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         /* Wait till primary CPU is done with debugging */
 587         while (atomic_read(&passive_cpu_wait[cpu]))
 588                 cpu_relax();
 589
 590         kgdb_info[cpu].debuggerinfo = NULL;
 591         kgdb_info[cpu].task = NULL;
 592
 593         /* fix up hardware debug registers on local cpu */
 594         if (arch_kgdb_ops.correct_hw_break)
 595                 arch_kgdb_ops.correct_hw_break();
 596
 597         /* Signal the primary CPU that we are done: */
 598         atomic_set(&cpu_in_kgdb[cpu], 0);
 599         touch_softlockup_watchdog();
 600         clocksource_touch_watchdog();
 601         local_irq_restore(flags);
 602 }
 603 #endif
 604
 605 /*
 606  * Some architectures need cache flushes when we set/clear a
 607  * breakpoint:
 608  */
 609 static void kgdb_flush_swbreak_addr(unsigned long addr)
 610 {
 611         if (!CACHE_FLUSH_IS_SAFE)
 612                 return;
 613
 614         if (current->mm && current->mm->mmap_cache) {
 615                 flush_cache_range(current->mm->mmap_cache,
 616                                   addr, addr + BREAK_INSTR_SIZE);
 617         }
 618         /* Force flush instruction cache if it was outside the mm */
 619         flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
 620 }
 621
 622 /*
 623  * SW breakpoint management:
 624  */
 625 static int kgdb_activate_sw_breakpoints(void)
 626 {
 627         unsigned long addr;
 628         int error;
 629         int ret = 0;
 630         int i;
 631
 632         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 633                 if (kgdb_break[i].state != BP_SET)
 634                         continue;
 635
 636                 addr = kgdb_break[i].bpt_addr;
 637                 error = kgdb_arch_set_breakpoint(addr,
 638                                 kgdb_break[i].saved_instr);
 639                 if (error) {
 640                         ret = error;
 641                         printk(KERN_INFO "KGDB: BP install failed: %lx", addr);
 642                         continue;
 643                 }
 644
 645                 kgdb_flush_swbreak_addr(addr);
 646                 kgdb_break[i].state = BP_ACTIVE;
 647         }
 648         return ret;
 649 }
 650
 651 static int kgdb_set_sw_break(unsigned long addr)
 652 {
 653         int err = kgdb_validate_break_address(addr);
 654         int breakno = -1;
 655         int i;
 656
 657         if (err)
 658                 return err;
 659
 660         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 661                 if ((kgdb_break[i].state == BP_SET) &&
 662                                         (kgdb_break[i].bpt_addr == addr))
 663                         return -EEXIST;
 664         }
 665         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 666                 if (kgdb_break[i].state == BP_REMOVED &&
 667                                         kgdb_break[i].bpt_addr == addr) {
 668                         breakno = i;
 669                         break;
 670                 }
 671         }
 672
 673         if (breakno == -1) {
 674                 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 675                         if (kgdb_break[i].state == BP_UNDEFINED) {
 676                                 breakno = i;
 677                                 break;
 678                         }
 679                 }
 680         }
 681
 682         if (breakno == -1)
 683                 return -E2BIG;
 684
 685         kgdb_break[breakno].state = BP_SET;
 686         kgdb_break[breakno].type = BP_BREAKPOINT;
 687         kgdb_break[breakno].bpt_addr = addr;
 688
 689         return 0;
 690 }
 691
 692 static int kgdb_deactivate_sw_breakpoints(void)
 693 {
 694         unsigned long addr;
 695         int error;
 696         int ret = 0;
 697         int i;
 698
 699         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 700                 if (kgdb_break[i].state != BP_ACTIVE)
 701                         continue;
 702                 addr = kgdb_break[i].bpt_addr;
 703                 error = kgdb_arch_remove_breakpoint(addr,
 704                                         kgdb_break[i].saved_instr);
 705                 if (error) {
 706                         printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr);
 707                         ret = error;
 708                 }
 709
 710                 kgdb_flush_swbreak_addr(addr);
 711                 kgdb_break[i].state = BP_SET;
 712         }
 713         return ret;
 714 }
 715
 716 static int kgdb_remove_sw_break(unsigned long addr)
 717 {
 718         int i;
 719
 720         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 721                 if ((kgdb_break[i].state == BP_SET) &&
 722                                 (kgdb_break[i].bpt_addr == addr)) {
 723                         kgdb_break[i].state = BP_REMOVED;
 724                         return 0;
 725                 }
 726         }
 727         return -ENOENT;
 728 }
 729
 730 int kgdb_isremovedbreak(unsigned long addr)
 731 {
 732         int i;
 733
 734         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 735                 if ((kgdb_break[i].state == BP_REMOVED) &&
 736                                         (kgdb_break[i].bpt_addr == addr))
 737                         return 1;
 738         }
 739         return 0;
 740 }
 741
 742 static int remove_all_break(void)
 743 {
 744         unsigned long addr;
 745         int error;
 746         int i;
 747
 748         /* Clear memory breakpoints. */
 749         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
 750                 if (kgdb_break[i].state != BP_ACTIVE)
 751                         goto setundefined;
 752                 addr = kgdb_break[i].bpt_addr;
 753                 error = kgdb_arch_remove_breakpoint(addr,
 754                                 kgdb_break[i].saved_instr);
 755                 if (error)
 756                         printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
 757                            addr);
 758 setundefined:
 759                 kgdb_break[i].state = BP_UNDEFINED;
 760         }
 761
 762         /* Clear hardware breakpoints. */
 763         if (arch_kgdb_ops.remove_all_hw_break)
 764                 arch_kgdb_ops.remove_all_hw_break();
 765
 766         return 0;
 767 }
 768
 769 /*
 770  * Remap normal tasks to their real PID,
 771  * CPU shadow threads are mapped to -CPU - 2
 772  */
 773 static inline int shadow_pid(int realpid)
 774 {
 775         if (realpid)
 776                 return realpid;
 777
 778         return -raw_smp_processor_id() - 2;
 779 }
 780
 781 static char gdbmsgbuf[BUFMAX + 1];
 782
 783 static void kgdb_msg_write(const char *s, int len)
 784 {
 785         char *bufptr;
 786         int wcount;
 787         int i;
 788
 789         /* 'O'utput */
 790         gdbmsgbuf[0] = 'O';
 791
 792         /* Fill and send buffers... */
 793         while (len > 0) {
 794                 bufptr = gdbmsgbuf + 1;
 795
 796                 /* Calculate how many this time */
 797                 if ((len << 1) > (BUFMAX - 2))
 798                         wcount = (BUFMAX - 2) >> 1;
 799                 else
 800                         wcount = len;
 801
 802                 /* Pack in hex chars */
 803                 for (i = 0; i < wcount; i++)
 804                         bufptr = pack_hex_byte(bufptr, s[i]);
 805                 *bufptr = '\0';
 806
 807                 /* Move up */
 808                 s += wcount;
 809                 len -= wcount;
 810
 811                 /* Write packet */
 812                 put_packet(gdbmsgbuf);
 813         }
 814 }
 815
 816 /*
 817  * Return true if there is a valid kgdb I/O module.  Also if no
 818  * debugger is attached a message can be printed to the console about
 819  * waiting for the debugger to attach.
 820  *
 821  * The print_wait argument is only to be true when called from inside
 822  * the core kgdb_handle_exception, because it will wait for the
 823  * debugger to attach.
 824  */
 825 static int kgdb_io_ready(int print_wait)
 826 {
 827         if (!kgdb_io_ops)
 828                 return 0;
 829         if (kgdb_connected)
 830                 return 1;
 831         if (atomic_read(&kgdb_setting_breakpoint))
 832                 return 1;
 833         if (print_wait)
 834                 printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
 835         return 1;
 836 }
 837
 838 /*
 839  * All the functions that start with gdb_cmd are the various
 840  * operations to implement the handlers for the gdbserial protocol
 841  * where KGDB is communicating with an external debugger
 842  */
 843
 844 /* Handle the '?' status packets */
 845 static void gdb_cmd_status(struct kgdb_state *ks)
 846 {
 847         /*
 848          * We know that this packet is only sent
 849          * during initial connect.  So to be safe,
 850          * we clear out our breakpoints now in case
 851          * GDB is reconnecting.
 852          */
 853         remove_all_break();
 854
 855         remcom_out_buffer[0] = 'S';
 856         pack_hex_byte(&remcom_out_buffer[1], ks->signo);
 857 }
 858
 859 /* Handle the 'g' get registers request */
 860 static void gdb_cmd_getregs(struct kgdb_state *ks)
 861 {
 862         struct task_struct *thread;
 863         void *local_debuggerinfo;
 864         int i;
 865
 866         thread = kgdb_usethread;
 867         if (!thread) {
 868                 thread = kgdb_info[ks->cpu].task;
 869                 local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
 870         } else {
 871                 local_debuggerinfo = NULL;
 872                 for_each_online_cpu(i) {
 873                         /*
 874                          * Try to find the task on some other
 875                          * or possibly this node if we do not
 876                          * find the matching task then we try
 877                          * to approximate the results.
 878                          */
 879                         if (thread == kgdb_info[i].task)
 880                                 local_debuggerinfo = kgdb_info[i].debuggerinfo;
 881                 }
 882         }
 883
 884         /*
 885          * All threads that don't have debuggerinfo should be
 886          * in schedule() sleeping, since all other CPUs
 887          * are in kgdb_wait, and thus have debuggerinfo.
 888          */
 889         if (local_debuggerinfo) {
 890                 pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
 891         } else {
 892                 /*
 893                  * Pull stuff saved during switch_to; nothing
 894                  * else is accessible (or even particularly
 895                  * relevant).
 896                  *
 897                  * This should be enough for a stack trace.
 898                  */
 899                 sleeping_thread_to_gdb_regs(gdb_regs, thread);
 900         }
 901         kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
 902 }
 903
 904 /* Handle the 'G' set registers request */
 905 static void gdb_cmd_setregs(struct kgdb_state *ks)
 906 {
 907         kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
 908
 909         if (kgdb_usethread && kgdb_usethread != current) {
 910                 error_packet(remcom_out_buffer, -EINVAL);
 911         } else {
 912                 gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
 913                 strcpy(remcom_out_buffer, "OK");
 914         }
 915 }
 916
 917 /* Handle the 'm' memory read bytes */
 918 static void gdb_cmd_memread(struct kgdb_state *ks)
 919 {
 920         char *ptr = &remcom_in_buffer[1];
 921         unsigned long length;
 922         unsigned long addr;
 923         int err;
 924
 925         if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
 926                                         kgdb_hex2long(&ptr, &length) > 0) {
 927                 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
 928                 if (err)
 929                         error_packet(remcom_out_buffer, err);
 930         } else {
 931                 error_packet(remcom_out_buffer, -EINVAL);
 932         }
 933 }
 934
 935 /* Handle the 'M' memory write bytes */
 936 static void gdb_cmd_memwrite(struct kgdb_state *ks)
 937 {
 938         int err = write_mem_msg(0);
 939
 940         if (err)
 941                 error_packet(remcom_out_buffer, err);
 942         else
 943                 strcpy(remcom_out_buffer, "OK");
 944 }
 945
 946 /* Handle the 'X' memory binary write bytes */
 947 static void gdb_cmd_binwrite(struct kgdb_state *ks)
 948 {
 949         int err = write_mem_msg(1);
 950
 951         if (err)
 952                 error_packet(remcom_out_buffer, err);
 953         else
 954                 strcpy(remcom_out_buffer, "OK");
 955 }
 956
 957 /* Handle the 'D' or 'k', detach or kill packets */
 958 static void gdb_cmd_detachkill(struct kgdb_state *ks)
 959 {
 960         int error;
 961
 962         /* The detach case */
 963         if (remcom_in_buffer[0] == 'D') {
 964                 error = remove_all_break();
 965                 if (error < 0) {
 966                         error_packet(remcom_out_buffer, error);
 967                 } else {
 968                         strcpy(remcom_out_buffer, "OK");
 969                         kgdb_connected = 0;
 970                 }
 971                 put_packet(remcom_out_buffer);
 972         } else {
 973                 /*
 974                  * Assume the kill case, with no exit code checking,
 975                  * trying to force detach the debugger:
 976                  */
 977                 remove_all_break();
 978                 kgdb_connected = 0;
 979         }
 980 }
 981
 982 /* Handle the 'R' reboot packets */
 983 static int gdb_cmd_reboot(struct kgdb_state *ks)
 984 {
 985         /* For now, only honor R0 */
 986         if (strcmp(remcom_in_buffer, "R0") == 0) {
 987                 printk(KERN_CRIT "Executing emergency reboot\n");
 988                 strcpy(remcom_out_buffer, "OK");
 989                 put_packet(remcom_out_buffer);
 990
 991                 /*
 992                  * Execution should not return from
 993                  * machine_emergency_restart()
 994                  */
 995                 machine_emergency_restart();
 996                 kgdb_connected = 0;
 997
 998                 return 1;
 999         }
1000         return 0;
1001 }
1002
1003 /* Handle the 'q' query packets */
1004 static void gdb_cmd_query(struct kgdb_state *ks)
1005 {
1006         struct task_struct *g;
1007         struct task_struct *p;
1008         unsigned char thref[8];
1009         char *ptr;
1010         int i;
1011         int cpu;
1012         int finished = 0;
1013
1014         switch (remcom_in_buffer[1]) {
1015         case 's':
1016         case 'f':
1017                 if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
1018                         error_packet(remcom_out_buffer, -EINVAL);
1019                         break;
1020                 }
1021
1022                 i = 0;
1023                 remcom_out_buffer[0] = 'm';
1024                 ptr = remcom_out_buffer + 1;
1025                 if (remcom_in_buffer[1] == 'f') {
1026                         /* Each cpu is a shadow thread */
1027                         for_each_online_cpu(cpu) {
1028                                 ks->thr_query = 0;
1029                                 int_to_threadref(thref, -cpu - 2);
1030                                 pack_threadid(ptr, thref);
1031                                 ptr += BUF_THREAD_ID_SIZE;
1032                                 *(ptr++) = ',';
1033                                 i++;
1034                         }
1035                 }
1036
1037                 do_each_thread(g, p) {
1038                         if (i >= ks->thr_query && !finished) {
1039                                 int_to_threadref(thref, p->pid);
1040                                 pack_threadid(ptr, thref);
1041                                 ptr += BUF_THREAD_ID_SIZE;
1042                                 *(ptr++) = ',';
1043                                 ks->thr_query++;
1044                                 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
1045                                         finished = 1;
1046                         }
1047                         i++;
1048                 } while_each_thread(g, p);
1049
1050                 *(--ptr) = '\0';
1051                 break;
1052
1053         case 'C':
1054                 /* Current thread id */
1055                 strcpy(remcom_out_buffer, "QC");
1056                 ks->threadid = shadow_pid(current->pid);
1057                 int_to_threadref(thref, ks->threadid);
1058                 pack_threadid(remcom_out_buffer + 2, thref);
1059                 break;
1060         case 'T':
1061                 if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
1062                         error_packet(remcom_out_buffer, -EINVAL);
1063                         break;
1064                 }
1065                 ks->threadid = 0;
1066                 ptr = remcom_in_buffer + 17;
1067                 kgdb_hex2long(&ptr, &ks->threadid);
1068                 if (!getthread(ks->linux_regs, ks->threadid)) {
1069                         error_packet(remcom_out_buffer, -EINVAL);
1070                         break;
1071                 }
1072                 if ((int)ks->threadid > 0) {
1073                         kgdb_mem2hex(getthread(ks->linux_regs,
1074                                         ks->threadid)->comm,
1075                                         remcom_out_buffer, 16);
1076                 } else {
1077                         static char tmpstr[23 + BUF_THREAD_ID_SIZE];
1078
1079                         sprintf(tmpstr, "shadowCPU%d",
1080                                         (int)(-ks->threadid - 2));
1081                         kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
1082                 }
1083                 break;
1084         }
1085 }
1086
1087 /* Handle the 'H' task query packets */
1088 static void gdb_cmd_task(struct kgdb_state *ks)
1089 {
1090         struct task_struct *thread;
1091         char *ptr;
1092
1093         switch (remcom_in_buffer[1]) {
1094         case 'g':
1095                 ptr = &remcom_in_buffer[2];
1096                 kgdb_hex2long(&ptr, &ks->threadid);
1097                 thread = getthread(ks->linux_regs, ks->threadid);
1098                 if (!thread && ks->threadid > 0) {
1099                         error_packet(remcom_out_buffer, -EINVAL);
1100                         break;
1101                 }
1102                 kgdb_usethread = thread;
1103                 ks->kgdb_usethreadid = ks->threadid;
1104                 strcpy(remcom_out_buffer, "OK");
1105                 break;
1106         case 'c':
1107                 ptr = &remcom_in_buffer[2];
1108                 kgdb_hex2long(&ptr, &ks->threadid);
1109                 if (!ks->threadid) {
1110                         kgdb_contthread = NULL;
1111                 } else {
1112                         thread = getthread(ks->linux_regs, ks->threadid);
1113                         if (!thread && ks->threadid > 0) {
1114                                 error_packet(remcom_out_buffer, -EINVAL);
1115                                 break;
1116                         }
1117                         kgdb_contthread = thread;
1118                 }
1119                 strcpy(remcom_out_buffer, "OK");
1120                 break;
1121         }
1122 }
1123
1124 /* Handle the 'T' thread query packets */
1125 static void gdb_cmd_thread(struct kgdb_state *ks)
1126 {
1127         char *ptr = &remcom_in_buffer[1];
1128         struct task_struct *thread;
1129
1130         kgdb_hex2long(&ptr, &ks->threadid);
1131         thread = getthread(ks->linux_regs, ks->threadid);
1132         if (thread)
1133                 strcpy(remcom_out_buffer, "OK");
1134         else
1135                 error_packet(remcom_out_buffer, -EINVAL);
1136 }
1137
1138 /* Handle the 'z' or 'Z' breakpoint remove or set packets */
1139 static void gdb_cmd_break(struct kgdb_state *ks)
1140 {
1141         /*
1142          * Since GDB-5.3, it's been drafted that '0' is a software
1143          * breakpoint, '1' is a hardware breakpoint, so let's do that.
1144          */
1145         char *bpt_type = &remcom_in_buffer[1];
1146         char *ptr = &remcom_in_buffer[2];
1147         unsigned long addr;
1148         unsigned long length;
1149         int error = 0;
1150
1151         if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
1152                 /* Unsupported */
1153                 if (*bpt_type > '4')
1154                         return;
1155         } else {
1156                 if (*bpt_type != '0' && *bpt_type != '1')
1157                         /* Unsupported. */
1158                         return;
1159         }
1160
1161         /*
1162          * Test if this is a hardware breakpoint, and
1163          * if we support it:
1164          */
1165         if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
1166                 /* Unsupported. */
1167                 return;
1168
1169         if (*(ptr++) != ',') {
1170                 error_packet(remcom_out_buffer, -EINVAL);
1171                 return;
1172         }
1173         if (!kgdb_hex2long(&ptr, &addr)) {
1174                 error_packet(remcom_out_buffer, -EINVAL);
1175                 return;
1176         }
1177         if (*(ptr++) != ',' ||
1178                 !kgdb_hex2long(&ptr, &length)) {
1179                 error_packet(remcom_out_buffer, -EINVAL);
1180                 return;
1181         }
1182
1183         if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
1184                 error = kgdb_set_sw_break(addr);
1185         else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
1186                 error = kgdb_remove_sw_break(addr);
1187         else if (remcom_in_buffer[0] == 'Z')
1188                 error = arch_kgdb_ops.set_hw_breakpoint(addr,
1189                         (int)length, *bpt_type - '0');
1190         else if (remcom_in_buffer[0] == 'z')
1191                 error = arch_kgdb_ops.remove_hw_breakpoint(addr,
1192                         (int) length, *bpt_type - '0');
1193
1194         if (error == 0)
1195                 strcpy(remcom_out_buffer, "OK");
1196         else
1197                 error_packet(remcom_out_buffer, error);
1198 }
1199
1200 /* Handle the 'C' signal / exception passing packets */
1201 static int gdb_cmd_exception_pass(struct kgdb_state *ks)
1202 {
1203         /* C09 == pass exception
1204          * C15 == detach kgdb, pass exception
1205          */
1206         if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
1207
1208                 ks->pass_exception = 1;
1209                 remcom_in_buffer[0] = 'c';
1210
1211         } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
1212
1213                 ks->pass_exception = 1;
1214                 remcom_in_buffer[0] = 'D';
1215                 remove_all_break();
1216                 kgdb_connected = 0;
1217                 return 1;
1218
1219         } else {
1220                 kgdb_msg_write("KGDB only knows signal 9 (pass)"
1221                         " and 15 (pass and disconnect)\n"
1222                         "Executing a continue without signal passing\n", 0);
1223                 remcom_in_buffer[0] = 'c';
1224         }
1225
1226         /* Indicate fall through */
1227         return -1;
1228 }
1229
1230 /*
1231  * This function performs all gdbserial command procesing
1232  */
1233 static int gdb_serial_stub(struct kgdb_state *ks)
1234 {
1235         int error = 0;
1236         int tmp;
1237
1238         /* Clear the out buffer. */
1239         memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1240
1241         if (kgdb_connected) {
1242                 unsigned char thref[8];
1243                 char *ptr;
1244
1245                 /* Reply to host that an exception has occurred */
1246                 ptr = remcom_out_buffer;
1247                 *ptr++ = 'T';
1248                 ptr = pack_hex_byte(ptr, ks->signo);
1249                 ptr += strlen(strcpy(ptr, "thread:"));
1250                 int_to_threadref(thref, shadow_pid(current->pid));
1251                 ptr = pack_threadid(ptr, thref);
1252                 *ptr++ = ';';
1253                 put_packet(remcom_out_buffer);
1254         }
1255
1256         kgdb_usethread = kgdb_info[ks->cpu].task;
1257         ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
1258         ks->pass_exception = 0;
1259
1260         while (1) {
1261                 error = 0;
1262
1263                 /* Clear the out buffer. */
1264                 memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1265
1266                 get_packet(remcom_in_buffer);
1267
1268                 switch (remcom_in_buffer[0]) {
1269                 case '?': /* gdbserial status */
1270                         gdb_cmd_status(ks);
1271                         break;
1272                 case 'g': /* return the value of the CPU registers */
1273                         gdb_cmd_getregs(ks);
1274                         break;
1275                 case 'G': /* set the value of the CPU registers - return OK */
1276                         gdb_cmd_setregs(ks);
1277                         break;
1278                 case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
1279                         gdb_cmd_memread(ks);
1280                         break;
1281                 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1282                         gdb_cmd_memwrite(ks);
1283                         break;
1284                 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1285                         gdb_cmd_binwrite(ks);
1286                         break;
1287                         /* kill or detach. KGDB should treat this like a
1288                          * continue.
1289                          */
1290                 case 'D': /* Debugger detach */
1291                 case 'k': /* Debugger detach via kill */
1292                         gdb_cmd_detachkill(ks);
1293                         goto default_handle;
1294                 case 'R': /* Reboot */
1295                         if (gdb_cmd_reboot(ks))
1296                                 goto default_handle;
1297                         break;
1298                 case 'q': /* query command */
1299                         gdb_cmd_query(ks);
1300                         break;
1301                 case 'H': /* task related */
1302                         gdb_cmd_task(ks);
1303                         break;
1304                 case 'T': /* Query thread status */
1305                         gdb_cmd_thread(ks);
1306                         break;
1307                 case 'z': /* Break point remove */
1308                 case 'Z': /* Break point set */
1309                         gdb_cmd_break(ks);
1310                         break;
1311                 case 'C': /* Exception passing */
1312                         tmp = gdb_cmd_exception_pass(ks);
1313                         if (tmp > 0)
1314                                 goto default_handle;
1315                         if (tmp == 0)
1316                                 break;
1317                         /* Fall through on tmp < 0 */
1318                 case 'c': /* Continue packet */
1319                 case 's': /* Single step packet */
1320                         if (kgdb_contthread && kgdb_contthread != current) {
1321                                 /* Can't switch threads in kgdb */
1322                                 error_packet(remcom_out_buffer, -EINVAL);
1323                                 break;
1324                         }
1325                         kgdb_activate_sw_breakpoints();
1326                         /* Fall through to default processing */
1327                 default:
1328 default_handle:
1329                         error = kgdb_arch_handle_exception(ks->ex_vector,
1330                                                 ks->signo,
1331                                                 ks->err_code,
1332                                                 remcom_in_buffer,
1333                                                 remcom_out_buffer,
1334                                                 ks->linux_regs);
1335                         /*
1336                          * Leave cmd processing on error, detach,
1337                          * kill, continue, or single step.
1338                          */
1339                         if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1340                             remcom_in_buffer[0] == 'k') {
1341                                 error = 0;
1342                                 goto kgdb_exit;
1343                         }
1344
1345                 }
1346
1347                 /* reply to the request */
1348                 put_packet(remcom_out_buffer);
1349         }
1350
1351 kgdb_exit:
1352         if (ks->pass_exception)
1353                 error = 1;
1354         return error;
1355 }
1356
1357 static int kgdb_reenter_check(struct kgdb_state *ks)
1358 {
1359         unsigned long addr;
1360
1361         if (atomic_read(&kgdb_active) != raw_smp_processor_id())
1362                 return 0;
1363
1364         /* Panic on recursive debugger calls: */
1365         exception_level++;
1366         addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
1367         kgdb_deactivate_sw_breakpoints();
1368
1369         /*
1370          * If the break point removed ok at the place exception
1371          * occurred, try to recover and print a warning to the end
1372          * user because the user planted a breakpoint in a place that
1373          * KGDB needs in order to function.
1374          */
1375         if (kgdb_remove_sw_break(addr) == 0) {
1376                 exception_level = 0;
1377                 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1378                 kgdb_activate_sw_breakpoints();
1379                 printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
1380                         addr);
1381                 WARN_ON_ONCE(1);
1382
1383                 return 1;
1384         }
1385         remove_all_break();
1386         kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1387
1388         if (exception_level > 1) {
1389                 dump_stack();
1390                 panic("Recursive entry to debugger");
1391         }
1392
1393         printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
1394         dump_stack();
1395         panic("Recursive entry to debugger");
1396
1397         return 1;
1398 }
1399
1400 /*
1401  * kgdb_handle_exception() - main entry point from a kernel exception
1402  *
1403  * Locking hierarchy:
1404  *      interface locks, if any (begin_session)
1405  *      kgdb lock (kgdb_active)
1406  */
1407 int
1408 kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
1409 {
1410         struct kgdb_state kgdb_var;
1411         struct kgdb_state *ks = &kgdb_var;
1412         unsigned long flags;
1413         int sstep_tries = 100;
1414         int error = 0;
1415         int i, cpu;
1416
1417         ks->cpu                 = raw_smp_processor_id();
1418         ks->ex_vector           = evector;
1419         ks->signo               = signo;
1420         ks->ex_vector           = evector;
1421         ks->err_code            = ecode;
1422         ks->kgdb_usethreadid    = 0;
1423         ks->linux_regs          = regs;
1424
1425         if (kgdb_reenter_check(ks))
1426                 return 0; /* Ouch, double exception ! */
1427
1428 acquirelock:
1429         /*
1430          * Interrupts will be restored by the 'trap return' code, except when
1431          * single stepping.
1432          */
1433         local_irq_save(flags);
1434
1435         cpu = raw_smp_processor_id();
1436
1437         /*
1438          * Acquire the kgdb_active lock:
1439          */
1440         while (atomic_cmpxchg(&kgdb_active, -1, cpu) != -1)
1441                 cpu_relax();
1442
1443         /*
1444          * For single stepping, try to only enter on the processor
1445          * that was single stepping.  To gaurd against a deadlock, the
1446          * kernel will only try for the value of sstep_tries before
1447          * giving up and continuing on.
1448          */
1449         if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
1450             (kgdb_info[cpu].task &&
1451              kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
1452                 atomic_set(&kgdb_active, -1);
1453                 touch_softlockup_watchdog();
1454                 clocksource_touch_watchdog();
1455                 local_irq_restore(flags);
1456
1457                 goto acquirelock;
1458         }
1459
1460         if (!kgdb_io_ready(1)) {
1461                 error = 1;
1462                 goto kgdb_restore; /* No I/O connection, so resume the system */
1463         }
1464
1465         /*
1466          * Don't enter if we have hit a removed breakpoint.
1467          */
1468         if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
1469                 goto kgdb_restore;
1470
1471         /* Call the I/O driver's pre_exception routine */
1472         if (kgdb_io_ops->pre_exception)
1473                 kgdb_io_ops->pre_exception();
1474
1475         kgdb_info[ks->cpu].debuggerinfo = ks->linux_regs;
1476         kgdb_info[ks->cpu].task = current;
1477
1478         kgdb_disable_hw_debug(ks->linux_regs);
1479
1480         /*
1481          * Get the passive CPU lock which will hold all the non-primary
1482          * CPU in a spin state while the debugger is active
1483          */
1484         if (!kgdb_single_step) {
1485                 for (i = 0; i < NR_CPUS; i++)
1486                         atomic_set(&passive_cpu_wait[i], 1);
1487         }
1488
1489         /*
1490          * spin_lock code is good enough as a barrier so we don't
1491          * need one here:
1492          */
1493         atomic_set(&cpu_in_kgdb[ks->cpu], 1);
1494
1495 #ifdef CONFIG_SMP
1496         /* Signal the other CPUs to enter kgdb_wait() */
1497         if ((!kgdb_single_step) && kgdb_do_roundup)
1498                 kgdb_roundup_cpus(flags);
1499 #endif
1500
1501         /*
1502          * Wait for the other CPUs to be notified and be waiting for us:
1503          */
1504         for_each_online_cpu(i) {
1505                 while (!atomic_read(&cpu_in_kgdb[i]))
1506                         cpu_relax();
1507         }
1508
1509         /*
1510          * At this point the primary processor is completely
1511          * in the debugger and all secondary CPUs are quiescent
1512          */
1513         kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code);
1514         kgdb_deactivate_sw_breakpoints();
1515         kgdb_single_step = 0;
1516         kgdb_contthread = current;
1517         exception_level = 0;
1518
1519         /* Talk to debugger with gdbserial protocol */
1520         error = gdb_serial_stub(ks);
1521
1522         /* Call the I/O driver's post_exception routine */
1523         if (kgdb_io_ops->post_exception)
1524                 kgdb_io_ops->post_exception();
1525
1526         kgdb_info[ks->cpu].debuggerinfo = NULL;
1527         kgdb_info[ks->cpu].task = NULL;
1528         atomic_set(&cpu_in_kgdb[ks->cpu], 0);
1529
1530         if (!kgdb_single_step) {
1531                 for (i = NR_CPUS-1; i >= 0; i--)
1532                         atomic_set(&passive_cpu_wait[i], 0);
1533                 /*
1534                  * Wait till all the CPUs have quit
1535                  * from the debugger.
1536                  */
1537                 for_each_online_cpu(i) {
1538                         while (atomic_read(&cpu_in_kgdb[i]))
1539                                 cpu_relax();
1540                 }
1541         }
1542
1543 kgdb_restore:
1544         if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
1545                 int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step);
1546                 if (kgdb_info[sstep_cpu].task)
1547                         kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid;
1548                 else
1549                         kgdb_sstep_pid = 0;
1550         }
1551         /* Free kgdb_active */
1552         atomic_set(&kgdb_active, -1);
1553         touch_softlockup_watchdog();
1554         clocksource_touch_watchdog();
1555         local_irq_restore(flags);
1556
1557         return error;
1558 }
1559
1560 int kgdb_nmicallback(int cpu, void *regs)
1561 {
1562 #ifdef CONFIG_SMP
1563         if (!atomic_read(&cpu_in_kgdb[cpu]) &&
1564                         atomic_read(&kgdb_active) != cpu &&
1565                         atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)])) {
1566                 kgdb_wait((struct pt_regs *)regs);
1567                 return 0;
1568         }
1569 #endif
1570         return 1;
1571 }
1572
1573 static void kgdb_console_write(struct console *co, const char *s,
1574    unsigned count)
1575 {
1576         unsigned long flags;
1577
1578         /* If we're debugging, or KGDB has not connected, don't try
1579          * and print. */
1580         if (!kgdb_connected || atomic_read(&kgdb_active) != -1)
1581                 return;
1582
1583         local_irq_save(flags);
1584         kgdb_msg_write(s, count);
1585         local_irq_restore(flags);
1586 }
1587
1588 static struct console kgdbcons = {
1589         .name           = "kgdb",
1590         .write          = kgdb_console_write,
1591         .flags          = CON_PRINTBUFFER | CON_ENABLED,
1592         .index          = -1,
1593 };
1594
1595 #ifdef CONFIG_MAGIC_SYSRQ
1596 static void sysrq_handle_gdb(int key, struct tty_struct *tty)
1597 {
1598         if (!kgdb_io_ops) {
1599                 printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
1600                 return;
1601         }
1602         if (!kgdb_connected)
1603                 printk(KERN_CRIT "Entering KGDB\n");
1604
1605         kgdb_breakpoint();
1606 }
1607
1608 static struct sysrq_key_op sysrq_gdb_op = {
1609         .handler        = sysrq_handle_gdb,
1610         .help_msg       = "debug(G)",
1611         .action_msg     = "DEBUG",
1612 };
1613 #endif
1614
1615 static void kgdb_register_callbacks(void)
1616 {
1617         if (!kgdb_io_module_registered) {
1618                 kgdb_io_module_registered = 1;
1619                 kgdb_arch_init();
1620 #ifdef CONFIG_MAGIC_SYSRQ
1621                 register_sysrq_key('g', &sysrq_gdb_op);
1622 #endif
1623                 if (kgdb_use_con && !kgdb_con_registered) {
1624                         register_console(&kgdbcons);
1625                         kgdb_con_registered = 1;
1626                 }
1627         }
1628 }
1629
1630 static void kgdb_unregister_callbacks(void)
1631 {
1632         /*
1633          * When this routine is called KGDB should unregister from the
1634          * panic handler and clean up, making sure it is not handling any
1635          * break exceptions at the time.
1636          */
1637         if (kgdb_io_module_registered) {
1638                 kgdb_io_module_registered = 0;
1639                 kgdb_arch_exit();
1640 #ifdef CONFIG_MAGIC_SYSRQ
1641                 unregister_sysrq_key('g', &sysrq_gdb_op);
1642 #endif
1643                 if (kgdb_con_registered) {
1644                         unregister_console(&kgdbcons);
1645                         kgdb_con_registered = 0;
1646                 }
1647         }
1648 }
1649
1650 static void kgdb_initial_breakpoint(void)
1651 {
1652         kgdb_break_asap = 0;
1653
1654         printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
1655         kgdb_breakpoint();
1656 }
1657
1658 /**
1659  *      kgdb_register_io_module - register KGDB IO module
1660  *      @new_kgdb_io_ops: the io ops vector
1661  *
1662  *      Register it with the KGDB core.
1663  */
1664 int kgdb_register_io_module(struct kgdb_io *new_kgdb_io_ops)
1665 {
1666         int err;
1667
1668         spin_lock(&kgdb_registration_lock);
1669
1670         if (kgdb_io_ops) {
1671                 spin_unlock(&kgdb_registration_lock);
1672
1673                 printk(KERN_ERR "kgdb: Another I/O driver is already "
1674                                 "registered with KGDB.\n");
1675                 return -EBUSY;
1676         }
1677
1678         if (new_kgdb_io_ops->init) {
1679                 err = new_kgdb_io_ops->init();
1680                 if (err) {
1681                         spin_unlock(&kgdb_registration_lock);
1682                         return err;
1683                 }
1684         }
1685
1686         kgdb_io_ops = new_kgdb_io_ops;
1687
1688         spin_unlock(&kgdb_registration_lock);
1689
1690         printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
1691                new_kgdb_io_ops->name);
1692
1693         /* Arm KGDB now. */
1694         kgdb_register_callbacks();
1695
1696         if (kgdb_break_asap)
1697                 kgdb_initial_breakpoint();
1698
1699         return 0;
1700 }
1701 EXPORT_SYMBOL_GPL(kgdb_register_io_module);
1702
1703 /**
1704  *      kkgdb_unregister_io_module - unregister KGDB IO module
1705  *      @old_kgdb_io_ops: the io ops vector
1706  *
1707  *      Unregister it with the KGDB core.
1708  */
1709 void kgdb_unregister_io_module(struct kgdb_io *old_kgdb_io_ops)
1710 {
1711         BUG_ON(kgdb_connected);
1712
1713         /*
1714          * KGDB is no longer able to communicate out, so
1715          * unregister our callbacks and reset state.
1716          */
1717         kgdb_unregister_callbacks();
1718
1719         spin_lock(&kgdb_registration_lock);
1720
1721         WARN_ON_ONCE(kgdb_io_ops != old_kgdb_io_ops);
1722         kgdb_io_ops = NULL;
1723
1724         spin_unlock(&kgdb_registration_lock);
1725
1726         printk(KERN_INFO
1727                 "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
1728                 old_kgdb_io_ops->name);
1729 }
1730 EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
1731
1732 /**
1733  * kgdb_breakpoint - generate breakpoint exception
1734  *
1735  * This function will generate a breakpoint exception.  It is used at the
1736  * beginning of a program to sync up with a debugger and can be used
1737  * otherwise as a quick means to stop program execution and "break" into
1738  * the debugger.
1739  */
1740 void kgdb_breakpoint(void)
1741 {
1742         atomic_set(&kgdb_setting_breakpoint, 1);
1743         wmb(); /* Sync point before breakpoint */
1744         arch_kgdb_breakpoint();
1745         wmb(); /* Sync point after breakpoint */
1746         atomic_set(&kgdb_setting_breakpoint, 0);
1747 }
1748 EXPORT_SYMBOL_GPL(kgdb_breakpoint);
1749
1750 static int __init opt_kgdb_wait(char *str)
1751 {
1752         kgdb_break_asap = 1;
1753
1754         if (kgdb_io_module_registered)
1755                 kgdb_initial_breakpoint();
1756
1757         return 0;
1758 }
1759
1760 early_param("kgdbwait", opt_kgdb_wait);