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("$FreeBSD$"); 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 49 int kdb_active = 0; 50 void *kdb_jmpbufp = NULL; 51 struct kdb_dbbe *kdb_dbbe = NULL; 52 struct pcb kdb_pcb; 53 struct pcb *kdb_thrctx = NULL; 54 struct thread *kdb_thread = NULL; 55 struct trapframe *kdb_frame = NULL; 56 57 KDB_BACKEND(null, NULL, NULL, NULL); 58 SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe); 59 60 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS); 61 static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS); 62 static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS); 63 static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS); 64 static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS); 65 static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS); 66 67 SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes"); 68 69 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, 0, 0, 70 kdb_sysctl_available, "A", "list of available KDB backends"); 71 72 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, 0, 0, 73 kdb_sysctl_current, "A", "currently selected KDB backend"); 74 75 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 76 kdb_sysctl_enter, "I", "set to enter the debugger"); 77 78 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 79 kdb_sysctl_panic, "I", "set to panic the kernel"); 80 81 SYSCTL_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 84 SYSCTL_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 94 static int kdb_stop_cpus = 1; 95 SYSCTL_INT(_debug_kdb, OID_AUTO, stop_cpus, CTLTYPE_INT | CTLFLAG_RW, 96 &kdb_stop_cpus, 0, "stop other CPUs when entering the debugger"); 97 TUNABLE_INT("debug.kdb.stop_cpus", &kdb_stop_cpus); 98 #endif 99 100 /* 101 * Flag to indicate to debuggers why the debugger was entered. 102 */ 103 const char * volatile kdb_why = KDB_WHY_UNSET; 104 105 static int 106 kdb_sysctl_available(SYSCTL_HANDLER_ARGS) 107 { 108 struct kdb_dbbe *be, **iter; 109 char *avail, *p; 110 ssize_t len, sz; 111 int error; 112 113 sz = 0; 114 SET_FOREACH(iter, kdb_dbbe_set) { 115 be = *iter; 116 if (be->dbbe_active == 0) 117 sz += strlen(be->dbbe_name) + 1; 118 } 119 sz++; 120 avail = malloc(sz, M_TEMP, M_WAITOK); 121 p = avail; 122 *p = '\0'; 123 124 SET_FOREACH(iter, kdb_dbbe_set) { 125 be = *iter; 126 if (be->dbbe_active == 0) { 127 len = snprintf(p, sz, "%s ", be->dbbe_name); 128 p += len; 129 sz -= len; 130 } 131 } 132 KASSERT(sz >= 0, ("%s", __func__)); 133 error = sysctl_handle_string(oidp, avail, 0, req); 134 free(avail, M_TEMP); 135 return (error); 136 } 137 138 static int 139 kdb_sysctl_current(SYSCTL_HANDLER_ARGS) 140 { 141 char buf[16]; 142 int error; 143 144 if (kdb_dbbe != NULL) { 145 strncpy(buf, kdb_dbbe->dbbe_name, sizeof(buf)); 146 buf[sizeof(buf) - 1] = '\0'; 147 } else 148 *buf = '\0'; 149 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 150 if (error != 0 || req->newptr == NULL) 151 return (error); 152 if (kdb_active) 153 return (EBUSY); 154 return (kdb_dbbe_select(buf)); 155 } 156 157 static int 158 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS) 159 { 160 int error, i; 161 162 error = sysctl_wire_old_buffer(req, sizeof(int)); 163 if (error == 0) { 164 i = 0; 165 error = sysctl_handle_int(oidp, &i, 0, req); 166 } 167 if (error != 0 || req->newptr == NULL) 168 return (error); 169 if (kdb_active) 170 return (EBUSY); 171 kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter"); 172 return (0); 173 } 174 175 static int 176 kdb_sysctl_panic(SYSCTL_HANDLER_ARGS) 177 { 178 int error, i; 179 180 error = sysctl_wire_old_buffer(req, sizeof(int)); 181 if (error == 0) { 182 i = 0; 183 error = sysctl_handle_int(oidp, &i, 0, req); 184 } 185 if (error != 0 || req->newptr == NULL) 186 return (error); 187 panic("kdb_sysctl_panic"); 188 return (0); 189 } 190 191 static int 192 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS) 193 { 194 int error, i; 195 int *addr = (int *)0x10; 196 197 error = sysctl_wire_old_buffer(req, sizeof(int)); 198 if (error == 0) { 199 i = 0; 200 error = sysctl_handle_int(oidp, &i, 0, req); 201 } 202 if (error != 0 || req->newptr == NULL) 203 return (error); 204 return (*addr); 205 } 206 207 static int 208 kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS) 209 { 210 int error, i; 211 void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de; 212 213 error = sysctl_wire_old_buffer(req, sizeof(int)); 214 if (error == 0) { 215 i = 0; 216 error = sysctl_handle_int(oidp, &i, 0, req); 217 } 218 if (error != 0 || req->newptr == NULL) 219 return (error); 220 (*fp)(0x11111111, 0x22222222, 0x33333333); 221 return (0); 222 } 223 224 /* 225 * Solaris implements a new BREAK which is initiated by a character sequence 226 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the 227 * Remote Console. 228 * 229 * Note that this function may be called from almost anywhere, with interrupts 230 * disabled and with unknown locks held, so it must not access data other than 231 * its arguments. Its up to the caller to ensure that the state variable is 232 * consistent. 233 */ 234 235 #define KEY_CR 13 /* CR '\r' */ 236 #define KEY_TILDE 126 /* ~ */ 237 #define KEY_CRTLB 2 /* ^B */ 238 239 int 240 kdb_alt_break(int key, int *state) 241 { 242 int brk; 243 244 brk = 0; 245 switch (key) { 246 case KEY_CR: 247 *state = KEY_TILDE; 248 break; 249 case KEY_TILDE: 250 *state = (*state == KEY_TILDE) ? KEY_CRTLB : 0; 251 break; 252 case KEY_CRTLB: 253 if (*state == KEY_CRTLB) 254 brk = 1; 255 /* FALLTHROUGH */ 256 default: 257 *state = 0; 258 break; 259 } 260 return (brk); 261 } 262 263 /* 264 * Print a backtrace of the calling thread. The backtrace is generated by 265 * the selected debugger, provided it supports backtraces. If no debugger 266 * is selected or the current debugger does not support backtraces, this 267 * function silently returns. 268 */ 269 270 void 271 kdb_backtrace() 272 { 273 274 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) { 275 printf("KDB: stack backtrace:\n"); 276 kdb_dbbe->dbbe_trace(); 277 } 278 } 279 280 /* 281 * Set/change the current backend. 282 */ 283 284 int 285 kdb_dbbe_select(const char *name) 286 { 287 struct kdb_dbbe *be, **iter; 288 289 SET_FOREACH(iter, kdb_dbbe_set) { 290 be = *iter; 291 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) { 292 kdb_dbbe = be; 293 return (0); 294 } 295 } 296 return (EINVAL); 297 } 298 299 /* 300 * Enter the currently selected debugger. If a message has been provided, 301 * it is printed first. If the debugger does not support the enter method, 302 * it is entered by using breakpoint(), which enters the debugger through 303 * kdb_trap(). The 'why' argument will contain a more mechanically usable 304 * string than 'msg', and is relied upon by DDB scripting to identify the 305 * reason for entering the debugger so that the right script can be run. 306 */ 307 void 308 kdb_enter(const char *why, const char *msg) 309 { 310 311 if (kdb_dbbe != NULL && kdb_active == 0) { 312 if (msg != NULL) 313 printf("KDB: enter: %s\n", msg); 314 kdb_why = why; 315 breakpoint(); 316 kdb_why = KDB_WHY_UNSET; 317 } 318 } 319 320 /* 321 * Initialize the kernel debugger interface. 322 */ 323 324 void 325 kdb_init() 326 { 327 struct kdb_dbbe *be, **iter; 328 int cur_pri, pri; 329 330 kdb_active = 0; 331 kdb_dbbe = NULL; 332 cur_pri = -1; 333 SET_FOREACH(iter, kdb_dbbe_set) { 334 be = *iter; 335 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1; 336 be->dbbe_active = (pri >= 0) ? 0 : -1; 337 if (pri > cur_pri) { 338 cur_pri = pri; 339 kdb_dbbe = be; 340 } 341 } 342 if (kdb_dbbe != NULL) { 343 printf("KDB: debugger backends:"); 344 SET_FOREACH(iter, kdb_dbbe_set) { 345 be = *iter; 346 if (be->dbbe_active == 0) 347 printf(" %s", be->dbbe_name); 348 } 349 printf("\n"); 350 printf("KDB: current backend: %s\n", 351 kdb_dbbe->dbbe_name); 352 } 353 } 354 355 /* 356 * Handle contexts. 357 */ 358 359 void * 360 kdb_jmpbuf(jmp_buf new) 361 { 362 void *old; 363 364 old = kdb_jmpbufp; 365 kdb_jmpbufp = new; 366 return (old); 367 } 368 369 void 370 kdb_reenter(void) 371 { 372 373 if (!kdb_active || kdb_jmpbufp == NULL) 374 return; 375 376 longjmp(kdb_jmpbufp, 1); 377 /* NOTREACHED */ 378 } 379 380 /* 381 * Thread related support functions. 382 */ 383 384 struct pcb * 385 kdb_thr_ctx(struct thread *thr) 386 { 387 #if defined(SMP) && defined(KDB_STOPPEDPCB) 388 struct pcpu *pc; 389 #endif 390 391 if (thr == curthread) 392 return (&kdb_pcb); 393 394 #if defined(SMP) && defined(KDB_STOPPEDPCB) 395 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) { 396 if (pc->pc_curthread == thr && (stopped_cpus & pc->pc_cpumask)) 397 return (KDB_STOPPEDPCB(pc)); 398 } 399 #endif 400 return (thr->td_pcb); 401 } 402 403 struct thread * 404 kdb_thr_first(void) 405 { 406 struct proc *p; 407 struct thread *thr; 408 409 p = LIST_FIRST(&allproc); 410 while (p != NULL) { 411 if (p->p_flag & P_INMEM) { 412 thr = FIRST_THREAD_IN_PROC(p); 413 if (thr != NULL) 414 return (thr); 415 } 416 p = LIST_NEXT(p, p_list); 417 } 418 return (NULL); 419 } 420 421 struct thread * 422 kdb_thr_from_pid(pid_t pid) 423 { 424 struct proc *p; 425 426 p = LIST_FIRST(&allproc); 427 while (p != NULL) { 428 if (p->p_flag & P_INMEM && p->p_pid == pid) 429 return (FIRST_THREAD_IN_PROC(p)); 430 p = LIST_NEXT(p, p_list); 431 } 432 return (NULL); 433 } 434 435 struct thread * 436 kdb_thr_lookup(lwpid_t tid) 437 { 438 struct thread *thr; 439 440 thr = kdb_thr_first(); 441 while (thr != NULL && thr->td_tid != tid) 442 thr = kdb_thr_next(thr); 443 return (thr); 444 } 445 446 struct thread * 447 kdb_thr_next(struct thread *thr) 448 { 449 struct proc *p; 450 451 p = thr->td_proc; 452 thr = TAILQ_NEXT(thr, td_plist); 453 do { 454 if (thr != NULL) 455 return (thr); 456 p = LIST_NEXT(p, p_list); 457 if (p != NULL && (p->p_flag & P_INMEM)) 458 thr = FIRST_THREAD_IN_PROC(p); 459 } while (p != NULL); 460 return (NULL); 461 } 462 463 int 464 kdb_thr_select(struct thread *thr) 465 { 466 if (thr == NULL) 467 return (EINVAL); 468 kdb_thread = thr; 469 kdb_thrctx = kdb_thr_ctx(thr); 470 return (0); 471 } 472 473 /* 474 * Enter the debugger due to a trap. 475 */ 476 477 int 478 kdb_trap(int type, int code, struct trapframe *tf) 479 { 480 register_t intr; 481 #ifdef SMP 482 int did_stop_cpus; 483 #endif 484 int handled; 485 486 if (kdb_dbbe == NULL || kdb_dbbe->dbbe_trap == NULL) 487 return (0); 488 489 /* We reenter the debugger through kdb_reenter(). */ 490 if (kdb_active) 491 return (0); 492 493 intr = intr_disable(); 494 495 #ifdef SMP 496 if ((did_stop_cpus = kdb_stop_cpus) != 0) 497 stop_cpus(PCPU_GET(other_cpus)); 498 #endif 499 500 kdb_active++; 501 502 kdb_frame = tf; 503 504 /* Let MD code do its thing first... */ 505 kdb_cpu_trap(type, code); 506 507 makectx(tf, &kdb_pcb); 508 kdb_thr_select(curthread); 509 510 handled = kdb_dbbe->dbbe_trap(type, code); 511 512 kdb_active--; 513 514 #ifdef SMP 515 if (did_stop_cpus) 516 restart_cpus(stopped_cpus); 517 #endif 518 519 intr_restore(intr); 520 521 return (handled); 522 } 523