kgdb_stub.c revision 1.26
1 /* $NetBSD: kgdb_stub.c,v 1.26 2013/05/11 15:44:46 skrll Exp $ */ 2 3 /* 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This software was developed by the Computer Systems Engineering group 8 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 9 * contributed to Berkeley. 10 * 11 * All advertising materials mentioning features or use of this software 12 * must display the following acknowledgement: 13 * This product includes software developed by the University of 14 * California, Lawrence Berkeley Laboratories. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 3. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * @(#)kgdb_stub.c 8.4 (Berkeley) 1/12/94 41 */ 42 43 /* 44 * "Stub" to allow remote CPU to debug over a serial line using gdb. 45 */ 46 47 #include <sys/cdefs.h> 48 __KERNEL_RCSID(0, "$NetBSD: kgdb_stub.c,v 1.26 2013/05/11 15:44:46 skrll Exp $"); 49 50 #include "opt_ddb.h" 51 #include "opt_kgdb.h" 52 53 #include <sys/param.h> 54 #include <sys/systm.h> 55 #include <sys/kgdb.h> 56 57 #undef DEBUG_KGDB 58 59 #ifdef DEBUG_KGDB 60 #define DPRINTF(x) printf x 61 #else 62 #define DPRINTF(x) 63 #endif 64 65 /* XXX: Maybe these should be in the MD files? */ 66 #ifndef KGDB_DEV 67 #define KGDB_DEV NODEV 68 #endif 69 #ifndef KGDB_DEVRATE 70 #define KGDB_DEVRATE 19200 71 #endif 72 73 dev_t kgdb_dev = KGDB_DEV; /* remote debugging device (NODEV if none) */ 74 int kgdb_rate = KGDB_DEVRATE; /* remote debugging baud rate */ 75 int kgdb_active = 0; /* remote debugging active if != 0 */ 76 int kgdb_debug_init = 0; /* != 0 waits for remote at system init */ 77 int kgdb_debug_panic = 0; /* != 0 waits for remote on panic */ 78 label_t *kgdb_recover = 0; 79 80 static int (*kgdb_getc)(void *); 81 static void (*kgdb_putc)(void *, int); 82 static void *kgdb_ioarg; 83 84 /* KGDB_BUFLEN must be at least (2*KGDB_NUMREGS*sizeof(kgdb_reg_t)+1) */ 85 static u_char buffer[KGDB_BUFLEN]; 86 static kgdb_reg_t gdb_regs[KGDB_NUMREGS]; 87 88 #define GETC() ((*kgdb_getc)(kgdb_ioarg)) 89 #define PUTC(c) ((*kgdb_putc)(kgdb_ioarg, c)) 90 91 /* 92 * db_trap_callback can be hooked by MD port code to handle special 93 * cases such as disabling hardware watchdogs while in kgdb. Name 94 * is shared with DDB. 95 */ 96 #ifdef DDB 97 extern void (*db_trap_callback)(int); 98 #else 99 void (*db_trap_callback)(int); 100 #endif 101 102 void kgdb_voidop(void); 103 104 __weak_alias(kgdb_entry_notice, kgdb_voidop); 105 106 void 107 kgdb_voidop(void) 108 { 109 return; 110 } 111 112 /* 113 * This little routine exists simply so that bcopy() can be debugged. 114 */ 115 static void 116 kgdb_copy(void *vsrc, void *vdst, int len) 117 { 118 char *src = vsrc; 119 char *dst = vdst; 120 121 while (--len >= 0) 122 *dst++ = *src++; 123 } 124 125 #if 0 126 /* ditto for bzero */ 127 static void 128 kgdb_zero(void *vptr, int len) 129 { 130 char *ptr = vptr; 131 132 while (--len >= 0) 133 *ptr++ = (char) 0; 134 } 135 #endif 136 137 /* 138 * Convert a hex digit into an integer. 139 * This returns -1 if the argument passed is no 140 * valid hex digit. 141 */ 142 static int 143 digit2i(u_char c) 144 { 145 if (c >= '0' && c <= '9') 146 return (c - '0'); 147 else if (c >= 'a' && c <= 'f') 148 return (c - 'a' + 10); 149 else if (c >= 'A' && c <= 'F') 150 151 return (c - 'A' + 10); 152 else 153 return (-1); 154 } 155 156 /* 157 * Convert the low 4 bits of an integer into 158 * an hex digit. 159 */ 160 static u_char 161 i2digit(int n) 162 { 163 return (hexdigits[n & 0x0f]); 164 } 165 166 /* 167 * Convert a byte array into an hex string. 168 */ 169 static void 170 mem2hex(void *vdst, void *vsrc, int len) 171 { 172 u_char *dst = vdst; 173 u_char *src = vsrc; 174 175 while (len--) { 176 *dst++ = i2digit(*src >> 4); 177 *dst++ = i2digit(*src++); 178 } 179 *dst = '\0'; 180 } 181 182 /* 183 * Convert an hex string into a byte array. 184 * This returns a pointer to the character following 185 * the last valid hex digit. If the string ends in 186 * the middle of a byte, NULL is returned. 187 */ 188 static u_char * 189 hex2mem(void *vdst, u_char *src, int maxlen) 190 { 191 u_char *dst = vdst; 192 int msb, lsb; 193 194 while (*src && maxlen--) { 195 msb = digit2i(*src++); 196 if (msb < 0) 197 return (src - 1); 198 lsb = digit2i(*src++); 199 if (lsb < 0) 200 return (NULL); 201 *dst++ = (msb << 4) | lsb; 202 } 203 return (src); 204 } 205 206 /* 207 * Convert an hex string into an integer. 208 * This returns a pointer to the character following 209 * the last valid hex digit. 210 */ 211 static vaddr_t 212 hex2i(u_char **srcp) 213 { 214 char *src = *srcp; 215 vaddr_t r = 0; 216 int nibble; 217 218 while ((nibble = digit2i(*src)) >= 0) { 219 r *= 16; 220 r += nibble; 221 src++; 222 } 223 *srcp = src; 224 return (r); 225 } 226 227 /* 228 * Send a packet. 229 */ 230 static void 231 kgdb_send(const u_char *bp) 232 { 233 const u_char *p; 234 u_char csum, c; 235 236 DPRINTF(("kgdb_send: %s\n", bp)); 237 do { 238 p = bp; 239 PUTC(KGDB_START); 240 for (csum = 0; (c = *p); p++) { 241 PUTC(c); 242 csum += c; 243 } 244 PUTC(KGDB_END); 245 PUTC(i2digit(csum >> 4)); 246 PUTC(i2digit(csum)); 247 } while ((c = GETC() & 0x7f) == KGDB_BADP); 248 } 249 250 /* 251 * Receive a packet. 252 */ 253 static int 254 kgdb_recv(u_char *bp, int maxlen) 255 { 256 u_char *p; 257 int c, csum, tmpcsum; 258 int len; 259 260 DPRINTF(("kgdb_recv: ")); 261 do { 262 p = bp; 263 csum = len = 0; 264 while ((c = GETC()) != KGDB_START) 265 DPRINTF(("%c",c)); 266 DPRINTF(("%c Start ",c)); 267 268 while ((c = GETC()) != KGDB_END && len < maxlen) { 269 DPRINTF(("%c",c)); 270 c &= 0x7f; 271 csum += c; 272 *p++ = c; 273 len++; 274 } 275 csum &= 0xff; 276 *p = '\0'; 277 DPRINTF(("%c End ", c)); 278 279 if (len >= maxlen) { 280 DPRINTF(("Long- ")); 281 PUTC(KGDB_BADP); 282 continue; 283 } 284 tmpcsum = csum; 285 286 c = GETC(); 287 DPRINTF(("%c",c)); 288 csum -= digit2i(c) * 16; 289 c = GETC(); 290 DPRINTF(("%c",c)); 291 csum -= digit2i(c); 292 293 if (csum == 0) { 294 DPRINTF(("Good+ ")); 295 PUTC(KGDB_GOODP); 296 /* Sequence present? */ 297 if (bp[2] == ':') { 298 DPRINTF(("Seq %c%c ", bp[0], bp[1])); 299 PUTC(bp[0]); 300 PUTC(bp[1]); 301 len -= 3; 302 kgdb_copy(bp + 3, bp, len); 303 } 304 break; 305 } 306 DPRINTF((" Bad(wanted %x, off by %d)- ", tmpcsum, csum)); 307 PUTC(KGDB_BADP); 308 } while (1); 309 DPRINTF(("kgdb_recv: %s\n", bp)); 310 return (len); 311 } 312 313 /* 314 * This is called by the appropriate tty driver. 315 */ 316 void 317 kgdb_attach(int (*getfn)(void *), void (*putfn)(void *, int), void *ioarg) 318 { 319 kgdb_getc = getfn; 320 kgdb_putc = putfn; 321 kgdb_ioarg = ioarg; 322 } 323 324 /* 325 * This function does all command processing for interfacing to 326 * a remote gdb. Note that the error codes are ignored by gdb 327 * at present, but might eventually become meaningful. (XXX) 328 * It might makes sense to use POSIX errno values, because 329 * that is what the gdb/remote.c functions want to return. 330 */ 331 int 332 kgdb_trap(int type, db_regs_t *regs) 333 { 334 label_t jmpbuf; 335 vaddr_t addr; 336 size_t len; 337 u_char *p; 338 339 kgdb_entry_notice(type, regs); 340 341 if (kgdb_dev == NODEV || kgdb_getc == NULL) { 342 /* not debugging */ 343 return (0); 344 } 345 346 db_clear_single_step(regs); 347 348 if (db_trap_callback) 349 db_trap_callback(1); 350 351 /* Detect and recover from unexpected traps. */ 352 if (kgdb_recover != 0) { 353 printf("kgdb: caught trap 0x%x at %p\n", 354 type, (void*)PC_REGS(regs)); 355 kgdb_send("E0E"); /* 14==EFAULT */ 356 longjmp(kgdb_recover); 357 } 358 359 /* 360 * The first entry to this function is normally through 361 * a breakpoint trap in kgdb_connect(), in which case we 362 * must advance past the breakpoint because gdb will not. 363 * 364 * Machines vary as to where they leave the PC after a 365 * breakpoint trap. Those that leave the PC set to the 366 * address of the trap instruction (i.e. pc532) will not 367 * define FIXUP_PC_AFTER_BREAK(), and therefore will just 368 * advance the PC. On machines that leave the PC set to 369 * the instruction after the trap, FIXUP_PC_AFTER_BREAK 370 * will be defined to back-up the PC, so that after the 371 * "first-time" part of the if statement below has run, 372 * the PC will be the same as it was on entry. 373 * 374 * On the first entry here, we expect that gdb is not yet 375 * listening to us, so just enter the interaction loop. 376 * After the debugger is "active" (connected) it will be 377 * waiting for a "signaled" message from us. 378 */ 379 if (kgdb_active == 0) { 380 if (!IS_BREAKPOINT_TRAP(type, 0)) { 381 /* No debugger active -- let trap handle this. */ 382 if (db_trap_callback) 383 db_trap_callback(0); 384 return (0); 385 } 386 /* Make the PC point at the breakpoint... */ 387 #ifdef FIXUP_PC_AFTER_BREAK 388 FIXUP_PC_AFTER_BREAK(regs); 389 #endif 390 /* ... and then advance past it. */ 391 #ifdef PC_ADVANCE 392 PC_ADVANCE(regs); 393 #else 394 PC_REGS(regs) += BKPT_SIZE; 395 #endif 396 kgdb_active = 1; 397 } else { 398 /* Tell remote host that an exception has occurred. */ 399 snprintf(buffer, sizeof(buffer), "S%02x", kgdb_signal(type)); 400 kgdb_send(buffer); 401 } 402 403 /* Stick frame regs into our reg cache. */ 404 kgdb_getregs(regs, gdb_regs); 405 406 /* 407 * Interact with gdb until it lets us go. 408 * If we cause a trap, resume here. 409 */ 410 (void)setjmp((kgdb_recover = &jmpbuf)); 411 for (;;) { 412 kgdb_recv(buffer, sizeof(buffer)); 413 switch (buffer[0]) { 414 415 default: 416 /* Unknown command. */ 417 kgdb_send(""); 418 continue; 419 420 case KGDB_SIGNAL: 421 /* 422 * if this command came from a running gdb, 423 * answer it -- the other guy has no way of 424 * knowing if we're in or out of this loop 425 * when he issues a "remote-signal". 426 */ 427 snprintf(buffer, sizeof(buffer), "S%02x", 428 kgdb_signal(type)); 429 kgdb_send(buffer); 430 continue; 431 432 case KGDB_REG_R: 433 mem2hex(buffer, gdb_regs, sizeof(gdb_regs)); 434 kgdb_send(buffer); 435 continue; 436 437 case KGDB_REG_W: 438 p = hex2mem(gdb_regs, buffer + 1, sizeof(gdb_regs)); 439 if (p == NULL || *p != '\0') 440 kgdb_send("E01"); 441 else { 442 kgdb_setregs(regs, gdb_regs); 443 kgdb_send("OK"); 444 } 445 continue; 446 447 case KGDB_MEM_R: 448 p = buffer + 1; 449 addr = hex2i(&p); 450 if (*p++ != ',') { 451 kgdb_send("E02"); 452 continue; 453 } 454 len = hex2i(&p); 455 if (*p != '\0') { 456 kgdb_send("E03"); 457 continue; 458 } 459 if (len > sizeof(buffer) / 2) { 460 kgdb_send("E04"); 461 continue; 462 } 463 if (kgdb_acc(addr, len) == 0) { 464 kgdb_send("E05"); 465 continue; 466 } 467 db_read_bytes(addr, (size_t)len, 468 (char *)buffer + sizeof(buffer) / 2); 469 mem2hex(buffer, buffer + sizeof(buffer) / 2, len); 470 kgdb_send(buffer); 471 continue; 472 473 case KGDB_MEM_W: 474 p = buffer + 1; 475 addr = hex2i(&p); 476 if (*p++ != ',') { 477 kgdb_send("E06"); 478 continue; 479 } 480 len = hex2i(&p); 481 if (*p++ != ':') { 482 kgdb_send("E07"); 483 continue; 484 } 485 if (len > (sizeof(buffer) - (p - buffer))) { 486 kgdb_send("E08"); 487 continue; 488 } 489 p = hex2mem(buffer, p, sizeof(buffer)); 490 if (p == NULL) { 491 kgdb_send("E09"); 492 continue; 493 } 494 if (kgdb_acc(addr, len) == 0) { 495 kgdb_send("E0A"); 496 continue; 497 } 498 db_write_bytes(addr, (size_t)len, (char *)buffer); 499 kgdb_send("OK"); 500 continue; 501 502 case KGDB_DETACH: 503 case KGDB_KILL: 504 kgdb_active = 0; 505 printf("kgdb detached\n"); 506 db_clear_single_step(regs); 507 kgdb_send("OK"); 508 goto out; 509 510 case KGDB_CONT: 511 if (buffer[1]) { 512 p = buffer + 1; 513 addr = hex2i(&p); 514 if (*p) { 515 kgdb_send("E0B"); 516 continue; 517 } 518 PC_REGS(regs) = addr; 519 DPRINTF(("kgdb: continuing at %08lx\n", addr)); 520 521 } else { 522 DPRINTF(( 523 "kgdb: continuing at old address %08lx\n", 524 (vaddr_t)PC_REGS(regs))); 525 } 526 527 db_clear_single_step(regs); 528 goto out; 529 530 case KGDB_STEP: 531 if (buffer[1]) { 532 p = buffer + 1; 533 addr = hex2i(&p); 534 if (*p) { 535 kgdb_send("E0B"); 536 continue; 537 } 538 PC_REGS(regs) = addr; 539 } 540 db_set_single_step(regs); 541 goto out; 542 } 543 } 544 out: 545 if (db_trap_callback) 546 db_trap_callback(0); 547 kgdb_recover = 0; 548 return (1); 549 } 550 551 int 552 kgdb_disconnected(void) 553 { 554 return 1; 555 } 556
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