1 /* 2 * Kernel Debug Core 3 * 4 * Maintainer: Jason Wessel <jason.wessel@windriver.com> 5 * 6 * Copyright (C) 2000-2001 VERITAS Software Corporation. 7 * Copyright (C) 2002-2004 Timesys Corporation 8 * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com> 9 * Copyright (C) 2004 Pavel Machek <pavel@ucw.cz> 10 * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org> 11 * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd. 12 * Copyright (C) 2005-2009 Wind River Systems, Inc. 13 * Copyright (C) 2007 MontaVista Software, Inc. 14 * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> 15 * 16 * Contributors at various stages not listed above: 17 * Jason Wessel ( jason.wessel@windriver.com ) 18 * George Anzinger <george@mvista.com> 19 * Anurekh Saxena (anurekh.saxena@timesys.com) 20 * Lake Stevens Instrument Division (Glenn Engel) 21 * Jim Kingdon, Cygnus Support. 22 * 23 * Original KGDB stub: David Grothe <dave@gcom.com>, 24 * Tigran Aivazian <tigran@sco.com> 25 * 26 * This file is licensed under the terms of the GNU General Public License 27 * version 2. This program is licensed "as is" without any warranty of any 28 * kind, whether express or implied. 29 */ 30 #include <linux/pid_namespace.h> 31 #include <linux/clocksource.h> 32 #include <linux/serial_core.h> 33 #include <linux/interrupt.h> 34 #include <linux/spinlock.h> 35 #include <linux/console.h> 36 #include <linux/threads.h> 37 #include <linux/uaccess.h> 38 #include <linux/kernel.h> 39 #include <linux/module.h> 40 #include <linux/ptrace.h> 41 #include <linux/string.h> 42 #include <linux/delay.h> 43 #include <linux/sched.h> 44 #include <linux/sysrq.h> 45 #include <linux/reboot.h> 46 #include <linux/init.h> 47 #include <linux/kgdb.h> 48 #include <linux/kdb.h> 49 #include <linux/pid.h> 50 #include <linux/smp.h> 51 #include <linux/mm.h> 52 #include <linux/rcupdate.h> 53 54 #include <asm/cacheflush.h> 55 #include <asm/byteorder.h> 56 #include <linux/atomic.h> 57 58 #include "debug_core.h" 59 60 static int kgdb_break_asap; 61 62 struct debuggerinfo_struct kgdb_info[NR_CPUS]; 63 64 /** 65 * kgdb_connected - Is a host GDB connected to us? 66 */ 67 int kgdb_connected; 68 EXPORT_SYMBOL_GPL(kgdb_connected); 69 70 /* All the KGDB handlers are installed */ 71 int kgdb_io_module_registered; 72 73 /* Guard for recursive entry */ 74 static int exception_level; 75 76 struct kgdb_io *dbg_io_ops; 77 static DEFINE_SPINLOCK(kgdb_registration_lock); 78 79 /* Action for the reboot notifiter, a global allow kdb to change it */ 80 static int kgdbreboot; 81 /* kgdb console driver is loaded */ 82 static int kgdb_con_registered; 83 /* determine if kgdb console output should be used */ 84 static int kgdb_use_con; 85 /* Flag for alternate operations for early debugging */ 86 bool dbg_is_early = true; 87 /* Next cpu to become the master debug core */ 88 int dbg_switch_cpu; 89 90 /* Use kdb or gdbserver mode */ 91 int dbg_kdb_mode = 1; 92 93 static int __init opt_kgdb_con(char *str) 94 { 95 kgdb_use_con = 1; 96 return 0; 97 } 98 99 early_param("kgdbcon", opt_kgdb_con); 100 101 module_param(kgdb_use_con, int, 0644); 102 module_param(kgdbreboot, int, 0644); 103 104 /* 105 * Holds information about breakpoints in a kernel. These breakpoints are 106 * added and removed by gdb. 107 */ 108 static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = { 109 [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED } 110 }; 111 112 /* 113 * The CPU# of the active CPU, or -1 if none: 114 */ 115 atomic_t kgdb_active = ATOMIC_INIT(-1); 116 EXPORT_SYMBOL_GPL(kgdb_active); 117 static DEFINE_RAW_SPINLOCK(dbg_master_lock); 118 static DEFINE_RAW_SPINLOCK(dbg_slave_lock); 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 masters_in_kgdb; 125 static atomic_t slaves_in_kgdb; 126 static atomic_t kgdb_break_tasklet_var; 127 atomic_t kgdb_setting_breakpoint; 128 129 struct task_struct *kgdb_usethread; 130 struct task_struct *kgdb_contthread; 131 132 int kgdb_single_step; 133 static pid_t kgdb_sstep_pid; 134 135 /* to keep track of the CPU which is doing the single stepping*/ 136 atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1); 137 138 /* 139 * If you are debugging a problem where roundup (the collection of 140 * all other CPUs) is a problem [this should be extremely rare], 141 * then use the nokgdbroundup option to avoid roundup. In that case 142 * the other CPUs might interfere with your debugging context, so 143 * use this with care: 144 */ 145 static int kgdb_do_roundup = 1; 146 147 static int __init opt_nokgdbroundup(char *str) 148 { 149 kgdb_do_roundup = 0; 150 151 return 0; 152 } 153 154 early_param("nokgdbroundup", opt_nokgdbroundup); 155 156 /* 157 * Finally, some KGDB code :-) 158 */ 159 160 /* 161 * Weak aliases for breakpoint management, 162 * can be overriden by architectures when needed: 163 */ 164 int __weak kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) 165 { 166 int err; 167 168 err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr, 169 BREAK_INSTR_SIZE); 170 if (err) 171 return err; 172 err = probe_kernel_write((char *)bpt->bpt_addr, 173 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE); 174 return err; 175 } 176 177 int __weak kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) 178 { 179 return probe_kernel_write((char *)bpt->bpt_addr, 180 (char *)bpt->saved_instr, BREAK_INSTR_SIZE); 181 } 182 183 int __weak kgdb_validate_break_address(unsigned long addr) 184 { 185 struct kgdb_bkpt tmp; 186 int err; 187 /* Validate setting the breakpoint and then removing it. If the 188 * remove fails, the kernel needs to emit a bad message because we 189 * are deep trouble not being able to put things back the way we 190 * found them. 191 */ 192 tmp.bpt_addr = addr; 193 err = kgdb_arch_set_breakpoint(&tmp); 194 if (err) 195 return err; 196 err = kgdb_arch_remove_breakpoint(&tmp); 197 if (err) 198 printk(KERN_ERR "KGDB: Critical breakpoint error, kernel " 199 "memory destroyed at: %lx", addr); 200 return err; 201 } 202 203 unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs) 204 { 205 return instruction_pointer(regs); 206 } 207 208 int __weak kgdb_arch_init(void) 209 { 210 return 0; 211 } 212 213 int __weak kgdb_skipexception(int exception, struct pt_regs *regs) 214 { 215 return 0; 216 } 217 218 /* 219 * Some architectures need cache flushes when we set/clear a 220 * breakpoint: 221 */ 222 static void kgdb_flush_swbreak_addr(unsigned long addr) 223 { 224 if (!CACHE_FLUSH_IS_SAFE) 225 return; 226 227 if (current->mm && current->mm->mmap_cache) { 228 flush_cache_range(current->mm->mmap_cache, 229 addr, addr + BREAK_INSTR_SIZE); 230 } 231 /* Force flush instruction cache if it was outside the mm */ 232 flush_icache_range(addr, addr + BREAK_INSTR_SIZE); 233 } 234 235 /* 236 * SW breakpoint management: 237 */ 238 int dbg_activate_sw_breakpoints(void) 239 { 240 int error; 241 int ret = 0; 242 int i; 243 244 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { 245 if (kgdb_break[i].state != BP_SET) 246 continue; 247 248 error = kgdb_arch_set_breakpoint(&kgdb_break[i]); 249 if (error) { 250 ret = error; 251 printk(KERN_INFO "KGDB: BP install failed: %lx", 252 kgdb_break[i].bpt_addr); 253 continue; 254 } 255 256 kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr); 257 kgdb_break[i].state = BP_ACTIVE; 258 } 259 return ret; 260 } 261 262 int dbg_set_sw_break(unsigned long addr) 263 { 264 int err = kgdb_validate_break_address(addr); 265 int breakno = -1; 266 int i; 267 268 if (err) 269 return err; 270 271 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { 272 if ((kgdb_break[i].state == BP_SET) && 273 (kgdb_break[i].bpt_addr == addr)) 274 return -EEXIST; 275 } 276 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { 277 if (kgdb_break[i].state == BP_REMOVED && 278 kgdb_break[i].bpt_addr == addr) { 279 breakno = i; 280 break; 281 } 282 } 283 284 if (breakno == -1) { 285 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { 286 if (kgdb_break[i].state == BP_UNDEFINED) { 287 breakno = i; 288 break; 289 } 290 } 291 } 292 293 if (breakno == -1) 294 return -E2BIG; 295 296 kgdb_break[breakno].state = BP_SET; 297 kgdb_break[breakno].type = BP_BREAKPOINT; 298 kgdb_break[breakno].bpt_addr = addr; 299 300 return 0; 301 } 302 303 int dbg_deactivate_sw_breakpoints(void) 304 { 305 int error; 306 int ret = 0; 307 int i; 308 309 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { 310 if (kgdb_break[i].state != BP_ACTIVE) 311 continue; 312 error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); 313 if (error) { 314 printk(KERN_INFO "KGDB: BP remove failed: %lx\n", 315 kgdb_break[i].bpt_addr); 316 ret = error; 317 } 318 319 kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr); 320 kgdb_break[i].state = BP_SET; 321 } 322 return ret; 323 } 324 325 int dbg_remove_sw_break(unsigned long addr) 326 { 327 int i; 328 329 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { 330 if ((kgdb_break[i].state == BP_SET) && 331 (kgdb_break[i].bpt_addr == addr)) { 332 kgdb_break[i].state = BP_REMOVED; 333 return 0; 334 } 335 } 336 return -ENOENT; 337 } 338 339 int kgdb_isremovedbreak(unsigned long addr) 340 { 341 int i; 342 343 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { 344 if ((kgdb_break[i].state == BP_REMOVED) && 345 (kgdb_break[i].bpt_addr == addr)) 346 return 1; 347 } 348 return 0; 349 } 350 351 int dbg_remove_all_break(void) 352 { 353 int error; 354 int i; 355 356 /* Clear memory breakpoints. */ 357 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { 358 if (kgdb_break[i].state != BP_ACTIVE) 359 goto setundefined; 360 error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); 361 if (error) 362 printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n", 363 kgdb_break[i].bpt_addr); 364 setundefined: 365 kgdb_break[i].state = BP_UNDEFINED; 366 } 367 368 /* Clear hardware breakpoints. */ 369 if (arch_kgdb_ops.remove_all_hw_break) 370 arch_kgdb_ops.remove_all_hw_break(); 371 372 return 0; 373 } 374 375 /* 376 * Return true if there is a valid kgdb I/O module. Also if no 377 * debugger is attached a message can be printed to the console about 378 * waiting for the debugger to attach. 379 * 380 * The print_wait argument is only to be true when called from inside 381 * the core kgdb_handle_exception, because it will wait for the 382 * debugger to attach. 383 */ 384 static int kgdb_io_ready(int print_wait) 385 { 386 if (!dbg_io_ops) 387 return 0; 388 if (kgdb_connected) 389 return 1; 390 if (atomic_read(&kgdb_setting_breakpoint)) 391 return 1; 392 if (print_wait) { 393 #ifdef CONFIG_KGDB_KDB 394 if (!dbg_kdb_mode) 395 printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n"); 396 #else 397 printk(KERN_CRIT "KGDB: Waiting for remote debugger\n"); 398 #endif 399 } 400 return 1; 401 } 402 403 static int kgdb_reenter_check(struct kgdb_state *ks) 404 { 405 unsigned long addr; 406 407 if (atomic_read(&kgdb_active) != raw_smp_processor_id()) 408 return 0; 409 410 /* Panic on recursive debugger calls: */ 411 exception_level++; 412 addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); 413 dbg_deactivate_sw_breakpoints(); 414 415 /* 416 * If the break point removed ok at the place exception 417 * occurred, try to recover and print a warning to the end 418 * user because the user planted a breakpoint in a place that 419 * KGDB needs in order to function. 420 */ 421 if (dbg_remove_sw_break(addr) == 0) { 422 exception_level = 0; 423 kgdb_skipexception(ks->ex_vector, ks->linux_regs); 424 dbg_activate_sw_breakpoints(); 425 printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n", 426 addr); 427 WARN_ON_ONCE(1); 428 429 return 1; 430 } 431 dbg_remove_all_break(); 432 kgdb_skipexception(ks->ex_vector, ks->linux_regs); 433 434 if (exception_level > 1) { 435 dump_stack(); 436 panic("Recursive entry to debugger"); 437 } 438 439 printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n"); 440 #ifdef CONFIG_KGDB_KDB 441 /* Allow kdb to debug itself one level */ 442 return 0; 443 #endif 444 dump_stack(); 445 panic("Recursive entry to debugger"); 446 447 return 1; 448 } 449 450 static void dbg_touch_watchdogs(void) 451 { 452 touch_softlockup_watchdog_sync(); 453 clocksource_touch_watchdog(); 454 rcu_cpu_stall_reset(); 455 } 456 457 static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, 458 int exception_state) 459 { 460 unsigned long flags; 461 int sstep_tries = 100; 462 int error; 463 int cpu; 464 int trace_on = 0; 465 int online_cpus = num_online_cpus(); 466 467 kgdb_info[ks->cpu].enter_kgdb++; 468 kgdb_info[ks->cpu].exception_state |= exception_state; 469 470 if (exception_state == DCPU_WANT_MASTER) 471 atomic_inc(&masters_in_kgdb); 472 else 473 atomic_inc(&slaves_in_kgdb); 474 475 if (arch_kgdb_ops.disable_hw_break) 476 arch_kgdb_ops.disable_hw_break(regs); 477 478 acquirelock: 479 /* 480 * Interrupts will be restored by the 'trap return' code, except when 481 * single stepping. 482 */ 483 local_irq_save(flags); 484 485 cpu = ks->cpu; 486 kgdb_info[cpu].debuggerinfo = regs; 487 kgdb_info[cpu].task = current; 488 kgdb_info[cpu].ret_state = 0; 489 kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT; 490 491 /* Make sure the above info reaches the primary CPU */ 492 smp_mb(); 493 494 if (exception_level == 1) { 495 if (raw_spin_trylock(&dbg_master_lock)) 496 atomic_xchg(&kgdb_active, cpu); 497 goto cpu_master_loop; 498 } 499 500 /* 501 * CPU will loop if it is a slave or request to become a kgdb 502 * master cpu and acquire the kgdb_active lock: 503 */ 504 while (1) { 505 cpu_loop: 506 if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) { 507 kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER; 508 goto cpu_master_loop; 509 } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) { 510 if (raw_spin_trylock(&dbg_master_lock)) { 511 atomic_xchg(&kgdb_active, cpu); 512 break; 513 } 514 } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { 515 if (!raw_spin_is_locked(&dbg_slave_lock)) 516 goto return_normal; 517 } else { 518 return_normal: 519 /* Return to normal operation by executing any 520 * hw breakpoint fixup. 521 */ 522 if (arch_kgdb_ops.correct_hw_break) 523 arch_kgdb_ops.correct_hw_break(); 524 if (trace_on) 525 tracing_on(); 526 kgdb_info[cpu].exception_state &= 527 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); 528 kgdb_info[cpu].enter_kgdb--; 529 smp_mb__before_atomic_dec(); 530 atomic_dec(&slaves_in_kgdb); 531 dbg_touch_watchdogs(); 532 local_irq_restore(flags); 533 return 0; 534 } 535 cpu_relax(); 536 } 537 538 /* 539 * For single stepping, try to only enter on the processor 540 * that was single stepping. To guard against a deadlock, the 541 * kernel will only try for the value of sstep_tries before 542 * giving up and continuing on. 543 */ 544 if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && 545 (kgdb_info[cpu].task && 546 kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) { 547 atomic_set(&kgdb_active, -1); 548 raw_spin_unlock(&dbg_master_lock); 549 dbg_touch_watchdogs(); 550 local_irq_restore(flags); 551 552 goto acquirelock; 553 } 554 555 if (!kgdb_io_ready(1)) { 556 kgdb_info[cpu].ret_state = 1; 557 goto kgdb_restore; /* No I/O connection, resume the system */ 558 } 559 560 /* 561 * Don't enter if we have hit a removed breakpoint. 562 */ 563 if (kgdb_skipexception(ks->ex_vector, ks->linux_regs)) 564 goto kgdb_restore; 565 566 /* Call the I/O driver's pre_exception routine */ 567 if (dbg_io_ops->pre_exception) 568 dbg_io_ops->pre_exception(); 569 570 /* 571 * Get the passive CPU lock which will hold all the non-primary 572 * CPU in a spin state while the debugger is active 573 */ 574 if (!kgdb_single_step) 575 raw_spin_lock(&dbg_slave_lock); 576 577 #ifdef CONFIG_SMP 578 /* If send_ready set, slaves are already waiting */ 579 if (ks->send_ready) 580 atomic_set(ks->send_ready, 1); 581 582 /* Signal the other CPUs to enter kgdb_wait() */ 583 else if ((!kgdb_single_step) && kgdb_do_roundup) 584 kgdb_roundup_cpus(flags); 585 #endif 586 587 /* 588 * Wait for the other CPUs to be notified and be waiting for us: 589 */ 590 while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) + 591 atomic_read(&slaves_in_kgdb)) != online_cpus) 592 cpu_relax(); 593 594 /* 595 * At this point the primary processor is completely 596 * in the debugger and all secondary CPUs are quiescent 597 */ 598 dbg_deactivate_sw_breakpoints(); 599 kgdb_single_step = 0; 600 kgdb_contthread = current; 601 exception_level = 0; 602 trace_on = tracing_is_on(); 603 if (trace_on) 604 tracing_off(); 605 606 while (1) { 607 cpu_master_loop: 608 if (dbg_kdb_mode) { 609 kgdb_connected = 1; 610 error = kdb_stub(ks); 611 if (error == -1) 612 continue; 613 kgdb_connected = 0; 614 } else { 615 error = gdb_serial_stub(ks); 616 } 617 618 if (error == DBG_PASS_EVENT) { 619 dbg_kdb_mode = !dbg_kdb_mode; 620 } else if (error == DBG_SWITCH_CPU_EVENT) { 621 kgdb_info[dbg_switch_cpu].exception_state |= 622 DCPU_NEXT_MASTER; 623 goto cpu_loop; 624 } else { 625 kgdb_info[cpu].ret_state = error; 626 break; 627 } 628 } 629 630 /* Call the I/O driver's post_exception routine */ 631 if (dbg_io_ops->post_exception) 632 dbg_io_ops->post_exception(); 633 634 if (!kgdb_single_step) { 635 raw_spin_unlock(&dbg_slave_lock); 636 /* Wait till all the CPUs have quit from the debugger. */ 637 while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb)) 638 cpu_relax(); 639 } 640 641 kgdb_restore: 642 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { 643 int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step); 644 if (kgdb_info[sstep_cpu].task) 645 kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid; 646 else 647 kgdb_sstep_pid = 0; 648 } 649 if (arch_kgdb_ops.correct_hw_break) 650 arch_kgdb_ops.correct_hw_break(); 651 if (trace_on) 652 tracing_on(); 653 654 kgdb_info[cpu].exception_state &= 655 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); 656 kgdb_info[cpu].enter_kgdb--; 657 smp_mb__before_atomic_dec(); 658 atomic_dec(&masters_in_kgdb); 659 /* Free kgdb_active */ 660 atomic_set(&kgdb_active, -1); 661 raw_spin_unlock(&dbg_master_lock); 662 dbg_touch_watchdogs(); 663 local_irq_restore(flags); 664 665 return kgdb_info[cpu].ret_state; 666 } 667 668 /* 669 * kgdb_handle_exception() - main entry point from a kernel exception 670 * 671 * Locking hierarchy: 672 * interface locks, if any (begin_session) 673 * kgdb lock (kgdb_active) 674 */ 675 int 676 kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) 677 { 678 struct kgdb_state kgdb_var; 679 struct kgdb_state *ks = &kgdb_var; 680 int ret = 0; 681 682 if (arch_kgdb_ops.enable_nmi) 683 arch_kgdb_ops.enable_nmi(0); 684 685 memset(ks, 0, sizeof(struct kgdb_state)); 686 ks->cpu = raw_smp_processor_id(); 687 ks->ex_vector = evector; 688 ks->signo = signo; 689 ks->err_code = ecode; 690 ks->linux_regs = regs; 691 692 if (kgdb_reenter_check(ks)) 693 goto out; /* Ouch, double exception ! */ 694 if (kgdb_info[ks->cpu].enter_kgdb != 0) 695 goto out; 696 697 ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); 698 out: 699 if (arch_kgdb_ops.enable_nmi) 700 arch_kgdb_ops.enable_nmi(1); 701 return ret; 702 } 703 704 /* 705 * GDB places a breakpoint at this function to know dynamically 706 * loaded objects. It's not defined static so that only one instance with this 707 * name exists in the kernel. 708 */ 709 710 static int module_event(struct notifier_block *self, unsigned long val, 711 void *data) 712 { 713 return 0; 714 } 715 716 static struct notifier_block dbg_module_load_nb = { 717 .notifier_call = module_event, 718 }; 719 720 int kgdb_nmicallback(int cpu, void *regs) 721 { 722 #ifdef CONFIG_SMP 723 struct kgdb_state kgdb_var; 724 struct kgdb_state *ks = &kgdb_var; 725 726 memset(ks, 0, sizeof(struct kgdb_state)); 727 ks->cpu = cpu; 728 ks->linux_regs = regs; 729 730 if (kgdb_info[ks->cpu].enter_kgdb == 0 && 731 raw_spin_is_locked(&dbg_master_lock)) { 732 kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE); 733 return 0; 734 } 735 #endif 736 return 1; 737 } 738 739 int kgdb_nmicallin(int cpu, int trapnr, void *regs, int err_code, 740 atomic_t *send_ready) 741 { 742 #ifdef CONFIG_SMP 743 if (!kgdb_io_ready(0) || !send_ready) 744 return 1; 745 746 if (kgdb_info[cpu].enter_kgdb == 0) { 747 struct kgdb_state kgdb_var; 748 struct kgdb_state *ks = &kgdb_var; 749 750 memset(ks, 0, sizeof(struct kgdb_state)); 751 ks->cpu = cpu; 752 ks->ex_vector = trapnr; 753 ks->signo = SIGTRAP; 754 ks->err_code = err_code; 755 ks->linux_regs = regs; 756 ks->send_ready = send_ready; 757 kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); 758 return 0; 759 } 760 #endif 761 return 1; 762 } 763 764 static void kgdb_console_write(struct console *co, const char *s, 765 unsigned count) 766 { 767 unsigned long flags; 768 769 /* If we're debugging, or KGDB has not connected, don't try 770 * and print. */ 771 if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode) 772 return; 773 774 local_irq_save(flags); 775 gdbstub_msg_write(s, count); 776 local_irq_restore(flags); 777 } 778 779 static struct console kgdbcons = { 780 .name = "kgdb", 781 .write = kgdb_console_write, 782 .flags = CON_PRINTBUFFER | CON_ENABLED, 783 .index = -1, 784 }; 785 786 #ifdef CONFIG_MAGIC_SYSRQ 787 static void sysrq_handle_dbg(int key) 788 { 789 if (!dbg_io_ops) { 790 printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); 791 return; 792 } 793 if (!kgdb_connected) { 794 #ifdef CONFIG_KGDB_KDB 795 if (!dbg_kdb_mode) 796 printk(KERN_CRIT "KGDB or $3#33 for KDB\n"); 797 #else 798 printk(KERN_CRIT "Entering KGDB\n"); 799 #endif 800 } 801 802 kgdb_breakpoint(); 803 } 804 805 static struct sysrq_key_op sysrq_dbg_op = { 806 .handler = sysrq_handle_dbg, 807 .help_msg = "debug(g)", 808 .action_msg = "DEBUG", 809 }; 810 #endif 811 812 static int kgdb_panic_event(struct notifier_block *self, 813 unsigned long val, 814 void *data) 815 { 816 if (dbg_kdb_mode) 817 kdb_printf("PANIC: %s\n", (char *)data); 818 kgdb_breakpoint(); 819 return NOTIFY_DONE; 820 } 821 822 static struct notifier_block kgdb_panic_event_nb = { 823 .notifier_call = kgdb_panic_event, 824 .priority = INT_MAX, 825 }; 826 827 void __weak kgdb_arch_late(void) 828 { 829 } 830 831 void __init dbg_late_init(void) 832 { 833 dbg_is_early = false; 834 if (kgdb_io_module_registered) 835 kgdb_arch_late(); 836 kdb_init(KDB_INIT_FULL); 837 } 838 839 static int 840 dbg_notify_reboot(struct notifier_block *this, unsigned long code, void *x) 841 { 842 /* 843 * Take the following action on reboot notify depending on value: 844 * 1 == Enter debugger 845 * 0 == [the default] detatch debug client 846 * -1 == Do nothing... and use this until the board resets 847 */ 848 switch (kgdbreboot) { 849 case 1: 850 kgdb_breakpoint(); 851 case -1: 852 goto done; 853 } 854 if (!dbg_kdb_mode) 855 gdbstub_exit(code); 856 done: 857 return NOTIFY_DONE; 858 } 859 860 static struct notifier_block dbg_reboot_notifier = { 861 .notifier_call = dbg_notify_reboot, 862 .next = NULL, 863 .priority = INT_MAX, 864 }; 865 866 static void kgdb_register_callbacks(void) 867 { 868 if (!kgdb_io_module_registered) { 869 kgdb_io_module_registered = 1; 870 kgdb_arch_init(); 871 if (!dbg_is_early) 872 kgdb_arch_late(); 873 register_module_notifier(&dbg_module_load_nb); 874 register_reboot_notifier(&dbg_reboot_notifier); 875 atomic_notifier_chain_register(&panic_notifier_list, 876 &kgdb_panic_event_nb); 877 #ifdef CONFIG_MAGIC_SYSRQ 878 register_sysrq_key('g', &sysrq_dbg_op); 879 #endif 880 if (kgdb_use_con && !kgdb_con_registered) { 881 register_console(&kgdbcons); 882 kgdb_con_registered = 1; 883 } 884 } 885 } 886 887 static void kgdb_unregister_callbacks(void) 888 { 889 /* 890 * When this routine is called KGDB should unregister from the 891 * panic handler and clean up, making sure it is not handling any 892 * break exceptions at the time. 893 */ 894 if (kgdb_io_module_registered) { 895 kgdb_io_module_registered = 0; 896 unregister_reboot_notifier(&dbg_reboot_notifier); 897 unregister_module_notifier(&dbg_module_load_nb); 898 atomic_notifier_chain_unregister(&panic_notifier_list, 899 &kgdb_panic_event_nb); 900 kgdb_arch_exit(); 901 #ifdef CONFIG_MAGIC_SYSRQ 902 unregister_sysrq_key('g', &sysrq_dbg_op); 903 #endif 904 if (kgdb_con_registered) { 905 unregister_console(&kgdbcons); 906 kgdb_con_registered = 0; 907 } 908 } 909 } 910 911 /* 912 * There are times a tasklet needs to be used vs a compiled in 913 * break point so as to cause an exception outside a kgdb I/O module, 914 * such as is the case with kgdboe, where calling a breakpoint in the 915 * I/O driver itself would be fatal. 916 */ 917 static void kgdb_tasklet_bpt(unsigned long ing) 918 { 919 kgdb_breakpoint(); 920 atomic_set(&kgdb_break_tasklet_var, 0); 921 } 922 923 static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0); 924 925 void kgdb_schedule_breakpoint(void) 926 { 927 if (atomic_read(&kgdb_break_tasklet_var) || 928 atomic_read(&kgdb_active) != -1 || 929 atomic_read(&kgdb_setting_breakpoint)) 930 return; 931 atomic_inc(&kgdb_break_tasklet_var); 932 tasklet_schedule(&kgdb_tasklet_breakpoint); 933 } 934 EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint); 935 936 static void kgdb_initial_breakpoint(void) 937 { 938 kgdb_break_asap = 0; 939 940 printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n"); 941 kgdb_breakpoint(); 942 } 943 944 /** 945 * kgdb_register_io_module - register KGDB IO module 946 * @new_dbg_io_ops: the io ops vector 947 * 948 * Register it with the KGDB core. 949 */ 950 int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) 951 { 952 int err; 953 954 spin_lock(&kgdb_registration_lock); 955 956 if (dbg_io_ops) { 957 spin_unlock(&kgdb_registration_lock); 958 959 printk(KERN_ERR "kgdb: Another I/O driver is already " 960 "registered with KGDB.\n"); 961 return -EBUSY; 962 } 963 964 if (new_dbg_io_ops->init) { 965 err = new_dbg_io_ops->init(); 966 if (err) { 967 spin_unlock(&kgdb_registration_lock); 968 return err; 969 } 970 } 971 972 dbg_io_ops = new_dbg_io_ops; 973 974 spin_unlock(&kgdb_registration_lock); 975 976 printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", 977 new_dbg_io_ops->name); 978 979 /* Arm KGDB now. */ 980 kgdb_register_callbacks(); 981 982 if (kgdb_break_asap) 983 kgdb_initial_breakpoint(); 984 985 return 0; 986 } 987 EXPORT_SYMBOL_GPL(kgdb_register_io_module); 988 989 /** 990 * kkgdb_unregister_io_module - unregister KGDB IO module 991 * @old_dbg_io_ops: the io ops vector 992 * 993 * Unregister it with the KGDB core. 994 */ 995 void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) 996 { 997 BUG_ON(kgdb_connected); 998 999 /* 1000 * KGDB is no longer able to communicate out, so 1001 * unregister our callbacks and reset state. 1002 */ 1003 kgdb_unregister_callbacks(); 1004 1005 spin_lock(&kgdb_registration_lock); 1006 1007 WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops); 1008 dbg_io_ops = NULL; 1009 1010 spin_unlock(&kgdb_registration_lock); 1011 1012 printk(KERN_INFO 1013 "kgdb: Unregistered I/O driver %s, debugger disabled.\n", 1014 old_dbg_io_ops->name); 1015 } 1016 EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); 1017 1018 int dbg_io_get_char(void) 1019 { 1020 int ret = dbg_io_ops->read_char(); 1021 if (ret == NO_POLL_CHAR) 1022 return -1; 1023 if (!dbg_kdb_mode) 1024 return ret; 1025 if (ret == 127) 1026 return 8; 1027 return ret; 1028 } 1029 1030 /** 1031 * kgdb_breakpoint - generate breakpoint exception 1032 * 1033 * This function will generate a breakpoint exception. It is used at the 1034 * beginning of a program to sync up with a debugger and can be used 1035 * otherwise as a quick means to stop program execution and "break" into 1036 * the debugger. 1037 */ 1038 void kgdb_breakpoint(void) 1039 { 1040 atomic_inc(&kgdb_setting_breakpoint); 1041 wmb(); /* Sync point before breakpoint */ 1042 arch_kgdb_breakpoint(); 1043 wmb(); /* Sync point after breakpoint */ 1044 atomic_dec(&kgdb_setting_breakpoint); 1045 } 1046 EXPORT_SYMBOL_GPL(kgdb_breakpoint); 1047 1048 static int __init opt_kgdb_wait(char *str) 1049 { 1050 kgdb_break_asap = 1; 1051 1052 kdb_init(KDB_INIT_EARLY); 1053 if (kgdb_io_module_registered) 1054 kgdb_initial_breakpoint(); 1055 1056 return 0; 1057 } 1058 1059 early_param("kgdbwait", opt_kgdb_wait); 1060