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[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
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 }
GDB Binutils - Deliverables
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