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 66 SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes"); 67 68 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, 0, 0, 69 kdb_sysctl_available, "A", "list of available KDB backends"); 70 71 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, 0, 0, 72 kdb_sysctl_current, "A", "currently selected KDB backend"); 73 74 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 75 kdb_sysctl_enter, "I", "set to enter the debugger"); 76 77 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 78 kdb_sysctl_panic, "I", "set to panic the kernel"); 79 80 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 81 kdb_sysctl_trap, "I", "set cause a page fault"); 82 83 /* 84 * Flag indicating whether or not to IPI the other CPUs to stop them on 85 * entering the debugger. Sometimes, this will result in a deadlock as 86 * stop_cpus() waits for the other cpus to stop, so we allow it to be 87 * disabled. 88 */ 89 #ifdef SMP 90 static int kdb_stop_cpus = 1; 91 SYSCTL_INT(_debug_kdb, OID_AUTO, stop_cpus, CTLTYPE_INT | CTLFLAG_RW, 92 &kdb_stop_cpus, 0, ""); 93 TUNABLE_INT("debug.kdb.stop_cpus", &kdb_stop_cpus); 94 #endif 95 96 static int 97 kdb_sysctl_available(SYSCTL_HANDLER_ARGS) 98 { 99 struct kdb_dbbe *be, **iter; 100 char *avail, *p; 101 ssize_t len, sz; 102 int error; 103 104 sz = 0; 105 SET_FOREACH(iter, kdb_dbbe_set) { 106 be = *iter; 107 if (be->dbbe_active == 0) 108 sz += strlen(be->dbbe_name) + 1; 109 } 110 sz++; 111 avail = malloc(sz, M_TEMP, M_WAITOK); 112 p = avail; 113 *p = '\0'; 114 115 SET_FOREACH(iter, kdb_dbbe_set) { 116 be = *iter; 117 if (be->dbbe_active == 0) { 118 len = snprintf(p, sz, "%s ", be->dbbe_name); 119 p += len; 120 sz -= len; 121 } 122 } 123 KASSERT(sz >= 0, ("%s", __func__)); 124 error = sysctl_handle_string(oidp, avail, 0, req); 125 free(avail, M_TEMP); 126 return (error); 127 } 128 129 static int 130 kdb_sysctl_current(SYSCTL_HANDLER_ARGS) 131 { 132 char buf[16]; 133 int error; 134 135 if (kdb_dbbe != NULL) { 136 strncpy(buf, kdb_dbbe->dbbe_name, sizeof(buf)); 137 buf[sizeof(buf) - 1] = '\0'; 138 } else 139 *buf = '\0'; 140 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 141 if (error != 0 || req->newptr == NULL) 142 return (error); 143 if (kdb_active) 144 return (EBUSY); 145 return (kdb_dbbe_select(buf)); 146 } 147 148 static int 149 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS) 150 { 151 int error, i; 152 153 error = sysctl_wire_old_buffer(req, sizeof(int)); 154 if (error == 0) { 155 i = 0; 156 error = sysctl_handle_int(oidp, &i, 0, req); 157 } 158 if (error != 0 || req->newptr == NULL) 159 return (error); 160 if (kdb_active) 161 return (EBUSY); 162 kdb_enter("sysctl debug.kdb.enter"); 163 return (0); 164 } 165 166 static int 167 kdb_sysctl_panic(SYSCTL_HANDLER_ARGS) 168 { 169 int error, i; 170 171 error = sysctl_wire_old_buffer(req, sizeof(int)); 172 if (error == 0) { 173 i = 0; 174 error = sysctl_handle_int(oidp, &i, 0, req); 175 } 176 if (error != 0 || req->newptr == NULL) 177 return (error); 178 panic("kdb_sysctl_panic"); 179 return (0); 180 } 181 182 static int 183 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS) 184 { 185 int error, i; 186 int *addr = (int *)0x10; 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 return (*addr); 196 } 197 198 /* 199 * Solaris implements a new BREAK which is initiated by a character sequence 200 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the 201 * Remote Console. 202 * 203 * Note that this function may be called from almost anywhere, with interrupts 204 * disabled and with unknown locks held, so it must not access data other than 205 * its arguments. Its up to the caller to ensure that the state variable is 206 * consistent. 207 */ 208 209 #define KEY_CR 13 /* CR '\r' */ 210 #define KEY_TILDE 126 /* ~ */ 211 #define KEY_CRTLB 2 /* ^B */ 212 213 int 214 kdb_alt_break(int key, int *state) 215 { 216 int brk; 217 218 brk = 0; 219 switch (key) { 220 case KEY_CR: 221 *state = KEY_TILDE; 222 break; 223 case KEY_TILDE: 224 *state = (*state == KEY_TILDE) ? KEY_CRTLB : 0; 225 break; 226 case KEY_CRTLB: 227 if (*state == KEY_CRTLB) 228 brk = 1; 229 /* FALLTHROUGH */ 230 default: 231 *state = 0; 232 break; 233 } 234 return (brk); 235 } 236 237 /* 238 * Print a backtrace of the calling thread. The backtrace is generated by 239 * the selected debugger, provided it supports backtraces. If no debugger 240 * is selected or the current debugger does not support backtraces, this 241 * function silently returns. 242 */ 243 244 void 245 kdb_backtrace() 246 { 247 248 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) { 249 printf("KDB: stack backtrace:\n"); 250 kdb_dbbe->dbbe_trace(); 251 } 252 } 253 254 /* 255 * Set/change the current backend. 256 */ 257 258 int 259 kdb_dbbe_select(const char *name) 260 { 261 struct kdb_dbbe *be, **iter; 262 263 SET_FOREACH(iter, kdb_dbbe_set) { 264 be = *iter; 265 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) { 266 kdb_dbbe = be; 267 return (0); 268 } 269 } 270 return (EINVAL); 271 } 272 273 /* 274 * Enter the currently selected debugger. If a message has been provided, 275 * it is printed first. If the debugger does not support the enter method, 276 * it is entered by using breakpoint(), which enters the debugger through 277 * kdb_trap(). 278 */ 279 280 void 281 kdb_enter(const char *msg) 282 { 283 284 if (kdb_dbbe != NULL && kdb_active == 0) { 285 if (msg != NULL) 286 printf("KDB: enter: %s\n", msg); 287 breakpoint(); 288 } 289 } 290 291 /* 292 * Initialize the kernel debugger interface. 293 */ 294 295 void 296 kdb_init() 297 { 298 struct kdb_dbbe *be, **iter; 299 int cur_pri, pri; 300 301 kdb_active = 0; 302 kdb_dbbe = NULL; 303 cur_pri = -1; 304 SET_FOREACH(iter, kdb_dbbe_set) { 305 be = *iter; 306 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1; 307 be->dbbe_active = (pri >= 0) ? 0 : -1; 308 if (pri > cur_pri) { 309 cur_pri = pri; 310 kdb_dbbe = be; 311 } 312 } 313 if (kdb_dbbe != NULL) { 314 printf("KDB: debugger backends:"); 315 SET_FOREACH(iter, kdb_dbbe_set) { 316 be = *iter; 317 if (be->dbbe_active == 0) 318 printf(" %s", be->dbbe_name); 319 } 320 printf("\n"); 321 printf("KDB: current backend: %s\n", 322 kdb_dbbe->dbbe_name); 323 } 324 } 325 326 /* 327 * Handle contexts. 328 */ 329 330 void * 331 kdb_jmpbuf(jmp_buf new) 332 { 333 void *old; 334 335 old = kdb_jmpbufp; 336 kdb_jmpbufp = new; 337 return (old); 338 } 339 340 void 341 kdb_reenter(void) 342 { 343 344 if (!kdb_active || kdb_jmpbufp == NULL) 345 return; 346 347 longjmp(kdb_jmpbufp, 1); 348 /* NOTREACHED */ 349 } 350 351 /* 352 * Thread related support functions. 353 */ 354 355 struct pcb * 356 kdb_thr_ctx(struct thread *thr) 357 { 358 #if defined(SMP) && defined(KDB_STOPPEDPCB) 359 struct pcpu *pc; 360 #endif 361 362 if (thr == curthread) 363 return (&kdb_pcb); 364 365 #if defined(SMP) && defined(KDB_STOPPEDPCB) 366 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) { 367 if (pc->pc_curthread == thr && (stopped_cpus & pc->pc_cpumask)) 368 return (KDB_STOPPEDPCB(pc)); 369 } 370 #endif 371 return (thr->td_pcb); 372 } 373 374 struct thread * 375 kdb_thr_first(void) 376 { 377 struct proc *p; 378 struct thread *thr; 379 380 p = LIST_FIRST(&allproc); 381 while (p != NULL) { 382 if (p->p_sflag & PS_INMEM) { 383 thr = FIRST_THREAD_IN_PROC(p); 384 if (thr != NULL) 385 return (thr); 386 } 387 p = LIST_NEXT(p, p_list); 388 } 389 return (NULL); 390 } 391 392 struct thread * 393 kdb_thr_from_pid(pid_t pid) 394 { 395 struct proc *p; 396 397 p = LIST_FIRST(&allproc); 398 while (p != NULL) { 399 if (p->p_sflag & PS_INMEM && p->p_pid == pid) 400 return (FIRST_THREAD_IN_PROC(p)); 401 p = LIST_NEXT(p, p_list); 402 } 403 return (NULL); 404 } 405 406 struct thread * 407 kdb_thr_lookup(lwpid_t tid) 408 { 409 struct thread *thr; 410 411 thr = kdb_thr_first(); 412 while (thr != NULL && thr->td_tid != tid) 413 thr = kdb_thr_next(thr); 414 return (thr); 415 } 416 417 struct thread * 418 kdb_thr_next(struct thread *thr) 419 { 420 struct proc *p; 421 422 p = thr->td_proc; 423 thr = TAILQ_NEXT(thr, td_plist); 424 do { 425 if (thr != NULL) 426 return (thr); 427 p = LIST_NEXT(p, p_list); 428 if (p != NULL && (p->p_sflag & PS_INMEM)) 429 thr = FIRST_THREAD_IN_PROC(p); 430 } while (p != NULL); 431 return (NULL); 432 } 433 434 int 435 kdb_thr_select(struct thread *thr) 436 { 437 if (thr == NULL) 438 return (EINVAL); 439 kdb_thread = thr; 440 kdb_thrctx = kdb_thr_ctx(thr); 441 return (0); 442 } 443 444 /* 445 * Enter the debugger due to a trap. 446 */ 447 448 int 449 kdb_trap(int type, int code, struct trapframe *tf) 450 { 451 register_t intr; 452 #ifdef SMP 453 int did_stop_cpus; 454 #endif 455 int handled; 456 457 if (kdb_dbbe == NULL || kdb_dbbe->dbbe_trap == NULL) 458 return (0); 459 460 /* We reenter the debugger through kdb_reenter(). */ 461 if (kdb_active) 462 return (0); 463 464 intr = intr_disable(); 465 466 #ifdef SMP 467 if ((did_stop_cpus = kdb_stop_cpus) != 0) 468 stop_cpus(PCPU_GET(other_cpus)); 469 #endif 470 471 kdb_active++; 472 473 kdb_frame = tf; 474 475 /* Let MD code do its thing first... */ 476 kdb_cpu_trap(type, code); 477 478 makectx(tf, &kdb_pcb); 479 kdb_thr_select(curthread); 480 481 handled = kdb_dbbe->dbbe_trap(type, code); 482 483 kdb_active--; 484 485 #ifdef SMP 486 if (did_stop_cpus) 487 restart_cpus(stopped_cpus); 488 #endif 489 490 intr_restore(intr); 491 492 return (handled); 493 } 494