1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2004 The FreeBSD Project 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include "opt_kdb.h" 33 #include "opt_stack.h" 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/cons.h> 38 #include <sys/kdb.h> 39 #include <sys/kernel.h> 40 #include <sys/malloc.h> 41 #include <sys/lock.h> 42 #include <sys/pcpu.h> 43 #include <sys/proc.h> 44 #include <sys/sbuf.h> 45 #include <sys/smp.h> 46 #include <sys/stack.h> 47 #include <sys/sysctl.h> 48 49 #include <machine/kdb.h> 50 #include <machine/pcb.h> 51 52 #ifdef SMP 53 #include <machine/smp.h> 54 #endif 55 56 #include <security/mac/mac_framework.h> 57 58 u_char __read_frequently kdb_active = 0; 59 static void *kdb_jmpbufp = NULL; 60 struct kdb_dbbe *kdb_dbbe = NULL; 61 static struct pcb kdb_pcb; 62 struct pcb *kdb_thrctx = NULL; 63 struct thread *kdb_thread = NULL; 64 struct trapframe *kdb_frame = NULL; 65 66 #ifdef BREAK_TO_DEBUGGER 67 #define KDB_BREAK_TO_DEBUGGER 1 68 #else 69 #define KDB_BREAK_TO_DEBUGGER 0 70 #endif 71 72 #ifdef ALT_BREAK_TO_DEBUGGER 73 #define KDB_ALT_BREAK_TO_DEBUGGER 1 74 #else 75 #define KDB_ALT_BREAK_TO_DEBUGGER 0 76 #endif 77 78 static int kdb_break_to_debugger = KDB_BREAK_TO_DEBUGGER; 79 static int kdb_alt_break_to_debugger = KDB_ALT_BREAK_TO_DEBUGGER; 80 81 KDB_BACKEND(null, NULL, NULL, NULL, NULL); 82 83 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS); 84 static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS); 85 static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS); 86 static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS); 87 static int kdb_sysctl_panic_str(SYSCTL_HANDLER_ARGS); 88 static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS); 89 static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS); 90 static int kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS); 91 92 static SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 93 "KDB nodes"); 94 95 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, 96 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, 97 kdb_sysctl_available, "A", 98 "list of available KDB backends"); 99 100 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, 101 CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0, 102 kdb_sysctl_current, "A", 103 "currently selected KDB backend"); 104 105 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter, 106 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_MPSAFE, NULL, 0, 107 kdb_sysctl_enter, "I", 108 "set to enter the debugger"); 109 110 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic, 111 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_MPSAFE, NULL, 0, 112 kdb_sysctl_panic, "I", 113 "set to panic the kernel"); 114 115 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic_str, 116 CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_MPSAFE, NULL, 0, 117 kdb_sysctl_panic_str, "A", 118 "trigger a kernel panic, using the provided string as the panic message"); 119 120 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap, 121 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_MPSAFE, NULL, 0, 122 kdb_sysctl_trap, "I", 123 "set to cause a page fault via data access"); 124 125 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code, 126 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_MPSAFE, NULL, 0, 127 kdb_sysctl_trap_code, "I", 128 "set to cause a page fault via code access"); 129 130 SYSCTL_PROC(_debug_kdb, OID_AUTO, stack_overflow, 131 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_MPSAFE, NULL, 0, 132 kdb_sysctl_stack_overflow, "I", 133 "set to cause a stack overflow"); 134 135 SYSCTL_INT(_debug_kdb, OID_AUTO, break_to_debugger, 136 CTLFLAG_RWTUN | CTLFLAG_SECURE, 137 &kdb_break_to_debugger, 0, "Enable break to debugger"); 138 139 SYSCTL_INT(_debug_kdb, OID_AUTO, alt_break_to_debugger, 140 CTLFLAG_RWTUN | CTLFLAG_SECURE, 141 &kdb_alt_break_to_debugger, 0, "Enable alternative break to debugger"); 142 143 /* 144 * Flag to indicate to debuggers why the debugger was entered. 145 */ 146 const char * volatile kdb_why = KDB_WHY_UNSET; 147 148 static int 149 kdb_sysctl_available(SYSCTL_HANDLER_ARGS) 150 { 151 struct kdb_dbbe **iter; 152 struct sbuf sbuf; 153 int error; 154 155 sbuf_new_for_sysctl(&sbuf, NULL, 64, req); 156 SET_FOREACH(iter, kdb_dbbe_set) { 157 if ((*iter)->dbbe_active == 0) 158 sbuf_printf(&sbuf, "%s ", (*iter)->dbbe_name); 159 } 160 error = sbuf_finish(&sbuf); 161 sbuf_delete(&sbuf); 162 return (error); 163 } 164 165 static int 166 kdb_sysctl_current(SYSCTL_HANDLER_ARGS) 167 { 168 char buf[16]; 169 int error; 170 171 if (kdb_dbbe != NULL) 172 strlcpy(buf, kdb_dbbe->dbbe_name, sizeof(buf)); 173 else 174 *buf = '\0'; 175 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 176 if (error != 0 || req->newptr == NULL) 177 return (error); 178 if (kdb_active) 179 return (EBUSY); 180 return (kdb_dbbe_select(buf)); 181 } 182 183 static int 184 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS) 185 { 186 int error, i; 187 188 error = sysctl_wire_old_buffer(req, sizeof(int)); 189 if (error == 0) { 190 i = 0; 191 error = sysctl_handle_int(oidp, &i, 0, req); 192 } 193 if (error != 0 || req->newptr == NULL) 194 return (error); 195 if (kdb_active) 196 return (EBUSY); 197 kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter"); 198 return (0); 199 } 200 201 static int 202 kdb_sysctl_panic(SYSCTL_HANDLER_ARGS) 203 { 204 int error, i; 205 206 error = sysctl_wire_old_buffer(req, sizeof(int)); 207 if (error == 0) { 208 i = 0; 209 error = sysctl_handle_int(oidp, &i, 0, req); 210 } 211 if (error != 0 || req->newptr == NULL) 212 return (error); 213 panic("kdb_sysctl_panic"); 214 return (0); 215 } 216 217 static int 218 kdb_sysctl_panic_str(SYSCTL_HANDLER_ARGS) 219 { 220 int error; 221 static char buf[256]; /* static buffer to limit mallocs when panicing */ 222 223 *buf = '\0'; 224 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 225 if (error != 0 || req->newptr == NULL) 226 return (error); 227 panic("kdb_sysctl_panic: %s", buf); 228 return (0); 229 } 230 231 static int 232 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS) 233 { 234 int error, i; 235 int *addr = (int *)0x10; 236 237 error = sysctl_wire_old_buffer(req, sizeof(int)); 238 if (error == 0) { 239 i = 0; 240 error = sysctl_handle_int(oidp, &i, 0, req); 241 } 242 if (error != 0 || req->newptr == NULL) 243 return (error); 244 return (*addr); 245 } 246 247 static int 248 kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS) 249 { 250 int error, i; 251 void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de; 252 253 error = sysctl_wire_old_buffer(req, sizeof(int)); 254 if (error == 0) { 255 i = 0; 256 error = sysctl_handle_int(oidp, &i, 0, req); 257 } 258 if (error != 0 || req->newptr == NULL) 259 return (error); 260 (*fp)(0x11111111, 0x22222222, 0x33333333); 261 return (0); 262 } 263 264 static void kdb_stack_overflow(volatile int *x) __noinline; 265 static void 266 kdb_stack_overflow(volatile int *x) 267 { 268 269 if (*x > 10000000) 270 return; 271 kdb_stack_overflow(x); 272 *x += PCPU_GET(cpuid) / 1000000; 273 } 274 275 static int 276 kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS) 277 { 278 int error, i; 279 volatile int x; 280 281 error = sysctl_wire_old_buffer(req, sizeof(int)); 282 if (error == 0) { 283 i = 0; 284 error = sysctl_handle_int(oidp, &i, 0, req); 285 } 286 if (error != 0 || req->newptr == NULL) 287 return (error); 288 x = 0; 289 kdb_stack_overflow(&x); 290 return (0); 291 } 292 293 void 294 kdb_panic(const char *msg) 295 { 296 297 kdb_why = KDB_WHY_PANIC; 298 printf("KDB: panic\n"); 299 panic("%s", msg); 300 } 301 302 void 303 kdb_reboot(void) 304 { 305 306 kdb_why = KDB_WHY_REBOOT; 307 printf("KDB: reboot requested\n"); 308 shutdown_nice(0); 309 } 310 311 /* 312 * Solaris implements a new BREAK which is initiated by a character sequence 313 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the 314 * Remote Console. 315 * 316 * Note that this function may be called from almost anywhere, with interrupts 317 * disabled and with unknown locks held, so it must not access data other than 318 * its arguments. Its up to the caller to ensure that the state variable is 319 * consistent. 320 */ 321 #define KEY_CR 13 /* CR '\r' */ 322 #define KEY_TILDE 126 /* ~ */ 323 #define KEY_CRTLB 2 /* ^B */ 324 #define KEY_CRTLP 16 /* ^P */ 325 #define KEY_CRTLR 18 /* ^R */ 326 327 /* States of th KDB "alternate break sequence" detecting state machine. */ 328 enum { 329 KDB_ALT_BREAK_SEEN_NONE, 330 KDB_ALT_BREAK_SEEN_CR, 331 KDB_ALT_BREAK_SEEN_CR_TILDE, 332 }; 333 334 int 335 kdb_break(void) 336 { 337 338 if (!kdb_break_to_debugger) 339 return (0); 340 kdb_enter(KDB_WHY_BREAK, "Break to debugger"); 341 return (KDB_REQ_DEBUGGER); 342 } 343 344 static int 345 kdb_alt_break_state(int key, int *state) 346 { 347 int brk; 348 349 /* All states transition to KDB_ALT_BREAK_SEEN_CR on a CR. */ 350 if (key == KEY_CR) { 351 *state = KDB_ALT_BREAK_SEEN_CR; 352 return (0); 353 } 354 355 brk = 0; 356 switch (*state) { 357 case KDB_ALT_BREAK_SEEN_CR: 358 *state = KDB_ALT_BREAK_SEEN_NONE; 359 if (key == KEY_TILDE) 360 *state = KDB_ALT_BREAK_SEEN_CR_TILDE; 361 break; 362 case KDB_ALT_BREAK_SEEN_CR_TILDE: 363 *state = KDB_ALT_BREAK_SEEN_NONE; 364 if (key == KEY_CRTLB) 365 brk = KDB_REQ_DEBUGGER; 366 else if (key == KEY_CRTLP) 367 brk = KDB_REQ_PANIC; 368 else if (key == KEY_CRTLR) 369 brk = KDB_REQ_REBOOT; 370 break; 371 case KDB_ALT_BREAK_SEEN_NONE: 372 default: 373 *state = KDB_ALT_BREAK_SEEN_NONE; 374 break; 375 } 376 return (brk); 377 } 378 379 static int 380 kdb_alt_break_internal(int key, int *state, int force_gdb) 381 { 382 int brk; 383 384 if (!kdb_alt_break_to_debugger) 385 return (0); 386 brk = kdb_alt_break_state(key, state); 387 switch (brk) { 388 case KDB_REQ_DEBUGGER: 389 if (force_gdb) 390 kdb_dbbe_select("gdb"); 391 kdb_enter(KDB_WHY_BREAK, "Break to debugger"); 392 break; 393 394 case KDB_REQ_PANIC: 395 if (force_gdb) 396 kdb_dbbe_select("gdb"); 397 kdb_panic("Panic sequence on console"); 398 break; 399 400 case KDB_REQ_REBOOT: 401 kdb_reboot(); 402 break; 403 } 404 return (0); 405 } 406 407 int 408 kdb_alt_break(int key, int *state) 409 { 410 411 return (kdb_alt_break_internal(key, state, 0)); 412 } 413 414 /* 415 * This variation on kdb_alt_break() is used only by dcons, which has its own 416 * configuration flag to force GDB use regardless of the global KDB 417 * configuration. 418 */ 419 int 420 kdb_alt_break_gdb(int key, int *state) 421 { 422 423 return (kdb_alt_break_internal(key, state, 1)); 424 } 425 426 /* 427 * Print a backtrace of the calling thread. The backtrace is generated by 428 * the selected debugger, provided it supports backtraces. If no debugger 429 * is selected or the current debugger does not support backtraces, this 430 * function silently returns. 431 */ 432 void 433 kdb_backtrace(void) 434 { 435 436 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) { 437 printf("KDB: stack backtrace:\n"); 438 kdb_dbbe->dbbe_trace(); 439 } 440 #ifdef STACK 441 else { 442 struct stack st; 443 444 printf("KDB: stack backtrace:\n"); 445 stack_save(&st); 446 stack_print_ddb(&st); 447 } 448 #endif 449 } 450 451 /* 452 * Similar to kdb_backtrace() except that it prints a backtrace of an 453 * arbitrary thread rather than the calling thread. 454 */ 455 void 456 kdb_backtrace_thread(struct thread *td) 457 { 458 459 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace_thread != NULL) { 460 printf("KDB: stack backtrace of thread %d:\n", td->td_tid); 461 kdb_dbbe->dbbe_trace_thread(td); 462 } 463 #ifdef STACK 464 else { 465 struct stack st; 466 467 printf("KDB: stack backtrace of thread %d:\n", td->td_tid); 468 if (stack_save_td(&st, td) == 0) 469 stack_print_ddb(&st); 470 } 471 #endif 472 } 473 474 /* 475 * Set/change the current backend. 476 */ 477 int 478 kdb_dbbe_select(const char *name) 479 { 480 struct kdb_dbbe *be, **iter; 481 482 SET_FOREACH(iter, kdb_dbbe_set) { 483 be = *iter; 484 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) { 485 kdb_dbbe = be; 486 return (0); 487 } 488 } 489 return (EINVAL); 490 } 491 492 /* 493 * Enter the currently selected debugger. If a message has been provided, 494 * it is printed first. If the debugger does not support the enter method, 495 * it is entered by using breakpoint(), which enters the debugger through 496 * kdb_trap(). The 'why' argument will contain a more mechanically usable 497 * string than 'msg', and is relied upon by DDB scripting to identify the 498 * reason for entering the debugger so that the right script can be run. 499 */ 500 void 501 kdb_enter(const char *why, const char *msg) 502 { 503 504 if (kdb_dbbe != NULL && kdb_active == 0) { 505 kdb_why = why; 506 if (msg != NULL) 507 printf("KDB: enter: %s\n", msg); 508 breakpoint(); 509 kdb_why = KDB_WHY_UNSET; 510 } 511 } 512 513 /* 514 * Initialize the kernel debugger interface. 515 */ 516 void 517 kdb_init(void) 518 { 519 struct kdb_dbbe *be, **iter; 520 int cur_pri, pri; 521 522 kdb_active = 0; 523 kdb_dbbe = NULL; 524 cur_pri = -1; 525 SET_FOREACH(iter, kdb_dbbe_set) { 526 be = *iter; 527 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1; 528 be->dbbe_active = (pri >= 0) ? 0 : -1; 529 if (pri > cur_pri) { 530 cur_pri = pri; 531 kdb_dbbe = be; 532 } 533 } 534 if (kdb_dbbe != NULL) { 535 printf("KDB: debugger backends:"); 536 SET_FOREACH(iter, kdb_dbbe_set) { 537 be = *iter; 538 if (be->dbbe_active == 0) 539 printf(" %s", be->dbbe_name); 540 } 541 printf("\n"); 542 printf("KDB: current backend: %s\n", 543 kdb_dbbe->dbbe_name); 544 } 545 } 546 547 /* 548 * Handle contexts. 549 */ 550 void * 551 kdb_jmpbuf(jmp_buf new) 552 { 553 void *old; 554 555 old = kdb_jmpbufp; 556 kdb_jmpbufp = new; 557 return (old); 558 } 559 560 void 561 kdb_reenter(void) 562 { 563 564 if (!kdb_active || kdb_jmpbufp == NULL) 565 return; 566 567 printf("KDB: reentering\n"); 568 kdb_backtrace(); 569 longjmp(kdb_jmpbufp, 1); 570 /* NOTREACHED */ 571 } 572 573 void 574 kdb_reenter_silent(void) 575 { 576 577 if (!kdb_active || kdb_jmpbufp == NULL) 578 return; 579 580 longjmp(kdb_jmpbufp, 1); 581 /* NOTREACHED */ 582 } 583 584 /* 585 * Thread-related support functions. 586 */ 587 struct pcb * 588 kdb_thr_ctx(struct thread *thr) 589 { 590 #if defined(SMP) && defined(KDB_STOPPEDPCB) 591 struct pcpu *pc; 592 #endif 593 594 if (thr == curthread) 595 return (&kdb_pcb); 596 597 #if defined(SMP) && defined(KDB_STOPPEDPCB) 598 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { 599 if (pc->pc_curthread == thr && 600 CPU_ISSET(pc->pc_cpuid, &stopped_cpus)) 601 return (KDB_STOPPEDPCB(pc)); 602 } 603 #endif 604 return (thr->td_pcb); 605 } 606 607 struct thread * 608 kdb_thr_first(void) 609 { 610 struct proc *p; 611 struct thread *thr; 612 u_int i; 613 614 /* This function may be called early. */ 615 if (pidhashtbl == NULL) 616 return (&thread0); 617 618 for (i = 0; i <= pidhash; i++) { 619 LIST_FOREACH(p, &pidhashtbl[i], p_hash) { 620 thr = FIRST_THREAD_IN_PROC(p); 621 if (thr != NULL) 622 return (thr); 623 } 624 } 625 return (NULL); 626 } 627 628 struct thread * 629 kdb_thr_from_pid(pid_t pid) 630 { 631 struct proc *p; 632 633 LIST_FOREACH(p, PIDHASH(pid), p_hash) { 634 if (p->p_pid == pid) 635 return (FIRST_THREAD_IN_PROC(p)); 636 } 637 return (NULL); 638 } 639 640 struct thread * 641 kdb_thr_lookup(lwpid_t tid) 642 { 643 struct thread *thr; 644 645 thr = kdb_thr_first(); 646 while (thr != NULL && thr->td_tid != tid) 647 thr = kdb_thr_next(thr); 648 return (thr); 649 } 650 651 struct thread * 652 kdb_thr_next(struct thread *thr) 653 { 654 struct proc *p; 655 u_int hash; 656 657 p = thr->td_proc; 658 thr = TAILQ_NEXT(thr, td_plist); 659 if (thr != NULL) 660 return (thr); 661 if (pidhashtbl == NULL) 662 return (NULL); 663 hash = p->p_pid & pidhash; 664 for (;;) { 665 p = LIST_NEXT(p, p_hash); 666 while (p == NULL) { 667 if (++hash > pidhash) 668 return (NULL); 669 p = LIST_FIRST(&pidhashtbl[hash]); 670 } 671 thr = FIRST_THREAD_IN_PROC(p); 672 if (thr != NULL) 673 return (thr); 674 } 675 } 676 677 int 678 kdb_thr_select(struct thread *thr) 679 { 680 if (thr == NULL) 681 return (EINVAL); 682 kdb_thread = thr; 683 kdb_thrctx = kdb_thr_ctx(thr); 684 return (0); 685 } 686 687 /* 688 * Enter the debugger due to a trap. 689 */ 690 int 691 kdb_trap(int type, int code, struct trapframe *tf) 692 { 693 #ifdef SMP 694 cpuset_t other_cpus; 695 #endif 696 struct kdb_dbbe *be; 697 register_t intr; 698 int handled; 699 int did_stop_cpus; 700 701 be = kdb_dbbe; 702 if (be == NULL || be->dbbe_trap == NULL) 703 return (0); 704 705 /* We reenter the debugger through kdb_reenter(). */ 706 if (kdb_active) 707 return (0); 708 709 intr = intr_disable(); 710 711 if (!SCHEDULER_STOPPED()) { 712 #ifdef SMP 713 other_cpus = all_cpus; 714 CPU_ANDNOT(&other_cpus, &other_cpus, &stopped_cpus); 715 CPU_CLR(PCPU_GET(cpuid), &other_cpus); 716 stop_cpus_hard(other_cpus); 717 #endif 718 curthread->td_stopsched = 1; 719 did_stop_cpus = 1; 720 } else 721 did_stop_cpus = 0; 722 723 kdb_active++; 724 725 kdb_frame = tf; 726 727 /* Let MD code do its thing first... */ 728 kdb_cpu_trap(type, code); 729 730 makectx(tf, &kdb_pcb); 731 kdb_thr_select(curthread); 732 733 cngrab(); 734 735 for (;;) { 736 #ifdef MAC 737 if (mac_kdb_check_backend(be) != 0) { 738 printf("MAC prevented execution of KDB backend: %s\n", 739 be->dbbe_name); 740 /* Unhandled breakpoint traps are fatal. */ 741 handled = 1; 742 break; 743 } 744 #endif 745 handled = be->dbbe_trap(type, code); 746 if (be == kdb_dbbe) 747 break; 748 be = kdb_dbbe; 749 if (be == NULL || be->dbbe_trap == NULL) 750 break; 751 printf("Switching to %s back-end\n", be->dbbe_name); 752 } 753 754 cnungrab(); 755 756 kdb_active--; 757 758 if (did_stop_cpus) { 759 curthread->td_stopsched = 0; 760 #ifdef SMP 761 CPU_AND(&other_cpus, &other_cpus, &stopped_cpus); 762 restart_cpus(other_cpus); 763 #endif 764 } 765 766 intr_restore(intr); 767 768 return (handled); 769 } 770