1 /**************************************************************************** 2 3 THIS SOFTWARE IS NOT COPYRIGHTED 4 5 HP offers the following for use in the public domain. HP makes no 6 warranty with regard to the software or it's performance and the 7 user accepts the software "AS IS" with all faults. 8 9 HP DISCLAIMS ANY WARRANTIES, EXPRESS OR IMPLIED, WITH REGARD 10 TO THIS SOFTWARE INCLUDING BUT NOT LIMITED TO THE WARRANTIES 11 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 12 13 ****************************************************************************/ 14 15 /**************************************************************************** 16 * Header: remcom.c,v 1.34 91/03/09 12:29:49 glenne Exp $ 17 * 18 * Module name: remcom.c $ 19 * Revision: 1.34 $ 20 * Date: 91/03/09 12:29:49 $ 21 * Contributor: Lake Stevens Instrument Division$ 22 * 23 * Description: low level support for gdb debugger. $ 24 * 25 * Considerations: only works on target hardware $ 26 * 27 * Written by: Glenn Engel $ 28 * ModuleState: Experimental $ 29 * 30 * NOTES: See Below $ 31 * 32 * To enable debugger support, two things need to happen. One, a 33 * call to set_debug_traps() is necessary in order to allow any breakpoints 34 * or error conditions to be properly intercepted and reported to gdb. 35 * Two, a breakpoint needs to be generated to begin communication. This 36 * is most easily accomplished by a call to breakpoint(). Breakpoint() 37 * simulates a breakpoint by executing a trap #1. The breakpoint instruction 38 * is hardwired to trap #1 because not to do so is a compatibility problem-- 39 * there either should be a standard breakpoint instruction, or the protocol 40 * should be extended to provide some means to communicate which breakpoint 41 * instruction is in use (or have the stub insert the breakpoint). 42 * 43 * Some explanation is probably necessary to explain how exceptions are 44 * handled. When an exception is encountered the 68000 pushes the current 45 * program counter and status register onto the supervisor stack and then 46 * transfers execution to a location specified in it's vector table. 47 * The handlers for the exception vectors are hardwired to jmp to an address 48 * given by the relation: (exception - 256) * 6. These are decending 49 * addresses starting from -6, -12, -18, ... By allowing 6 bytes for 50 * each entry, a jsr, jmp, bsr, ... can be used to enter the exception 51 * handler. Using a jsr to handle an exception has an added benefit of 52 * allowing a single handler to service several exceptions and use the 53 * return address as the key differentiation. The vector number can be 54 * computed from the return address by [ exception = (addr + 1530) / 6 ]. 55 * The sole purpose of the routine _catchException is to compute the 56 * exception number and push it on the stack in place of the return address. 57 * The external function exceptionHandler() is 58 * used to attach a specific handler to a specific m68k exception. 59 * For 68020 machines, the ability to have a return address around just 60 * so the vector can be determined is not necessary because the '020 pushes an 61 * extra word onto the stack containing the vector offset 62 * 63 * Because gdb will sometimes write to the stack area to execute function 64 * calls, this program cannot rely on using the supervisor stack so it 65 * uses it's own stack area reserved in the int array remcomStack. 66 * 67 ************* 68 * 69 * The following gdb commands are supported: 70 * 71 * command function Return value 72 * 73 * g return the value of the CPU registers hex data or ENN 74 * G set the value of the CPU registers OK or ENN 75 * 76 * mAA..AA,LLLL Read LLLL bytes at address AA..AA hex data or ENN 77 * MAA..AA,LLLL: Write LLLL bytes at address AA.AA OK or ENN 78 * 79 * c Resume at current address SNN ( signal NN) 80 * cAA..AA Continue at address AA..AA SNN 81 * 82 * s Step one instruction SNN 83 * sAA..AA Step one instruction from AA..AA SNN 84 * 85 * k kill 86 * 87 * ? What was the last sigval ? SNN (signal NN) 88 * 89 * All commands and responses are sent with a packet which includes a 90 * checksum. A packet consists of 91 * 92 * $<packet info>#<checksum>. 93 * 94 * where 95 * <packet info> :: <characters representing the command or response> 96 * <checksum> :: < two hex digits computed as modulo 256 sum of <packetinfo>> 97 * 98 * When a packet is received, it is first acknowledged with either '+' or '-'. 99 * '+' indicates a successful transfer. '-' indicates a failed transfer. 100 * 101 * Example: 102 * 103 * Host: Reply: 104 * $m0,10#2a +$00010203040506070809101112131415#42 105 * 106 ****************************************************************************/ 107 108 #include <stdio.h> 109 #include <string.h> 110 #include <setjmp.h> 111 112 /************************************************************************ 113 * 114 * external low-level support routines 115 */ 116 typedef void (*ExceptionHook)(int); /* pointer to function with int parm */ 117 typedef void (*Function)(); /* pointer to a function */ 118 119 extern putDebugChar(); /* write a single character */ 120 extern getDebugChar(); /* read and return a single char */ 121 122 extern Function exceptionHandler(); /* assign an exception handler */ 123 extern ExceptionHook exceptionHook; /* hook variable for errors/exceptions */ 124 125 /************************/ 126 /* FORWARD DECLARATIONS */ 127 /************************/ 128 static void 129 initializeRemcomErrorFrame (); 130 131 /************************************************************************/ 132 /* BUFMAX defines the maximum number of characters in inbound/outbound buffers*/ 133 /* at least NUMREGBYTES*2 are needed for register packets */ 134 #define BUFMAX 400 135 136 static char initialized; /* boolean flag. != 0 means we've been initialized */ 137 138 int remote_debug; 139 /* debug > 0 prints ill-formed commands in valid packets & checksum errors */ 140 141 static const char hexchars[]="0123456789abcdef"; 142 143 /* there are 180 bytes of registers on a 68020 w/68881 */ 144 /* many of the fpa registers are 12 byte (96 bit) registers */ 145 #define NUMREGBYTES 180 146 enum regnames {D0,D1,D2,D3,D4,D5,D6,D7, 147 A0,A1,A2,A3,A4,A5,A6,A7, 148 PS,PC, 149 FP0,FP1,FP2,FP3,FP4,FP5,FP6,FP7, 150 FPCONTROL,FPSTATUS,FPIADDR 151 }; 152 153 154 /* We keep a whole frame cache here. "Why?", I hear you cry, "doesn't 155 GDB handle that sort of thing?" Well, yes, I believe the only 156 reason for this cache is to save and restore floating point state 157 (fsave/frestore). A cleaner way to do this would be to make the 158 fsave data part of the registers which GDB deals with like any 159 other registers. This should not be a performance problem if the 160 ability to read individual registers is added to the protocol. */ 161 162 typedef struct FrameStruct 163 { 164 struct FrameStruct *previous; 165 int exceptionPC; /* pc value when this frame created */ 166 int exceptionVector; /* cpu vector causing exception */ 167 short frameSize; /* size of cpu frame in words */ 168 short sr; /* for 68000, this not always sr */ 169 int pc; 170 short format; 171 int fsaveHeader; 172 int morejunk[0]; /* exception frame, fp save... */ 173 } Frame; 174 175 #define FRAMESIZE 500 176 int gdbFrameStack[FRAMESIZE]; 177 static Frame *lastFrame; 178 179 /* 180 * these should not be static cuz they can be used outside this module 181 */ 182 int registers[NUMREGBYTES/4]; 183 int superStack; 184 185 #define STACKSIZE 10000 186 int remcomStack[STACKSIZE/sizeof(int)]; 187 static int* stackPtr = &remcomStack[STACKSIZE/sizeof(int) - 1]; 188 189 /* 190 * In many cases, the system will want to continue exception processing 191 * when a continue command is given. 192 * oldExceptionHook is a function to invoke in this case. 193 */ 194 195 static ExceptionHook oldExceptionHook; 196 197 #ifdef mc68020 198 /* the size of the exception stack on the 68020 varies with the type of 199 * exception. The following table is the number of WORDS used 200 * for each exception format. 201 */ 202 const short exceptionSize[] = { 4,4,6,4,4,4,4,4,29,10,16,46,12,4,4,4 }; 203 #endif 204 205 #ifdef mc68332 206 static const short exceptionSize[] = { 4,4,6,4,4,4,4,4,4,4,4,4,16,4,4,4 }; 207 #endif 208 209 /************* jump buffer used for setjmp/longjmp **************************/ 210 jmp_buf remcomEnv; 211 212 /*************************** ASSEMBLY CODE MACROS *************************/ 213 /* */ 214 215 #ifdef __HAVE_68881__ 216 /* do an fsave, then remember the address to begin a restore from */ 217 #define SAVE_FP_REGS() asm(" fsave a0@-"); \ 218 asm(" fmovemx fp0-fp7,_registers+72"); \ 219 asm(" fmoveml fpcr/fpsr/fpi,_registers+168"); 220 #define RESTORE_FP_REGS() \ 221 asm(" \n\ 222 fmoveml _registers+168,fpcr/fpsr/fpi \n\ 223 fmovemx _registers+72,fp0-fp7 \n\ 224 cmpl #-1,a0@ | skip frestore flag set ? \n\ 225 beq skip_frestore \n\ 226 frestore a0@+ \n\ 227 skip_frestore: \n\ 228 "); 229 230 #else 231 #define SAVE_FP_REGS() 232 #define RESTORE_FP_REGS() 233 #endif /* __HAVE_68881__ */ 234 235 void return_to_super(); 236 void return_to_user(); 237 238 asm(" 239 .text 240 .globl _return_to_super 241 _return_to_super: 242 movel _registers+60,sp /* get new stack pointer */ 243 movel _lastFrame,a0 /* get last frame info */ 244 bra return_to_any 245 246 .globl _return_to_user 247 _return_to_user: 248 movel _registers+60,a0 /* get usp */ 249 movel a0,usp /* set usp */ 250 movel _superStack,sp /* get original stack pointer */ 251 252 return_to_any: 253 movel _lastFrame,a0 /* get last frame info */ 254 movel a0@+,_lastFrame /* link in previous frame */ 255 addql #8,a0 /* skip over pc, vector#*/ 256 movew a0@+,d0 /* get # of words in cpu frame */ 257 addw d0,a0 /* point to end of data */ 258 addw d0,a0 /* point to end of data */ 259 movel a0,a1 260 # 261 # copy the stack frame 262 subql #1,d0 263 copyUserLoop: 264 movew a1@-,sp@- 265 dbf d0,copyUserLoop 266 "); 267 RESTORE_FP_REGS() 268 asm(" moveml _registers,d0-d7/a0-a6"); 269 asm(" rte"); /* pop and go! */ 270 271 #define DISABLE_INTERRUPTS() asm(" oriw #0x0700,sr"); 272 #define BREAKPOINT() asm(" trap #1"); 273 274 /* this function is called immediately when a level 7 interrupt occurs */ 275 /* if the previous interrupt level was 7 then we're already servicing */ 276 /* this interrupt and an rte is in order to return to the debugger. */ 277 /* For the 68000, the offset for sr is 6 due to the jsr return address */ 278 asm(" 279 .text 280 .globl __debug_level7 281 __debug_level7: 282 movew d0,sp@-"); 283 #if defined (mc68020) || defined (mc68332) 284 asm(" movew sp@(2),d0"); 285 #else 286 asm(" movew sp@(6),d0"); 287 #endif 288 asm(" andiw #0x700,d0 289 cmpiw #0x700,d0 290 beq _already7 291 movew sp@+,d0 292 bra __catchException 293 _already7: 294 movew sp@+,d0"); 295 #if !defined (mc68020) && !defined (mc68332) 296 asm(" lea sp@(4),sp"); /* pull off 68000 return address */ 297 #endif 298 asm(" rte"); 299 300 extern void _catchException (); 301 302 #if defined (mc68020) || defined (mc68332) 303 /* This function is called when a 68020 exception occurs. It saves 304 * all the cpu and fpcp regs in the _registers array, creates a frame on a 305 * linked list of frames which has the cpu and fpcp stack frames needed 306 * to properly restore the context of these processors, and invokes 307 * an exception handler (remcom_handler). 308 * 309 * stack on entry: stack on exit: 310 * N bytes of junk exception # MSWord 311 * Exception Format Word exception # MSWord 312 * Program counter LSWord 313 * Program counter MSWord 314 * Status Register 315 * 316 * 317 */ 318 asm(" 319 .text 320 .globl __catchException 321 __catchException:"); 322 DISABLE_INTERRUPTS(); 323 asm(" 324 moveml d0-d7/a0-a6,_registers /* save registers */ 325 movel _lastFrame,a0 /* last frame pointer */ 326 "); 327 SAVE_FP_REGS(); 328 asm(" 329 lea _registers,a5 /* get address of registers */ 330 movew sp@,d1 /* get status register */ 331 movew d1,a5@(66) /* save sr */ 332 movel sp@(2),a4 /* save pc in a4 for later use */ 333 movel a4,a5@(68) /* save pc in _regisers[] */ 334 335 # 336 # figure out how many bytes in the stack frame 337 movew sp@(6),d0 /* get '020 exception format */ 338 movew d0,d2 /* make a copy of format word */ 339 andiw #0xf000,d0 /* mask off format type */ 340 rolw #5,d0 /* rotate into the low byte *2 */ 341 lea _exceptionSize,a1 342 addw d0,a1 /* index into the table */ 343 movew a1@,d0 /* get number of words in frame */ 344 movew d0,d3 /* save it */ 345 subw d0,a0 /* adjust save pointer */ 346 subw d0,a0 /* adjust save pointer(bytes) */ 347 movel a0,a1 /* copy save pointer */ 348 subql #1,d0 /* predecrement loop counter */ 349 # 350 # copy the frame 351 saveFrameLoop: 352 movew sp@+,a1@+ 353 dbf d0,saveFrameLoop 354 # 355 # now that the stack has been clenaed, 356 # save the a7 in use at time of exception 357 movel sp,_superStack /* save supervisor sp */ 358 andiw #0x2000,d1 /* were we in supervisor mode ? */ 359 beq userMode 360 movel a7,a5@(60) /* save a7 */ 361 bra a7saveDone 362 userMode: 363 movel usp,a1 364 movel a1,a5@(60) /* save user stack pointer */ 365 a7saveDone: 366 367 # 368 # save size of frame 369 movew d3,a0@- 370 371 # 372 # compute exception number 373 andl #0xfff,d2 /* mask off vector offset */ 374 lsrw #2,d2 /* divide by 4 to get vect num */ 375 movel d2,a0@- /* save it */ 376 # 377 # save pc causing exception 378 movel a4,a0@- 379 # 380 # save old frame link and set the new value 381 movel _lastFrame,a1 /* last frame pointer */ 382 movel a1,a0@- /* save pointer to prev frame */ 383 movel a0,_lastFrame 384 385 movel d2,sp@- /* push exception num */ 386 movel _exceptionHook,a0 /* get address of handler */ 387 jbsr a0@ /* and call it */ 388 clrl sp@ /* replace exception num parm with frame ptr */ 389 jbsr __returnFromException /* jbsr, but never returns */ 390 "); 391 #else /* mc68000 */ 392 /* This function is called when an exception occurs. It translates the 393 * return address found on the stack into an exception vector # which 394 * is then handled by either handle_exception or a system handler. 395 * _catchException provides a front end for both. 396 * 397 * stack on entry: stack on exit: 398 * Program counter MSWord exception # MSWord 399 * Program counter LSWord exception # MSWord 400 * Status Register 401 * Return Address MSWord 402 * Return Address LSWord 403 */ 404 asm(" 405 .text 406 .globl __catchException 407 __catchException:"); 408 DISABLE_INTERRUPTS(); 409 asm(" 410 moveml d0-d7/a0-a6,_registers /* save registers */ 411 movel _lastFrame,a0 /* last frame pointer */ 412 "); 413 SAVE_FP_REGS(); 414 asm(" 415 lea _registers,a5 /* get address of registers */ 416 movel sp@+,d2 /* pop return address */ 417 addl #1530,d2 /* convert return addr to */ 418 divs #6,d2 /* exception number */ 419 extl d2 420 421 moveql #3,d3 /* assume a three word frame */ 422 423 cmpiw #3,d2 /* bus error or address error ? */ 424 bgt normal /* if >3 then normal error */ 425 movel sp@+,a0@- /* copy error info to frame buff*/ 426 movel sp@+,a0@- /* these are never used */ 427 moveql #7,d3 /* this is a 7 word frame */ 428 429 normal: 430 movew sp@+,d1 /* pop status register */ 431 movel sp@+,a4 /* pop program counter */ 432 movew d1,a5@(66) /* save sr */ 433 movel a4,a5@(68) /* save pc in _regisers[] */ 434 movel a4,a0@- /* copy pc to frame buffer */ 435 movew d1,a0@- /* copy sr to frame buffer */ 436 437 movel sp,_superStack /* save supervisor sp */ 438 439 andiw #0x2000,d1 /* were we in supervisor mode ? */ 440 beq userMode 441 movel a7,a5@(60) /* save a7 */ 442 bra saveDone 443 userMode: 444 movel usp,a1 /* save user stack pointer */ 445 movel a1,a5@(60) /* save user stack pointer */ 446 saveDone: 447 448 movew d3,a0@- /* push frame size in words */ 449 movel d2,a0@- /* push vector number */ 450 movel a4,a0@- /* push exception pc */ 451 452 # 453 # save old frame link and set the new value 454 movel _lastFrame,a1 /* last frame pointer */ 455 movel a1,a0@- /* save pointer to prev frame */ 456 movel a0,_lastFrame 457 458 movel d2,sp@- /* push exception num */ 459 movel _exceptionHook,a0 /* get address of handler */ 460 jbsr a0@ /* and call it */ 461 clrl sp@ /* replace exception num parm with frame ptr */ 462 jbsr __returnFromException /* jbsr, but never returns */ 463 "); 464 #endif 465 466 467 /* 468 * remcomHandler is a front end for handle_exception. It moves the 469 * stack pointer into an area reserved for debugger use in case the 470 * breakpoint happened in supervisor mode. 471 */ 472 asm("_remcomHandler:"); 473 asm(" addl #4,sp"); /* pop off return address */ 474 asm(" movel sp@+,d0"); /* get the exception number */ 475 asm(" movel _stackPtr,sp"); /* move to remcom stack area */ 476 asm(" movel d0,sp@-"); /* push exception onto stack */ 477 asm(" jbsr _handle_exception"); /* this never returns */ 478 asm(" rts"); /* return */ 479 480 void _returnFromException( Frame *frame ) 481 { 482 /* if no passed in frame, use the last one */ 483 if (! frame) 484 { 485 frame = lastFrame; 486 frame->frameSize = 4; 487 frame->format = 0; 488 frame->fsaveHeader = -1; /* restore regs, but we dont have fsave info*/ 489 } 490 491 #if !defined (mc68020) && !defined (mc68332) 492 /* a 68000 cannot use the internal info pushed onto a bus error 493 * or address error frame when doing an RTE so don't put this info 494 * onto the stack or the stack will creep every time this happens. 495 */ 496 frame->frameSize=3; 497 #endif 498 499 /* throw away any frames in the list after this frame */ 500 lastFrame = frame; 501 502 frame->sr = registers[(int) PS]; 503 frame->pc = registers[(int) PC]; 504 505 if (registers[(int) PS] & 0x2000) 506 { 507 /* return to supervisor mode... */ 508 return_to_super(); 509 } 510 else 511 { /* return to user mode */ 512 return_to_user(); 513 } 514 } 515 516 int hex(ch) 517 char ch; 518 { 519 if ((ch >= 'a') && (ch <= 'f')) return (ch-'a'+10); 520 if ((ch >= '0') && (ch <= '9')) return (ch-'0'); 521 if ((ch >= 'A') && (ch <= 'F')) return (ch-'A'+10); 522 return (-1); 523 } 524 525 526 /* scan for the sequence $<data>#<checksum> */ 527 void getpacket(buffer) 528 char * buffer; 529 { 530 unsigned char checksum; 531 unsigned char xmitcsum; 532 int i; 533 int count; 534 char ch; 535 536 do { 537 /* wait around for the start character, ignore all other characters */ 538 while ((ch = (getDebugChar() & 0x7f)) != '$'); 539 checksum = 0; 540 xmitcsum = -1; 541 542 count = 0; 543 544 /* now, read until a # or end of buffer is found */ 545 while (count < BUFMAX) { 546 ch = getDebugChar() & 0x7f; 547 if (ch == '#') break; 548 checksum = checksum + ch; 549 buffer[count] = ch; 550 count = count + 1; 551 } 552 buffer[count] = 0; 553 554 if (ch == '#') { 555 xmitcsum = hex(getDebugChar() & 0x7f) << 4; 556 xmitcsum += hex(getDebugChar() & 0x7f); 557 if ((remote_debug ) && (checksum != xmitcsum)) { 558 fprintf (stderr,"bad checksum. My count = 0x%x, sent=0x%x. buf=%s\n", 559 checksum,xmitcsum,buffer); 560 } 561 562 if (checksum != xmitcsum) putDebugChar('-'); /* failed checksum */ 563 else { 564 putDebugChar('+'); /* successful transfer */ 565 /* if a sequence char is present, reply the sequence ID */ 566 if (buffer[2] == ':') { 567 putDebugChar( buffer[0] ); 568 putDebugChar( buffer[1] ); 569 /* remove sequence chars from buffer */ 570 count = strlen(buffer); 571 for (i=3; i <= count; i++) buffer[i-3] = buffer[i]; 572 } 573 } 574 } 575 } while (checksum != xmitcsum); 576 577 } 578 579 /* send the packet in buffer. The host get's one chance to read it. 580 This routine does not wait for a positive acknowledge. */ 581 582 583 void putpacket(buffer) 584 char * buffer; 585 { 586 unsigned char checksum; 587 int count; 588 char ch; 589 590 /* $<packet info>#<checksum>. */ 591 do { 592 putDebugChar('$'); 593 checksum = 0; 594 count = 0; 595 596 while (ch=buffer[count]) { 597 if (! putDebugChar(ch)) return; 598 checksum += ch; 599 count += 1; 600 } 601 602 putDebugChar('#'); 603 putDebugChar(hexchars[checksum >> 4]); 604 putDebugChar(hexchars[checksum % 16]); 605 606 } while (1 == 0); /* (getDebugChar() != '+'); */ 607 608 } 609 610 char remcomInBuffer[BUFMAX]; 611 char remcomOutBuffer[BUFMAX]; 612 static short error; 613 614 615 void debug_error(format, parm) 616 char * format; 617 char * parm; 618 { 619 if (remote_debug) fprintf (stderr,format,parm); 620 } 621 622 /* convert the memory pointed to by mem into hex, placing result in buf */ 623 /* return a pointer to the last char put in buf (null) */ 624 char* mem2hex(mem, buf, count) 625 char* mem; 626 char* buf; 627 int count; 628 { 629 int i; 630 unsigned char ch; 631 for (i=0;i<count;i++) { 632 ch = *mem++; 633 *buf++ = hexchars[ch >> 4]; 634 *buf++ = hexchars[ch % 16]; 635 } 636 *buf = 0; 637 return(buf); 638 } 639 640 /* convert the hex array pointed to by buf into binary to be placed in mem */ 641 /* return a pointer to the character AFTER the last byte written */ 642 char* hex2mem(buf, mem, count) 643 char* buf; 644 char* mem; 645 int count; 646 { 647 int i; 648 unsigned char ch; 649 for (i=0;i<count;i++) { 650 ch = hex(*buf++) << 4; 651 ch = ch + hex(*buf++); 652 *mem++ = ch; 653 } 654 return(mem); 655 } 656 657 /* a bus error has occurred, perform a longjmp 658 to return execution and allow handling of the error */ 659 660 void handle_buserror() 661 { 662 longjmp(remcomEnv,1); 663 } 664 665 /* this function takes the 68000 exception number and attempts to 666 translate this number into a unix compatible signal value */ 667 int computeSignal( exceptionVector ) 668 int exceptionVector; 669 { 670 int sigval; 671 switch (exceptionVector) { 672 case 2 : sigval = 10; break; /* bus error */ 673 case 3 : sigval = 10; break; /* address error */ 674 case 4 : sigval = 4; break; /* illegal instruction */ 675 case 5 : sigval = 8; break; /* zero divide */ 676 case 6 : sigval = 8; break; /* chk instruction */ 677 case 7 : sigval = 8; break; /* trapv instruction */ 678 case 8 : sigval = 11; break; /* privilege violation */ 679 case 9 : sigval = 5; break; /* trace trap */ 680 case 10: sigval = 4; break; /* line 1010 emulator */ 681 case 11: sigval = 4; break; /* line 1111 emulator */ 682 683 /* Coprocessor protocol violation. Using a standard MMU or FPU 684 this cannot be triggered by software. Call it a SIGBUS. */ 685 case 13: sigval = 10; break; 686 687 case 31: sigval = 2; break; /* interrupt */ 688 case 33: sigval = 5; break; /* breakpoint */ 689 690 /* This is a trap #8 instruction. Apparently it is someone's software 691 convention for some sort of SIGFPE condition. Whose? How many 692 people are being screwed by having this code the way it is? 693 Is there a clean solution? */ 694 case 40: sigval = 8; break; /* floating point err */ 695 696 case 48: sigval = 8; break; /* floating point err */ 697 case 49: sigval = 8; break; /* floating point err */ 698 case 50: sigval = 8; break; /* zero divide */ 699 case 51: sigval = 8; break; /* underflow */ 700 case 52: sigval = 8; break; /* operand error */ 701 case 53: sigval = 8; break; /* overflow */ 702 case 54: sigval = 8; break; /* NAN */ 703 default: 704 sigval = 7; /* "software generated"*/ 705 } 706 return (sigval); 707 } 708 709 /**********************************************/ 710 /* WHILE WE FIND NICE HEX CHARS, BUILD AN INT */ 711 /* RETURN NUMBER OF CHARS PROCESSED */ 712 /**********************************************/ 713 int hexToInt(char **ptr, int *intValue) 714 { 715 int numChars = 0; 716 int hexValue; 717 718 *intValue = 0; 719 720 while (**ptr) 721 { 722 hexValue = hex(**ptr); 723 if (hexValue >=0) 724 { 725 *intValue = (*intValue <<4) | hexValue; 726 numChars ++; 727 } 728 else 729 break; 730 731 (*ptr)++; 732 } 733 734 return (numChars); 735 } 736 737 /* 738 * This function does all command procesing for interfacing to gdb. 739 */ 740 void handle_exception(int exceptionVector) 741 { 742 int sigval; 743 int addr, length; 744 char * ptr; 745 int newPC; 746 Frame *frame; 747 748 if (remote_debug) printf("vector=%d, sr=0x%x, pc=0x%x\n", 749 exceptionVector, 750 registers[ PS ], 751 registers[ PC ]); 752 753 /* reply to host that an exception has occurred */ 754 sigval = computeSignal( exceptionVector ); 755 remcomOutBuffer[0] = 'S'; 756 remcomOutBuffer[1] = hexchars[sigval >> 4]; 757 remcomOutBuffer[2] = hexchars[sigval % 16]; 758 remcomOutBuffer[3] = 0; 759 760 putpacket(remcomOutBuffer); 761 762 while (1==1) { 763 error = 0; 764 remcomOutBuffer[0] = 0; 765 getpacket(remcomInBuffer); 766 switch (remcomInBuffer[0]) { 767 case '?' : remcomOutBuffer[0] = 'S'; 768 remcomOutBuffer[1] = hexchars[sigval >> 4]; 769 remcomOutBuffer[2] = hexchars[sigval % 16]; 770 remcomOutBuffer[3] = 0; 771 break; 772 case 'd' : remote_debug = !(remote_debug); /* toggle debug flag */ 773 break; 774 case 'g' : /* return the value of the CPU registers */ 775 mem2hex((char*) registers, remcomOutBuffer, NUMREGBYTES); 776 break; 777 case 'G' : /* set the value of the CPU registers - return OK */ 778 hex2mem(&remcomInBuffer[1], (char*) registers, NUMREGBYTES); 779 strcpy(remcomOutBuffer,"OK"); 780 break; 781 782 /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */ 783 case 'm' : 784 if (setjmp(remcomEnv) == 0) 785 { 786 exceptionHandler(2,handle_buserror); 787 788 /* TRY TO READ %x,%x. IF SUCCEED, SET PTR = 0 */ 789 ptr = &remcomInBuffer[1]; 790 if (hexToInt(&ptr,&addr)) 791 if (*(ptr++) == ',') 792 if (hexToInt(&ptr,&length)) 793 { 794 ptr = 0; 795 mem2hex((char*) addr, remcomOutBuffer, length); 796 } 797 798 if (ptr) 799 { 800 strcpy(remcomOutBuffer,"E01"); 801 debug_error("malformed read memory command: %s",remcomInBuffer); 802 } 803 } 804 else { 805 exceptionHandler(2,_catchException); 806 strcpy(remcomOutBuffer,"E03"); 807 debug_error("bus error"); 808 } 809 810 /* restore handler for bus error */ 811 exceptionHandler(2,_catchException); 812 break; 813 814 /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */ 815 case 'M' : 816 if (setjmp(remcomEnv) == 0) { 817 exceptionHandler(2,handle_buserror); 818 819 /* TRY TO READ '%x,%x:'. IF SUCCEED, SET PTR = 0 */ 820 ptr = &remcomInBuffer[1]; 821 if (hexToInt(&ptr,&addr)) 822 if (*(ptr++) == ',') 823 if (hexToInt(&ptr,&length)) 824 if (*(ptr++) == ':') 825 { 826 hex2mem(ptr, (char*) addr, length); 827 ptr = 0; 828 strcpy(remcomOutBuffer,"OK"); 829 } 830 if (ptr) 831 { 832 strcpy(remcomOutBuffer,"E02"); 833 debug_error("malformed write memory command: %s",remcomInBuffer); 834 } 835 } 836 else { 837 exceptionHandler(2,_catchException); 838 strcpy(remcomOutBuffer,"E03"); 839 debug_error("bus error"); 840 } 841 842 /* restore handler for bus error */ 843 exceptionHandler(2,_catchException); 844 break; 845 846 /* cAA..AA Continue at address AA..AA(optional) */ 847 /* sAA..AA Step one instruction from AA..AA(optional) */ 848 case 'c' : 849 case 's' : 850 /* try to read optional parameter, pc unchanged if no parm */ 851 ptr = &remcomInBuffer[1]; 852 if (hexToInt(&ptr,&addr)) 853 registers[ PC ] = addr; 854 855 newPC = registers[ PC]; 856 857 /* clear the trace bit */ 858 registers[ PS ] &= 0x7fff; 859 860 /* set the trace bit if we're stepping */ 861 if (remcomInBuffer[0] == 's') registers[ PS ] |= 0x8000; 862 863 /* 864 * look for newPC in the linked list of exception frames. 865 * if it is found, use the old frame it. otherwise, 866 * fake up a dummy frame in returnFromException(). 867 */ 868 if (remote_debug) printf("new pc = 0x%x\n",newPC); 869 frame = lastFrame; 870 while (frame) 871 { 872 if (remote_debug) 873 printf("frame at 0x%x has pc=0x%x, except#=%d\n", 874 frame,frame->exceptionPC, 875 frame->exceptionVector); 876 if (frame->exceptionPC == newPC) break; /* bingo! a match */ 877 /* 878 * for a breakpoint instruction, the saved pc may 879 * be off by two due to re-executing the instruction 880 * replaced by the trap instruction. Check for this. 881 */ 882 if ((frame->exceptionVector == 33) && 883 (frame->exceptionPC == (newPC+2))) break; 884 if (frame == frame->previous) 885 { 886 frame = 0; /* no match found */ 887 break; 888 } 889 frame = frame->previous; 890 } 891 892 /* 893 * If we found a match for the PC AND we are not returning 894 * as a result of a breakpoint (33), 895 * trace exception (9), nmi (31), jmp to 896 * the old exception handler as if this code never ran. 897 */ 898 if (frame) 899 { 900 if ((frame->exceptionVector != 9) && 901 (frame->exceptionVector != 31) && 902 (frame->exceptionVector != 33)) 903 { 904 /* 905 * invoke the previous handler. 906 */ 907 if (oldExceptionHook) 908 (*oldExceptionHook) (frame->exceptionVector); 909 newPC = registers[ PC ]; /* pc may have changed */ 910 if (newPC != frame->exceptionPC) 911 { 912 if (remote_debug) 913 printf("frame at 0x%x has pc=0x%x, except#=%d\n", 914 frame,frame->exceptionPC, 915 frame->exceptionVector); 916 /* re-use the last frame, we're skipping it (longjump?)*/ 917 frame = (Frame *) 0; 918 _returnFromException( frame ); /* this is a jump */ 919 } 920 } 921 } 922 923 /* if we couldn't find a frame, create one */ 924 if (frame == 0) 925 { 926 frame = lastFrame -1 ; 927 928 /* by using a bunch of print commands with breakpoints, 929 it's possible for the frame stack to creep down. If it creeps 930 too far, give up and reset it to the top. Normal use should 931 not see this happen. 932 */ 933 if ((unsigned int) (frame-2) < (unsigned int) &gdbFrameStack) 934 { 935 initializeRemcomErrorFrame(); 936 frame = lastFrame; 937 } 938 frame->previous = lastFrame; 939 lastFrame = frame; 940 frame = 0; /* null so _return... will properly initialize it */ 941 } 942 943 _returnFromException( frame ); /* this is a jump */ 944 945 break; 946 947 /* kill the program */ 948 case 'k' : /* do nothing */ 949 break; 950 } /* switch */ 951 952 /* reply to the request */ 953 putpacket(remcomOutBuffer); 954 } 955 } 956 957 958 void 959 initializeRemcomErrorFrame() 960 { 961 lastFrame = ((Frame *) &gdbFrameStack[FRAMESIZE-1]) - 1; 962 lastFrame->previous = lastFrame; 963 } 964 965 /* this function is used to set up exception handlers for tracing and 966 breakpoints */ 967 void set_debug_traps() 968 { 969 extern void _debug_level7(); 970 extern void remcomHandler(); 971 int exception; 972 973 initializeRemcomErrorFrame(); 974 stackPtr = &remcomStack[STACKSIZE/sizeof(int) - 1]; 975 976 for (exception = 2; exception <= 23; exception++) 977 exceptionHandler(exception,_catchException); 978 979 /* level 7 interrupt */ 980 exceptionHandler(31,_debug_level7); 981 982 /* breakpoint exception (trap #1) */ 983 exceptionHandler(33,_catchException); 984 985 /* This is a trap #8 instruction. Apparently it is someone's software 986 convention for some sort of SIGFPE condition. Whose? How many 987 people are being screwed by having this code the way it is? 988 Is there a clean solution? */ 989 exceptionHandler(40,_catchException); 990 991 /* 48 to 54 are floating point coprocessor errors */ 992 for (exception = 48; exception <= 54; exception++) 993 exceptionHandler(exception,_catchException); 994 995 if (oldExceptionHook != remcomHandler) 996 { 997 oldExceptionHook = exceptionHook; 998 exceptionHook = remcomHandler; 999 } 1000 1001 initialized = 1; 1002 1003 } 1004 1005 /* This function will generate a breakpoint exception. It is used at the 1006 beginning of a program to sync up with a debugger and can be used 1007 otherwise as a quick means to stop program execution and "break" into 1008 the debugger. */ 1009 1010 void breakpoint() 1011 { 1012 if (initialized) BREAKPOINT(); 1013 } 1014 1015