subr_kdb.c revision 159726
1/*- 2 * Copyright (c) 2004 The FreeBSD Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27#include <sys/cdefs.h> 28__FBSDID("$FreeBSD: head/sys/kern/subr_kdb.c 159726 2006-06-18 12:27:59Z yar $"); 29 30#include "opt_kdb.h" 31 32#include <sys/param.h> 33#include <sys/systm.h> 34#include <sys/kdb.h> 35#include <sys/kernel.h> 36#include <sys/malloc.h> 37#include <sys/pcpu.h> 38#include <sys/proc.h> 39#include <sys/smp.h> 40#include <sys/sysctl.h> 41 42#include <machine/kdb.h> 43#include <machine/pcb.h> 44 45#ifdef SMP 46#include <machine/smp.h> 47#endif 48 49int kdb_active = 0; 50void *kdb_jmpbufp = NULL; 51struct kdb_dbbe *kdb_dbbe = NULL; 52struct pcb kdb_pcb; 53struct pcb *kdb_thrctx = NULL; 54struct thread *kdb_thread = NULL; 55struct trapframe *kdb_frame = NULL; 56 57KDB_BACKEND(null, NULL, NULL, NULL); 58SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe); 59 60static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS); 61static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS); 62static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS); 63static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS); 64static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS); 65static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS); 66 67SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes"); 68 69SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, 0, 0, 70 kdb_sysctl_available, "A", "list of available KDB backends"); 71 72SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, 0, 0, 73 kdb_sysctl_current, "A", "currently selected KDB backend"); 74 75SYSCTL_PROC(_debug_kdb, OID_AUTO, enter, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 76 kdb_sysctl_enter, "I", "set to enter the debugger"); 77 78SYSCTL_PROC(_debug_kdb, OID_AUTO, panic, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 79 kdb_sysctl_panic, "I", "set to panic the kernel"); 80 81SYSCTL_PROC(_debug_kdb, OID_AUTO, trap, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 82 kdb_sysctl_trap, "I", "set to cause a page fault via data access"); 83 84SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 85 kdb_sysctl_trap_code, "I", "set to cause a page fault via code access"); 86 87/* 88 * Flag indicating whether or not to IPI the other CPUs to stop them on 89 * entering the debugger. Sometimes, this will result in a deadlock as 90 * stop_cpus() waits for the other cpus to stop, so we allow it to be 91 * disabled. 92 */ 93#ifdef SMP 94static int kdb_stop_cpus = 1; 95SYSCTL_INT(_debug_kdb, OID_AUTO, stop_cpus, CTLTYPE_INT | CTLFLAG_RW, 96 &kdb_stop_cpus, 0, "stop other CPUs when entering the debugger"); 97TUNABLE_INT("debug.kdb.stop_cpus", &kdb_stop_cpus); 98#endif 99 100static int 101kdb_sysctl_available(SYSCTL_HANDLER_ARGS) 102{ 103 struct kdb_dbbe *be, **iter; 104 char *avail, *p; 105 ssize_t len, sz; 106 int error; 107 108 sz = 0; 109 SET_FOREACH(iter, kdb_dbbe_set) { 110 be = *iter; 111 if (be->dbbe_active == 0) 112 sz += strlen(be->dbbe_name) + 1; 113 } 114 sz++; 115 avail = malloc(sz, M_TEMP, M_WAITOK); 116 p = avail; 117 *p = '\0'; 118 119 SET_FOREACH(iter, kdb_dbbe_set) { 120 be = *iter; 121 if (be->dbbe_active == 0) { 122 len = snprintf(p, sz, "%s ", be->dbbe_name); 123 p += len; 124 sz -= len; 125 } 126 } 127 KASSERT(sz >= 0, ("%s", __func__)); 128 error = sysctl_handle_string(oidp, avail, 0, req); 129 free(avail, M_TEMP); 130 return (error); 131} 132 133static int 134kdb_sysctl_current(SYSCTL_HANDLER_ARGS) 135{ 136 char buf[16]; 137 int error; 138 139 if (kdb_dbbe != NULL) { 140 strncpy(buf, kdb_dbbe->dbbe_name, sizeof(buf)); 141 buf[sizeof(buf) - 1] = '\0'; 142 } else 143 *buf = '\0'; 144 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 145 if (error != 0 || req->newptr == NULL) 146 return (error); 147 if (kdb_active) 148 return (EBUSY); 149 return (kdb_dbbe_select(buf)); 150} 151 152static int 153kdb_sysctl_enter(SYSCTL_HANDLER_ARGS) 154{ 155 int error, i; 156 157 error = sysctl_wire_old_buffer(req, sizeof(int)); 158 if (error == 0) { 159 i = 0; 160 error = sysctl_handle_int(oidp, &i, 0, req); 161 } 162 if (error != 0 || req->newptr == NULL) 163 return (error); 164 if (kdb_active) 165 return (EBUSY); 166 kdb_enter("sysctl debug.kdb.enter"); 167 return (0); 168} 169 170static int 171kdb_sysctl_panic(SYSCTL_HANDLER_ARGS) 172{ 173 int error, i; 174 175 error = sysctl_wire_old_buffer(req, sizeof(int)); 176 if (error == 0) { 177 i = 0; 178 error = sysctl_handle_int(oidp, &i, 0, req); 179 } 180 if (error != 0 || req->newptr == NULL) 181 return (error); 182 panic("kdb_sysctl_panic"); 183 return (0); 184} 185 186static int 187kdb_sysctl_trap(SYSCTL_HANDLER_ARGS) 188{ 189 int error, i; 190 int *addr = (int *)0x10; 191 192 error = sysctl_wire_old_buffer(req, sizeof(int)); 193 if (error == 0) { 194 i = 0; 195 error = sysctl_handle_int(oidp, &i, 0, req); 196 } 197 if (error != 0 || req->newptr == NULL) 198 return (error); 199 return (*addr); 200} 201 202static int 203kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS) 204{ 205 int error, i; 206 void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de; 207 208 error = sysctl_wire_old_buffer(req, sizeof(int)); 209 if (error == 0) { 210 i = 0; 211 error = sysctl_handle_int(oidp, &i, 0, req); 212 } 213 if (error != 0 || req->newptr == NULL) 214 return (error); 215 (*fp)(0x11111111, 0x22222222, 0x33333333); 216 return (0); 217} 218 219/* 220 * Solaris implements a new BREAK which is initiated by a character sequence 221 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the 222 * Remote Console. 223 * 224 * Note that this function may be called from almost anywhere, with interrupts 225 * disabled and with unknown locks held, so it must not access data other than 226 * its arguments. Its up to the caller to ensure that the state variable is 227 * consistent. 228 */ 229 230#define KEY_CR 13 /* CR '\r' */ 231#define KEY_TILDE 126 /* ~ */ 232#define KEY_CRTLB 2 /* ^B */ 233 234int 235kdb_alt_break(int key, int *state) 236{ 237 int brk; 238 239 brk = 0; 240 switch (key) { 241 case KEY_CR: 242 *state = KEY_TILDE; 243 break; 244 case KEY_TILDE: 245 *state = (*state == KEY_TILDE) ? KEY_CRTLB : 0; 246 break; 247 case KEY_CRTLB: 248 if (*state == KEY_CRTLB) 249 brk = 1; 250 /* FALLTHROUGH */ 251 default: 252 *state = 0; 253 break; 254 } 255 return (brk); 256} 257 258/* 259 * Print a backtrace of the calling thread. The backtrace is generated by 260 * the selected debugger, provided it supports backtraces. If no debugger 261 * is selected or the current debugger does not support backtraces, this 262 * function silently returns. 263 */ 264 265void 266kdb_backtrace() 267{ 268 269 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) { 270 printf("KDB: stack backtrace:\n"); 271 kdb_dbbe->dbbe_trace(); 272 } 273} 274 275/* 276 * Set/change the current backend. 277 */ 278 279int 280kdb_dbbe_select(const char *name) 281{ 282 struct kdb_dbbe *be, **iter; 283 284 SET_FOREACH(iter, kdb_dbbe_set) { 285 be = *iter; 286 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) { 287 kdb_dbbe = be; 288 return (0); 289 } 290 } 291 return (EINVAL); 292} 293 294/* 295 * Enter the currently selected debugger. If a message has been provided, 296 * it is printed first. If the debugger does not support the enter method, 297 * it is entered by using breakpoint(), which enters the debugger through 298 * kdb_trap(). 299 */ 300 301void 302kdb_enter(const char *msg) 303{ 304 305 if (kdb_dbbe != NULL && kdb_active == 0) { 306 if (msg != NULL) 307 printf("KDB: enter: %s\n", msg); 308 breakpoint(); 309 } 310} 311 312/* 313 * Initialize the kernel debugger interface. 314 */ 315 316void 317kdb_init() 318{ 319 struct kdb_dbbe *be, **iter; 320 int cur_pri, pri; 321 322 kdb_active = 0; 323 kdb_dbbe = NULL; 324 cur_pri = -1; 325 SET_FOREACH(iter, kdb_dbbe_set) { 326 be = *iter; 327 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1; 328 be->dbbe_active = (pri >= 0) ? 0 : -1; 329 if (pri > cur_pri) { 330 cur_pri = pri; 331 kdb_dbbe = be; 332 } 333 } 334 if (kdb_dbbe != NULL) { 335 printf("KDB: debugger backends:"); 336 SET_FOREACH(iter, kdb_dbbe_set) { 337 be = *iter; 338 if (be->dbbe_active == 0) 339 printf(" %s", be->dbbe_name); 340 } 341 printf("\n"); 342 printf("KDB: current backend: %s\n", 343 kdb_dbbe->dbbe_name); 344 } 345} 346 347/* 348 * Handle contexts. 349 */ 350 351void * 352kdb_jmpbuf(jmp_buf new) 353{ 354 void *old; 355 356 old = kdb_jmpbufp; 357 kdb_jmpbufp = new; 358 return (old); 359} 360 361void 362kdb_reenter(void) 363{ 364 365 if (!kdb_active || kdb_jmpbufp == NULL) 366 return; 367 368 longjmp(kdb_jmpbufp, 1); 369 /* NOTREACHED */ 370} 371 372/* 373 * Thread related support functions. 374 */ 375 376struct pcb * 377kdb_thr_ctx(struct thread *thr) 378{ 379#if defined(SMP) && defined(KDB_STOPPEDPCB) 380 struct pcpu *pc; 381#endif 382 383 if (thr == curthread) 384 return (&kdb_pcb); 385 386#if defined(SMP) && defined(KDB_STOPPEDPCB) 387 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) { 388 if (pc->pc_curthread == thr && (stopped_cpus & pc->pc_cpumask)) 389 return (KDB_STOPPEDPCB(pc)); 390 } 391#endif 392 return (thr->td_pcb); 393} 394 395struct thread * 396kdb_thr_first(void) 397{ 398 struct proc *p; 399 struct thread *thr; 400 401 p = LIST_FIRST(&allproc); 402 while (p != NULL) { 403 if (p->p_sflag & PS_INMEM) { 404 thr = FIRST_THREAD_IN_PROC(p); 405 if (thr != NULL) 406 return (thr); 407 } 408 p = LIST_NEXT(p, p_list); 409 } 410 return (NULL); 411} 412 413struct thread * 414kdb_thr_from_pid(pid_t pid) 415{ 416 struct proc *p; 417 418 p = LIST_FIRST(&allproc); 419 while (p != NULL) { 420 if (p->p_sflag & PS_INMEM && p->p_pid == pid) 421 return (FIRST_THREAD_IN_PROC(p)); 422 p = LIST_NEXT(p, p_list); 423 } 424 return (NULL); 425} 426 427struct thread * 428kdb_thr_lookup(lwpid_t tid) 429{ 430 struct thread *thr; 431 432 thr = kdb_thr_first(); 433 while (thr != NULL && thr->td_tid != tid) 434 thr = kdb_thr_next(thr); 435 return (thr); 436} 437 438struct thread * 439kdb_thr_next(struct thread *thr) 440{ 441 struct proc *p; 442 443 p = thr->td_proc; 444 thr = TAILQ_NEXT(thr, td_plist); 445 do { 446 if (thr != NULL) 447 return (thr); 448 p = LIST_NEXT(p, p_list); 449 if (p != NULL && (p->p_sflag & PS_INMEM)) 450 thr = FIRST_THREAD_IN_PROC(p); 451 } while (p != NULL); 452 return (NULL); 453} 454 455int 456kdb_thr_select(struct thread *thr) 457{ 458 if (thr == NULL) 459 return (EINVAL); 460 kdb_thread = thr; 461 kdb_thrctx = kdb_thr_ctx(thr); 462 return (0); 463} 464 465/* 466 * Enter the debugger due to a trap. 467 */ 468 469int 470kdb_trap(int type, int code, struct trapframe *tf) 471{ 472 register_t intr; 473#ifdef SMP 474 int did_stop_cpus; 475#endif 476 int handled; 477 478 if (kdb_dbbe == NULL || kdb_dbbe->dbbe_trap == NULL) 479 return (0); 480 481 /* We reenter the debugger through kdb_reenter(). */ 482 if (kdb_active) 483 return (0); 484 485 intr = intr_disable(); 486 487#ifdef SMP 488 if ((did_stop_cpus = kdb_stop_cpus) != 0) 489 stop_cpus(PCPU_GET(other_cpus)); 490#endif 491 492 kdb_active++; 493 494 kdb_frame = tf; 495 496 /* Let MD code do its thing first... */ 497 kdb_cpu_trap(type, code); 498 499 makectx(tf, &kdb_pcb); 500 kdb_thr_select(curthread); 501 502 handled = kdb_dbbe->dbbe_trap(type, code); 503 504 kdb_active--; 505 506#ifdef SMP 507 if (did_stop_cpus) 508 restart_cpus(stopped_cpus); 509#endif 510 511 intr_restore(intr); 512 513 return (handled); 514} 515