
 682         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 683                 if ((kgdb_break[i].state == BP_SET) &&
 684                                 (kgdb_break[i].bpt_addr == addr)) {
 685                         kgdb_break[i].state = BP_REMOVED;
 686                         return 0;
 687                 }
 688         }
 689         return -ENOENT;
 690 }
 691
 692 int kgdb_isremovedbreak(unsigned long addr)
 693 {
 694         int i;
 695
 696         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 697                 if ((kgdb_break[i].state == BP_REMOVED) &&
 698                                         (kgdb_break[i].bpt_addr == addr))
 699                         return 1;
 700         }
 701         return 0;
 702 }
 703
 704 static int remove_all_break(void)
 705 {
 706         unsigned long addr;
 707         int error;
 708         int i;
 709
 710         /* Clear memory breakpoints. */
 711         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 712                 if (kgdb_break[i].state != BP_ACTIVE)
 713                         goto setundefined;
 714                 addr = kgdb_break[i].bpt_addr;
 715                 error = kgdb_arch_remove_breakpoint(addr,
 716                                 kgdb_break[i].saved_instr);
 717                 if (error)
 718                         printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
 719                            addr);
 720 setundefined:
 721                 kgdb_break[i].state = BP_UNDEFINED;
 722         }
 723
 724         /* Clear hardware breakpoints. */
 725         if (arch_kgdb_ops.remove_all_hw_break)
 726                 arch_kgdb_ops.remove_all_hw_break();
 727
 728         return 0;
 729 }
 730
 731 /*
 732  * Remap normal tasks to their real PID, idle tasks to -1 ... -NR_CPUs:
 733  */
 734 static inline int shadow_pid(int realpid)
 735 {
 736         if (realpid)
 737                 return realpid;
 738
 739         return -1-raw_smp_processor_id();
 740 }
 741
 742 static char gdbmsgbuf[BUFMAX + 1];
 743
 744 static void kgdb_msg_write(const char *s, int len)
 745 {
 746         char *bufptr;
 747         int wcount;
 748         int i;
 749
 750         /* 'O'utput */
 751         gdbmsgbuf[0] = 'O';
 752
 753         /* Fill and send buffers... */
 754         while (len > 0) {
 755                 bufptr = gdbmsgbuf + 1;
 756
 757                 /* Calculate how many this time */
 758                 if ((len << 1) > (BUFMAX - 2))
 759                         wcount = (BUFMAX - 2) >> 1;
 760                 else
 761                         wcount = len;
 762
 763                 /* Pack in hex chars */
 764                 for (i = 0; i < wcount; i++)
 765                         bufptr = pack_hex_byte(bufptr, s[i]);
 766                 *bufptr = '\0';
 767
 768                 /* Move up */
 769                 s += wcount;
 770                 len -= wcount;
 771
 772                 /* Write packet */
 773                 put_packet(gdbmsgbuf);
 774         }
 775 }
 776
 777 /*
 778  * Return true if there is a valid kgdb I/O module.  Also if no
 779  * debugger is attached a message can be printed to the console about
 780  * waiting for the debugger to attach.
 781  *
 782  * The print_wait argument is only to be true when called from inside
 783  * the core kgdb_handle_exception, because it will wait for the
 784  * debugger to attach.
 785  */
 786 static int kgdb_io_ready(int print_wait)
 787 {
 788         if (!kgdb_io_ops)
 789                 return 0;
 790         if (kgdb_connected)
 791                 return 1;
 792         if (atomic_read(&kgdb_setting_breakpoint))
 793                 return 1;
 794         if (print_wait)
 795                 printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
 796         return 1;
 797 }
 798
 799 /*
 800  * All the functions that start with gdb_cmd are the various
 801  * operations to implement the handlers for the gdbserial protocol
 802  * where KGDB is communicating with an external debugger
 803  */
 804
 805 /* Handle the '?' status packets */
 806 static void gdb_cmd_status(struct kgdb_state *ks)
 807 {
 808         /*
 809          * We know that this packet is only sent
 810          * during initial connect.  So to be safe,
 811          * we clear out our breakpoints now in case
 812          * GDB is reconnecting.
 813          */
 814         remove_all_break();
 815
 816         remcom_out_buffer[0] = 'S';
 817         pack_hex_byte(&remcom_out_buffer[1], ks->signo);
 818 }
 819
 820 /* Handle the 'g' get registers request */
 821 static void gdb_cmd_getregs(struct kgdb_state *ks)
 822 {
 823         struct task_struct *thread;
 824         void *local_debuggerinfo;
 825         int i;
 826
 827         thread = kgdb_usethread;
 828         if (!thread) {
 829                 thread = kgdb_info[ks->cpu].task;
 830                 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
 831         } else {
 832                 local_debuggerinfo = NULL;
 833                 for (i = 0; i < NR_CPUS; i++) {
 834                         /*
 835                          * Try to find the task on some other
 836                          * or possibly this node if we do not
 837                          * find the matching task then we try
 838                          * to approximate the results.
 839                          */
 840                         if (thread == kgdb_info[i].task)
 841                                 local_debuggerinfo = kgdb_info[i].debuggerinfo;
 842                 }
 843         }
 844
 845         /*
 846          * All threads that don't have debuggerinfo should be
 847          * in __schedule() sleeping, since all other CPUs
 848          * are in kgdb_wait, and thus have debuggerinfo.
 849          */
 850         if (local_debuggerinfo) {
 851                 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
 852         } else {
 853                 /*
 854                  * Pull stuff saved during switch_to; nothing
 855                  * else is accessible (or even particularly
 856                  * relevant).
 857                  *
 858                  * This should be enough for a stack trace.
 859                  */
 860                 sleeping_thread_to_gdb_regs(gdb_regs, thread);
 861         }
 862         kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
 863 }
 864
 865 /* Handle the 'G' set registers request */
 866 static void gdb_cmd_setregs(struct kgdb_state *ks)
 867 {
 868         kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
 869
 870         if (kgdb_usethread && kgdb_usethread != current) {
 871                 error_packet(remcom_out_buffer, -EINVAL);
 872         } else {
 873                 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
 874                 strcpy(remcom_out_buffer, "OK");
 875         }
 876 }
 877
 878 /* Handle the 'm' memory read bytes */
 879 static void gdb_cmd_memread(struct kgdb_state *ks)
 880 {
 881         char *ptr = &remcom_in_buffer[1];
 882         unsigned long length;
 883         unsigned long addr;
 884         int err;
 885
 886         if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
 887                                         kgdb_hex2long(&ptr, &length) > 0) {
 888                 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
 889                 if (err)
 890                         error_packet(remcom_out_buffer, err);
 891         } else {
 892                 error_packet(remcom_out_buffer, -EINVAL);
 893         }
 894 }
 895
 896 /* Handle the 'M' memory write bytes */
 897 static void gdb_cmd_memwrite(struct kgdb_state *ks)
 898 {
 899         int err = write_mem_msg(0);
 900
 901         if (err)
 902                 error_packet(remcom_out_buffer, err);
 903         else
 904                 strcpy(remcom_out_buffer, "OK");
 905 }
 906
 907 /* Handle the 'X' memory binary write bytes */
 908 static void gdb_cmd_binwrite(struct kgdb_state *ks)
 909 {
 910         int err = write_mem_msg(1);
 911
 912         if (err)
 913                 error_packet(remcom_out_buffer, err);
 914         else
 915                 strcpy(remcom_out_buffer, "OK");
 916 }
 917
 918 /* Handle the 'D' or 'k', detach or kill packets */
 919 static void gdb_cmd_detachkill(struct kgdb_state *ks)
 920 {
 921         int error;
 922
 923         /* The detach case */
 924         if (remcom_in_buffer[0] == 'D') {
 925                 error = remove_all_break();
 926                 if (error < 0) {
 927                         error_packet(remcom_out_buffer, error);
 928                 } else {
 929                         strcpy(remcom_out_buffer, "OK");
 930                         kgdb_connected = 0;
 931                 }
 932                 put_packet(remcom_out_buffer);
 933         } else {
 934                 /*
 935                  * Assume the kill case, with no exit code checking,
 936                  * trying to force detach the debugger:
 937                  */
 938                 remove_all_break();
 939                 kgdb_connected = 0;
 940         }
 941 }
 942
 943 /* Handle the 'R' reboot packets */
 944 static int gdb_cmd_reboot(struct kgdb_state *ks)
 945 {
 946         /* For now, only honor R0 */
 947         if (strcmp(remcom_in_buffer, "R0") == 0) {
 948                 printk(KERN_CRIT "Executing emergency reboot\n");
 949                 strcpy(remcom_out_buffer, "OK");
 950                 put_packet(remcom_out_buffer);
 951
 952                 /*
 953                  * Execution should not return from
 954                  * machine_emergency_restart()
 955                  */
 956                 machine_emergency_restart();
 957                 kgdb_connected = 0;
 958
 959                 return 1;
 960         }
 961         return 0;
 962 }
 963
 964 /* Handle the 'q' query packets */
 965 static void gdb_cmd_query(struct kgdb_state *ks)
 966 {
 967         struct task_struct *thread;
 968         unsigned char thref[8];
 969         char *ptr;
 970         int i;
 971
 972         switch (remcom_in_buffer[1]) {
 973         case 's':
 974         case 'f':
 975                 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
 976                         error_packet(remcom_out_buffer, -EINVAL);
 977                         break;
 978                 }
 979
 980                 if (remcom_in_buffer[1] == 'f')
 981                         ks->threadid = 1;
 982
 983                 remcom_out_buffer[0] = 'm';
 984                 ptr = remcom_out_buffer + 1;
 985
 986                 for (i = 0; i < 17; ks->threadid++) {
 987                         thread = getthread(ks->linux_regs, ks->threadid);
 988                         if (thread) {
 989                                 int_to_threadref(thref, ks->threadid);
 990                                 pack_threadid(ptr, thref);
 991                                 ptr += BUF_THREAD_ID_SIZE;
 992                                 *(ptr++) = ',';
 993                                 i++;
 994                         }
 995                 }
 996                 *(--ptr) = '\0';
 997                 break;
 998
 999         case 'C':
1000                 /* Current thread id */
1001                 strcpy(remcom_out_buffer, "QC");
1002                 ks->threadid = shadow_pid(current->pid);
1003                 int_to_threadref(thref, ks->threadid);
1004                 pack_threadid(remcom_out_buffer + 2, thref);
1005                 break;
1006         case 'T':
1007                 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
1008                         error_packet(remcom_out_buffer, -EINVAL);
1009                         break;
1010                 }
1011                 ks->threadid = 0;
1012                 ptr = remcom_in_buffer + 17;
1013                 kgdb_hex2long(&ptr, &ks->threadid);
1014                 if (!getthread(ks->linux_regs, ks->threadid)) {
1015                         error_packet(remcom_out_buffer, -EINVAL);
1016                         break;
1017                 }
1018                 if (ks->threadid > 0) {
1019                         kgdb_mem2hex(getthread(ks->linux_regs,
1020                                         ks->threadid)->comm,
1021                                         remcom_out_buffer, 16);
1022                 } else {
1023                         static char tmpstr[23 + BUF_THREAD_ID_SIZE];
1024
1025                         sprintf(tmpstr, "Shadow task %d for pid 0",
1026                                         (int)(-ks->threadid-1));
1027                         kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
1028                 }
1029                 break;
1030         }
1031 }
1032
1033 /* Handle the 'H' task query packets */
1034 static void gdb_cmd_task(struct kgdb_state *ks)
1035 {
1036         struct task_struct *thread;
1037         char *ptr;
1038
1039         switch (remcom_in_buffer[1]) {
1040         case 'g':
1041                 ptr = &remcom_in_buffer[2];
1042                 kgdb_hex2long(&ptr, &ks->threadid);
1043                 thread = getthread(ks->linux_regs, ks->threadid);
1044                 if (!thread && ks->threadid > 0) {
1045                         error_packet(remcom_out_buffer, -EINVAL);
1046                         break;
1047                 }
1048                 kgdb_usethread = thread;
1049                 ks->kgdb_usethreadid = ks->threadid;
1050                 strcpy(remcom_out_buffer, "OK");
1051                 break;
1052         case 'c':
1053                 ptr = &remcom_in_buffer[2];
1054                 kgdb_hex2long(&ptr, &ks->threadid);
1055                 if (!ks->threadid) {
1056                         kgdb_contthread = NULL;
1057                 } else {
1058                         thread = getthread(ks->linux_regs, ks->threadid);
1059                         if (!thread && ks->threadid > 0) {
1060                                 error_packet(remcom_out_buffer, -EINVAL);
1061                                 break;
1062                         }
1063                         kgdb_contthread = thread;
1064                 }
1065                 strcpy(remcom_out_buffer, "OK");
1066                 break;
1067         }
1068 }
1069
1070 /* Handle the 'T' thread query packets */
1071 static void gdb_cmd_thread(struct kgdb_state *ks)
1072 {
1073         char *ptr = &remcom_in_buffer[1];
1074         struct task_struct *thread;
1075
1076         kgdb_hex2long(&ptr, &ks->threadid);
1077         thread = getthread(ks->linux_regs, ks->threadid);
1078         if (thread)
1079                 strcpy(remcom_out_buffer, "OK");
1080         else
1081                 error_packet(remcom_out_buffer, -EINVAL);
1082 }
1083
1084 /* Handle the 'z' or 'Z' breakpoint remove or set packets */
1085 static void gdb_cmd_break(struct kgdb_state *ks)
1086 {
1087         /*
1088          * Since GDB-5.3, it's been drafted that '0' is a software
1089          * breakpoint, '1' is a hardware breakpoint, so let's do that.
1090          */
1091         char *bpt_type = &remcom_in_buffer[1];
1092         char *ptr = &remcom_in_buffer[2];
1093         unsigned long addr;
1094         unsigned long length;
1095         int error = 0;
1096
1097         if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
1098                 /* Unsupported */
1099                 if (*bpt_type > '4')
1100                         return;
1101         } else {
1102                 if (*bpt_type != '0' && *bpt_type != '1')
1103                         /* Unsupported. */
1104                         return;
1105         }
1106
1107         /*
1108          * Test if this is a hardware breakpoint, and
1109          * if we support it:
1110          */
1111         if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
1112                 /* Unsupported. */
1113                 return;
1114
1115         if (*(ptr++) != ',') {
1116                 error_packet(remcom_out_buffer, -EINVAL);
1117                 return;
1118         }
1119         if (!kgdb_hex2long(&ptr, &addr)) {
1120                 error_packet(remcom_out_buffer, -EINVAL);
1121                 return;
1122         }
1123         if (*(ptr++) != ',' ||
1124                 !kgdb_hex2long(&ptr, &length)) {
1125                 error_packet(remcom_out_buffer, -EINVAL);
1126                 return;
1127         }
1128
1129         if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
1130                 error = kgdb_set_sw_break(addr);
1131         else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
1132                 error = kgdb_remove_sw_break(addr);
1133         else if (remcom_in_buffer[0] == 'Z')
1134                 error = arch_kgdb_ops.set_hw_breakpoint(addr,
1135                         (int)length, *bpt_type - '0');
1136         else if (remcom_in_buffer[0] == 'z')
1137                 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
1138                         (int) length, *bpt_type - '0');
1139
1140         if (error == 0)
1141                 strcpy(remcom_out_buffer, "OK");
1142         else
1143                 error_packet(remcom_out_buffer, error);
1144 }
1145
1146 /* Handle the 'C' signal / exception passing packets */
1147 static int gdb_cmd_exception_pass(struct kgdb_state *ks)
1148 {
1149         /* C09 == pass exception
1150          * C15 == detach kgdb, pass exception
1151          */
1152         if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
1153
1154                 ks->pass_exception = 1;
1155                 remcom_in_buffer[0] = 'c';
1156
1157         } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
1158
1159                 ks->pass_exception = 1;
1160                 remcom_in_buffer[0] = 'D';
1161                 remove_all_break();
1162                 kgdb_connected = 0;
1163                 return 1;
1164
1165         } else {
1166                 error_packet(remcom_out_buffer, -EINVAL);
1167                 return 0;
1168         }
1169
1170         /* Indicate fall through */
1171         return -1;
1172 }
1173
1174 /*
1175  * This function performs all gdbserial command procesing
1176  */
1177 static int gdb_serial_stub(struct kgdb_state *ks)
1178 {
1179         int error = 0;
1180         int tmp;
1181
1182         /* Clear the out buffer. */
1183         memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1184
1185         if (kgdb_connected) {
1186                 unsigned char thref[8];
1187                 char *ptr;
1188
1189                 /* Reply to host that an exception has occurred */
1190                 ptr = remcom_out_buffer;
1191                 *ptr++ = 'T';
1192                 ptr = pack_hex_byte(ptr, ks->signo);
1193                 ptr += strlen(strcpy(ptr, "thread:"));
1194                 int_to_threadref(thref, shadow_pid(current->pid));
1195                 ptr = pack_threadid(ptr, thref);
1196                 *ptr++ = ';';
1197                 put_packet(remcom_out_buffer);
1198         }
1199
1200         kgdb_usethread = kgdb_info[ks->cpu].task;
1201         ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
1202         ks->pass_exception = 0;
1203
1204         while (1) {
1205                 error = 0;
1206
1207                 /* Clear the out buffer. */
1208                 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1209
1210                 get_packet(remcom_in_buffer);
1211
1212                 switch (remcom_in_buffer[0]) {
1213                 case '?': /* gdbserial status */
1214                         gdb_cmd_status(ks);
1215                         break;
1216                 case 'g': /* return the value of the CPU registers */
1217                         gdb_cmd_getregs(ks);
1218                         break;
1219                 case 'G': /* set the value of the CPU registers - return OK */
1220                         gdb_cmd_setregs(ks);
1221                         break;
1222                 case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
1223                         gdb_cmd_memread(ks);
1224                         break;
1225                 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1226                         gdb_cmd_memwrite(ks);
1227                         break;
1228                 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1229                         gdb_cmd_binwrite(ks);
1230                         break;
1231                         /* kill or detach. KGDB should treat this like a
1232                          * continue.
1233                          */
1234                 case 'D': /* Debugger detach */
1235                 case 'k': /* Debugger detach via kill */
1236                         gdb_cmd_detachkill(ks);
1237                         goto default_handle;
1238                 case 'R': /* Reboot */
1239                         if (gdb_cmd_reboot(ks))
1240                                 goto default_handle;
1241                         break;
1242                 case 'q': /* query command */
1243                         gdb_cmd_query(ks);
1244                         break;
1245                 case 'H': /* task related */
1246                         gdb_cmd_task(ks);
1247                         break;
1248                 case 'T': /* Query thread status */
1249                         gdb_cmd_thread(ks);
1250                         break;
1251                 case 'z': /* Break point remove */
1252                 case 'Z': /* Break point set */
1253                         gdb_cmd_break(ks);
1254                         break;
1255                 case 'C': /* Exception passing */
1256                         tmp = gdb_cmd_exception_pass(ks);
1257                         if (tmp > 0)
1258                                 goto default_handle;
1259                         if (tmp == 0)
1260                                 break;
1261                         /* Fall through on tmp < 0 */
1262                 case 'c': /* Continue packet */
1263                 case 's': /* Single step packet */
1264                         if (kgdb_contthread && kgdb_contthread != current) {
1265                                 /* Can't switch threads in kgdb */
1266                                 error_packet(remcom_out_buffer, -EINVAL);
1267                                 break;
1268                         }
1269                         kgdb_activate_sw_breakpoints();
1270                         /* Fall through to default processing */
1271                 default:
1272 default_handle:
1273                         error = kgdb_arch_handle_exception(ks->ex_vector,
1274                                                 ks->signo,
1275                                                 ks->err_code,
1276                                                 remcom_in_buffer,
1277                                                 remcom_out_buffer,
1278                                                 ks->linux_regs);
1279                         /*
1280                          * Leave cmd processing on error, detach,
1281                          * kill, continue, or single step.
1282                          */
1283                         if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1284                             remcom_in_buffer[0] == 'k') {
1285                                 error = 0;
1286                                 goto kgdb_exit;
1287                         }
1288
1289                 }
1290
1291                 /* reply to the request */
1292                 put_packet(remcom_out_buffer);
1293         }
1294
1295 kgdb_exit:
1296         if (ks->pass_exception)
1297                 error = 1;
1298         return error;
1299 }
1300
1301 static int kgdb_reenter_check(struct kgdb_state *ks)
1302 {
1303         unsigned long addr;
1304
1305         if (atomic_read(&kgdb_active) != raw_smp_processor_id())
1306                 return 0;
1307
1308         /* Panic on recursive debugger calls: */
1309         exception_level++;
1310         addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
1311         kgdb_deactivate_sw_breakpoints();
1312
1313         /*
1314          * If the break point removed ok at the place exception
1315          * occurred, try to recover and print a warning to the end
1316          * user because the user planted a breakpoint in a place that
1317          * KGDB needs in order to function.
1318          */
1319         if (kgdb_remove_sw_break(addr) == 0) {
1320                 exception_level = 0;
1321                 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1322                 kgdb_activate_sw_breakpoints();
1323                 printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
1324                         addr);
1325                 WARN_ON_ONCE(1);
1326
1327                 return 1;
1328         }
1329         remove_all_break();
1330         kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1331
1332         if (exception_level > 1) {
1333                 dump_stack();
1334                 panic("Recursive entry to debugger");
1335         }
1336
1337         printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
1338         dump_stack();
1339         panic("Recursive entry to debugger");
1340
1341         return 1;
1342 }
1343
1344 /*
1345  * kgdb_handle_exception() - main entry point from a kernel exception
1346  *
1347  * Locking hierarchy:
1348  *      interface locks, if any (begin_session)
1349  *      kgdb lock (kgdb_active)
1350  */
1351 int
1352 kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
1353 {
1354         struct kgdb_state kgdb_var;
1355         struct kgdb_state *ks = &kgdb_var;
1356         unsigned long flags;
1357         int error = 0;
1358         int i, cpu;
1359
1360         ks->cpu                 = raw_smp_processor_id();
1361         ks->ex_vector           = evector;
1362         ks->signo               = signo;
1363         ks->ex_vector           = evector;
1364         ks->err_code            = ecode;
1365         ks->kgdb_usethreadid    = 0;
1366         ks->linux_regs          = regs;
1367
1368         if (kgdb_reenter_check(ks))
1369                 return 0; /* Ouch, double exception ! */
1370
1371 acquirelock:
1372         /*
1373          * Interrupts will be restored by the 'trap return' code, except when
1374          * single stepping.
1375          */
1376         local_irq_save(flags);
1377
1378         cpu = raw_smp_processor_id();
1379
1380         /*
1381          * Acquire the kgdb_active lock:
1382          */
1383         while (atomic_cmpxchg(&kgdb_active, -1, cpu) != -1)
1384                 cpu_relax();
1385
1386         /*
1387          * Do not start the debugger connection on this CPU if the last
1388          * instance of the exception handler wanted to come into the
1389          * debugger on a different CPU via a single step
1390          */
1391         if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
1392             atomic_read(&kgdb_cpu_doing_single_step) != cpu) {
1393
1394                 atomic_set(&kgdb_active, -1);
1395                 clocksource_touch_watchdog();
1396                 local_irq_restore(flags);
1397
1398                 goto acquirelock;
1399         }
1400
1401         if (!kgdb_io_ready(1)) {
1402                 error = 1;
1403                 goto kgdb_restore; /* No I/O connection, so resume the system */
1404         }
1405
1406         /*
1407          * Don't enter if we have hit a removed breakpoint.
1408          */
1409         if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
1410                 goto kgdb_restore;
1411
1412         /* Call the I/O driver's pre_exception routine */
1413         if (kgdb_io_ops->pre_exception)
1414                 kgdb_io_ops->pre_exception();
1415
1416         kgdb_info[ks->cpu].debuggerinfo = ks->linux_regs;
1417         kgdb_info[ks->cpu].task = current;
1418
1419         kgdb_disable_hw_debug(ks->linux_regs);
1420
1421         /*
1422          * Get the passive CPU lock which will hold all the non-primary
1423          * CPU in a spin state while the debugger is active
1424          */
1425         if (!kgdb_single_step || !kgdb_contthread) {
1426                 for (i = 0; i < NR_CPUS; i++)
1427                         atomic_set(&passive_cpu_wait[i], 1);
1428         }
1429
1430         /*
1431          * spin_lock code is good enough as a barrier so we don't
1432          * need one here:
1433          */
1434         atomic_set(&cpu_in_kgdb[ks->cpu], 1);
1435
1436 #ifdef CONFIG_SMP
1437         /* Signal the other CPUs to enter kgdb_wait() */
1438         if ((!kgdb_single_step || !kgdb_contthread) && kgdb_do_roundup)
1439                 kgdb_roundup_cpus(flags);
1440 #endif
1441
1442         /*
1443          * Wait for the other CPUs to be notified and be waiting for us:
1444          */
1445         for_each_online_cpu(i) {
1446                 while (!atomic_read(&cpu_in_kgdb[i]))
1447                         cpu_relax();
1448         }
1449
1450         /*
1451          * At this point the primary processor is completely
1452          * in the debugger and all secondary CPUs are quiescent
1453          */
1454         kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code);
1455         kgdb_deactivate_sw_breakpoints();
1456         kgdb_single_step = 0;
1457         kgdb_contthread = NULL;
1458         exception_level = 0;
1459
1460         /* Talk to debugger with gdbserial protocol */
1461         error = gdb_serial_stub(ks);
1462
1463         /* Call the I/O driver's post_exception routine */
1464         if (kgdb_io_ops->post_exception)
1465                 kgdb_io_ops->post_exception();
1466
1467         kgdb_info[ks->cpu].debuggerinfo = NULL;
1468         kgdb_info[ks->cpu].task = NULL;
1469         atomic_set(&cpu_in_kgdb[ks->cpu], 0);
1470
1471         if (!kgdb_single_step || !kgdb_contthread) {
1472                 for (i = NR_CPUS-1; i >= 0; i--)
1473                         atomic_set(&passive_cpu_wait[i], 0);
1474                 /*
1475                  * Wait till all the CPUs have quit
1476                  * from the debugger.
1477                  */
1478                 for_each_online_cpu(i) {
1479                         while (atomic_read(&cpu_in_kgdb[i]))
1480                                 cpu_relax();
1481                 }
1482         }
1483
1484 kgdb_restore:
1485         /* Free kgdb_active */
1486         atomic_set(&kgdb_active, -1);
1487         clocksource_touch_watchdog();
1488         local_irq_restore(flags);
1489
1490         return error;
1491 }
1492
1493 int kgdb_nmicallback(int cpu, void *regs)
1494 {
1495 #ifdef CONFIG_SMP
1496         if (!atomic_read(&cpu_in_kgdb[cpu]) &&
1497                         atomic_read(&kgdb_active) != cpu &&
1498                         atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)])) {
1499                 kgdb_wait((struct pt_regs *)regs);
1500                 return 0;
1501         }
1502 #endif
1503         return 1;
1504 }
1505
1506 void kgdb_console_write(struct console *co, const char *s, unsigned count)
1507 {
1508         unsigned long flags;
1509
1510         /* If we're debugging, or KGDB has not connected, don't try
1511          * and print. */
1512         if (!kgdb_connected || atomic_read(&kgdb_active) != -1)
1513                 return;
1514
1515         local_irq_save(flags);
1516         kgdb_msg_write(s, count);
1517         local_irq_restore(flags);
1518 }
1519
1520 static struct console kgdbcons = {
1521         .name           = "kgdb",
1522         .write          = kgdb_console_write,
1523         .flags          = CON_PRINTBUFFER | CON_ENABLED,
1524         .index          = -1,
1525 };
1526
1527 #ifdef CONFIG_MAGIC_SYSRQ
1528 static void sysrq_handle_gdb(int key, struct tty_struct *tty)
1529 {
1530         if (!kgdb_io_ops) {
1531                 printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
1532                 return;
1533         }
1534         if (!kgdb_connected)
1535                 printk(KERN_CRIT "Entering KGDB\n");
1536
1537         kgdb_breakpoint();
1538 }
1539
1540 static struct sysrq_key_op sysrq_gdb_op = {
1541         .handler        = sysrq_handle_gdb,
1542         .help_msg       = "Gdb",
1543         .action_msg     = "GDB",
1544 };
1545 #endif
1546
1547 static void kgdb_register_callbacks(void)
1548 {
1549         if (!kgdb_io_module_registered) {
1550                 kgdb_io_module_registered = 1;
1551                 kgdb_arch_init();
1552 #ifdef CONFIG_MAGIC_SYSRQ
1553                 register_sysrq_key('g', &sysrq_gdb_op);
1554 #endif
1555                 if (kgdb_use_con && !kgdb_con_registered) {
1556                         register_console(&kgdbcons);
1557                         kgdb_con_registered = 1;
1558                 }
1559         }
1560 }
1561
1562 static void kgdb_unregister_callbacks(void)
1563 {
1564         /*
1565          * When this routine is called KGDB should unregister from the
1566          * panic handler and clean up, making sure it is not handling any
1567          * break exceptions at the time.
1568          */
1569         if (kgdb_io_module_registered) {
1570                 kgdb_io_module_registered = 0;
1571                 kgdb_arch_exit();
1572 #ifdef CONFIG_MAGIC_SYSRQ
1573                 unregister_sysrq_key('g', &sysrq_gdb_op);
1574 #endif
1575                 if (kgdb_con_registered) {
1576                         unregister_console(&kgdbcons);
1577                         kgdb_con_registered = 0;
1578                 }
1579         }
1580 }
1581
1582 static void kgdb_initial_breakpoint(void)
1583 {
1584         kgdb_break_asap = 0;
1585
1586         printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
1587         kgdb_breakpoint();
1588 }
1589
1590 /**
1591  *      kgdb_register_io_module - register KGDB IO module
1592  *      @new_kgdb_io_ops: the io ops vector
1593  *
1594  *      Register it with the KGDB core.
1595  */
1596 int kgdb_register_io_module(struct kgdb_io *new_kgdb_io_ops)
1597 {
1598         int err;
1599
1600         spin_lock(&kgdb_registration_lock);
1601
1602         if (kgdb_io_ops) {
1603                 spin_unlock(&kgdb_registration_lock);
1604
1605                 printk(KERN_ERR "kgdb: Another I/O driver is already "
1606                                 "registered with KGDB.\n");
1607                 return -EBUSY;
1608         }
1609
1610         if (new_kgdb_io_ops->init) {
1611                 err = new_kgdb_io_ops->init();
1612                 if (err) {
1613                         spin_unlock(&kgdb_registration_lock);
1614                         return err;
1615                 }
1616         }
1617
1618         kgdb_io_ops = new_kgdb_io_ops;
1619
1620         spin_unlock(&kgdb_registration_lock);
1621
1622         printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
1623                new_kgdb_io_ops->name);
1624
1625         /* Arm KGDB now. */
1626         kgdb_register_callbacks();
1627
1628         if (kgdb_break_asap)
1629                 kgdb_initial_breakpoint();
1630
1631         return 0;
1632 }
1633 EXPORT_SYMBOL_GPL(kgdb_register_io_module);
1634
1635 /**
1636  *      kkgdb_unregister_io_module - unregister KGDB IO module
1637  *      @old_kgdb_io_ops: the io ops vector
1638  *
1639  *      Unregister it with the KGDB core.
1640  */
1641 void kgdb_unregister_io_module(struct kgdb_io *old_kgdb_io_ops)
1642 {
1643         BUG_ON(kgdb_connected);
1644
1645         /*
1646          * KGDB is no longer able to communicate out, so
1647          * unregister our callbacks and reset state.
1648          */
1649         kgdb_unregister_callbacks();
1650
1651         spin_lock(&kgdb_registration_lock);
1652
1653         WARN_ON_ONCE(kgdb_io_ops != old_kgdb_io_ops);
1654         kgdb_io_ops = NULL;
1655
1656         spin_unlock(&kgdb_registration_lock);
1657
1658         printk(KERN_INFO
1659                 "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
1660                 old_kgdb_io_ops->name);
1661 }
1662 EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
1663
1664 /**
1665  * kgdb_breakpoint - generate breakpoint exception
1666  *
1667  * This function will generate a breakpoint exception.  It is used at the
1668  * beginning of a program to sync up with a debugger and can be used
1669  * otherwise as a quick means to stop program execution and "break" into
1670  * the debugger.
1671  */
1672 void kgdb_breakpoint(void)
1673 {
1674         atomic_set(&kgdb_setting_breakpoint, 1);
1675         wmb(); /* Sync point before breakpoint */
1676         arch_kgdb_breakpoint();
1677         wmb(); /* Sync point after breakpoint */
1678         atomic_set(&kgdb_setting_breakpoint, 0);
1679 }
1680 EXPORT_SYMBOL_GPL(kgdb_breakpoint);
1681
1682 static int __init opt_kgdb_wait(char *str)
1683 {
1684         kgdb_break_asap = 1;
1685
1686         if (kgdb_io_module_registered)
1687                 kgdb_initial_breakpoint();
1688
1689         return 0;
1690 }
1691
1692 early_param("kgdbwait", opt_kgdb_wait);