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 #include <asm/unaligned.h>
  56
  57 static int kgdb_break_asap;
  58
  59 #define KGDB_MAX_THREAD_QUERY 17
  60 struct kgdb_state {
  61         int                     ex_vector;
  62         int                     signo;
  63         int                     err_code;
  64         int                     cpu;
  65         int                     pass_exception;
  66         unsigned long           thr_query;
  67         unsigned long           threadid;
  68         long                    kgdb_usethreadid;
  69         struct pt_regs          *linux_regs;
  70 };
  71
  72 static struct debuggerinfo_struct {
  73         void                    *debuggerinfo;
  74         struct task_struct      *task;
  75 } kgdb_info[NR_CPUS];
  76
  77 /**
  78  * kgdb_connected - Is a host GDB connected to us?
  79  */
  80 int                             kgdb_connected;
  81 EXPORT_SYMBOL_GPL(kgdb_connected);
  82
  83 /* All the KGDB handlers are installed */
  84 static int                      kgdb_io_module_registered;
  85
  86 /* Guard for recursive entry */
  87 static int                      exception_level;
  88
  89 static struct kgdb_io           *kgdb_io_ops;
  90 static DEFINE_SPINLOCK(kgdb_registration_lock);
  91
  92 /* kgdb console driver is loaded */
  93 static int kgdb_con_registered;
  94 /* determine if kgdb console output should be used */
  95 static int kgdb_use_con;
  96
  97 static int __init opt_kgdb_con(char *str)
  98 {
  99         kgdb_use_con = 1;
 100         return 0;
 101 }
 102
 103 early_param("kgdbcon", opt_kgdb_con);
 104
 105 module_param(kgdb_use_con, int, 0644);
 106
 107 /*
 108  * Holds information about breakpoints in a kernel. These breakpoints are
 109  * added and removed by gdb.
 110  */
 111 static struct kgdb_bkpt         kgdb_break[KGDB_MAX_BREAKPOINTS] = {
 112         [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
 113 };
 114
 115 /*
 116  * The CPU# of the active CPU, or -1 if none:
 117  */
 118 atomic_t                        kgdb_active = ATOMIC_INIT(-1);
 119
 120 /*
 121  * We use NR_CPUs not PERCPU, in case kgdb is used to debug early
 122  * bootup code (which might not have percpu set up yet):
 123  */
 124 static atomic_t                 passive_cpu_wait[NR_CPUS];
 125 static atomic_t                 cpu_in_kgdb[NR_CPUS];
 126 atomic_t                        kgdb_setting_breakpoint;
 127
 128 struct task_struct              *kgdb_usethread;
 129 struct task_struct              *kgdb_contthread;
 130
 131 int                             kgdb_single_step;
 132 pid_t                           kgdb_sstep_pid;
 133
 134 /* Our I/O buffers. */
 135 static char                     remcom_in_buffer[BUFMAX];
 136 static char                     remcom_out_buffer[BUFMAX];
 137
 138 /* Storage for the registers, in GDB format. */
 139 static unsigned long            gdb_regs[(NUMREGBYTES +
 140                                         sizeof(unsigned long) - 1) /
 141                                         sizeof(unsigned long)];
 142
 143 /* to keep track of the CPU which is doing the single stepping*/
 144 atomic_t                        kgdb_cpu_doing_single_step = ATOMIC_INIT(-1);
 145
 146 /*
 147  * If you are debugging a problem where roundup (the collection of
 148  * all other CPUs) is a problem [this should be extremely rare],
 149  * then use the nokgdbroundup option to avoid roundup. In that case
 150  * the other CPUs might interfere with your debugging context, so
 151  * use this with care:
 152  */
 153 static int kgdb_do_roundup = 1;
 154
 155 static int __init opt_nokgdbroundup(char *str)
 156 {
 157         kgdb_do_roundup = 0;
 158
 159         return 0;
 160 }
 161
 162 early_param("nokgdbroundup", opt_nokgdbroundup);
 163
 164 /*
 165  * Finally, some KGDB code :-)
 166  */
 167
 168 /*
 169  * Weak aliases for breakpoint management,
 170  * can be overriden by architectures when needed:
 171  */
 172 int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr)
 173 {
 174         int err;
 175
 176         err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE);
 177         if (err)
 178                 return err;
 179
 180         return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr,
 181                                   BREAK_INSTR_SIZE);
 182 }
 183
 184 int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle)
 185 {
 186         return probe_kernel_write((char *)addr,
 187                                   (char *)bundle, BREAK_INSTR_SIZE);
 188 }
 189
 190 int __weak kgdb_validate_break_address(unsigned long addr)
 191 {
 192         char tmp_variable[BREAK_INSTR_SIZE];
 193         int err;
 194         /* Validate setting the breakpoint and then removing it.  In the
 195          * remove fails, the kernel needs to emit a bad message because we
 196          * are deep trouble not being able to put things back the way we
 197          * found them.
 198          */
 199         err = kgdb_arch_set_breakpoint(addr, tmp_variable);
 200         if (err)
 201                 return err;
 202         err = kgdb_arch_remove_breakpoint(addr, tmp_variable);
 203         if (err)
 204                 printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
 205                    "memory destroyed at: %lx", addr);
 206         return err;
 207 }
 208
 209 unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
 210 {
 211         return instruction_pointer(regs);
 212 }
 213
 214 int __weak kgdb_arch_init(void)
 215 {
 216         return 0;
 217 }
 218
 219 int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
 220 {
 221         return 0;
 222 }
 223
 224 void __weak
 225 kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
 226 {
 227         return;
 228 }
 229
 230 /**
 231  *      kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
 232  *      @regs: Current &struct pt_regs.
 233  *
 234  *      This function will be called if the particular architecture must
 235  *      disable hardware debugging while it is processing gdb packets or
 236  *      handling exception.
 237  */
 238 void __weak kgdb_disable_hw_debug(struct pt_regs *regs)
 239 {
 240 }
 241
 242 /*
 243  * GDB remote protocol parser:
 244  */
 245
 246 static int hex(char ch)
 247 {
 248         if ((ch >= 'a') && (ch <= 'f'))
 249                 return ch - 'a' + 10;
 250         if ((ch >= '0') && (ch <= '9'))
 251                 return ch - '0';
 252         if ((ch >= 'A') && (ch <= 'F'))
 253                 return ch - 'A' + 10;
 254         return -1;
 255 }
 256
 257 /* scan for the sequence $<data>#<checksum> */
 258 static void get_packet(char *buffer)
 259 {
 260         unsigned char checksum;
 261         unsigned char xmitcsum;
 262         int count;
 263         char ch;
 264
 265         do {
 266                 /*
 267                  * Spin and wait around for the start character, ignore all
 268                  * other characters:
 269                  */
 270                 while ((ch = (kgdb_io_ops->read_char())) != '$')
 271                         /* nothing */;
 272
 273                 kgdb_connected = 1;
 274                 checksum = 0;
 275                 xmitcsum = -1;
 276
 277                 count = 0;
 278
 279                 /*
 280                  * now, read until a # or end of buffer is found:
 281                  */
 282                 while (count < (BUFMAX - 1)) {
 283                         ch = kgdb_io_ops->read_char();
 284                         if (ch == '#')
 285                                 break;
 286                         checksum = checksum + ch;
 287                         buffer[count] = ch;
 288                         count = count + 1;
 289                 }
 290                 buffer[count] = 0;
 291
 292                 if (ch == '#') {
 293                         xmitcsum = hex(kgdb_io_ops->read_char()) << 4;
 294                         xmitcsum += hex(kgdb_io_ops->read_char());
 295
 296                         if (checksum != xmitcsum)
 297                                 /* failed checksum */
 298                                 kgdb_io_ops->write_char('-');
 299                         else
 300                                 /* successful transfer */
 301                                 kgdb_io_ops->write_char('+');
 302                         if (kgdb_io_ops->flush)
 303                                 kgdb_io_ops->flush();
 304                 }
 305         } while (checksum != xmitcsum);
 306 }
 307
 308 /*
 309  * Send the packet in buffer.
 310  * Check for gdb connection if asked for.
 311  */
 312 static void put_packet(char *buffer)
 313 {
 314         unsigned char checksum;
 315         int count;
 316         char ch;
 317
 318         /*
 319          * $<packet info>#<checksum>.
 320          */
 321         while (1) {
 322                 kgdb_io_ops->write_char('$');
 323                 checksum = 0;
 324                 count = 0;
 325
 326                 while ((ch = buffer[count])) {
 327                         kgdb_io_ops->write_char(ch);
 328                         checksum += ch;
 329                         count++;
 330                 }
 331
 332                 kgdb_io_ops->write_char('#');
 333                 kgdb_io_ops->write_char(hex_asc_hi(checksum));
 334                 kgdb_io_ops->write_char(hex_asc_lo(checksum));
 335                 if (kgdb_io_ops->flush)
 336                         kgdb_io_ops->flush();
 337
 338                 /* Now see what we get in reply. */
 339                 ch = kgdb_io_ops->read_char();
 340
 341                 if (ch == 3)
 342                         ch = kgdb_io_ops->read_char();
 343
 344                 /* If we get an ACK, we are done. */
 345                 if (ch == '+')
 346                         return;
 347
 348                 /*
 349                  * If we get the start of another packet, this means
 350                  * that GDB is attempting to reconnect.  We will NAK
 351                  * the packet being sent, and stop trying to send this
 352                  * packet.
 353                  */
 354                 if (ch == '$') {
 355                         kgdb_io_ops->write_char('-');
 356                         if (kgdb_io_ops->flush)
 357                                 kgdb_io_ops->flush();
 358                         return;
 359                 }
 360         }
 361 }
 362
 363 /*
 364  * Convert the memory pointed to by mem into hex, placing result in buf.
 365  * Return a pointer to the last char put in buf (null). May return an error.
 366  */
 367 int kgdb_mem2hex(char *mem, char *buf, int count)
 368 {
 369         char *tmp;
 370         int err;
 371
 372         /*
 373          * We use the upper half of buf as an intermediate buffer for the
 374          * raw memory copy.  Hex conversion will work against this one.
 375          */
 376         tmp = buf + count;
 377
 378         err = probe_kernel_read(tmp, mem, count);
 379         if (!err) {
 380                 while (count > 0) {
 381                         buf = pack_hex_byte(buf, *tmp);
 382                         tmp++;
 383                         count--;
 384                 }
 385
 386                 *buf = 0;
 387         }
 388
 389         return err;
 390 }
 391
 392 /*
 393  * Copy the binary array pointed to by buf into mem.  Fix $, #, and
 394  * 0x7d escaped with 0x7d.  Return a pointer to the character after
 395  * the last byte written.
 396  */
 397 static int kgdb_ebin2mem(char *buf, char *mem, int count)
 398 {
 399         int err = 0;
 400         char c;
 401
 402         while (count-- > 0) {
 403                 c = *buf++;
 404                 if (c == 0x7d)
 405                         c = *buf++ ^ 0x20;
 406
 407                 err = probe_kernel_write(mem, &c, 1);
 408                 if (err)
 409                         break;
 410
 411                 mem++;
 412         }
 413
 414         return err;
 415 }
 416
 417 /*
 418  * Convert the hex array pointed to by buf into binary to be placed in mem.
 419  * Return a pointer to the character AFTER the last byte written.
 420  * May return an error.
 421  */
 422 int kgdb_hex2mem(char *buf, char *mem, int count)
 423 {
 424         char *tmp_raw;
 425         char *tmp_hex;
 426
 427         /*
 428          * We use the upper half of buf as an intermediate buffer for the
 429          * raw memory that is converted from hex.
 430          */
 431         tmp_raw = buf + count * 2;
 432
 433         tmp_hex = tmp_raw - 1;
 434         while (tmp_hex >= buf) {
 435                 tmp_raw--;
 436                 *tmp_raw = hex(*tmp_hex--);
 437                 *tmp_raw |= hex(*tmp_hex--) << 4;
 438         }
 439
 440         return probe_kernel_write(mem, tmp_raw, count);
 441 }
 442
 443 /*
 444  * While we find nice hex chars, build a long_val.
 445  * Return number of chars processed.
 446  */
 447 int kgdb_hex2long(char **ptr, unsigned long *long_val)
 448 {
 449         int hex_val;
 450         int num = 0;
 451         int negate = 0;
 452
 453         *long_val = 0;
 454
 455         if (**ptr == '-') {
 456                 negate = 1;
 457                 (*ptr)++;
 458         }
 459         while (**ptr) {
 460                 hex_val = hex(**ptr);
 461                 if (hex_val < 0)
 462                         break;
 463
 464                 *long_val = (*long_val << 4) | hex_val;
 465                 num++;
 466                 (*ptr)++;
 467         }
 468
 469         if (negate)
 470                 *long_val = -*long_val;
 471
 472         return num;
 473 }
 474
 475 /* Write memory due to an 'M' or 'X' packet. */
 476 static int write_mem_msg(int binary)
 477 {
 478         char *ptr = &remcom_in_buffer[1];
 479         unsigned long addr;
 480         unsigned long length;
 481         int err;
 482
 483         if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
 484             kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
 485                 if (binary)
 486                         err = kgdb_ebin2mem(ptr, (char *)addr, length);
 487                 else
 488                         err = kgdb_hex2mem(ptr, (char *)addr, length);
 489                 if (err)
 490                         return err;
 491                 if (CACHE_FLUSH_IS_SAFE)
 492                         flush_icache_range(addr, addr + length);
 493                 return 0;
 494         }
 495
 496         return -EINVAL;
 497 }
 498
 499 static void error_packet(char *pkt, int error)
 500 {
 501         error = -error;
 502         pkt[0] = 'E';
 503         pkt[1] = hex_asc[(error / 10)];
 504         pkt[2] = hex_asc[(error % 10)];
 505         pkt[3] = '\0';
 506 }
 507
 508 /*
 509  * Thread ID accessors. We represent a flat TID space to GDB, where
 510  * the per CPU idle threads (which under Linux all have PID 0) are
 511  * remapped to negative TIDs.
 512  */
 513
 514 #define BUF_THREAD_ID_SIZE      16
 515
 516 static char *pack_threadid(char *pkt, unsigned char *id)
 517 {
 518         char *limit;
 519
 520         limit = pkt + BUF_THREAD_ID_SIZE;
 521         while (pkt < limit)
 522                 pkt = pack_hex_byte(pkt, *id++);
 523
 524         return pkt;
 525 }
 526
 527 static void int_to_threadref(unsigned char *id, int value)
 528 {
 529         unsigned char *scan;
 530         int i = 4;
 531
 532         scan = (unsigned char *)id;
 533         while (i--)
 534                 *scan++ = 0;
 535         put_unaligned_be32(value, scan);
 536 }
 537
 538 static struct task_struct *getthread(struct pt_regs *regs, int tid)
 539 {
 540         /*
 541          * Non-positive TIDs are remapped to the cpu shadow information
 542          */
 543         if (tid == 0 || tid == -1)
 544                 tid = -atomic_read(&kgdb_active) - 2;
 545         if (tid < -1 && tid > -NR_CPUS - 2) {
 546                 if (kgdb_info[-tid - 2].task)
 547                         return kgdb_info[-tid - 2].task;
 548                 else
 549                         return idle_task(-tid - 2);
 550         }
 551         if (tid <= 0) {
 552                 printk(KERN_ERR "KGDB: Internal thread select error\n");
 553                 dump_stack();
 554                 return NULL;
 555         }
 556
 557         /*
 558          * find_task_by_pid_ns() does not take the tasklist lock anymore
 559          * but is nicely RCU locked - hence is a pretty resilient
 560          * thing to use:
 561          */
 562         return find_task_by_pid_ns(tid, &init_pid_ns);
 563 }
 564
 565 /*
 566  * CPU debug state control:
 567  */
 568
 569 #ifdef CONFIG_SMP
 570 static void kgdb_wait(struct pt_regs *regs)
 571 {
 572         unsigned long flags;
 573         int cpu;
 574
 575         local_irq_save(flags);
 576         cpu = raw_smp_processor_id();
 577         kgdb_info[cpu].debuggerinfo = regs;
 578         kgdb_info[cpu].task = current;
 579         /*
 580          * Make sure the above info reaches the primary CPU before
 581          * our cpu_in_kgdb[] flag setting does:
 582          */
 583         smp_wmb();
 584         atomic_set(&cpu_in_kgdb[cpu], 1);
 585
 586         /* Disable any cpu specific hw breakpoints */
 587         kgdb_disable_hw_debug(regs);
 588
 589         /* Wait till primary CPU is done with debugging */
 590         while (atomic_read(&passive_cpu_wait[cpu]))
 591                 cpu_relax();
 592
 593         kgdb_info[cpu].debuggerinfo = NULL;
 594         kgdb_info[cpu].task = NULL;
 595
 596         /* fix up hardware debug registers on local cpu */
 597         if (arch_kgdb_ops.correct_hw_break)
 598                 arch_kgdb_ops.correct_hw_break();
 599
 600         /* Signal the primary CPU that we are done: */
 601         atomic_set(&cpu_in_kgdb[cpu], 0);
 602         touch_softlockup_watchdog_sync();
 603         clocksource_touch_watchdog();
 604         local_irq_restore(flags);
 605 }
 606 #endif
 607
 608 /*
 609  * Some architectures need cache flushes when we set/clear a
 610  * breakpoint:
 611  */
 612 static void kgdb_flush_swbreak_addr(unsigned long addr)
 613 {
 614         if (!CACHE_FLUSH_IS_SAFE)
 615                 return;
 616
 617         if (current->mm && current->mm->mmap_cache) {
 618                 flush_cache_range(current->mm->mmap_cache,
 619                                   addr, addr + BREAK_INSTR_SIZE);
 620         }
 621         /* Force flush instruction cache if it was outside the mm */
 622         flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
 623 }
 624
 625 /*
 626  * SW breakpoint management:
 627  */
 628 static int kgdb_activate_sw_breakpoints(void)
 629 {
 630         unsigned long addr;
 631         int error;
 632         int ret = 0;
 633         int i;
 634
 635         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 636                 if (kgdb_break[i].state != BP_SET)
 637                         continue;
 638
 639                 addr = kgdb_break[i].bpt_addr;
 640                 error = kgdb_arch_set_breakpoint(addr,
 641                                 kgdb_break[i].saved_instr);
 642                 if (error) {
 643                         ret = error;
 644                         printk(KERN_INFO "KGDB: BP install failed: %lx", addr);
 645                         continue;
 646                 }
 647
 648                 kgdb_flush_swbreak_addr(addr);
 649                 kgdb_break[i].state = BP_ACTIVE;
 650         }
 651         return ret;
 652 }
 653
 654 static int kgdb_set_sw_break(unsigned long addr)
 655 {
 656         int err = kgdb_validate_break_address(addr);
 657         int breakno = -1;
 658         int i;
 659
 660         if (err)
 661                 return err;
 662
 663         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 664                 if ((kgdb_break[i].state == BP_SET) &&
 665                                         (kgdb_break[i].bpt_addr == addr))
 666                         return -EEXIST;
 667         }
 668         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 669                 if (kgdb_break[i].state == BP_REMOVED &&
 670                                         kgdb_break[i].bpt_addr == addr) {
 671                         breakno = i;
 672                         break;
 673                 }
 674         }
 675
 676         if (breakno == -1) {
 677                 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 678                         if (kgdb_break[i].state == BP_UNDEFINED) {
 679                                 breakno = i;
 680                                 break;
 681                         }
 682                 }
 683         }
 684
 685         if (breakno == -1)
 686                 return -E2BIG;
 687
 688         kgdb_break[breakno].state = BP_SET;
 689         kgdb_break[breakno].type = BP_BREAKPOINT;
 690         kgdb_break[breakno].bpt_addr = addr;
 691
 692         return 0;
 693 }
 694
 695 static int kgdb_deactivate_sw_breakpoints(void)
 696 {
 697         unsigned long addr;
 698         int error;
 699         int ret = 0;
 700         int i;
 701
 702         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 703                 if (kgdb_break[i].state != BP_ACTIVE)
 704                         continue;
 705                 addr = kgdb_break[i].bpt_addr;
 706                 error = kgdb_arch_remove_breakpoint(addr,
 707                                         kgdb_break[i].saved_instr);
 708                 if (error) {
 709                         printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr);
 710                         ret = error;
 711                 }
 712
 713                 kgdb_flush_swbreak_addr(addr);
 714                 kgdb_break[i].state = BP_SET;
 715         }
 716         return ret;
 717 }
 718
 719 static int kgdb_remove_sw_break(unsigned long addr)
 720 {
 721         int i;
 722
 723         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 724                 if ((kgdb_break[i].state == BP_SET) &&
 725                                 (kgdb_break[i].bpt_addr == addr)) {
 726                         kgdb_break[i].state = BP_REMOVED;
 727                         return 0;
 728                 }
 729         }
 730         return -ENOENT;
 731 }
 732
 733 int kgdb_isremovedbreak(unsigned long addr)
 734 {
 735         int i;
 736
 737         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 738                 if ((kgdb_break[i].state == BP_REMOVED) &&
 739                                         (kgdb_break[i].bpt_addr == addr))
 740                         return 1;
 741         }
 742         return 0;
 743 }
 744
 745 static int remove_all_break(void)
 746 {
 747         unsigned long addr;
 748         int error;
 749         int i;
 750
 751         /* Clear memory breakpoints. */
 752         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 753                 if (kgdb_break[i].state != BP_ACTIVE)
 754                         goto setundefined;
 755                 addr = kgdb_break[i].bpt_addr;
 756                 error = kgdb_arch_remove_breakpoint(addr,
 757                                 kgdb_break[i].saved_instr);
 758                 if (error)
 759                         printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
 760                            addr);
 761 setundefined:
 762                 kgdb_break[i].state = BP_UNDEFINED;
 763         }
 764
 765         /* Clear hardware breakpoints. */
 766         if (arch_kgdb_ops.remove_all_hw_break)
 767                 arch_kgdb_ops.remove_all_hw_break();
 768
 769         return 0;
 770 }
 771
 772 /*
 773  * Remap normal tasks to their real PID,
 774  * CPU shadow threads are mapped to -CPU - 2
 775  */
 776 static inline int shadow_pid(int realpid)
 777 {
 778         if (realpid)
 779                 return realpid;
 780
 781         return -raw_smp_processor_id() - 2;
 782 }
 783
 784 static char gdbmsgbuf[BUFMAX + 1];
 785
 786 static void kgdb_msg_write(const char *s, int len)
 787 {
 788         char *bufptr;
 789         int wcount;
 790         int i;
 791
 792         /* 'O'utput */
 793         gdbmsgbuf[0] = 'O';
 794
 795         /* Fill and send buffers... */
 796         while (len > 0) {
 797                 bufptr = gdbmsgbuf + 1;
 798
 799                 /* Calculate how many this time */
 800                 if ((len << 1) > (BUFMAX - 2))
 801                         wcount = (BUFMAX - 2) >> 1;
 802                 else
 803                         wcount = len;
 804
 805                 /* Pack in hex chars */
 806                 for (i = 0; i < wcount; i++)
 807                         bufptr = pack_hex_byte(bufptr, s[i]);
 808                 *bufptr = '\0';
 809
 810                 /* Move up */
 811                 s += wcount;
 812                 len -= wcount;
 813
 814                 /* Write packet */
 815                 put_packet(gdbmsgbuf);
 816         }
 817 }
 818
 819 /*
 820  * Return true if there is a valid kgdb I/O module.  Also if no
 821  * debugger is attached a message can be printed to the console about
 822  * waiting for the debugger to attach.
 823  *
 824  * The print_wait argument is only to be true when called from inside
 825  * the core kgdb_handle_exception, because it will wait for the
 826  * debugger to attach.
 827  */
 828 static int kgdb_io_ready(int print_wait)
 829 {
 830         if (!kgdb_io_ops)
 831                 return 0;
 832         if (kgdb_connected)
 833                 return 1;
 834         if (atomic_read(&kgdb_setting_breakpoint))
 835                 return 1;
 836         if (print_wait)
 837                 printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
 838         return 1;
 839 }
 840
 841 /*
 842  * All the functions that start with gdb_cmd are the various
 843  * operations to implement the handlers for the gdbserial protocol
 844  * where KGDB is communicating with an external debugger
 845  */
 846
 847 /* Handle the '?' status packets */
 848 static void gdb_cmd_status(struct kgdb_state *ks)
 849 {
 850         /*
 851          * We know that this packet is only sent
 852          * during initial connect.  So to be safe,
 853          * we clear out our breakpoints now in case
 854          * GDB is reconnecting.
 855          */
 856         remove_all_break();
 857
 858         remcom_out_buffer[0] = 'S';
 859         pack_hex_byte(&remcom_out_buffer[1], ks->signo);
 860 }
 861
 862 /* Handle the 'g' get registers request */
 863 static void gdb_cmd_getregs(struct kgdb_state *ks)
 864 {
 865         struct task_struct *thread;
 866         void *local_debuggerinfo;
 867         int i;
 868
 869         thread = kgdb_usethread;
 870         if (!thread) {
 871                 thread = kgdb_info[ks->cpu].task;
 872                 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
 873         } else {
 874                 local_debuggerinfo = NULL;
 875                 for_each_online_cpu(i) {
 876                         /*
 877                          * Try to find the task on some other
 878                          * or possibly this node if we do not
 879                          * find the matching task then we try
 880                          * to approximate the results.
 881                          */
 882                         if (thread == kgdb_info[i].task)
 883                                 local_debuggerinfo = kgdb_info[i].debuggerinfo;
 884                 }
 885         }
 886
 887         /*
 888          * All threads that don't have debuggerinfo should be
 889          * in schedule() sleeping, since all other CPUs
 890          * are in kgdb_wait, and thus have debuggerinfo.
 891          */
 892         if (local_debuggerinfo) {
 893                 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
 894         } else {
 895                 /*
 896                  * Pull stuff saved during switch_to; nothing
 897                  * else is accessible (or even particularly
 898                  * relevant).
 899                  *
 900                  * This should be enough for a stack trace.
 901                  */
 902                 sleeping_thread_to_gdb_regs(gdb_regs, thread);
 903         }
 904         kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
 905 }
 906
 907 /* Handle the 'G' set registers request */
 908 static void gdb_cmd_setregs(struct kgdb_state *ks)
 909 {
 910         kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
 911
 912         if (kgdb_usethread && kgdb_usethread != current) {
 913                 error_packet(remcom_out_buffer, -EINVAL);
 914         } else {
 915                 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
 916                 strcpy(remcom_out_buffer, "OK");
 917         }
 918 }
 919
 920 /* Handle the 'm' memory read bytes */
 921 static void gdb_cmd_memread(struct kgdb_state *ks)
 922 {
 923         char *ptr = &remcom_in_buffer[1];
 924         unsigned long length;
 925         unsigned long addr;
 926         int err;
 927
 928         if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
 929                                         kgdb_hex2long(&ptr, &length) > 0) {
 930                 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
 931                 if (err)
 932                         error_packet(remcom_out_buffer, err);
 933         } else {
 934                 error_packet(remcom_out_buffer, -EINVAL);
 935         }
 936 }
 937
 938 /* Handle the 'M' memory write bytes */
 939 static void gdb_cmd_memwrite(struct kgdb_state *ks)
 940 {
 941         int err = write_mem_msg(0);
 942
 943         if (err)
 944                 error_packet(remcom_out_buffer, err);
 945         else
 946                 strcpy(remcom_out_buffer, "OK");
 947 }
 948
 949 /* Handle the 'X' memory binary write bytes */
 950 static void gdb_cmd_binwrite(struct kgdb_state *ks)
 951 {
 952         int err = write_mem_msg(1);
 953
 954         if (err)
 955                 error_packet(remcom_out_buffer, err);
 956         else
 957                 strcpy(remcom_out_buffer, "OK");
 958 }
 959
 960 /* Handle the 'D' or 'k', detach or kill packets */
 961 static void gdb_cmd_detachkill(struct kgdb_state *ks)
 962 {
 963         int error;
 964
 965         /* The detach case */
 966         if (remcom_in_buffer[0] == 'D') {
 967                 error = remove_all_break();
 968                 if (error < 0) {
 969                         error_packet(remcom_out_buffer, error);
 970                 } else {
 971                         strcpy(remcom_out_buffer, "OK");
 972                         kgdb_connected = 0;
 973                 }
 974                 put_packet(remcom_out_buffer);
 975         } else {
 976                 /*
 977                  * Assume the kill case, with no exit code checking,
 978                  * trying to force detach the debugger:
 979                  */
 980                 remove_all_break();
 981                 kgdb_connected = 0;
 982         }
 983 }
 984
 985 /* Handle the 'R' reboot packets */
 986 static int gdb_cmd_reboot(struct kgdb_state *ks)
 987 {
 988         /* For now, only honor R0 */
 989         if (strcmp(remcom_in_buffer, "R0") == 0) {
 990                 printk(KERN_CRIT "Executing emergency reboot\n");
 991                 strcpy(remcom_out_buffer, "OK");
 992                 put_packet(remcom_out_buffer);
 993
 994                 /*
 995                  * Execution should not return from
 996                  * machine_emergency_restart()
 997                  */
 998                 machine_emergency_restart();
 999                 kgdb_connected = 0;
1000
1001                 return 1;
1002         }
1003         return 0;
1004 }
1005
1006 /* Handle the 'q' query packets */
1007 static void gdb_cmd_query(struct kgdb_state *ks)
1008 {
1009         struct task_struct *g;
1010         struct task_struct *p;
1011         unsigned char thref[8];
1012         char *ptr;
1013         int i;
1014         int cpu;
1015         int finished = 0;
1016
1017         switch (remcom_in_buffer[1]) {
1018         case 's':
1019         case 'f':
1020                 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
1021                         error_packet(remcom_out_buffer, -EINVAL);
1022                         break;
1023                 }
1024
1025                 i = 0;
1026                 remcom_out_buffer[0] = 'm';
1027                 ptr = remcom_out_buffer + 1;
1028                 if (remcom_in_buffer[1] == 'f') {
1029                         /* Each cpu is a shadow thread */
1030                         for_each_online_cpu(cpu) {
1031                                 ks->thr_query = 0;
1032                                 int_to_threadref(thref, -cpu - 2);
1033                                 pack_threadid(ptr, thref);
1034                                 ptr += BUF_THREAD_ID_SIZE;
1035                                 *(ptr++) = ',';
1036                                 i++;
1037                         }
1038                 }
1039
1040                 do_each_thread(g, p) {
1041                         if (i >= ks->thr_query && !finished) {
1042                                 int_to_threadref(thref, p->pid);
1043                                 pack_threadid(ptr, thref);
1044                                 ptr += BUF_THREAD_ID_SIZE;
1045                                 *(ptr++) = ',';
1046                                 ks->thr_query++;
1047                                 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
1048                                         finished = 1;
1049                         }
1050                         i++;
1051                 } while_each_thread(g, p);
1052
1053                 *(--ptr) = '\0';
1054                 break;
1055
1056         case 'C':
1057                 /* Current thread id */
1058                 strcpy(remcom_out_buffer, "QC");
1059                 ks->threadid = shadow_pid(current->pid);
1060                 int_to_threadref(thref, ks->threadid);
1061                 pack_threadid(remcom_out_buffer + 2, thref);
1062                 break;
1063         case 'T':
1064                 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
1065                         error_packet(remcom_out_buffer, -EINVAL);
1066                         break;
1067                 }
1068                 ks->threadid = 0;
1069                 ptr = remcom_in_buffer + 17;
1070                 kgdb_hex2long(&ptr, &ks->threadid);
1071                 if (!getthread(ks->linux_regs, ks->threadid)) {
1072                         error_packet(remcom_out_buffer, -EINVAL);
1073                         break;
1074                 }
1075                 if ((int)ks->threadid > 0) {
1076                         kgdb_mem2hex(getthread(ks->linux_regs,
1077                                         ks->threadid)->comm,
1078                                         remcom_out_buffer, 16);
1079                 } else {
1080                         static char tmpstr[23 + BUF_THREAD_ID_SIZE];
1081
1082                         sprintf(tmpstr, "shadowCPU%d",
1083                                         (int)(-ks->threadid - 2));
1084                         kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
1085                 }
1086                 break;
1087         }
1088 }
1089
1090 /* Handle the 'H' task query packets */
1091 static void gdb_cmd_task(struct kgdb_state *ks)
1092 {
1093         struct task_struct *thread;
1094         char *ptr;
1095
1096         switch (remcom_in_buffer[1]) {
1097         case 'g':
1098                 ptr = &remcom_in_buffer[2];
1099                 kgdb_hex2long(&ptr, &ks->threadid);
1100                 thread = getthread(ks->linux_regs, ks->threadid);
1101                 if (!thread && ks->threadid > 0) {
1102                         error_packet(remcom_out_buffer, -EINVAL);
1103                         break;
1104                 }
1105                 kgdb_usethread = thread;
1106                 ks->kgdb_usethreadid = ks->threadid;
1107                 strcpy(remcom_out_buffer, "OK");
1108                 break;
1109         case 'c':
1110                 ptr = &remcom_in_buffer[2];
1111                 kgdb_hex2long(&ptr, &ks->threadid);
1112                 if (!ks->threadid) {
1113                         kgdb_contthread = NULL;
1114                 } else {
1115                         thread = getthread(ks->linux_regs, ks->threadid);
1116                         if (!thread && ks->threadid > 0) {
1117                                 error_packet(remcom_out_buffer, -EINVAL);
1118                                 break;
1119                         }
1120                         kgdb_contthread = thread;
1121                 }
1122                 strcpy(remcom_out_buffer, "OK");
1123                 break;
1124         }
1125 }
1126
1127 /* Handle the 'T' thread query packets */
1128 static void gdb_cmd_thread(struct kgdb_state *ks)
1129 {
1130         char *ptr = &remcom_in_buffer[1];
1131         struct task_struct *thread;
1132
1133         kgdb_hex2long(&ptr, &ks->threadid);
1134         thread = getthread(ks->linux_regs, ks->threadid);
1135         if (thread)
1136                 strcpy(remcom_out_buffer, "OK");
1137         else
1138                 error_packet(remcom_out_buffer, -EINVAL);
1139 }
1140
1141 /* Handle the 'z' or 'Z' breakpoint remove or set packets */
1142 static void gdb_cmd_break(struct kgdb_state *ks)
1143 {
1144         /*
1145          * Since GDB-5.3, it's been drafted that '0' is a software
1146          * breakpoint, '1' is a hardware breakpoint, so let's do that.
1147          */
1148         char *bpt_type = &remcom_in_buffer[1];
1149         char *ptr = &remcom_in_buffer[2];
1150         unsigned long addr;
1151         unsigned long length;
1152         int error = 0;
1153
1154         if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
1155                 /* Unsupported */
1156                 if (*bpt_type > '4')
1157                         return;
1158         } else {
1159                 if (*bpt_type != '0' && *bpt_type != '1')
1160                         /* Unsupported. */
1161                         return;
1162         }
1163
1164         /*
1165          * Test if this is a hardware breakpoint, and
1166          * if we support it:
1167          */
1168         if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
1169                 /* Unsupported. */
1170                 return;
1171
1172         if (*(ptr++) != ',') {
1173                 error_packet(remcom_out_buffer, -EINVAL);
1174                 return;
1175         }
1176         if (!kgdb_hex2long(&ptr, &addr)) {
1177                 error_packet(remcom_out_buffer, -EINVAL);
1178                 return;
1179         }
1180         if (*(ptr++) != ',' ||
1181                 !kgdb_hex2long(&ptr, &length)) {
1182                 error_packet(remcom_out_buffer, -EINVAL);
1183                 return;
1184         }
1185
1186         if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
1187                 error = kgdb_set_sw_break(addr);
1188         else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
1189                 error = kgdb_remove_sw_break(addr);
1190         else if (remcom_in_buffer[0] == 'Z')
1191                 error = arch_kgdb_ops.set_hw_breakpoint(addr,
1192                         (int)length, *bpt_type - '0');
1193         else if (remcom_in_buffer[0] == 'z')
1194                 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
1195                         (int) length, *bpt_type - '0');
1196
1197         if (error == 0)
1198                 strcpy(remcom_out_buffer, "OK");
1199         else
1200                 error_packet(remcom_out_buffer, error);
1201 }
1202
1203 /* Handle the 'C' signal / exception passing packets */
1204 static int gdb_cmd_exception_pass(struct kgdb_state *ks)
1205 {
1206         /* C09 == pass exception
1207          * C15 == detach kgdb, pass exception
1208          */
1209         if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
1210
1211                 ks->pass_exception = 1;
1212                 remcom_in_buffer[0] = 'c';
1213
1214         } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
1215
1216                 ks->pass_exception = 1;
1217                 remcom_in_buffer[0] = 'D';
1218                 remove_all_break();
1219                 kgdb_connected = 0;
1220                 return 1;
1221
1222         } else {
1223                 kgdb_msg_write("KGDB only knows signal 9 (pass)"
1224                         " and 15 (pass and disconnect)\n"
1225                         "Executing a continue without signal passing\n", 0);
1226                 remcom_in_buffer[0] = 'c';
1227         }
1228
1229         /* Indicate fall through */
1230         return -1;
1231 }
1232
1233 /*
1234  * This function performs all gdbserial command procesing
1235  */
1236 static int gdb_serial_stub(struct kgdb_state *ks)
1237 {
1238         int error = 0;
1239         int tmp;
1240
1241         /* Clear the out buffer. */
1242         memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1243
1244         if (kgdb_connected) {
1245                 unsigned char thref[8];
1246                 char *ptr;
1247
1248                 /* Reply to host that an exception has occurred */
1249                 ptr = remcom_out_buffer;
1250                 *ptr++ = 'T';
1251                 ptr = pack_hex_byte(ptr, ks->signo);
1252                 ptr += strlen(strcpy(ptr, "thread:"));
1253                 int_to_threadref(thref, shadow_pid(current->pid));
1254                 ptr = pack_threadid(ptr, thref);
1255                 *ptr++ = ';';
1256                 put_packet(remcom_out_buffer);
1257         }
1258
1259         kgdb_usethread = kgdb_info[ks->cpu].task;
1260         ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
1261         ks->pass_exception = 0;
1262
1263         while (1) {
1264                 error = 0;
1265
1266                 /* Clear the out buffer. */
1267                 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1268
1269                 get_packet(remcom_in_buffer);
1270
1271                 switch (remcom_in_buffer[0]) {
1272                 case '?': /* gdbserial status */
1273                         gdb_cmd_status(ks);
1274                         break;
1275                 case 'g': /* return the value of the CPU registers */
1276                         gdb_cmd_getregs(ks);
1277                         break;
1278                 case 'G': /* set the value of the CPU registers - return OK */
1279                         gdb_cmd_setregs(ks);
1280                         break;
1281                 case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
1282                         gdb_cmd_memread(ks);
1283                         break;
1284                 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1285                         gdb_cmd_memwrite(ks);
1286                         break;
1287                 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1288                         gdb_cmd_binwrite(ks);
1289                         break;
1290                         /* kill or detach. KGDB should treat this like a
1291                          * continue.
1292                          */
1293                 case 'D': /* Debugger detach */
1294                 case 'k': /* Debugger detach via kill */
1295                         gdb_cmd_detachkill(ks);
1296                         goto default_handle;
1297                 case 'R': /* Reboot */
1298                         if (gdb_cmd_reboot(ks))
1299                                 goto default_handle;
1300                         break;
1301                 case 'q': /* query command */
1302                         gdb_cmd_query(ks);
1303                         break;
1304                 case 'H': /* task related */
1305                         gdb_cmd_task(ks);
1306                         break;
1307                 case 'T': /* Query thread status */
1308                         gdb_cmd_thread(ks);
1309                         break;
1310                 case 'z': /* Break point remove */
1311                 case 'Z': /* Break point set */
1312                         gdb_cmd_break(ks);
1313                         break;
1314                 case 'C': /* Exception passing */
1315                         tmp = gdb_cmd_exception_pass(ks);
1316                         if (tmp > 0)
1317                                 goto default_handle;
1318                         if (tmp == 0)
1319                                 break;
1320                         /* Fall through on tmp < 0 */
1321                 case 'c': /* Continue packet */
1322                 case 's': /* Single step packet */
1323                         if (kgdb_contthread && kgdb_contthread != current) {
1324                                 /* Can't switch threads in kgdb */
1325                                 error_packet(remcom_out_buffer, -EINVAL);
1326                                 break;
1327                         }
1328                         kgdb_activate_sw_breakpoints();
1329                         /* Fall through to default processing */
1330                 default:
1331 default_handle:
1332                         error = kgdb_arch_handle_exception(ks->ex_vector,
1333                                                 ks->signo,
1334                                                 ks->err_code,
1335                                                 remcom_in_buffer,
1336                                                 remcom_out_buffer,
1337                                                 ks->linux_regs);
1338                         /*
1339                          * Leave cmd processing on error, detach,
1340                          * kill, continue, or single step.
1341                          */
1342                         if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1343                             remcom_in_buffer[0] == 'k') {
1344                                 error = 0;
1345                                 goto kgdb_exit;
1346                         }
1347
1348                 }
1349
1350                 /* reply to the request */
1351                 put_packet(remcom_out_buffer);
1352         }
1353
1354 kgdb_exit:
1355         if (ks->pass_exception)
1356                 error = 1;
1357         return error;
1358 }
1359
1360 static int kgdb_reenter_check(struct kgdb_state *ks)
1361 {
1362         unsigned long addr;
1363
1364         if (atomic_read(&kgdb_active) != raw_smp_processor_id())
1365                 return 0;
1366
1367         /* Panic on recursive debugger calls: */
1368         exception_level++;
1369         addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
1370         kgdb_deactivate_sw_breakpoints();
1371
1372         /*
1373          * If the break point removed ok at the place exception
1374          * occurred, try to recover and print a warning to the end
1375          * user because the user planted a breakpoint in a place that
1376          * KGDB needs in order to function.
1377          */
1378         if (kgdb_remove_sw_break(addr) == 0) {
1379                 exception_level = 0;
1380                 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1381                 kgdb_activate_sw_breakpoints();
1382                 printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
1383                         addr);
1384                 WARN_ON_ONCE(1);
1385
1386                 return 1;
1387         }
1388         remove_all_break();
1389         kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1390
1391         if (exception_level > 1) {
1392                 dump_stack();
1393                 panic("Recursive entry to debugger");
1394         }
1395
1396         printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
1397         dump_stack();
1398         panic("Recursive entry to debugger");
1399
1400         return 1;
1401 }
1402
1403 /*
1404  * kgdb_handle_exception() - main entry point from a kernel exception
1405  *
1406  * Locking hierarchy:
1407  *      interface locks, if any (begin_session)
1408  *      kgdb lock (kgdb_active)
1409  */
1410 int
1411 kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
1412 {
1413         struct kgdb_state kgdb_var;
1414         struct kgdb_state *ks = &kgdb_var;
1415         unsigned long flags;
1416         int sstep_tries = 100;
1417         int error = 0;
1418         int i, cpu;
1419
1420         ks->cpu                 = raw_smp_processor_id();
1421         ks->ex_vector           = evector;
1422         ks->signo               = signo;
1423         ks->ex_vector           = evector;
1424         ks->err_code            = ecode;
1425         ks->kgdb_usethreadid    = 0;
1426         ks->linux_regs          = regs;
1427
1428         if (kgdb_reenter_check(ks))
1429                 return 0; /* Ouch, double exception ! */
1430
1431 acquirelock:
1432         /*
1433          * Interrupts will be restored by the 'trap return' code, except when
1434          * single stepping.
1435          */
1436         local_irq_save(flags);
1437
1438         cpu = raw_smp_processor_id();
1439
1440         /*
1441          * Acquire the kgdb_active lock:
1442          */
1443         while (atomic_cmpxchg(&kgdb_active, -1, cpu) != -1)
1444                 cpu_relax();
1445
1446         /*
1447          * For single stepping, try to only enter on the processor
1448          * that was single stepping.  To gaurd against a deadlock, the
1449          * kernel will only try for the value of sstep_tries before
1450          * giving up and continuing on.
1451          */
1452         if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
1453             (kgdb_info[cpu].task &&
1454              kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
1455                 atomic_set(&kgdb_active, -1);
1456                 touch_softlockup_watchdog_sync();
1457                 clocksource_touch_watchdog();
1458                 local_irq_restore(flags);
1459
1460                 goto acquirelock;
1461         }
1462
1463         if (!kgdb_io_ready(1)) {
1464                 error = 1;
1465                 goto kgdb_restore; /* No I/O connection, so resume the system */
1466         }
1467
1468         /*
1469          * Don't enter if we have hit a removed breakpoint.
1470          */
1471         if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
1472                 goto kgdb_restore;
1473
1474         /* Call the I/O driver's pre_exception routine */
1475         if (kgdb_io_ops->pre_exception)
1476                 kgdb_io_ops->pre_exception();
1477
1478         kgdb_info[ks->cpu].debuggerinfo = ks->linux_regs;
1479         kgdb_info[ks->cpu].task = current;
1480
1481         kgdb_disable_hw_debug(ks->linux_regs);
1482
1483         /*
1484          * Get the passive CPU lock which will hold all the non-primary
1485          * CPU in a spin state while the debugger is active
1486          */
1487         if (!kgdb_single_step) {
1488                 for (i = 0; i < NR_CPUS; i++)
1489                         atomic_set(&passive_cpu_wait[i], 1);
1490         }
1491
1492         /*
1493          * spin_lock code is good enough as a barrier so we don't
1494          * need one here:
1495          */
1496         atomic_set(&cpu_in_kgdb[ks->cpu], 1);
1497
1498 #ifdef CONFIG_SMP
1499         /* Signal the other CPUs to enter kgdb_wait() */
1500         if ((!kgdb_single_step) && kgdb_do_roundup)
1501                 kgdb_roundup_cpus(flags);
1502 #endif
1503
1504         /*
1505          * Wait for the other CPUs to be notified and be waiting for us:
1506          */
1507         for_each_online_cpu(i) {
1508                 while (!atomic_read(&cpu_in_kgdb[i]))
1509                         cpu_relax();
1510         }
1511
1512         /*
1513          * At this point the primary processor is completely
1514          * in the debugger and all secondary CPUs are quiescent
1515          */
1516         kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code);
1517         kgdb_deactivate_sw_breakpoints();
1518         kgdb_single_step = 0;
1519         kgdb_contthread = current;
1520         exception_level = 0;
1521
1522         /* Talk to debugger with gdbserial protocol */
1523         error = gdb_serial_stub(ks);
1524
1525         /* Call the I/O driver's post_exception routine */
1526         if (kgdb_io_ops->post_exception)
1527                 kgdb_io_ops->post_exception();
1528
1529         kgdb_info[ks->cpu].debuggerinfo = NULL;
1530         kgdb_info[ks->cpu].task = NULL;
1531         atomic_set(&cpu_in_kgdb[ks->cpu], 0);
1532
1533         if (!kgdb_single_step) {
1534                 for (i = NR_CPUS-1; i >= 0; i--)
1535                         atomic_set(&passive_cpu_wait[i], 0);
1536                 /*
1537                  * Wait till all the CPUs have quit
1538                  * from the debugger.
1539                  */
1540                 for_each_online_cpu(i) {
1541                         while (atomic_read(&cpu_in_kgdb[i]))
1542                                 cpu_relax();
1543                 }
1544         }
1545
1546 kgdb_restore:
1547         if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
1548                 int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step);
1549                 if (kgdb_info[sstep_cpu].task)
1550                         kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid;
1551                 else
1552                         kgdb_sstep_pid = 0;
1553         }
1554         /* Free kgdb_active */
1555         atomic_set(&kgdb_active, -1);
1556         touch_softlockup_watchdog_sync();
1557         clocksource_touch_watchdog();
1558         local_irq_restore(flags);
1559
1560         return error;
1561 }
1562
1563 int kgdb_nmicallback(int cpu, void *regs)
1564 {
1565 #ifdef CONFIG_SMP
1566         if (!atomic_read(&cpu_in_kgdb[cpu]) &&
1567                         atomic_read(&kgdb_active) != cpu &&
1568                         atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)])) {
1569                 kgdb_wait((struct pt_regs *)regs);
1570                 return 0;
1571         }
1572 #endif
1573         return 1;
1574 }
1575
1576 static void kgdb_console_write(struct console *co, const char *s,
1577    unsigned count)
1578 {
1579         unsigned long flags;
1580
1581         /* If we're debugging, or KGDB has not connected, don't try
1582          * and print. */
1583         if (!kgdb_connected || atomic_read(&kgdb_active) != -1)
1584                 return;
1585
1586         local_irq_save(flags);
1587         kgdb_msg_write(s, count);
1588         local_irq_restore(flags);
1589 }
1590
1591 static struct console kgdbcons = {
1592         .name           = "kgdb",
1593         .write          = kgdb_console_write,
1594         .flags          = CON_PRINTBUFFER | CON_ENABLED,
1595         .index          = -1,
1596 };
1597
1598 #ifdef CONFIG_MAGIC_SYSRQ
1599 static void sysrq_handle_gdb(int key, struct tty_struct *tty)
1600 {
1601         if (!kgdb_io_ops) {
1602                 printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
1603                 return;
1604         }
1605         if (!kgdb_connected)
1606                 printk(KERN_CRIT "Entering KGDB\n");
1607
1608         kgdb_breakpoint();
1609 }
1610
1611 static struct sysrq_key_op sysrq_gdb_op = {
1612         .handler        = sysrq_handle_gdb,
1613         .help_msg       = "debug(G)",
1614         .action_msg     = "DEBUG",
1615 };
1616 #endif
1617
1618 static void kgdb_register_callbacks(void)
1619 {
1620         if (!kgdb_io_module_registered) {
1621                 kgdb_io_module_registered = 1;
1622                 kgdb_arch_init();
1623 #ifdef CONFIG_MAGIC_SYSRQ
1624                 register_sysrq_key('g', &sysrq_gdb_op);
1625 #endif
1626                 if (kgdb_use_con && !kgdb_con_registered) {
1627                         register_console(&kgdbcons);
1628                         kgdb_con_registered = 1;
1629                 }
1630         }
1631 }
1632
1633 static void kgdb_unregister_callbacks(void)
1634 {
1635         /*
1636          * When this routine is called KGDB should unregister from the
1637          * panic handler and clean up, making sure it is not handling any
1638          * break exceptions at the time.
1639          */
1640         if (kgdb_io_module_registered) {
1641                 kgdb_io_module_registered = 0;
1642                 kgdb_arch_exit();
1643 #ifdef CONFIG_MAGIC_SYSRQ
1644                 unregister_sysrq_key('g', &sysrq_gdb_op);
1645 #endif
1646                 if (kgdb_con_registered) {
1647                         unregister_console(&kgdbcons);
1648                         kgdb_con_registered = 0;
1649                 }
1650         }
1651 }
1652
1653 static void kgdb_initial_breakpoint(void)
1654 {
1655         kgdb_break_asap = 0;
1656
1657         printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
1658         kgdb_breakpoint();
1659 }
1660
1661 /**
1662  *      kgdb_register_io_module - register KGDB IO module
1663  *      @new_kgdb_io_ops: the io ops vector
1664  *
1665  *      Register it with the KGDB core.
1666  */
1667 int kgdb_register_io_module(struct kgdb_io *new_kgdb_io_ops)
1668 {
1669         int err;
1670
1671         spin_lock(&kgdb_registration_lock);
1672
1673         if (kgdb_io_ops) {
1674                 spin_unlock(&kgdb_registration_lock);
1675
1676                 printk(KERN_ERR "kgdb: Another I/O driver is already "
1677                                 "registered with KGDB.\n");
1678                 return -EBUSY;
1679         }
1680
1681         if (new_kgdb_io_ops->init) {
1682                 err = new_kgdb_io_ops->init();
1683                 if (err) {
1684                         spin_unlock(&kgdb_registration_lock);
1685                         return err;
1686                 }
1687         }
1688
1689         kgdb_io_ops = new_kgdb_io_ops;
1690
1691         spin_unlock(&kgdb_registration_lock);
1692
1693         printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
1694                new_kgdb_io_ops->name);
1695
1696         /* Arm KGDB now. */
1697         kgdb_register_callbacks();
1698
1699         if (kgdb_break_asap)
1700                 kgdb_initial_breakpoint();
1701
1702         return 0;
1703 }
1704 EXPORT_SYMBOL_GPL(kgdb_register_io_module);
1705
1706 /**
1707  *      kkgdb_unregister_io_module - unregister KGDB IO module
1708  *      @old_kgdb_io_ops: the io ops vector
1709  *
1710  *      Unregister it with the KGDB core.
1711  */
1712 void kgdb_unregister_io_module(struct kgdb_io *old_kgdb_io_ops)
1713 {
1714         BUG_ON(kgdb_connected);
1715
1716         /*
1717          * KGDB is no longer able to communicate out, so
1718          * unregister our callbacks and reset state.
1719          */
1720         kgdb_unregister_callbacks();
1721
1722         spin_lock(&kgdb_registration_lock);
1723
1724         WARN_ON_ONCE(kgdb_io_ops != old_kgdb_io_ops);
1725         kgdb_io_ops = NULL;
1726
1727         spin_unlock(&kgdb_registration_lock);
1728
1729         printk(KERN_INFO
1730                 "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
1731                 old_kgdb_io_ops->name);
1732 }
1733 EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
1734
1735 /**
1736  * kgdb_breakpoint - generate breakpoint exception
1737  *
1738  * This function will generate a breakpoint exception.  It is used at the
1739  * beginning of a program to sync up with a debugger and can be used
1740  * otherwise as a quick means to stop program execution and "break" into
1741  * the debugger.
1742  */
1743 void kgdb_breakpoint(void)
1744 {
1745         atomic_set(&kgdb_setting_breakpoint, 1);
1746         wmb(); /* Sync point before breakpoint */
1747         arch_kgdb_breakpoint();
1748         wmb(); /* Sync point after breakpoint */
1749         atomic_set(&kgdb_setting_breakpoint, 0);
1750 }
1751 EXPORT_SYMBOL_GPL(kgdb_breakpoint);
1752
1753 static int __init opt_kgdb_wait(char *str)
1754 {
1755         kgdb_break_asap = 1;
1756
1757         if (kgdb_io_module_registered)
1758                 kgdb_initial_breakpoint();
1759
1760         return 0;
1761 }
1762
1763 early_param("kgdbwait", opt_kgdb_wait);