1 /****************************************************************************
3 THIS SOFTWARE IS NOT COPYRIGHTED
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.
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.
13 ****************************************************************************/
15 /****************************************************************************
16 * Header: remcom.c,v 1.34 91/03/09 12:29:49 glenne Exp $
18 * Module name: remcom.c $
20 * Date: 91/03/09 12:29:49 $
21 * Contributor: Lake Stevens Instrument Division$
23 * Description: low level support for gdb debugger. $
25 * Considerations: only works on target hardware $
27 * Written by: Glenn Engel $
28 * ModuleState: Experimental $
32 * Modified for 386 by Jim Kingdon, Cygnus Support.
34 * To enable debugger support, two things need to happen. One, a
35 * call to set_debug_traps() is necessary in order to allow any breakpoints
36 * or error conditions to be properly intercepted and reported to gdb.
37 * Two, a breakpoint needs to be generated to begin communication. This
38 * is most easily accomplished by a call to breakpoint(). Breakpoint()
39 * simulates a breakpoint by executing a trap #1.
41 * The external function exceptionHandler() is
42 * used to attach a specific handler to a specific 386 vector number.
43 * It should use the same privilege level it runs at. It should
44 * install it as an interrupt gate so that interrupts are masked
45 * while the handler runs.
47 * Because gdb will sometimes write to the stack area to execute function
48 * calls, this program cannot rely on using the supervisor stack so it
49 * uses it's own stack area reserved in the int array remcomStack.
53 * The following gdb commands are supported:
55 * command function Return value
57 * g return the value of the CPU registers hex data or ENN
58 * G set the value of the CPU registers OK or ENN
60 * mAA..AA,LLLL Read LLLL bytes at address AA..AA hex data or ENN
61 * MAA..AA,LLLL: Write LLLL bytes at address AA.AA OK or ENN
63 * c Resume at current address SNN ( signal NN)
64 * cAA..AA Continue at address AA..AA SNN
66 * s Step one instruction SNN
67 * sAA..AA Step one instruction from AA..AA SNN
71 * ? What was the last sigval ? SNN (signal NN)
73 * All commands and responses are sent with a packet which includes a
74 * checksum. A packet consists of
76 * $<packet info>#<checksum>.
79 * <packet info> :: <characters representing the command or response>
80 * <checksum> :: < two hex digits computed as modulo 256 sum of <packetinfo>>
82 * When a packet is received, it is first acknowledged with either '+' or '-'.
83 * '+' indicates a successful transfer. '-' indicates a failed transfer.
88 * $m0,10#2a +$00010203040506070809101112131415#42
90 ****************************************************************************/
95 /************************************************************************
97 * external low-level support routines
100 extern void putDebugChar(); /* write a single character */
101 extern int getDebugChar(); /* read and return a single char */
102 extern void exceptionHandler(); /* assign an exception handler */
104 /************************************************************************/
105 /* BUFMAX defines the maximum number of characters in inbound/outbound buffers*/
106 /* at least NUMREGBYTES*2 are needed for register packets */
109 static char initialized
; /* boolean flag. != 0 means we've been initialized */
112 /* debug > 0 prints ill-formed commands in valid packets & checksum errors */
114 static const char hexchars
[]="0123456789abcdef";
116 /* Number of registers. */
119 /* Number of bytes of registers. */
120 #define NUMREGBYTES (NUMREGS * 4)
122 enum regnames
{EAX
, ECX
, EDX
, EBX
, ESP
, EBP
, ESI
, EDI
,
123 PC
/* also known as eip */,
124 PS
/* also known as eflags */,
125 CS
, SS
, DS
, ES
, FS
, GS
};
128 * these should not be static cuz they can be used outside this module
130 int registers
[NUMREGS
];
132 #define STACKSIZE 10000
133 int remcomStack
[STACKSIZE
/sizeof(int)];
134 static int* stackPtr
= &remcomStack
[STACKSIZE
/sizeof(int) - 1];
136 /*************************** ASSEMBLY CODE MACROS *************************/
142 /* Restore the program's registers (including the stack pointer, which
143 means we get the right stack and don't have to worry about popping our
144 return address and any stack frames and so on) and return. */
146 asm(".globl _return_to_prog");
147 asm("_return_to_prog:");
148 asm(" movw _registers+44, %ss");
149 asm(" movl _registers+16, %esp");
150 asm(" movl _registers+4, %ecx");
151 asm(" movl _registers+8, %edx");
152 asm(" movl _registers+12, %ebx");
153 asm(" movl _registers+20, %ebp");
154 asm(" movl _registers+24, %esi");
155 asm(" movl _registers+28, %edi");
156 asm(" movw _registers+48, %ds");
157 asm(" movw _registers+52, %es");
158 asm(" movw _registers+56, %fs");
159 asm(" movw _registers+60, %gs");
160 asm(" movl _registers+36, %eax");
161 asm(" pushl %eax"); /* saved eflags */
162 asm(" movl _registers+40, %eax");
163 asm(" pushl %eax"); /* saved cs */
164 asm(" movl _registers+32, %eax");
165 asm(" pushl %eax"); /* saved eip */
166 asm(" movl _registers, %eax");
167 /* use iret to restore pc and flags together so
168 that trace flag works right. */
171 #define BREAKPOINT() asm(" int $3");
173 /* Put the error code here just in case the user cares. */
175 /* Likewise, the vector number here (since GDB only gets the signal
176 number through the usual means, and that's not very specific). */
177 int gdb_i386vector
= -1;
179 /* GDB stores segment registers in 32-bit words (that's just the way
180 m-i386v.h is written). So zero the appropriate areas in registers. */
181 #define SAVE_REGISTERS1() \
182 asm ("movl %eax, _registers"); \
183 asm ("movl %ecx, _registers+4"); \
184 asm ("movl %edx, _registers+8"); \
185 asm ("movl %ebx, _registers+12"); \
186 asm ("movl %ebp, _registers+20"); \
187 asm ("movl %esi, _registers+24"); \
188 asm ("movl %edi, _registers+28"); \
189 asm ("movw $0, %ax"); \
190 asm ("movw %ds, _registers+48"); \
191 asm ("movw %ax, _registers+50"); \
192 asm ("movw %es, _registers+52"); \
193 asm ("movw %ax, _registers+54"); \
194 asm ("movw %fs, _registers+56"); \
195 asm ("movw %ax, _registers+58"); \
196 asm ("movw %gs, _registers+60"); \
197 asm ("movw %ax, _registers+62");
198 #define SAVE_ERRCODE() \
200 asm ("movl %ebx, _gdb_i386errcode");
201 #define SAVE_REGISTERS2() \
202 asm ("popl %ebx"); /* old eip */ \
203 asm ("movl %ebx, _registers+32"); \
204 asm ("popl %ebx"); /* old cs */ \
205 asm ("movl %ebx, _registers+40"); \
206 asm ("movw %ax, _registers+42"); \
207 asm ("popl %ebx"); /* old eflags */ \
208 asm ("movl %ebx, _registers+36"); \
209 /* Now that we've done the pops, we can save the stack pointer."); */ \
210 asm ("movw %ss, _registers+44"); \
211 asm ("movw %ax, _registers+46"); \
212 asm ("movl %esp, _registers+16");
214 /* See if mem_fault_routine is set, if so just IRET to that address. */
215 #define CHECK_FAULT() \
216 asm ("cmpl $0, _mem_fault_routine"); \
217 asm ("jne mem_fault");
221 /* OK to clobber temp registers; we're just going to end up in set_mem_err. */
222 /* Pop error code from the stack and save it. */
224 asm (" movl %eax, _gdb_i386errcode");
226 asm (" popl %eax"); /* eip */
227 /* We don't want to return there, we want to return to the function
228 pointed to by mem_fault_routine instead. */
229 asm (" movl _mem_fault_routine, %eax");
230 asm (" popl %ecx"); /* cs (low 16 bits; junk in hi 16 bits). */
231 asm (" popl %edx"); /* eflags */
233 /* Remove this stack frame; when we do the iret, we will be going to
234 the start of a function, so we want the stack to look just like it
235 would after a "call" instruction. */
238 /* Push the stuff that iret wants. */
239 asm (" pushl %edx"); /* eflags */
240 asm (" pushl %ecx"); /* cs */
241 asm (" pushl %eax"); /* eip */
243 /* Zero mem_fault_routine. */
244 asm (" movl $0, %eax");
245 asm (" movl %eax, _mem_fault_routine");
249 #define CALL_HOOK() asm("call _remcomHandler");
251 /* This function is called when a i386 exception occurs. It saves
252 * all the cpu regs in the _registers array, munges the stack a bit,
253 * and invokes an exception handler (remcom_handler).
255 * stack on entry: stack on exit:
256 * old eflags vector number
257 * old cs (zero-filled to 32 bits)
261 extern void _catchException3();
263 asm(".globl __catchException3");
264 asm("__catchException3:");
270 /* Same thing for exception 1. */
271 extern void _catchException1();
273 asm(".globl __catchException1");
274 asm("__catchException1:");
280 /* Same thing for exception 0. */
281 extern void _catchException0();
283 asm(".globl __catchException0");
284 asm("__catchException0:");
290 /* Same thing for exception 4. */
291 extern void _catchException4();
293 asm(".globl __catchException4");
294 asm("__catchException4:");
300 /* Same thing for exception 5. */
301 extern void _catchException5();
303 asm(".globl __catchException5");
304 asm("__catchException5:");
310 /* Same thing for exception 6. */
311 extern void _catchException6();
313 asm(".globl __catchException6");
314 asm("__catchException6:");
320 /* Same thing for exception 7. */
321 extern void _catchException7();
323 asm(".globl __catchException7");
324 asm("__catchException7:");
330 /* Same thing for exception 8. */
331 extern void _catchException8();
333 asm(".globl __catchException8");
334 asm("__catchException8:");
341 /* Same thing for exception 9. */
342 extern void _catchException9();
344 asm(".globl __catchException9");
345 asm("__catchException9:");
351 /* Same thing for exception 10. */
352 extern void _catchException10();
354 asm(".globl __catchException10");
355 asm("__catchException10:");
362 /* Same thing for exception 12. */
363 extern void _catchException12();
365 asm(".globl __catchException12");
366 asm("__catchException12:");
373 /* Same thing for exception 16. */
374 extern void _catchException16();
376 asm(".globl __catchException16");
377 asm("__catchException16:");
383 /* For 13, 11, and 14 we have to deal with the CHECK_FAULT stuff. */
385 /* Same thing for exception 13. */
386 extern void _catchException13 ();
388 asm (".globl __catchException13");
389 asm ("__catchException13:");
397 /* Same thing for exception 11. */
398 extern void _catchException11 ();
400 asm (".globl __catchException11");
401 asm ("__catchException11:");
409 /* Same thing for exception 14. */
410 extern void _catchException14 ();
412 asm (".globl __catchException14");
413 asm ("__catchException14:");
422 * remcomHandler is a front end for handle_exception. It moves the
423 * stack pointer into an area reserved for debugger use.
425 asm("_remcomHandler:");
426 asm(" popl %eax"); /* pop off return address */
427 asm(" popl %eax"); /* get the exception number */
428 asm(" movl _stackPtr, %esp"); /* move to remcom stack area */
429 asm(" pushl %eax"); /* push exception onto stack */
430 asm(" call _handle_exception"); /* this never returns */
433 _returnFromException ()
442 if ((ch
>= 'a') && (ch
<= 'f'))
443 return (ch
- 'a' + 10);
444 if ((ch
>= '0') && (ch
<= '9'))
446 if ((ch
>= 'A') && (ch
<= 'F'))
447 return (ch
- 'A' + 10);
451 static char remcomInBuffer
[BUFMAX
];
452 static char remcomOutBuffer
[BUFMAX
];
454 /* scan for the sequence $<data>#<checksum> */
459 unsigned char *buffer
= &remcomInBuffer
[0];
460 unsigned char checksum
;
461 unsigned char xmitcsum
;
467 /* wait around for the start character, ignore all other characters */
468 while ((ch
= getDebugChar ()) != '$')
476 /* now, read until a # or end of buffer is found */
477 while (count
< BUFMAX
- 1)
479 ch
= getDebugChar ();
484 checksum
= checksum
+ ch
;
492 ch
= getDebugChar ();
493 xmitcsum
= hex (ch
) << 4;
494 ch
= getDebugChar ();
495 xmitcsum
+= hex (ch
);
497 if (checksum
!= xmitcsum
)
502 "bad checksum. My count = 0x%x, sent=0x%x. buf=%s\n",
503 checksum
, xmitcsum
, buffer
);
505 putDebugChar ('-'); /* failed checksum */
509 putDebugChar ('+'); /* successful transfer */
511 /* if a sequence char is present, reply the sequence ID */
512 if (buffer
[2] == ':')
514 putDebugChar (buffer
[0]);
515 putDebugChar (buffer
[1]);
526 /* send the packet in buffer. */
529 putpacket (unsigned char *buffer
)
531 unsigned char checksum
;
535 /* $<packet info>#<checksum>. */
542 while (ch
= buffer
[count
])
550 putDebugChar (hexchars
[checksum
>> 4]);
551 putDebugChar (hexchars
[checksum
% 16]);
554 while (getDebugChar () != '+');
558 debug_error (format
, parm
)
563 fprintf (stderr
, format
, parm
);
566 /* Address of a routine to RTE to if we get a memory fault. */
567 static void (*volatile mem_fault_routine
) () = NULL
;
569 /* Indicate to caller of mem2hex or hex2mem that there has been an
571 static volatile int mem_err
= 0;
579 /* These are separate functions so that they are so short and sweet
580 that the compiler won't save any registers (if there is a fault
581 to mem_fault, they won't get restored, so there better not be any
584 get_char (char *addr
)
590 set_char (char *addr
, int val
)
595 /* convert the memory pointed to by mem into hex, placing result in buf */
596 /* return a pointer to the last char put in buf (null) */
597 /* If MAY_FAULT is non-zero, then we should set mem_err in response to
598 a fault; if zero treat a fault like any other fault in the stub. */
600 mem2hex (mem
, buf
, count
, may_fault
)
610 mem_fault_routine
= set_mem_err
;
611 for (i
= 0; i
< count
; i
++)
613 ch
= get_char (mem
++);
614 if (may_fault
&& mem_err
)
616 *buf
++ = hexchars
[ch
>> 4];
617 *buf
++ = hexchars
[ch
% 16];
621 mem_fault_routine
= NULL
;
625 /* convert the hex array pointed to by buf into binary to be placed in mem */
626 /* return a pointer to the character AFTER the last byte written */
628 hex2mem (buf
, mem
, count
, may_fault
)
638 mem_fault_routine
= set_mem_err
;
639 for (i
= 0; i
< count
; i
++)
641 ch
= hex (*buf
++) << 4;
642 ch
= ch
+ hex (*buf
++);
643 set_char (mem
++, ch
);
644 if (may_fault
&& mem_err
)
648 mem_fault_routine
= NULL
;
652 /* this function takes the 386 exception vector and attempts to
653 translate this number into a unix compatible signal value */
655 computeSignal (int exceptionVector
)
658 switch (exceptionVector
)
662 break; /* divide by zero */
665 break; /* debug exception */
668 break; /* breakpoint */
671 break; /* into instruction (overflow) */
674 break; /* bound instruction */
677 break; /* Invalid opcode */
680 break; /* coprocessor not available */
683 break; /* double fault */
686 break; /* coprocessor segment overrun */
689 break; /* Invalid TSS */
692 break; /* Segment not present */
695 break; /* stack exception */
698 break; /* general protection */
701 break; /* page fault */
704 break; /* coprocessor error */
706 sigval
= 7; /* "software generated" */
711 /**********************************************/
712 /* WHILE WE FIND NICE HEX CHARS, BUILD AN INT */
713 /* RETURN NUMBER OF CHARS PROCESSED */
714 /**********************************************/
716 hexToInt (char **ptr
, int *intValue
)
725 hexValue
= hex (**ptr
);
728 *intValue
= (*intValue
<< 4) | hexValue
;
741 * This function does all command procesing for interfacing to gdb.
744 handle_exception (int exceptionVector
)
746 int sigval
, stepping
;
751 gdb_i386vector
= exceptionVector
;
755 printf ("vector=%d, sr=0x%x, pc=0x%x\n",
756 exceptionVector
, registers
[PS
], registers
[PC
]);
759 /* reply to host that an exception has occurred */
760 sigval
= computeSignal (exceptionVector
);
762 ptr
= remcomOutBuffer
;
764 *ptr
++ = 'T'; /* notify gdb with signo, PC, FP and SP */
765 *ptr
++ = hexchars
[sigval
>> 4];
766 *ptr
++ = hexchars
[sigval
& 0xf];
768 *ptr
++ = hexchars
[ESP
];
770 ptr
= mem2hex((char *)®isters
[ESP
], ptr
, 4, 0); /* SP */
773 *ptr
++ = hexchars
[EBP
];
775 ptr
= mem2hex((char *)®isters
[EBP
], ptr
, 4, 0); /* FP */
778 *ptr
++ = hexchars
[PC
];
780 ptr
= mem2hex((char *)®isters
[PC
], ptr
, 4, 0); /* PC */
785 putpacket (remcomOutBuffer
);
791 remcomOutBuffer
[0] = 0;
797 remcomOutBuffer
[0] = 'S';
798 remcomOutBuffer
[1] = hexchars
[sigval
>> 4];
799 remcomOutBuffer
[2] = hexchars
[sigval
% 16];
800 remcomOutBuffer
[3] = 0;
803 remote_debug
= !(remote_debug
); /* toggle debug flag */
805 case 'g': /* return the value of the CPU registers */
806 mem2hex ((char *) registers
, remcomOutBuffer
, NUMREGBYTES
, 0);
808 case 'G': /* set the value of the CPU registers - return OK */
809 hex2mem (ptr
, (char *) registers
, NUMREGBYTES
, 0);
810 strcpy (remcomOutBuffer
, "OK");
812 case 'P': /* set the value of a single CPU register - return OK */
816 if (hexToInt (&ptr
, ®no
) && *ptr
++ == '=')
817 if (regno
>= 0 && regno
< NUMREGS
)
819 hex2mem (ptr
, (char *) ®isters
[regno
], 4, 0);
820 strcpy (remcomOutBuffer
, "OK");
824 strcpy (remcomOutBuffer
, "E01");
828 /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */
830 /* TRY TO READ %x,%x. IF SUCCEED, SET PTR = 0 */
831 if (hexToInt (&ptr
, &addr
))
833 if (hexToInt (&ptr
, &length
))
837 mem2hex ((char *) addr
, remcomOutBuffer
, length
, 1);
840 strcpy (remcomOutBuffer
, "E03");
841 debug_error ("memory fault");
847 strcpy (remcomOutBuffer
, "E01");
851 /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */
853 /* TRY TO READ '%x,%x:'. IF SUCCEED, SET PTR = 0 */
854 if (hexToInt (&ptr
, &addr
))
856 if (hexToInt (&ptr
, &length
))
860 hex2mem (ptr
, (char *) addr
, length
, 1);
864 strcpy (remcomOutBuffer
, "E03");
865 debug_error ("memory fault");
869 strcpy (remcomOutBuffer
, "OK");
876 strcpy (remcomOutBuffer
, "E02");
880 /* cAA..AA Continue at address AA..AA(optional) */
881 /* sAA..AA Step one instruction from AA..AA(optional) */
885 /* try to read optional parameter, pc unchanged if no parm */
886 if (hexToInt (&ptr
, &addr
))
887 registers
[PC
] = addr
;
889 newPC
= registers
[PC
];
891 /* clear the trace bit */
892 registers
[PS
] &= 0xfffffeff;
894 /* set the trace bit if we're stepping */
896 registers
[PS
] |= 0x100;
898 _returnFromException (); /* this is a jump */
901 /* kill the program */
902 case 'k': /* do nothing */
904 /* Huh? This doesn't look like "nothing".
905 m68k-stub.c and sparc-stub.c don't have it. */
911 /* reply to the request */
912 putpacket (remcomOutBuffer
);
916 /* this function is used to set up exception handlers for tracing and
919 set_debug_traps (void)
921 stackPtr
= &remcomStack
[STACKSIZE
/ sizeof (int) - 1];
923 exceptionHandler (0, _catchException0
);
924 exceptionHandler (1, _catchException1
);
925 exceptionHandler (3, _catchException3
);
926 exceptionHandler (4, _catchException4
);
927 exceptionHandler (5, _catchException5
);
928 exceptionHandler (6, _catchException6
);
929 exceptionHandler (7, _catchException7
);
930 exceptionHandler (8, _catchException8
);
931 exceptionHandler (9, _catchException9
);
932 exceptionHandler (10, _catchException10
);
933 exceptionHandler (11, _catchException11
);
934 exceptionHandler (12, _catchException12
);
935 exceptionHandler (13, _catchException13
);
936 exceptionHandler (14, _catchException14
);
937 exceptionHandler (16, _catchException16
);
942 /* This function will generate a breakpoint exception. It is used at the
943 beginning of a program to sync up with a debugger and can be used
944 otherwise as a quick means to stop program execution and "break" into
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