1 /* taken from arch/powerpc/kernel/ppc-stub.c */ 2 3 /**************************************************************************** 4 5 THIS SOFTWARE IS NOT COPYRIGHTED 6 7 HP offers the following for use in the public domain. HP makes no 8 warranty with regard to the software or its performance and the 9 user accepts the software "AS IS" with all faults. 10 11 HP DISCLAIMS ANY WARRANTIES, EXPRESS OR IMPLIED, WITH REGARD 12 TO THIS SOFTWARE INCLUDING BUT NOT LIMITED TO THE WARRANTIES 13 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 14 15 ****************************************************************************/ 16 17 /**************************************************************************** 18 * Header: remcom.c,v 1.34 91/03/09 12:29:49 glenne Exp $ 19 * 20 * Module name: remcom.c $ 21 * Revision: 1.34 $ 22 * Date: 91/03/09 12:29:49 $ 23 * Contributor: Lake Stevens Instrument Division$ 24 * 25 * Description: low level support for gdb debugger. $ 26 * 27 * Considerations: only works on target hardware $ 28 * 29 * Written by: Glenn Engel $ 30 * ModuleState: Experimental $ 31 * 32 * NOTES: See Below $ 33 * 34 * Modified for SPARC by Stu Grossman, Cygnus Support. 35 * 36 * This code has been extensively tested on the Fujitsu SPARClite demo board. 37 * 38 * To enable debugger support, two things need to happen. One, a 39 * call to set_debug_traps() is necessary in order to allow any breakpoints 40 * or error conditions to be properly intercepted and reported to gdb. 41 * Two, a breakpoint needs to be generated to begin communication. This 42 * is most easily accomplished by a call to breakpoint(). Breakpoint() 43 * simulates a breakpoint by executing a trap #1. 44 * 45 ************* 46 * 47 * The following gdb commands are supported: 48 * 49 * command function Return value 50 * 51 * g return the value of the CPU registers hex data or ENN 52 * G set the value of the CPU registers OK or ENN 53 * qOffsets Get section offsets. Reply is Text=xxx;Data=yyy;Bss=zzz 54 * 55 * mAA..AA,LLLL Read LLLL bytes at address AA..AA hex data or ENN 56 * MAA..AA,LLLL: Write LLLL bytes at address AA.AA OK or ENN 57 * 58 * c Resume at current address SNN ( signal NN) 59 * cAA..AA Continue at address AA..AA SNN 60 * 61 * s Step one instruction SNN 62 * sAA..AA Step one instruction from AA..AA SNN 63 * 64 * k kill 65 * 66 * ? What was the last sigval ? SNN (signal NN) 67 * 68 * bBB..BB Set baud rate to BB..BB OK or BNN, then sets 69 * baud rate 70 * 71 * All commands and responses are sent with a packet which includes a 72 * checksum. A packet consists of 73 * 74 * $<packet info>#<checksum>. 75 * 76 * where 77 * <packet info> :: <characters representing the command or response> 78 * <checksum> :: <two hex digits computed as modulo 256 sum of <packetinfo>> 79 * 80 * When a packet is received, it is first acknowledged with either '+' or '-'. 81 * '+' indicates a successful transfer. '-' indicates a failed transfer. 82 * 83 * Example: 84 * 85 * Host: Reply: 86 * $m0,10#2a +$00010203040506070809101112131415#42 87 * 88 ****************************************************************************/ 89 90 #include <common.h> 91 92 #include <kgdb.h> 93 #include <command.h> 94 95 #undef KGDB_DEBUG 96 97 /* 98 * BUFMAX defines the maximum number of characters in inbound/outbound buffers 99 */ 100 #define BUFMAX 1024 101 static char remcomInBuffer[BUFMAX]; 102 static char remcomOutBuffer[BUFMAX]; 103 static char remcomRegBuffer[BUFMAX]; 104 105 static int initialized = 0; 106 static int kgdb_active = 0, first_entry = 1; 107 static struct pt_regs entry_regs; 108 static long error_jmp_buf[BUFMAX/2]; 109 static int longjmp_on_fault = 0; 110 #ifdef KGDB_DEBUG 111 static int kdebug = 1; 112 #endif 113 114 static const char hexchars[]="0123456789abcdef"; 115 116 /* Convert ch from a hex digit to an int */ 117 static int 118 hex(unsigned char ch) 119 { 120 if (ch >= 'a' && ch <= 'f') 121 return ch-'a'+10; 122 if (ch >= '0' && ch <= '9') 123 return ch-'0'; 124 if (ch >= 'A' && ch <= 'F') 125 return ch-'A'+10; 126 return -1; 127 } 128 129 /* Convert the memory pointed to by mem into hex, placing result in buf. 130 * Return a pointer to the last char put in buf (null). 131 */ 132 static unsigned char * 133 mem2hex(char *mem, char *buf, int count) 134 { 135 char *tmp; 136 unsigned char ch; 137 138 /* 139 * We use the upper half of buf as an intermediate buffer for the 140 * raw memory copy. Hex conversion will work against this one. 141 */ 142 tmp = buf + count; 143 longjmp_on_fault = 1; 144 145 memcpy(tmp, mem, count); 146 147 while (count-- > 0) { 148 ch = *tmp++; 149 *buf++ = hexchars[ch >> 4]; 150 *buf++ = hexchars[ch & 0xf]; 151 } 152 *buf = 0; 153 longjmp_on_fault = 0; 154 return (unsigned char *)buf; 155 } 156 157 /* convert the hex array pointed to by buf into binary to be placed in mem 158 * return a pointer to the character AFTER the last byte fetched from buf. 159 */ 160 static char * 161 hex2mem(char *buf, char *mem, int count) 162 { 163 int hexValue; 164 char *tmp_raw, *tmp_hex; 165 166 /* 167 * We use the upper half of buf as an intermediate buffer for the 168 * raw memory that is converted from hex. 169 */ 170 tmp_raw = buf + count * 2; 171 tmp_hex = tmp_raw - 1; 172 173 longjmp_on_fault = 1; 174 while (tmp_hex >= buf) { 175 tmp_raw--; 176 hexValue = hex(*tmp_hex--); 177 if (hexValue < 0) 178 kgdb_error(KGDBERR_NOTHEXDIG); 179 *tmp_raw = hexValue; 180 hexValue = hex(*tmp_hex--); 181 if (hexValue < 0) 182 kgdb_error(KGDBERR_NOTHEXDIG); 183 *tmp_raw |= hexValue << 4; 184 185 } 186 187 memcpy(mem, tmp_raw, count); 188 189 kgdb_flush_cache_range((void *)mem, (void *)(mem+count)); 190 longjmp_on_fault = 0; 191 192 return buf; 193 } 194 195 /* 196 * While we find nice hex chars, build an int. 197 * Return number of chars processed. 198 */ 199 static int 200 hexToInt(char **ptr, int *intValue) 201 { 202 int numChars = 0; 203 int hexValue; 204 205 *intValue = 0; 206 207 longjmp_on_fault = 1; 208 while (**ptr) { 209 hexValue = hex(**ptr); 210 if (hexValue < 0) 211 break; 212 213 *intValue = (*intValue << 4) | hexValue; 214 numChars ++; 215 216 (*ptr)++; 217 } 218 longjmp_on_fault = 0; 219 220 return (numChars); 221 } 222 223 /* scan for the sequence $<data>#<checksum> */ 224 static void 225 getpacket(char *buffer) 226 { 227 unsigned char checksum; 228 unsigned char xmitcsum; 229 int i; 230 int count; 231 unsigned char ch; 232 233 do { 234 /* wait around for the start character, ignore all other 235 * characters */ 236 while ((ch = (getDebugChar() & 0x7f)) != '$') { 237 #ifdef KGDB_DEBUG 238 if (kdebug) 239 putc(ch); 240 #endif 241 ; 242 } 243 244 checksum = 0; 245 xmitcsum = -1; 246 247 count = 0; 248 249 /* now, read until a # or end of buffer is found */ 250 while (count < BUFMAX) { 251 ch = getDebugChar() & 0x7f; 252 if (ch == '#') 253 break; 254 checksum = checksum + ch; 255 buffer[count] = ch; 256 count = count + 1; 257 } 258 259 if (count >= BUFMAX) 260 continue; 261 262 buffer[count] = 0; 263 264 if (ch == '#') { 265 xmitcsum = hex(getDebugChar() & 0x7f) << 4; 266 xmitcsum |= hex(getDebugChar() & 0x7f); 267 if (checksum != xmitcsum) 268 putDebugChar('-'); /* failed checksum */ 269 else { 270 putDebugChar('+'); /* successful transfer */ 271 /* if a sequence char is present, reply the ID */ 272 if (buffer[2] == ':') { 273 putDebugChar(buffer[0]); 274 putDebugChar(buffer[1]); 275 /* remove sequence chars from buffer */ 276 count = strlen(buffer); 277 for (i=3; i <= count; i++) 278 buffer[i-3] = buffer[i]; 279 } 280 } 281 } 282 } while (checksum != xmitcsum); 283 } 284 285 /* send the packet in buffer. */ 286 static void 287 putpacket(unsigned char *buffer) 288 { 289 unsigned char checksum; 290 int count; 291 unsigned char ch, recv; 292 293 /* $<packet info>#<checksum>. */ 294 do { 295 putDebugChar('$'); 296 checksum = 0; 297 count = 0; 298 299 while ((ch = buffer[count])) { 300 putDebugChar(ch); 301 checksum += ch; 302 count += 1; 303 } 304 305 putDebugChar('#'); 306 putDebugChar(hexchars[checksum >> 4]); 307 putDebugChar(hexchars[checksum & 0xf]); 308 recv = getDebugChar(); 309 } while ((recv & 0x7f) != '+'); 310 } 311 312 /* 313 * This function does all command processing for interfacing to gdb. 314 */ 315 static int 316 handle_exception (struct pt_regs *regs) 317 { 318 int addr; 319 int length; 320 char *ptr; 321 kgdb_data kd; 322 int i; 323 324 if (!initialized) { 325 printf("kgdb: exception before kgdb is initialized! huh?\n"); 326 return (0); 327 } 328 329 /* probably should check which exception occured as well */ 330 if (longjmp_on_fault) { 331 longjmp_on_fault = 0; 332 kgdb_longjmp(error_jmp_buf, KGDBERR_MEMFAULT); 333 panic("kgdb longjump failed!\n"); 334 } 335 336 if (kgdb_active) { 337 printf("kgdb: unexpected exception from within kgdb\n"); 338 return (0); 339 } 340 kgdb_active = 1; 341 342 kgdb_interruptible(0); 343 344 printf("kgdb: handle_exception; trap [0x%x]\n", kgdb_trap(regs)); 345 346 if (kgdb_setjmp(error_jmp_buf) != 0) 347 panic("kgdb: error or fault in entry init!\n"); 348 349 kgdb_enter(regs, &kd); 350 351 if (first_entry) { 352 /* 353 * the first time we enter kgdb, we save the processor 354 * state so that we can return to the monitor if the 355 * remote end quits gdb (or at least, tells us to quit 356 * with the 'k' packet) 357 */ 358 entry_regs = *regs; 359 first_entry = 0; 360 } 361 362 ptr = remcomOutBuffer; 363 364 *ptr++ = 'T'; 365 366 *ptr++ = hexchars[kd.sigval >> 4]; 367 *ptr++ = hexchars[kd.sigval & 0xf]; 368 369 for (i = 0; i < kd.nregs; i++) { 370 kgdb_reg *rp = &kd.regs[i]; 371 372 *ptr++ = hexchars[rp->num >> 4]; 373 *ptr++ = hexchars[rp->num & 0xf]; 374 *ptr++ = ':'; 375 ptr = (char *)mem2hex((char *)&rp->val, ptr, 4); 376 *ptr++ = ';'; 377 } 378 379 *ptr = 0; 380 381 #ifdef KGDB_DEBUG 382 if (kdebug) 383 printf("kgdb: remcomOutBuffer: %s\n", remcomOutBuffer); 384 #endif 385 386 putpacket((unsigned char *)&remcomOutBuffer); 387 388 while (1) { 389 volatile int errnum; 390 391 remcomOutBuffer[0] = 0; 392 393 getpacket(remcomInBuffer); 394 ptr = &remcomInBuffer[1]; 395 396 #ifdef KGDB_DEBUG 397 if (kdebug) 398 printf("kgdb: remcomInBuffer: %s\n", remcomInBuffer); 399 #endif 400 401 errnum = kgdb_setjmp(error_jmp_buf); 402 403 if (errnum == 0) switch (remcomInBuffer[0]) { 404 405 case '?': /* report most recent signal */ 406 remcomOutBuffer[0] = 'S'; 407 remcomOutBuffer[1] = hexchars[kd.sigval >> 4]; 408 remcomOutBuffer[2] = hexchars[kd.sigval & 0xf]; 409 remcomOutBuffer[3] = 0; 410 break; 411 412 #ifdef KGDB_DEBUG 413 case 'd': 414 /* toggle debug flag */ 415 kdebug ^= 1; 416 break; 417 #endif 418 419 case 'g': /* return the value of the CPU registers. */ 420 length = kgdb_getregs(regs, remcomRegBuffer, BUFMAX); 421 mem2hex(remcomRegBuffer, remcomOutBuffer, length); 422 break; 423 424 case 'G': /* set the value of the CPU registers */ 425 length = strlen(ptr); 426 if ((length & 1) != 0) kgdb_error(KGDBERR_BADPARAMS); 427 hex2mem(ptr, remcomRegBuffer, length/2); 428 kgdb_putregs(regs, remcomRegBuffer, length/2); 429 strcpy(remcomOutBuffer,"OK"); 430 break; 431 432 case 'm': /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */ 433 /* Try to read %x,%x. */ 434 435 if (hexToInt(&ptr, &addr) 436 && *ptr++ == ',' 437 && hexToInt(&ptr, &length)) { 438 mem2hex((char *)addr, remcomOutBuffer, length); 439 } else { 440 kgdb_error(KGDBERR_BADPARAMS); 441 } 442 break; 443 444 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */ 445 /* Try to read '%x,%x:'. */ 446 447 if (hexToInt(&ptr, &addr) 448 && *ptr++ == ',' 449 && hexToInt(&ptr, &length) 450 && *ptr++ == ':') { 451 hex2mem(ptr, (char *)addr, length); 452 strcpy(remcomOutBuffer, "OK"); 453 } else { 454 kgdb_error(KGDBERR_BADPARAMS); 455 } 456 break; 457 458 459 case 'k': /* kill the program, actually return to monitor */ 460 kd.extype = KGDBEXIT_KILL; 461 *regs = entry_regs; 462 first_entry = 1; 463 goto doexit; 464 465 case 'C': /* CSS continue with signal SS */ 466 *ptr = '\0'; /* ignore the signal number for now */ 467 /* fall through */ 468 469 case 'c': /* cAA..AA Continue; address AA..AA optional */ 470 /* try to read optional parameter, pc unchanged if no parm */ 471 kd.extype = KGDBEXIT_CONTINUE; 472 473 if (hexToInt(&ptr, &addr)) { 474 kd.exaddr = addr; 475 kd.extype |= KGDBEXIT_WITHADDR; 476 } 477 478 goto doexit; 479 480 case 'S': /* SSS single step with signal SS */ 481 *ptr = '\0'; /* ignore the signal number for now */ 482 /* fall through */ 483 484 case 's': 485 kd.extype = KGDBEXIT_SINGLE; 486 487 if (hexToInt(&ptr, &addr)) { 488 kd.exaddr = addr; 489 kd.extype |= KGDBEXIT_WITHADDR; 490 } 491 492 doexit: 493 /* Need to flush the instruction cache here, as we may have deposited a 494 * breakpoint, and the icache probably has no way of knowing that a data ref to 495 * some location may have changed something that is in the instruction cache. 496 */ 497 kgdb_flush_cache_all(); 498 kgdb_exit(regs, &kd); 499 kgdb_active = 0; 500 kgdb_interruptible(1); 501 return (1); 502 503 case 'r': /* Reset (if user process..exit ???)*/ 504 panic("kgdb reset."); 505 break; 506 507 case 'P': /* Pr=v set reg r to value v (r and v are hex) */ 508 if (hexToInt(&ptr, &addr) 509 && *ptr++ == '=' 510 && ((length = strlen(ptr)) & 1) == 0) { 511 hex2mem(ptr, remcomRegBuffer, length/2); 512 kgdb_putreg(regs, addr, 513 remcomRegBuffer, length/2); 514 strcpy(remcomOutBuffer,"OK"); 515 } else { 516 kgdb_error(KGDBERR_BADPARAMS); 517 } 518 break; 519 } /* switch */ 520 521 if (errnum != 0) 522 sprintf(remcomOutBuffer, "E%02d", errnum); 523 524 #ifdef KGDB_DEBUG 525 if (kdebug) 526 printf("kgdb: remcomOutBuffer: %s\n", remcomOutBuffer); 527 #endif 528 529 /* reply to the request */ 530 putpacket((unsigned char *)&remcomOutBuffer); 531 532 } /* while(1) */ 533 } 534 535 /* 536 * kgdb_init must be called *after* the 537 * monitor is relocated into ram 538 */ 539 void 540 kgdb_init(void) 541 { 542 kgdb_serial_init(); 543 debugger_exception_handler = handle_exception; 544 initialized = 1; 545 546 putDebugStr("kgdb ready\n"); 547 puts("ready\n"); 548 } 549 550 void 551 kgdb_error(int errnum) 552 { 553 longjmp_on_fault = 0; 554 kgdb_longjmp(error_jmp_buf, errnum); 555 panic("kgdb_error: longjmp failed!\n"); 556 } 557 558 /* Output string in GDB O-packet format if GDB has connected. If nothing 559 output, returns 0 (caller must then handle output). */ 560 int 561 kgdb_output_string (const char* s, unsigned int count) 562 { 563 char buffer[512]; 564 565 count = (count <= (sizeof(buffer) / 2 - 2)) 566 ? count : (sizeof(buffer) / 2 - 2); 567 568 buffer[0] = 'O'; 569 mem2hex ((char *)s, &buffer[1], count); 570 putpacket((unsigned char *)&buffer); 571 572 return 1; 573 } 574 575 void 576 breakpoint(void) 577 { 578 if (!initialized) { 579 printf("breakpoint() called b4 kgdb init\n"); 580 return; 581 } 582 583 kgdb_breakpoint(0, 0); 584 } 585 586 int 587 do_kgdb(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) 588 { 589 printf("Entering KGDB mode via exception handler...\n\n"); 590 kgdb_breakpoint(argc - 1, argv + 1); 591 printf("\nReturned from KGDB mode\n"); 592 return 0; 593 } 594 595 U_BOOT_CMD( 596 kgdb, CONFIG_SYS_MAXARGS, 1, do_kgdb, 597 "enter gdb remote debug mode", 598 "[arg0 arg1 .. argN]\n" 599 " - executes a breakpoint so that kgdb mode is\n" 600 " entered via the exception handler. To return\n" 601 " to the monitor, the remote gdb debugger must\n" 602 " execute a \"continue\" or \"quit\" command.\n" 603 "\n" 604 " if a program is loaded by the remote gdb, any args\n" 605 " passed to the kgdb command are given to the loaded\n" 606 " program if it is executed (see the \"hello_world\"\n" 607 " example program in the U-Boot examples directory)." 608 ); 609