| 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 void putDebugChar(); /* write a single character */ |
| 120 | extern int 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 | \f |
| 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 |
| 481 | _returnFromException (Frame * frame) |
| 482 | { |
| 483 | /* if no passed in frame, use the last one */ |
| 484 | if (!frame) |
| 485 | { |
| 486 | frame = lastFrame; |
| 487 | frame->frameSize = 4; |
| 488 | frame->format = 0; |
| 489 | frame->fsaveHeader = -1; /* restore regs, but we dont have fsave info */ |
| 490 | } |
| 491 | |
| 492 | #if !defined (mc68020) && !defined (mc68332) |
| 493 | /* a 68000 cannot use the internal info pushed onto a bus error |
| 494 | * or address error frame when doing an RTE so don't put this info |
| 495 | * onto the stack or the stack will creep every time this happens. |
| 496 | */ |
| 497 | frame->frameSize = 3; |
| 498 | #endif |
| 499 | |
| 500 | /* throw away any frames in the list after this frame */ |
| 501 | lastFrame = frame; |
| 502 | |
| 503 | frame->sr = registers[(int) PS]; |
| 504 | frame->pc = registers[(int) PC]; |
| 505 | |
| 506 | if (registers[(int) PS] & 0x2000) |
| 507 | { |
| 508 | /* return to supervisor mode... */ |
| 509 | return_to_super (); |
| 510 | } |
| 511 | else |
| 512 | { /* return to user mode */ |
| 513 | return_to_user (); |
| 514 | } |
| 515 | } |
| 516 | |
| 517 | int |
| 518 | hex (ch) |
| 519 | char ch; |
| 520 | { |
| 521 | if ((ch >= 'a') && (ch <= 'f')) |
| 522 | return (ch - 'a' + 10); |
| 523 | if ((ch >= '0') && (ch <= '9')) |
| 524 | return (ch - '0'); |
| 525 | if ((ch >= 'A') && (ch <= 'F')) |
| 526 | return (ch - 'A' + 10); |
| 527 | return (-1); |
| 528 | } |
| 529 | |
| 530 | static char remcomInBuffer[BUFMAX]; |
| 531 | static char remcomOutBuffer[BUFMAX]; |
| 532 | |
| 533 | /* scan for the sequence $<data>#<checksum> */ |
| 534 | |
| 535 | unsigned char * |
| 536 | getpacket (void) |
| 537 | { |
| 538 | unsigned char *buffer = &remcomInBuffer[0]; |
| 539 | unsigned char checksum; |
| 540 | unsigned char xmitcsum; |
| 541 | int count; |
| 542 | char ch; |
| 543 | |
| 544 | while (1) |
| 545 | { |
| 546 | /* wait around for the start character, ignore all other characters */ |
| 547 | while ((ch = getDebugChar ()) != '$') |
| 548 | ; |
| 549 | |
| 550 | retry: |
| 551 | checksum = 0; |
| 552 | xmitcsum = -1; |
| 553 | count = 0; |
| 554 | |
| 555 | /* now, read until a # or end of buffer is found */ |
| 556 | while (count < BUFMAX - 1) |
| 557 | { |
| 558 | ch = getDebugChar (); |
| 559 | if (ch == '$') |
| 560 | goto retry; |
| 561 | if (ch == '#') |
| 562 | break; |
| 563 | checksum = checksum + ch; |
| 564 | buffer[count] = ch; |
| 565 | count = count + 1; |
| 566 | } |
| 567 | buffer[count] = 0; |
| 568 | |
| 569 | if (ch == '#') |
| 570 | { |
| 571 | ch = getDebugChar (); |
| 572 | xmitcsum = hex (ch) << 4; |
| 573 | ch = getDebugChar (); |
| 574 | xmitcsum += hex (ch); |
| 575 | |
| 576 | if (checksum != xmitcsum) |
| 577 | { |
| 578 | if (remote_debug) |
| 579 | { |
| 580 | fprintf (stderr, |
| 581 | "bad checksum. My count = 0x%x, sent=0x%x. buf=%s\n", |
| 582 | checksum, xmitcsum, buffer); |
| 583 | } |
| 584 | putDebugChar ('-'); /* failed checksum */ |
| 585 | } |
| 586 | else |
| 587 | { |
| 588 | putDebugChar ('+'); /* successful transfer */ |
| 589 | |
| 590 | /* if a sequence char is present, reply the sequence ID */ |
| 591 | if (buffer[2] == ':') |
| 592 | { |
| 593 | putDebugChar (buffer[0]); |
| 594 | putDebugChar (buffer[1]); |
| 595 | |
| 596 | return &buffer[3]; |
| 597 | } |
| 598 | |
| 599 | return &buffer[0]; |
| 600 | } |
| 601 | } |
| 602 | } |
| 603 | } |
| 604 | |
| 605 | /* send the packet in buffer. */ |
| 606 | |
| 607 | void |
| 608 | putpacket (buffer) |
| 609 | char *buffer; |
| 610 | { |
| 611 | unsigned char checksum; |
| 612 | int count; |
| 613 | char ch; |
| 614 | |
| 615 | /* $<packet info>#<checksum>. */ |
| 616 | do |
| 617 | { |
| 618 | putDebugChar ('$'); |
| 619 | checksum = 0; |
| 620 | count = 0; |
| 621 | |
| 622 | while (ch = buffer[count]) |
| 623 | { |
| 624 | putDebugChar (ch); |
| 625 | checksum += ch; |
| 626 | count += 1; |
| 627 | } |
| 628 | |
| 629 | putDebugChar ('#'); |
| 630 | putDebugChar (hexchars[checksum >> 4]); |
| 631 | putDebugChar (hexchars[checksum % 16]); |
| 632 | |
| 633 | } |
| 634 | while (getDebugChar () != '+'); |
| 635 | |
| 636 | } |
| 637 | |
| 638 | void |
| 639 | debug_error (format, parm) |
| 640 | char *format; |
| 641 | char *parm; |
| 642 | { |
| 643 | if (remote_debug) |
| 644 | fprintf (stderr, format, parm); |
| 645 | } |
| 646 | |
| 647 | /* convert the memory pointed to by mem into hex, placing result in buf */ |
| 648 | /* return a pointer to the last char put in buf (null) */ |
| 649 | char * |
| 650 | mem2hex (mem, buf, count) |
| 651 | char *mem; |
| 652 | char *buf; |
| 653 | int count; |
| 654 | { |
| 655 | int i; |
| 656 | unsigned char ch; |
| 657 | for (i = 0; i < count; i++) |
| 658 | { |
| 659 | ch = *mem++; |
| 660 | *buf++ = hexchars[ch >> 4]; |
| 661 | *buf++ = hexchars[ch % 16]; |
| 662 | } |
| 663 | *buf = 0; |
| 664 | return (buf); |
| 665 | } |
| 666 | |
| 667 | /* convert the hex array pointed to by buf into binary to be placed in mem */ |
| 668 | /* return a pointer to the character AFTER the last byte written */ |
| 669 | char * |
| 670 | hex2mem (buf, mem, count) |
| 671 | char *buf; |
| 672 | char *mem; |
| 673 | int count; |
| 674 | { |
| 675 | int i; |
| 676 | unsigned char ch; |
| 677 | for (i = 0; i < count; i++) |
| 678 | { |
| 679 | ch = hex (*buf++) << 4; |
| 680 | ch = ch + hex (*buf++); |
| 681 | *mem++ = ch; |
| 682 | } |
| 683 | return (mem); |
| 684 | } |
| 685 | |
| 686 | /* a bus error has occurred, perform a longjmp |
| 687 | to return execution and allow handling of the error */ |
| 688 | |
| 689 | void |
| 690 | handle_buserror () |
| 691 | { |
| 692 | longjmp (remcomEnv, 1); |
| 693 | } |
| 694 | |
| 695 | /* this function takes the 68000 exception number and attempts to |
| 696 | translate this number into a unix compatible signal value */ |
| 697 | int |
| 698 | computeSignal (exceptionVector) |
| 699 | int exceptionVector; |
| 700 | { |
| 701 | int sigval; |
| 702 | switch (exceptionVector) |
| 703 | { |
| 704 | case 2: |
| 705 | sigval = 10; |
| 706 | break; /* bus error */ |
| 707 | case 3: |
| 708 | sigval = 10; |
| 709 | break; /* address error */ |
| 710 | case 4: |
| 711 | sigval = 4; |
| 712 | break; /* illegal instruction */ |
| 713 | case 5: |
| 714 | sigval = 8; |
| 715 | break; /* zero divide */ |
| 716 | case 6: |
| 717 | sigval = 8; |
| 718 | break; /* chk instruction */ |
| 719 | case 7: |
| 720 | sigval = 8; |
| 721 | break; /* trapv instruction */ |
| 722 | case 8: |
| 723 | sigval = 11; |
| 724 | break; /* privilege violation */ |
| 725 | case 9: |
| 726 | sigval = 5; |
| 727 | break; /* trace trap */ |
| 728 | case 10: |
| 729 | sigval = 4; |
| 730 | break; /* line 1010 emulator */ |
| 731 | case 11: |
| 732 | sigval = 4; |
| 733 | break; /* line 1111 emulator */ |
| 734 | |
| 735 | /* Coprocessor protocol violation. Using a standard MMU or FPU |
| 736 | this cannot be triggered by software. Call it a SIGBUS. */ |
| 737 | case 13: |
| 738 | sigval = 10; |
| 739 | break; |
| 740 | |
| 741 | case 31: |
| 742 | sigval = 2; |
| 743 | break; /* interrupt */ |
| 744 | case 33: |
| 745 | sigval = 5; |
| 746 | break; /* breakpoint */ |
| 747 | |
| 748 | /* This is a trap #8 instruction. Apparently it is someone's software |
| 749 | convention for some sort of SIGFPE condition. Whose? How many |
| 750 | people are being screwed by having this code the way it is? |
| 751 | Is there a clean solution? */ |
| 752 | case 40: |
| 753 | sigval = 8; |
| 754 | break; /* floating point err */ |
| 755 | |
| 756 | case 48: |
| 757 | sigval = 8; |
| 758 | break; /* floating point err */ |
| 759 | case 49: |
| 760 | sigval = 8; |
| 761 | break; /* floating point err */ |
| 762 | case 50: |
| 763 | sigval = 8; |
| 764 | break; /* zero divide */ |
| 765 | case 51: |
| 766 | sigval = 8; |
| 767 | break; /* underflow */ |
| 768 | case 52: |
| 769 | sigval = 8; |
| 770 | break; /* operand error */ |
| 771 | case 53: |
| 772 | sigval = 8; |
| 773 | break; /* overflow */ |
| 774 | case 54: |
| 775 | sigval = 8; |
| 776 | break; /* NAN */ |
| 777 | default: |
| 778 | sigval = 7; /* "software generated" */ |
| 779 | } |
| 780 | return (sigval); |
| 781 | } |
| 782 | |
| 783 | /**********************************************/ |
| 784 | /* WHILE WE FIND NICE HEX CHARS, BUILD AN INT */ |
| 785 | /* RETURN NUMBER OF CHARS PROCESSED */ |
| 786 | /**********************************************/ |
| 787 | int |
| 788 | hexToInt (char **ptr, int *intValue) |
| 789 | { |
| 790 | int numChars = 0; |
| 791 | int hexValue; |
| 792 | |
| 793 | *intValue = 0; |
| 794 | |
| 795 | while (**ptr) |
| 796 | { |
| 797 | hexValue = hex (**ptr); |
| 798 | if (hexValue >= 0) |
| 799 | { |
| 800 | *intValue = (*intValue << 4) | hexValue; |
| 801 | numChars++; |
| 802 | } |
| 803 | else |
| 804 | break; |
| 805 | |
| 806 | (*ptr)++; |
| 807 | } |
| 808 | |
| 809 | return (numChars); |
| 810 | } |
| 811 | |
| 812 | /* |
| 813 | * This function does all command procesing for interfacing to gdb. |
| 814 | */ |
| 815 | void |
| 816 | handle_exception (int exceptionVector) |
| 817 | { |
| 818 | int sigval, stepping; |
| 819 | int addr, length; |
| 820 | char *ptr; |
| 821 | int newPC; |
| 822 | Frame *frame; |
| 823 | |
| 824 | if (remote_debug) |
| 825 | printf ("vector=%d, sr=0x%x, pc=0x%x\n", |
| 826 | exceptionVector, registers[PS], registers[PC]); |
| 827 | |
| 828 | /* reply to host that an exception has occurred */ |
| 829 | sigval = computeSignal (exceptionVector); |
| 830 | remcomOutBuffer[0] = 'S'; |
| 831 | remcomOutBuffer[1] = hexchars[sigval >> 4]; |
| 832 | remcomOutBuffer[2] = hexchars[sigval % 16]; |
| 833 | remcomOutBuffer[3] = 0; |
| 834 | |
| 835 | putpacket (remcomOutBuffer); |
| 836 | |
| 837 | stepping = 0; |
| 838 | |
| 839 | while (1 == 1) |
| 840 | { |
| 841 | remcomOutBuffer[0] = 0; |
| 842 | ptr = getpacket (); |
| 843 | switch (*ptr++) |
| 844 | { |
| 845 | case '?': |
| 846 | remcomOutBuffer[0] = 'S'; |
| 847 | remcomOutBuffer[1] = hexchars[sigval >> 4]; |
| 848 | remcomOutBuffer[2] = hexchars[sigval % 16]; |
| 849 | remcomOutBuffer[3] = 0; |
| 850 | break; |
| 851 | case 'd': |
| 852 | remote_debug = !(remote_debug); /* toggle debug flag */ |
| 853 | break; |
| 854 | case 'g': /* return the value of the CPU registers */ |
| 855 | mem2hex ((char *) registers, remcomOutBuffer, NUMREGBYTES); |
| 856 | break; |
| 857 | case 'G': /* set the value of the CPU registers - return OK */ |
| 858 | hex2mem (ptr, (char *) registers, NUMREGBYTES); |
| 859 | strcpy (remcomOutBuffer, "OK"); |
| 860 | break; |
| 861 | |
| 862 | /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */ |
| 863 | case 'm': |
| 864 | if (setjmp (remcomEnv) == 0) |
| 865 | { |
| 866 | exceptionHandler (2, handle_buserror); |
| 867 | |
| 868 | /* TRY TO READ %x,%x. IF SUCCEED, SET PTR = 0 */ |
| 869 | if (hexToInt (&ptr, &addr)) |
| 870 | if (*(ptr++) == ',') |
| 871 | if (hexToInt (&ptr, &length)) |
| 872 | { |
| 873 | ptr = 0; |
| 874 | mem2hex ((char *) addr, remcomOutBuffer, length); |
| 875 | } |
| 876 | |
| 877 | if (ptr) |
| 878 | { |
| 879 | strcpy (remcomOutBuffer, "E01"); |
| 880 | } |
| 881 | } |
| 882 | else |
| 883 | { |
| 884 | exceptionHandler (2, _catchException); |
| 885 | strcpy (remcomOutBuffer, "E03"); |
| 886 | debug_error ("bus error"); |
| 887 | } |
| 888 | |
| 889 | /* restore handler for bus error */ |
| 890 | exceptionHandler (2, _catchException); |
| 891 | break; |
| 892 | |
| 893 | /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */ |
| 894 | case 'M': |
| 895 | if (setjmp (remcomEnv) == 0) |
| 896 | { |
| 897 | exceptionHandler (2, handle_buserror); |
| 898 | |
| 899 | /* TRY TO READ '%x,%x:'. IF SUCCEED, SET PTR = 0 */ |
| 900 | if (hexToInt (&ptr, &addr)) |
| 901 | if (*(ptr++) == ',') |
| 902 | if (hexToInt (&ptr, &length)) |
| 903 | if (*(ptr++) == ':') |
| 904 | { |
| 905 | hex2mem (ptr, (char *) addr, length); |
| 906 | ptr = 0; |
| 907 | strcpy (remcomOutBuffer, "OK"); |
| 908 | } |
| 909 | if (ptr) |
| 910 | { |
| 911 | strcpy (remcomOutBuffer, "E02"); |
| 912 | } |
| 913 | } |
| 914 | else |
| 915 | { |
| 916 | exceptionHandler (2, _catchException); |
| 917 | strcpy (remcomOutBuffer, "E03"); |
| 918 | debug_error ("bus error"); |
| 919 | } |
| 920 | |
| 921 | /* restore handler for bus error */ |
| 922 | exceptionHandler (2, _catchException); |
| 923 | break; |
| 924 | |
| 925 | /* cAA..AA Continue at address AA..AA(optional) */ |
| 926 | /* sAA..AA Step one instruction from AA..AA(optional) */ |
| 927 | case 's': |
| 928 | stepping = 1; |
| 929 | case 'c': |
| 930 | /* try to read optional parameter, pc unchanged if no parm */ |
| 931 | if (hexToInt (&ptr, &addr)) |
| 932 | registers[PC] = addr; |
| 933 | |
| 934 | newPC = registers[PC]; |
| 935 | |
| 936 | /* clear the trace bit */ |
| 937 | registers[PS] &= 0x7fff; |
| 938 | |
| 939 | /* set the trace bit if we're stepping */ |
| 940 | if (stepping) |
| 941 | registers[PS] |= 0x8000; |
| 942 | |
| 943 | /* |
| 944 | * look for newPC in the linked list of exception frames. |
| 945 | * if it is found, use the old frame it. otherwise, |
| 946 | * fake up a dummy frame in returnFromException(). |
| 947 | */ |
| 948 | if (remote_debug) |
| 949 | printf ("new pc = 0x%x\n", newPC); |
| 950 | frame = lastFrame; |
| 951 | while (frame) |
| 952 | { |
| 953 | if (remote_debug) |
| 954 | printf ("frame at 0x%x has pc=0x%x, except#=%d\n", |
| 955 | frame, frame->exceptionPC, frame->exceptionVector); |
| 956 | if (frame->exceptionPC == newPC) |
| 957 | break; /* bingo! a match */ |
| 958 | /* |
| 959 | * for a breakpoint instruction, the saved pc may |
| 960 | * be off by two due to re-executing the instruction |
| 961 | * replaced by the trap instruction. Check for this. |
| 962 | */ |
| 963 | if ((frame->exceptionVector == 33) && |
| 964 | (frame->exceptionPC == (newPC + 2))) |
| 965 | break; |
| 966 | if (frame == frame->previous) |
| 967 | { |
| 968 | frame = 0; /* no match found */ |
| 969 | break; |
| 970 | } |
| 971 | frame = frame->previous; |
| 972 | } |
| 973 | |
| 974 | /* |
| 975 | * If we found a match for the PC AND we are not returning |
| 976 | * as a result of a breakpoint (33), |
| 977 | * trace exception (9), nmi (31), jmp to |
| 978 | * the old exception handler as if this code never ran. |
| 979 | */ |
| 980 | if (frame) |
| 981 | { |
| 982 | if ((frame->exceptionVector != 9) && |
| 983 | (frame->exceptionVector != 31) && |
| 984 | (frame->exceptionVector != 33)) |
| 985 | { |
| 986 | /* |
| 987 | * invoke the previous handler. |
| 988 | */ |
| 989 | if (oldExceptionHook) |
| 990 | (*oldExceptionHook) (frame->exceptionVector); |
| 991 | newPC = registers[PC]; /* pc may have changed */ |
| 992 | if (newPC != frame->exceptionPC) |
| 993 | { |
| 994 | if (remote_debug) |
| 995 | printf ("frame at 0x%x has pc=0x%x, except#=%d\n", |
| 996 | frame, frame->exceptionPC, |
| 997 | frame->exceptionVector); |
| 998 | /* re-use the last frame, we're skipping it (longjump?) */ |
| 999 | frame = (Frame *) 0; |
| 1000 | _returnFromException (frame); /* this is a jump */ |
| 1001 | } |
| 1002 | } |
| 1003 | } |
| 1004 | |
| 1005 | /* if we couldn't find a frame, create one */ |
| 1006 | if (frame == 0) |
| 1007 | { |
| 1008 | frame = lastFrame - 1; |
| 1009 | |
| 1010 | /* by using a bunch of print commands with breakpoints, |
| 1011 | it's possible for the frame stack to creep down. If it creeps |
| 1012 | too far, give up and reset it to the top. Normal use should |
| 1013 | not see this happen. |
| 1014 | */ |
| 1015 | if ((unsigned int) (frame - 2) < (unsigned int) &gdbFrameStack) |
| 1016 | { |
| 1017 | initializeRemcomErrorFrame (); |
| 1018 | frame = lastFrame; |
| 1019 | } |
| 1020 | frame->previous = lastFrame; |
| 1021 | lastFrame = frame; |
| 1022 | frame = 0; /* null so _return... will properly initialize it */ |
| 1023 | } |
| 1024 | |
| 1025 | _returnFromException (frame); /* this is a jump */ |
| 1026 | |
| 1027 | break; |
| 1028 | |
| 1029 | /* kill the program */ |
| 1030 | case 'k': /* do nothing */ |
| 1031 | break; |
| 1032 | } /* switch */ |
| 1033 | |
| 1034 | /* reply to the request */ |
| 1035 | putpacket (remcomOutBuffer); |
| 1036 | } |
| 1037 | } |
| 1038 | |
| 1039 | |
| 1040 | void |
| 1041 | initializeRemcomErrorFrame (void) |
| 1042 | { |
| 1043 | lastFrame = ((Frame *) & gdbFrameStack[FRAMESIZE - 1]) - 1; |
| 1044 | lastFrame->previous = lastFrame; |
| 1045 | } |
| 1046 | |
| 1047 | /* this function is used to set up exception handlers for tracing and |
| 1048 | breakpoints */ |
| 1049 | void |
| 1050 | set_debug_traps () |
| 1051 | { |
| 1052 | extern void _debug_level7 (); |
| 1053 | extern void remcomHandler (); |
| 1054 | int exception; |
| 1055 | |
| 1056 | initializeRemcomErrorFrame (); |
| 1057 | stackPtr = &remcomStack[STACKSIZE / sizeof (int) - 1]; |
| 1058 | |
| 1059 | for (exception = 2; exception <= 23; exception++) |
| 1060 | exceptionHandler (exception, _catchException); |
| 1061 | |
| 1062 | /* level 7 interrupt */ |
| 1063 | exceptionHandler (31, _debug_level7); |
| 1064 | |
| 1065 | /* breakpoint exception (trap #1) */ |
| 1066 | exceptionHandler (33, _catchException); |
| 1067 | |
| 1068 | /* This is a trap #8 instruction. Apparently it is someone's software |
| 1069 | convention for some sort of SIGFPE condition. Whose? How many |
| 1070 | people are being screwed by having this code the way it is? |
| 1071 | Is there a clean solution? */ |
| 1072 | exceptionHandler (40, _catchException); |
| 1073 | |
| 1074 | /* 48 to 54 are floating point coprocessor errors */ |
| 1075 | for (exception = 48; exception <= 54; exception++) |
| 1076 | exceptionHandler (exception, _catchException); |
| 1077 | |
| 1078 | if (oldExceptionHook != remcomHandler) |
| 1079 | { |
| 1080 | oldExceptionHook = exceptionHook; |
| 1081 | exceptionHook = remcomHandler; |
| 1082 | } |
| 1083 | |
| 1084 | initialized = 1; |
| 1085 | |
| 1086 | } |
| 1087 | |
| 1088 | /* This function will generate a breakpoint exception. It is used at the |
| 1089 | beginning of a program to sync up with a debugger and can be used |
| 1090 | otherwise as a quick means to stop program execution and "break" into |
| 1091 | the debugger. */ |
| 1092 | |
| 1093 | void |
| 1094 | breakpoint () |
| 1095 | { |
| 1096 | if (initialized) |
| 1097 | BREAKPOINT (); |
| 1098 | } |