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 <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/kdb.h> 33 #include <sys/kernel.h> 34 #include <sys/malloc.h> 35 #include <sys/pcpu.h> 36 #include <sys/proc.h> 37 #include <sys/smp.h> 38 #include <sys/sysctl.h> 39 40 #include <machine/kdb.h> 41 #include <machine/pcb.h> 42 43 int kdb_active = 0; 44 void *kdb_jmpbufp = NULL; 45 struct kdb_dbbe *kdb_dbbe = NULL; 46 struct pcb kdb_pcb; 47 struct pcb *kdb_thrctx = NULL; 48 struct thread *kdb_thread = NULL; 49 struct trapframe *kdb_frame = NULL; 50 51 KDB_BACKEND(null, NULL, NULL, NULL); 52 SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe); 53 54 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS); 55 static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS); 56 static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS); 57 58 SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes"); 59 60 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, 0, 0, 61 kdb_sysctl_available, "A", "list of available KDB backends"); 62 63 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, 0, 0, 64 kdb_sysctl_current, "A", "currently selected KDB backend"); 65 66 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 67 kdb_sysctl_enter, "I", "set to enter the debugger"); 68 69 /* 70 * Flag indicating whether or not to IPI the other CPUs to stop them on 71 * entering the debugger. Sometimes, this will result in a deadlock as 72 * stop_cpus() waits for the other cpus to stop, so we allow it to be 73 * disabled. 74 */ 75 #ifdef SMP 76 static int kdb_stop_cpus = 1; 77 SYSCTL_INT(_debug_kdb, OID_AUTO, stop_cpus, CTLTYPE_INT | CTLFLAG_RW, 78 &kdb_stop_cpus, 0, ""); 79 TUNABLE_INT("debug.kdb.stop_cpus", &kdb_stop_cpus); 80 #endif 81 82 static int 83 kdb_sysctl_available(SYSCTL_HANDLER_ARGS) 84 { 85 struct kdb_dbbe *be, **iter; 86 char *avail, *p; 87 ssize_t len, sz; 88 int error; 89 90 sz = 0; 91 SET_FOREACH(iter, kdb_dbbe_set) { 92 be = *iter; 93 if (be->dbbe_active == 0) 94 sz += strlen(be->dbbe_name) + 1; 95 } 96 sz++; 97 avail = malloc(sz, M_TEMP, M_WAITOK); 98 p = avail; 99 *p = '\0'; 100 101 SET_FOREACH(iter, kdb_dbbe_set) { 102 be = *iter; 103 if (be->dbbe_active == 0) { 104 len = snprintf(p, sz, "%s ", be->dbbe_name); 105 p += len; 106 sz -= len; 107 } 108 } 109 KASSERT(sz >= 0, ("%s", __func__)); 110 error = sysctl_handle_string(oidp, avail, 0, req); 111 free(avail, M_TEMP); 112 return (error); 113 } 114 115 static int 116 kdb_sysctl_current(SYSCTL_HANDLER_ARGS) 117 { 118 char buf[16]; 119 int error; 120 121 if (kdb_dbbe != NULL) { 122 strncpy(buf, kdb_dbbe->dbbe_name, sizeof(buf)); 123 buf[sizeof(buf) - 1] = '\0'; 124 } else 125 *buf = '\0'; 126 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 127 if (error != 0 || req->newptr == NULL) 128 return (error); 129 if (kdb_active) 130 return (EBUSY); 131 return (kdb_dbbe_select(buf)); 132 } 133 134 static int 135 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS) 136 { 137 int error, i; 138 139 error = sysctl_wire_old_buffer(req, sizeof(int)); 140 if (error == 0) { 141 i = 0; 142 error = sysctl_handle_int(oidp, &i, 0, req); 143 } 144 if (error != 0 || req->newptr == NULL) 145 return (error); 146 if (kdb_active) 147 return (EBUSY); 148 kdb_enter("sysctl debug.kdb.enter"); 149 return (0); 150 } 151 152 /* 153 * Solaris implements a new BREAK which is initiated by a character sequence 154 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the 155 * Remote Console. 156 * 157 * Note that this function may be called from almost anywhere, with interrupts 158 * disabled and with unknown locks held, so it must not access data other than 159 * its arguments. Its up to the caller to ensure that the state variable is 160 * consistent. 161 */ 162 163 #define KEY_CR 13 /* CR '\r' */ 164 #define KEY_TILDE 126 /* ~ */ 165 #define KEY_CRTLB 2 /* ^B */ 166 167 int 168 kdb_alt_break(int key, int *state) 169 { 170 int brk; 171 172 brk = 0; 173 switch (key) { 174 case KEY_CR: 175 *state = KEY_TILDE; 176 break; 177 case KEY_TILDE: 178 *state = (*state == KEY_TILDE) ? KEY_CRTLB : 0; 179 break; 180 case KEY_CRTLB: 181 if (*state == KEY_CRTLB) 182 brk = 1; 183 /* FALLTHROUGH */ 184 default: 185 *state = 0; 186 break; 187 } 188 return (brk); 189 } 190 191 /* 192 * Print a backtrace of the calling thread. The backtrace is generated by 193 * the selected debugger, provided it supports backtraces. If no debugger 194 * is selected or the current debugger does not support backtraces, this 195 * function silently returns. 196 */ 197 198 void 199 kdb_backtrace() 200 { 201 202 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) { 203 printf("KDB: stack backtrace:\n"); 204 kdb_dbbe->dbbe_trace(); 205 } 206 } 207 208 /* 209 * Set/change the current backend. 210 */ 211 212 int 213 kdb_dbbe_select(const char *name) 214 { 215 struct kdb_dbbe *be, **iter; 216 217 SET_FOREACH(iter, kdb_dbbe_set) { 218 be = *iter; 219 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) { 220 kdb_dbbe = be; 221 return (0); 222 } 223 } 224 return (EINVAL); 225 } 226 227 /* 228 * Enter the currently selected debugger. If a message has been provided, 229 * it is printed first. If the debugger does not support the enter method, 230 * it is entered by using breakpoint(), which enters the debugger through 231 * kdb_trap(). 232 */ 233 234 void 235 kdb_enter(const char *msg) 236 { 237 238 if (kdb_dbbe != NULL && kdb_active == 0) { 239 if (msg != NULL) 240 printf("KDB: enter: %s\n", msg); 241 breakpoint(); 242 } 243 } 244 245 /* 246 * Initialize the kernel debugger interface. 247 */ 248 249 void 250 kdb_init() 251 { 252 struct kdb_dbbe *be, **iter; 253 int cur_pri, pri; 254 255 kdb_active = 0; 256 kdb_dbbe = NULL; 257 cur_pri = -1; 258 SET_FOREACH(iter, kdb_dbbe_set) { 259 be = *iter; 260 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1; 261 be->dbbe_active = (pri >= 0) ? 0 : -1; 262 if (pri > cur_pri) { 263 cur_pri = pri; 264 kdb_dbbe = be; 265 } 266 } 267 if (kdb_dbbe != NULL) { 268 printf("KDB: debugger backends:"); 269 SET_FOREACH(iter, kdb_dbbe_set) { 270 be = *iter; 271 if (be->dbbe_active == 0) 272 printf(" %s", be->dbbe_name); 273 } 274 printf("\n"); 275 printf("KDB: current backend: %s\n", 276 kdb_dbbe->dbbe_name); 277 } 278 } 279 280 /* 281 * Handle contexts. 282 */ 283 284 void * 285 kdb_jmpbuf(jmp_buf new) 286 { 287 void *old; 288 289 old = kdb_jmpbufp; 290 kdb_jmpbufp = new; 291 return (old); 292 } 293 294 void 295 kdb_reenter(void) 296 { 297 298 if (!kdb_active || kdb_jmpbufp == NULL) 299 return; 300 301 longjmp(kdb_jmpbufp, 1); 302 /* NOTREACHED */ 303 } 304 305 /* 306 * Thread related support functions. 307 */ 308 309 struct pcb * 310 kdb_thr_ctx(struct thread *thr) 311 { 312 return ((thr == curthread) ? &kdb_pcb : thr->td_pcb); 313 } 314 315 struct thread * 316 kdb_thr_first(void) 317 { 318 struct proc *p; 319 struct thread *thr; 320 321 p = LIST_FIRST(&allproc); 322 while (p != NULL) { 323 if (p->p_sflag & PS_INMEM) { 324 thr = FIRST_THREAD_IN_PROC(p); 325 if (thr != NULL) 326 return (thr); 327 } 328 p = LIST_NEXT(p, p_list); 329 } 330 return (NULL); 331 } 332 333 struct thread * 334 kdb_thr_from_pid(pid_t pid) 335 { 336 struct proc *p; 337 338 p = LIST_FIRST(&allproc); 339 while (p != NULL) { 340 if (p->p_sflag & PS_INMEM && p->p_pid == pid) 341 return (FIRST_THREAD_IN_PROC(p)); 342 p = LIST_NEXT(p, p_list); 343 } 344 return (NULL); 345 } 346 347 struct thread * 348 kdb_thr_lookup(lwpid_t tid) 349 { 350 struct thread *thr; 351 352 thr = kdb_thr_first(); 353 while (thr != NULL && thr->td_tid != tid) 354 thr = kdb_thr_next(thr); 355 return (thr); 356 } 357 358 struct thread * 359 kdb_thr_next(struct thread *thr) 360 { 361 struct proc *p; 362 363 p = thr->td_proc; 364 thr = TAILQ_NEXT(thr, td_plist); 365 do { 366 if (thr != NULL) 367 return (thr); 368 p = LIST_NEXT(p, p_list); 369 if (p != NULL && (p->p_sflag & PS_INMEM)) 370 thr = FIRST_THREAD_IN_PROC(p); 371 } while (p != NULL); 372 return (NULL); 373 } 374 375 int 376 kdb_thr_select(struct thread *thr) 377 { 378 if (thr == NULL) 379 return (EINVAL); 380 kdb_thread = thr; 381 kdb_thrctx = kdb_thr_ctx(thr); 382 return (0); 383 } 384 385 /* 386 * Enter the debugger due to a trap. 387 */ 388 389 int 390 kdb_trap(int type, int code, struct trapframe *tf) 391 { 392 #ifdef SMP 393 int did_stop_cpus; 394 #endif 395 int handled; 396 397 if (kdb_dbbe == NULL || kdb_dbbe->dbbe_trap == NULL) 398 return (0); 399 400 /* We reenter the debugger through kdb_reenter(). */ 401 if (kdb_active) 402 return (0); 403 404 critical_enter(); 405 406 kdb_active++; 407 408 #ifdef SMP 409 if ((did_stop_cpus = kdb_stop_cpus) != 0) 410 stop_cpus(PCPU_GET(other_cpus)); 411 #endif 412 413 kdb_frame = tf; 414 415 /* Let MD code do its thing first... */ 416 kdb_cpu_trap(type, code); 417 418 makectx(tf, &kdb_pcb); 419 kdb_thr_select(curthread); 420 421 handled = kdb_dbbe->dbbe_trap(type, code); 422 423 #ifdef SMP 424 if (did_stop_cpus) 425 restart_cpus(stopped_cpus); 426 #endif 427 428 kdb_active--; 429 430 critical_exit(); 431 432 return (handled); 433 } 434