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import gdb-1999-08-30 snapshot
[deliverable/binutils-gdb.git] / gdb / m68k-stub.c
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 _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 unsigned char *
527 getpacket (unsigned char *buffer)
528 {
529 unsigned char checksum;
530 unsigned char xmitcsum;
531 int count;
532 char ch;
533
534 while (1)
535 {
536 /* wait around for the start character, ignore all other characters */
537 while ((ch = getDebugChar ()) != '$')
538 ;
539
540 retry:
541 checksum = 0;
542 xmitcsum = -1;
543 count = 0;
544
545 /* now, read until a # or end of buffer is found */
546 while (count < BUFMAX)
547 {
548 ch = getDebugChar ();
549 if (ch == '$')
550 goto retry;
551 if (ch == '#')
552 break;
553 checksum = checksum + ch;
554 buffer[count] = ch;
555 count = count + 1;
556 }
557 buffer[count] = 0;
558
559 if (ch == '#')
560 {
561 ch = getDebugChar ();
562 xmitcsum = hex (ch) << 4;
563 ch = getDebugChar ();
564 xmitcsum += hex (ch);
565
566 if (checksum != xmitcsum)
567 {
568 if (remote_debug)
569 {
570 fprintf (stderr,
571 "bad checksum. My count = 0x%x, sent=0x%x. buf=%s\n",
572 checksum, xmitcsum, buffer);
573 }
574 putDebugChar ('-'); /* failed checksum */
575 }
576 else
577 {
578 putDebugChar ('+'); /* successful transfer */
579
580 /* if a sequence char is present, reply the sequence ID */
581 if (buffer[2] == ':')
582 {
583 putDebugChar (buffer[0]);
584 putDebugChar (buffer[1]);
585
586 return &buffer[3];
587 }
588
589 return &buffer[0];
590 }
591 }
592 }
593 }
594
595 /* send the packet in buffer. */
596
597
598 void putpacket(buffer)
599 char * buffer;
600 {
601 unsigned char checksum;
602 int count;
603 char ch;
604
605 /* $<packet info>#<checksum>. */
606 do {
607 putDebugChar('$');
608 checksum = 0;
609 count = 0;
610
611 while (ch=buffer[count]) {
612 putDebugChar(ch);
613 checksum += ch;
614 count += 1;
615 }
616
617 putDebugChar('#');
618 putDebugChar(hexchars[checksum >> 4]);
619 putDebugChar(hexchars[checksum % 16]);
620
621 } while (getDebugChar() != '+');
622
623 }
624
625 char remcomInBuffer[BUFMAX];
626 char remcomOutBuffer[BUFMAX];
627 static short error;
628
629
630 void debug_error(format, parm)
631 char * format;
632 char * parm;
633 {
634 if (remote_debug) fprintf (stderr,format,parm);
635 }
636
637 /* convert the memory pointed to by mem into hex, placing result in buf */
638 /* return a pointer to the last char put in buf (null) */
639 char* mem2hex(mem, buf, count)
640 char* mem;
641 char* buf;
642 int count;
643 {
644 int i;
645 unsigned char ch;
646 for (i=0;i<count;i++) {
647 ch = *mem++;
648 *buf++ = hexchars[ch >> 4];
649 *buf++ = hexchars[ch % 16];
650 }
651 *buf = 0;
652 return(buf);
653 }
654
655 /* convert the hex array pointed to by buf into binary to be placed in mem */
656 /* return a pointer to the character AFTER the last byte written */
657 char* hex2mem(buf, mem, count)
658 char* buf;
659 char* mem;
660 int count;
661 {
662 int i;
663 unsigned char ch;
664 for (i=0;i<count;i++) {
665 ch = hex(*buf++) << 4;
666 ch = ch + hex(*buf++);
667 *mem++ = ch;
668 }
669 return(mem);
670 }
671
672 /* a bus error has occurred, perform a longjmp
673 to return execution and allow handling of the error */
674
675 void handle_buserror()
676 {
677 longjmp(remcomEnv,1);
678 }
679
680 /* this function takes the 68000 exception number and attempts to
681 translate this number into a unix compatible signal value */
682 int computeSignal( exceptionVector )
683 int exceptionVector;
684 {
685 int sigval;
686 switch (exceptionVector) {
687 case 2 : sigval = 10; break; /* bus error */
688 case 3 : sigval = 10; break; /* address error */
689 case 4 : sigval = 4; break; /* illegal instruction */
690 case 5 : sigval = 8; break; /* zero divide */
691 case 6 : sigval = 8; break; /* chk instruction */
692 case 7 : sigval = 8; break; /* trapv instruction */
693 case 8 : sigval = 11; break; /* privilege violation */
694 case 9 : sigval = 5; break; /* trace trap */
695 case 10: sigval = 4; break; /* line 1010 emulator */
696 case 11: sigval = 4; break; /* line 1111 emulator */
697
698 /* Coprocessor protocol violation. Using a standard MMU or FPU
699 this cannot be triggered by software. Call it a SIGBUS. */
700 case 13: sigval = 10; break;
701
702 case 31: sigval = 2; break; /* interrupt */
703 case 33: sigval = 5; break; /* breakpoint */
704
705 /* This is a trap #8 instruction. Apparently it is someone's software
706 convention for some sort of SIGFPE condition. Whose? How many
707 people are being screwed by having this code the way it is?
708 Is there a clean solution? */
709 case 40: sigval = 8; break; /* floating point err */
710
711 case 48: sigval = 8; break; /* floating point err */
712 case 49: sigval = 8; break; /* floating point err */
713 case 50: sigval = 8; break; /* zero divide */
714 case 51: sigval = 8; break; /* underflow */
715 case 52: sigval = 8; break; /* operand error */
716 case 53: sigval = 8; break; /* overflow */
717 case 54: sigval = 8; break; /* NAN */
718 default:
719 sigval = 7; /* "software generated"*/
720 }
721 return (sigval);
722 }
723
724 /**********************************************/
725 /* WHILE WE FIND NICE HEX CHARS, BUILD AN INT */
726 /* RETURN NUMBER OF CHARS PROCESSED */
727 /**********************************************/
728 int hexToInt(char **ptr, int *intValue)
729 {
730 int numChars = 0;
731 int hexValue;
732
733 *intValue = 0;
734
735 while (**ptr)
736 {
737 hexValue = hex(**ptr);
738 if (hexValue >=0)
739 {
740 *intValue = (*intValue <<4) | hexValue;
741 numChars ++;
742 }
743 else
744 break;
745
746 (*ptr)++;
747 }
748
749 return (numChars);
750 }
751
752 /*
753 * This function does all command procesing for interfacing to gdb.
754 */
755 void handle_exception(int exceptionVector)
756 {
757 int sigval, stepping;
758 int addr, length;
759 char * ptr;
760 int newPC;
761 Frame *frame;
762
763 if (remote_debug) printf("vector=%d, sr=0x%x, pc=0x%x\n",
764 exceptionVector,
765 registers[ PS ],
766 registers[ PC ]);
767
768 /* reply to host that an exception has occurred */
769 sigval = computeSignal( exceptionVector );
770 remcomOutBuffer[0] = 'S';
771 remcomOutBuffer[1] = hexchars[sigval >> 4];
772 remcomOutBuffer[2] = hexchars[sigval % 16];
773 remcomOutBuffer[3] = 0;
774
775 putpacket(remcomOutBuffer);
776
777 stepping = 0;
778
779 while (1==1) {
780 error = 0;
781 remcomOutBuffer[0] = 0;
782 ptr = getpacket(remcomInBuffer);
783 switch (*ptr++) {
784 case '?' : remcomOutBuffer[0] = 'S';
785 remcomOutBuffer[1] = hexchars[sigval >> 4];
786 remcomOutBuffer[2] = hexchars[sigval % 16];
787 remcomOutBuffer[3] = 0;
788 break;
789 case 'd' : remote_debug = !(remote_debug); /* toggle debug flag */
790 break;
791 case 'g' : /* return the value of the CPU registers */
792 mem2hex((char*) registers, remcomOutBuffer, NUMREGBYTES);
793 break;
794 case 'G' : /* set the value of the CPU registers - return OK */
795 hex2mem(&ptr, (char*) registers, NUMREGBYTES);
796 strcpy(remcomOutBuffer,"OK");
797 break;
798
799 /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */
800 case 'm' :
801 if (setjmp(remcomEnv) == 0)
802 {
803 exceptionHandler(2,handle_buserror);
804
805 /* TRY TO READ %x,%x. IF SUCCEED, SET PTR = 0 */
806 if (hexToInt(&ptr,&addr))
807 if (*(ptr++) == ',')
808 if (hexToInt(&ptr,&length))
809 {
810 ptr = 0;
811 mem2hex((char*) addr, remcomOutBuffer, length);
812 }
813
814 if (ptr)
815 {
816 strcpy(remcomOutBuffer,"E01");
817 }
818 } else {
819 exceptionHandler(2,_catchException);
820 strcpy(remcomOutBuffer,"E03");
821 debug_error("bus error");
822 }
823
824 /* restore handler for bus error */
825 exceptionHandler(2,_catchException);
826 break;
827
828 /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */
829 case 'M' :
830 if (setjmp(remcomEnv) == 0) {
831 exceptionHandler(2,handle_buserror);
832
833 /* TRY TO READ '%x,%x:'. IF SUCCEED, SET PTR = 0 */
834 if (hexToInt(&ptr,&addr))
835 if (*(ptr++) == ',')
836 if (hexToInt(&ptr,&length))
837 if (*(ptr++) == ':')
838 {
839 hex2mem(ptr, (char*) addr, length);
840 ptr = 0;
841 strcpy(remcomOutBuffer,"OK");
842 }
843 if (ptr)
844 {
845 strcpy(remcomOutBuffer,"E02");
846 }
847 } else {
848 exceptionHandler(2,_catchException);
849 strcpy(remcomOutBuffer,"E03");
850 debug_error("bus error");
851 }
852
853 /* restore handler for bus error */
854 exceptionHandler(2,_catchException);
855 break;
856
857 /* cAA..AA Continue at address AA..AA(optional) */
858 /* sAA..AA Step one instruction from AA..AA(optional) */
859 case 's' :
860 stepping = 1;
861 case 'c' :
862 /* try to read optional parameter, pc unchanged if no parm */
863 if (hexToInt(&ptr,&addr))
864 registers[ PC ] = addr;
865
866 newPC = registers[ PC];
867
868 /* clear the trace bit */
869 registers[ PS ] &= 0x7fff;
870
871 /* set the trace bit if we're stepping */
872 if (stepping) registers[ PS ] |= 0x8000;
873
874 /*
875 * look for newPC in the linked list of exception frames.
876 * if it is found, use the old frame it. otherwise,
877 * fake up a dummy frame in returnFromException().
878 */
879 if (remote_debug) printf("new pc = 0x%x\n",newPC);
880 frame = lastFrame;
881 while (frame)
882 {
883 if (remote_debug)
884 printf("frame at 0x%x has pc=0x%x, except#=%d\n",
885 frame,frame->exceptionPC,
886 frame->exceptionVector);
887 if (frame->exceptionPC == newPC) break; /* bingo! a match */
888 /*
889 * for a breakpoint instruction, the saved pc may
890 * be off by two due to re-executing the instruction
891 * replaced by the trap instruction. Check for this.
892 */
893 if ((frame->exceptionVector == 33) &&
894 (frame->exceptionPC == (newPC+2))) break;
895 if (frame == frame->previous)
896 {
897 frame = 0; /* no match found */
898 break;
899 }
900 frame = frame->previous;
901 }
902
903 /*
904 * If we found a match for the PC AND we are not returning
905 * as a result of a breakpoint (33),
906 * trace exception (9), nmi (31), jmp to
907 * the old exception handler as if this code never ran.
908 */
909 if (frame)
910 {
911 if ((frame->exceptionVector != 9) &&
912 (frame->exceptionVector != 31) &&
913 (frame->exceptionVector != 33))
914 {
915 /*
916 * invoke the previous handler.
917 */
918 if (oldExceptionHook)
919 (*oldExceptionHook) (frame->exceptionVector);
920 newPC = registers[ PC ]; /* pc may have changed */
921 if (newPC != frame->exceptionPC)
922 {
923 if (remote_debug)
924 printf("frame at 0x%x has pc=0x%x, except#=%d\n",
925 frame,frame->exceptionPC,
926 frame->exceptionVector);
927 /* re-use the last frame, we're skipping it (longjump?)*/
928 frame = (Frame *) 0;
929 _returnFromException( frame ); /* this is a jump */
930 }
931 }
932 }
933
934 /* if we couldn't find a frame, create one */
935 if (frame == 0)
936 {
937 frame = lastFrame -1 ;
938
939 /* by using a bunch of print commands with breakpoints,
940 it's possible for the frame stack to creep down. If it creeps
941 too far, give up and reset it to the top. Normal use should
942 not see this happen.
943 */
944 if ((unsigned int) (frame-2) < (unsigned int) &gdbFrameStack)
945 {
946 initializeRemcomErrorFrame();
947 frame = lastFrame;
948 }
949 frame->previous = lastFrame;
950 lastFrame = frame;
951 frame = 0; /* null so _return... will properly initialize it */
952 }
953
954 _returnFromException( frame ); /* this is a jump */
955
956 break;
957
958 /* kill the program */
959 case 'k' : /* do nothing */
960 break;
961 } /* switch */
962
963 /* reply to the request */
964 putpacket(remcomOutBuffer);
965 }
966 }
967
968
969 void
970 initializeRemcomErrorFrame()
971 {
972 lastFrame = ((Frame *) &gdbFrameStack[FRAMESIZE-1]) - 1;
973 lastFrame->previous = lastFrame;
974 }
975
976 /* this function is used to set up exception handlers for tracing and
977 breakpoints */
978 void set_debug_traps()
979 {
980 extern void _debug_level7();
981 extern void remcomHandler();
982 int exception;
983
984 initializeRemcomErrorFrame();
985 stackPtr = &remcomStack[STACKSIZE/sizeof(int) - 1];
986
987 for (exception = 2; exception <= 23; exception++)
988 exceptionHandler(exception,_catchException);
989
990 /* level 7 interrupt */
991 exceptionHandler(31,_debug_level7);
992
993 /* breakpoint exception (trap #1) */
994 exceptionHandler(33,_catchException);
995
996 /* This is a trap #8 instruction. Apparently it is someone's software
997 convention for some sort of SIGFPE condition. Whose? How many
998 people are being screwed by having this code the way it is?
999 Is there a clean solution? */
1000 exceptionHandler(40,_catchException);
1001
1002 /* 48 to 54 are floating point coprocessor errors */
1003 for (exception = 48; exception <= 54; exception++)
1004 exceptionHandler(exception,_catchException);
1005
1006 if (oldExceptionHook != remcomHandler)
1007 {
1008 oldExceptionHook = exceptionHook;
1009 exceptionHook = remcomHandler;
1010 }
1011
1012 initialized = 1;
1013
1014 }
1015
1016 /* This function will generate a breakpoint exception. It is used at the
1017 beginning of a program to sync up with a debugger and can be used
1018 otherwise as a quick means to stop program execution and "break" into
1019 the debugger. */
1020
1021 void breakpoint()
1022 {
1023 if (initialized) BREAKPOINT();
1024 }
1025
GDB Binutils - Deliverables
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