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 #if defined (__i386__) || defined(__amd64__) || defined(__sparc64__) || defined(__alpha__) 47 #define HAVE_STOPPEDPCBS 48 #include <machine/smp.h> 49 #endif 50 #endif 51 52 int kdb_active = 0; 53 void *kdb_jmpbufp = NULL; 54 struct kdb_dbbe *kdb_dbbe = NULL; 55 struct pcb kdb_pcb; 56 struct pcb *kdb_thrctx = NULL; 57 struct thread *kdb_thread = NULL; 58 struct trapframe *kdb_frame = NULL; 59 60 KDB_BACKEND(null, NULL, NULL, NULL); 61 SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe); 62 63 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS); 64 static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS); 65 static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS); 66 static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS); 67 static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS); 68 69 SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes"); 70 71 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, 0, 0, 72 kdb_sysctl_available, "A", "list of available KDB backends"); 73 74 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, 0, 0, 75 kdb_sysctl_current, "A", "currently selected KDB backend"); 76 77 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 78 kdb_sysctl_enter, "I", "set to enter the debugger"); 79 80 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 81 kdb_sysctl_panic, "I", "set to panic the kernel"); 82 83 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 84 kdb_sysctl_trap, "I", "set cause a page fault"); 85 86 /* 87 * Flag indicating whether or not to IPI the other CPUs to stop them on 88 * entering the debugger. Sometimes, this will result in a deadlock as 89 * stop_cpus() waits for the other cpus to stop, so we allow it to be 90 * disabled. 91 */ 92 #ifdef SMP 93 static int kdb_stop_cpus = 1; 94 SYSCTL_INT(_debug_kdb, OID_AUTO, stop_cpus, CTLTYPE_INT | CTLFLAG_RW, 95 &kdb_stop_cpus, 0, ""); 96 TUNABLE_INT("debug.kdb.stop_cpus", &kdb_stop_cpus); 97 #endif 98 99 static int 100 kdb_sysctl_available(SYSCTL_HANDLER_ARGS) 101 { 102 struct kdb_dbbe *be, **iter; 103 char *avail, *p; 104 ssize_t len, sz; 105 int error; 106 107 sz = 0; 108 SET_FOREACH(iter, kdb_dbbe_set) { 109 be = *iter; 110 if (be->dbbe_active == 0) 111 sz += strlen(be->dbbe_name) + 1; 112 } 113 sz++; 114 avail = malloc(sz, M_TEMP, M_WAITOK); 115 p = avail; 116 *p = '\0'; 117 118 SET_FOREACH(iter, kdb_dbbe_set) { 119 be = *iter; 120 if (be->dbbe_active == 0) { 121 len = snprintf(p, sz, "%s ", be->dbbe_name); 122 p += len; 123 sz -= len; 124 } 125 } 126 KASSERT(sz >= 0, ("%s", __func__)); 127 error = sysctl_handle_string(oidp, avail, 0, req); 128 free(avail, M_TEMP); 129 return (error); 130 } 131 132 static int 133 kdb_sysctl_current(SYSCTL_HANDLER_ARGS) 134 { 135 char buf[16]; 136 int error; 137 138 if (kdb_dbbe != NULL) { 139 strncpy(buf, kdb_dbbe->dbbe_name, sizeof(buf)); 140 buf[sizeof(buf) - 1] = '\0'; 141 } else 142 *buf = '\0'; 143 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 144 if (error != 0 || req->newptr == NULL) 145 return (error); 146 if (kdb_active) 147 return (EBUSY); 148 return (kdb_dbbe_select(buf)); 149 } 150 151 static int 152 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS) 153 { 154 int error, i; 155 156 error = sysctl_wire_old_buffer(req, sizeof(int)); 157 if (error == 0) { 158 i = 0; 159 error = sysctl_handle_int(oidp, &i, 0, req); 160 } 161 if (error != 0 || req->newptr == NULL) 162 return (error); 163 if (kdb_active) 164 return (EBUSY); 165 kdb_enter("sysctl debug.kdb.enter"); 166 return (0); 167 } 168 169 static int 170 kdb_sysctl_panic(SYSCTL_HANDLER_ARGS) 171 { 172 int error, i; 173 174 error = sysctl_wire_old_buffer(req, sizeof(int)); 175 if (error == 0) { 176 i = 0; 177 error = sysctl_handle_int(oidp, &i, 0, req); 178 } 179 if (error != 0 || req->newptr == NULL) 180 return (error); 181 panic("kdb_sysctl_panic"); 182 return (0); 183 } 184 185 static int 186 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS) 187 { 188 int error, i; 189 int *addr = (int *)0x10; 190 191 error = sysctl_wire_old_buffer(req, sizeof(int)); 192 if (error == 0) { 193 i = 0; 194 error = sysctl_handle_int(oidp, &i, 0, req); 195 } 196 if (error != 0 || req->newptr == NULL) 197 return (error); 198 return (*addr); 199 } 200 201 /* 202 * Solaris implements a new BREAK which is initiated by a character sequence 203 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the 204 * Remote Console. 205 * 206 * Note that this function may be called from almost anywhere, with interrupts 207 * disabled and with unknown locks held, so it must not access data other than 208 * its arguments. Its up to the caller to ensure that the state variable is 209 * consistent. 210 */ 211 212 #define KEY_CR 13 /* CR '\r' */ 213 #define KEY_TILDE 126 /* ~ */ 214 #define KEY_CRTLB 2 /* ^B */ 215 216 int 217 kdb_alt_break(int key, int *state) 218 { 219 int brk; 220 221 brk = 0; 222 switch (key) { 223 case KEY_CR: 224 *state = KEY_TILDE; 225 break; 226 case KEY_TILDE: 227 *state = (*state == KEY_TILDE) ? KEY_CRTLB : 0; 228 break; 229 case KEY_CRTLB: 230 if (*state == KEY_CRTLB) 231 brk = 1; 232 /* FALLTHROUGH */ 233 default: 234 *state = 0; 235 break; 236 } 237 return (brk); 238 } 239 240 /* 241 * Print a backtrace of the calling thread. The backtrace is generated by 242 * the selected debugger, provided it supports backtraces. If no debugger 243 * is selected or the current debugger does not support backtraces, this 244 * function silently returns. 245 */ 246 247 void 248 kdb_backtrace() 249 { 250 251 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) { 252 printf("KDB: stack backtrace:\n"); 253 kdb_dbbe->dbbe_trace(); 254 } 255 } 256 257 /* 258 * Set/change the current backend. 259 */ 260 261 int 262 kdb_dbbe_select(const char *name) 263 { 264 struct kdb_dbbe *be, **iter; 265 266 SET_FOREACH(iter, kdb_dbbe_set) { 267 be = *iter; 268 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) { 269 kdb_dbbe = be; 270 return (0); 271 } 272 } 273 return (EINVAL); 274 } 275 276 /* 277 * Enter the currently selected debugger. If a message has been provided, 278 * it is printed first. If the debugger does not support the enter method, 279 * it is entered by using breakpoint(), which enters the debugger through 280 * kdb_trap(). 281 */ 282 283 void 284 kdb_enter(const char *msg) 285 { 286 287 if (kdb_dbbe != NULL && kdb_active == 0) { 288 if (msg != NULL) 289 printf("KDB: enter: %s\n", msg); 290 breakpoint(); 291 } 292 } 293 294 /* 295 * Initialize the kernel debugger interface. 296 */ 297 298 void 299 kdb_init() 300 { 301 struct kdb_dbbe *be, **iter; 302 int cur_pri, pri; 303 304 kdb_active = 0; 305 kdb_dbbe = NULL; 306 cur_pri = -1; 307 SET_FOREACH(iter, kdb_dbbe_set) { 308 be = *iter; 309 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1; 310 be->dbbe_active = (pri >= 0) ? 0 : -1; 311 if (pri > cur_pri) { 312 cur_pri = pri; 313 kdb_dbbe = be; 314 } 315 } 316 if (kdb_dbbe != NULL) { 317 printf("KDB: debugger backends:"); 318 SET_FOREACH(iter, kdb_dbbe_set) { 319 be = *iter; 320 if (be->dbbe_active == 0) 321 printf(" %s", be->dbbe_name); 322 } 323 printf("\n"); 324 printf("KDB: current backend: %s\n", 325 kdb_dbbe->dbbe_name); 326 } 327 } 328 329 /* 330 * Handle contexts. 331 */ 332 333 void * 334 kdb_jmpbuf(jmp_buf new) 335 { 336 void *old; 337 338 old = kdb_jmpbufp; 339 kdb_jmpbufp = new; 340 return (old); 341 } 342 343 void 344 kdb_reenter(void) 345 { 346 347 if (!kdb_active || kdb_jmpbufp == NULL) 348 return; 349 350 longjmp(kdb_jmpbufp, 1); 351 /* NOTREACHED */ 352 } 353 354 /* 355 * Thread related support functions. 356 */ 357 358 struct pcb * 359 kdb_thr_ctx(struct thread *thr) 360 { 361 #ifdef HAVE_STOPPEDPCBS 362 struct pcpu *pc; 363 u_int cpuid; 364 #endif 365 366 if (thr == curthread) 367 return (&kdb_pcb); 368 369 #ifdef HAVE_STOPPEDPCBS 370 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) { 371 cpuid = pc->pc_cpuid; 372 if (pc->pc_curthread == thr && (stopped_cpus & (1 << cpuid))) 373 return (&stoppcbs[cpuid]); 374 } 375 #endif 376 return (thr->td_pcb); 377 } 378 379 struct thread * 380 kdb_thr_first(void) 381 { 382 struct proc *p; 383 struct thread *thr; 384 385 p = LIST_FIRST(&allproc); 386 while (p != NULL) { 387 if (p->p_sflag & PS_INMEM) { 388 thr = FIRST_THREAD_IN_PROC(p); 389 if (thr != NULL) 390 return (thr); 391 } 392 p = LIST_NEXT(p, p_list); 393 } 394 return (NULL); 395 } 396 397 struct thread * 398 kdb_thr_from_pid(pid_t pid) 399 { 400 struct proc *p; 401 402 p = LIST_FIRST(&allproc); 403 while (p != NULL) { 404 if (p->p_sflag & PS_INMEM && p->p_pid == pid) 405 return (FIRST_THREAD_IN_PROC(p)); 406 p = LIST_NEXT(p, p_list); 407 } 408 return (NULL); 409 } 410 411 struct thread * 412 kdb_thr_lookup(lwpid_t tid) 413 { 414 struct thread *thr; 415 416 thr = kdb_thr_first(); 417 while (thr != NULL && thr->td_tid != tid) 418 thr = kdb_thr_next(thr); 419 return (thr); 420 } 421 422 struct thread * 423 kdb_thr_next(struct thread *thr) 424 { 425 struct proc *p; 426 427 p = thr->td_proc; 428 thr = TAILQ_NEXT(thr, td_plist); 429 do { 430 if (thr != NULL) 431 return (thr); 432 p = LIST_NEXT(p, p_list); 433 if (p != NULL && (p->p_sflag & PS_INMEM)) 434 thr = FIRST_THREAD_IN_PROC(p); 435 } while (p != NULL); 436 return (NULL); 437 } 438 439 int 440 kdb_thr_select(struct thread *thr) 441 { 442 if (thr == NULL) 443 return (EINVAL); 444 kdb_thread = thr; 445 kdb_thrctx = kdb_thr_ctx(thr); 446 return (0); 447 } 448 449 /* 450 * Enter the debugger due to a trap. 451 */ 452 453 int 454 kdb_trap(int type, int code, struct trapframe *tf) 455 { 456 #ifdef SMP 457 int did_stop_cpus; 458 #endif 459 int handled; 460 461 if (kdb_dbbe == NULL || kdb_dbbe->dbbe_trap == NULL) 462 return (0); 463 464 /* We reenter the debugger through kdb_reenter(). */ 465 if (kdb_active) 466 return (0); 467 468 critical_enter(); 469 470 kdb_active++; 471 472 #ifdef SMP 473 if ((did_stop_cpus = kdb_stop_cpus) != 0) 474 stop_cpus(PCPU_GET(other_cpus)); 475 #endif 476 477 kdb_frame = tf; 478 479 /* Let MD code do its thing first... */ 480 kdb_cpu_trap(type, code); 481 482 makectx(tf, &kdb_pcb); 483 kdb_thr_select(curthread); 484 485 handled = kdb_dbbe->dbbe_trap(type, code); 486 487 #ifdef SMP 488 if (did_stop_cpus) 489 restart_cpus(stopped_cpus); 490 #endif 491 492 kdb_active--; 493 494 critical_exit(); 495 496 return (handled); 497 } 498