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