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Diffstat (limited to 'gdb/m68k-stub.c')
| -rw-r--r-- | gdb/m68k-stub.c | 1014 |
1 files changed, 1014 insertions, 0 deletions
diff --git a/gdb/m68k-stub.c b/gdb/m68k-stub.c new file mode 100644 index 0000000..c2f1d3f --- /dev/null +++ b/gdb/m68k-stub.c @@ -0,0 +1,1014 @@ +/**************************************************************************** + + THIS SOFTWARE IS NOT COPYRIGHTED + + HP offers the following for use in the public domain. HP makes no + warranty with regard to the software or it's performance and the + user accepts the software "AS IS" with all faults. + + HP DISCLAIMS ANY WARRANTIES, EXPRESS OR IMPLIED, WITH REGARD + TO THIS SOFTWARE INCLUDING BUT NOT LIMITED TO THE WARRANTIES + OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. + +****************************************************************************/ + +/**************************************************************************** + * Header: remcom.c,v 1.34 91/03/09 12:29:49 glenne Exp $ + * + * Module name: remcom.c $ + * Revision: 1.34 $ + * Date: 91/03/09 12:29:49 $ + * Contributor: Lake Stevens Instrument Division$ + * + * Description: low level support for gdb debugger. $ + * + * Considerations: only works on target hardware $ + * + * Written by: Glenn Engel $ + * ModuleState: Experimental $ + * + * NOTES: See Below $ + * + * To enable debugger support, two things need to happen. One, a + * call to set_debug_traps() is necessary in order to allow any breakpoints + * or error conditions to be properly intercepted and reported to gdb. + * Two, a breakpoint needs to be generated to begin communication. This + * is most easily accomplished by a call to breakpoint(). Breakpoint() + * simulates a breakpoint by executing a trap #1. The breakpoint instruction + * is hardwired to trap #1 because not to do so is a compatibility problem-- + * there either should be a standard breakpoint instruction, or the protocol + * should be extended to provide some means to communicate which breakpoint + * instruction is in use (or have the stub insert the breakpoint). + * + * Some explanation is probably necessary to explain how exceptions are + * handled. When an exception is encountered the 68000 pushes the current + * program counter and status register onto the supervisor stack and then + * transfers execution to a location specified in it's vector table. + * The handlers for the exception vectors are hardwired to jmp to an address + * given by the relation: (exception - 256) * 6. These are decending + * addresses starting from -6, -12, -18, ... By allowing 6 bytes for + * each entry, a jsr, jmp, bsr, ... can be used to enter the exception + * handler. Using a jsr to handle an exception has an added benefit of + * allowing a single handler to service several exceptions and use the + * return address as the key differentiation. The vector number can be + * computed from the return address by [ exception = (addr + 1530) / 6 ]. + * The sole purpose of the routine _catchException is to compute the + * exception number and push it on the stack in place of the return address. + * The external function exceptionHandler() is + * used to attach a specific handler to a specific m68k exception. + * For 68020 machines, the ability to have a return address around just + * so the vector can be determined is not necessary because the '020 pushes an + * extra word onto the stack containing the vector offset + * + * Because gdb will sometimes write to the stack area to execute function + * calls, this program cannot rely on using the supervisor stack so it + * uses it's own stack area reserved in the int array remcomStack. + * + ************* + * + * The following gdb commands are supported: + * + * command function Return value + * + * g return the value of the CPU registers hex data or ENN + * G set the value of the CPU registers OK or ENN + * + * mAA..AA,LLLL Read LLLL bytes at address AA..AA hex data or ENN + * MAA..AA,LLLL: Write LLLL bytes at address AA.AA OK or ENN + * + * c Resume at current address SNN ( signal NN) + * cAA..AA Continue at address AA..AA SNN + * + * s Step one instruction SNN + * sAA..AA Step one instruction from AA..AA SNN + * + * k kill + * + * ? What was the last sigval ? SNN (signal NN) + * + * All commands and responses are sent with a packet which includes a + * checksum. A packet consists of + * + * $<packet info>#<checksum>. + * + * where + * <packet info> :: <characters representing the command or response> + * <checksum> :: < two hex digits computed as modulo 256 sum of <packetinfo>> + * + * When a packet is received, it is first acknowledged with either '+' or '-'. + * '+' indicates a successful transfer. '-' indicates a failed transfer. + * + * Example: + * + * Host: Reply: + * $m0,10#2a +$00010203040506070809101112131415#42 + * + ****************************************************************************/ + +#include <stdio.h> +#include <string.h> +#include <setjmp.h> + +/************************************************************************ + * + * external low-level support routines + */ +typedef void (*ExceptionHook)(int); /* pointer to function with int parm */ +typedef void (*Function)(); /* pointer to a function */ + +extern void putDebugChar(); /* write a single character */ +extern int getDebugChar(); /* read and return a single char */ + +extern Function exceptionHandler(); /* assign an exception handler */ +extern ExceptionHook exceptionHook; /* hook variable for errors/exceptions */ + +/************************/ +/* FORWARD DECLARATIONS */ +/************************/ +static void +initializeRemcomErrorFrame (); + +/************************************************************************/ +/* BUFMAX defines the maximum number of characters in inbound/outbound buffers*/ +/* at least NUMREGBYTES*2 are needed for register packets */ +#define BUFMAX 400 + +static char initialized; /* boolean flag. != 0 means we've been initialized */ + +int remote_debug; +/* debug > 0 prints ill-formed commands in valid packets & checksum errors */ + +static const char hexchars[]="0123456789abcdef"; + +/* there are 180 bytes of registers on a 68020 w/68881 */ +/* many of the fpa registers are 12 byte (96 bit) registers */ +#define NUMREGBYTES 180 +enum regnames {D0,D1,D2,D3,D4,D5,D6,D7, + A0,A1,A2,A3,A4,A5,A6,A7, + PS,PC, + FP0,FP1,FP2,FP3,FP4,FP5,FP6,FP7, + FPCONTROL,FPSTATUS,FPIADDR + }; + + +/* We keep a whole frame cache here. "Why?", I hear you cry, "doesn't + GDB handle that sort of thing?" Well, yes, I believe the only + reason for this cache is to save and restore floating point state + (fsave/frestore). A cleaner way to do this would be to make the + fsave data part of the registers which GDB deals with like any + other registers. This should not be a performance problem if the + ability to read individual registers is added to the protocol. */ + +typedef struct FrameStruct +{ + struct FrameStruct *previous; + int exceptionPC; /* pc value when this frame created */ + int exceptionVector; /* cpu vector causing exception */ + short frameSize; /* size of cpu frame in words */ + short sr; /* for 68000, this not always sr */ + int pc; + short format; + int fsaveHeader; + int morejunk[0]; /* exception frame, fp save... */ +} Frame; + +#define FRAMESIZE 500 +int gdbFrameStack[FRAMESIZE]; +static Frame *lastFrame; + +/* + * these should not be static cuz they can be used outside this module + */ +int registers[NUMREGBYTES/4]; +int superStack; + +#define STACKSIZE 10000 +int remcomStack[STACKSIZE/sizeof(int)]; +static int* stackPtr = &remcomStack[STACKSIZE/sizeof(int) - 1]; + +/* + * In many cases, the system will want to continue exception processing + * when a continue command is given. + * oldExceptionHook is a function to invoke in this case. + */ + +static ExceptionHook oldExceptionHook; + +#ifdef mc68020 +/* the size of the exception stack on the 68020 varies with the type of + * exception. The following table is the number of WORDS used + * for each exception format. + */ +const short exceptionSize[] = { 4,4,6,4,4,4,4,4,29,10,16,46,12,4,4,4 }; +#endif + +#ifdef mc68332 +static const short exceptionSize[] = { 4,4,6,4,4,4,4,4,4,4,4,4,16,4,4,4 }; +#endif + +/************* jump buffer used for setjmp/longjmp **************************/ +jmp_buf remcomEnv; + +/*************************** ASSEMBLY CODE MACROS *************************/ +/* */ + +#ifdef __HAVE_68881__ +/* do an fsave, then remember the address to begin a restore from */ +#define SAVE_FP_REGS() asm(" fsave a0@-"); \ + asm(" fmovemx fp0-fp7,_registers+72"); \ + asm(" fmoveml fpcr/fpsr/fpi,_registers+168"); +#define RESTORE_FP_REGS() \ +asm(" \n\ + fmoveml _registers+168,fpcr/fpsr/fpi \n\ + fmovemx _registers+72,fp0-fp7 \n\ + cmpl #-1,a0@ | skip frestore flag set ? \n\ + beq skip_frestore \n\ + frestore a0@+ \n\ +skip_frestore: \n\ +"); + +#else +#define SAVE_FP_REGS() +#define RESTORE_FP_REGS() +#endif /* __HAVE_68881__ */ + +void return_to_super(); +void return_to_user(); + +asm(" +.text +.globl _return_to_super +_return_to_super: + movel _registers+60,sp /* get new stack pointer */ + movel _lastFrame,a0 /* get last frame info */ + bra return_to_any + +.globl _return_to_user +_return_to_user: + movel _registers+60,a0 /* get usp */ + movel a0,usp /* set usp */ + movel _superStack,sp /* get original stack pointer */ + +return_to_any: + movel _lastFrame,a0 /* get last frame info */ + movel a0@+,_lastFrame /* link in previous frame */ + addql #8,a0 /* skip over pc, vector#*/ + movew a0@+,d0 /* get # of words in cpu frame */ + addw d0,a0 /* point to end of data */ + addw d0,a0 /* point to end of data */ + movel a0,a1 +# +# copy the stack frame + subql #1,d0 +copyUserLoop: + movew a1@-,sp@- + dbf d0,copyUserLoop +"); + RESTORE_FP_REGS() + asm(" moveml _registers,d0-d7/a0-a6"); + asm(" rte"); /* pop and go! */ + +#define DISABLE_INTERRUPTS() asm(" oriw #0x0700,sr"); +#define BREAKPOINT() asm(" trap #1"); + +/* this function is called immediately when a level 7 interrupt occurs */ +/* if the previous interrupt level was 7 then we're already servicing */ +/* this interrupt and an rte is in order to return to the debugger. */ +/* For the 68000, the offset for sr is 6 due to the jsr return address */ +asm(" +.text +.globl __debug_level7 +__debug_level7: + movew d0,sp@-"); +#if defined (mc68020) || defined (mc68332) +asm(" movew sp@(2),d0"); +#else +asm(" movew sp@(6),d0"); +#endif +asm(" andiw #0x700,d0 + cmpiw #0x700,d0 + beq _already7 + movew sp@+,d0 + bra __catchException +_already7: + movew sp@+,d0"); +#if !defined (mc68020) && !defined (mc68332) +asm(" lea sp@(4),sp"); /* pull off 68000 return address */ +#endif +asm(" rte"); + +extern void _catchException (); + +#if defined (mc68020) || defined (mc68332) +/* This function is called when a 68020 exception occurs. It saves + * all the cpu and fpcp regs in the _registers array, creates a frame on a + * linked list of frames which has the cpu and fpcp stack frames needed + * to properly restore the context of these processors, and invokes + * an exception handler (remcom_handler). + * + * stack on entry: stack on exit: + * N bytes of junk exception # MSWord + * Exception Format Word exception # MSWord + * Program counter LSWord + * Program counter MSWord + * Status Register + * + * + */ +asm(" +.text +.globl __catchException +__catchException:"); +DISABLE_INTERRUPTS(); +asm(" + moveml d0-d7/a0-a6,_registers /* save registers */ + movel _lastFrame,a0 /* last frame pointer */ +"); +SAVE_FP_REGS(); +asm(" + lea _registers,a5 /* get address of registers */ + movew sp@,d1 /* get status register */ + movew d1,a5@(66) /* save sr */ + movel sp@(2),a4 /* save pc in a4 for later use */ + movel a4,a5@(68) /* save pc in _regisers[] */ + +# +# figure out how many bytes in the stack frame + movew sp@(6),d0 /* get '020 exception format */ + movew d0,d2 /* make a copy of format word */ + andiw #0xf000,d0 /* mask off format type */ + rolw #5,d0 /* rotate into the low byte *2 */ + lea _exceptionSize,a1 + addw d0,a1 /* index into the table */ + movew a1@,d0 /* get number of words in frame */ + movew d0,d3 /* save it */ + subw d0,a0 /* adjust save pointer */ + subw d0,a0 /* adjust save pointer(bytes) */ + movel a0,a1 /* copy save pointer */ + subql #1,d0 /* predecrement loop counter */ +# +# copy the frame +saveFrameLoop: + movew sp@+,a1@+ + dbf d0,saveFrameLoop +# +# now that the stack has been clenaed, +# save the a7 in use at time of exception + movel sp,_superStack /* save supervisor sp */ + andiw #0x2000,d1 /* were we in supervisor mode ? */ + beq userMode + movel a7,a5@(60) /* save a7 */ + bra a7saveDone +userMode: + movel usp,a1 + movel a1,a5@(60) /* save user stack pointer */ +a7saveDone: + +# +# save size of frame + movew d3,a0@- + +# +# compute exception number + andl #0xfff,d2 /* mask off vector offset */ + lsrw #2,d2 /* divide by 4 to get vect num */ + movel d2,a0@- /* save it */ +# +# save pc causing exception + movel a4,a0@- +# +# save old frame link and set the new value + movel _lastFrame,a1 /* last frame pointer */ + movel a1,a0@- /* save pointer to prev frame */ + movel a0,_lastFrame + + movel d2,sp@- /* push exception num */ + movel _exceptionHook,a0 /* get address of handler */ + jbsr a0@ /* and call it */ + clrl sp@ /* replace exception num parm with frame ptr */ + jbsr __returnFromException /* jbsr, but never returns */ +"); +#else /* mc68000 */ +/* This function is called when an exception occurs. It translates the + * return address found on the stack into an exception vector # which + * is then handled by either handle_exception or a system handler. + * _catchException provides a front end for both. + * + * stack on entry: stack on exit: + * Program counter MSWord exception # MSWord + * Program counter LSWord exception # MSWord + * Status Register + * Return Address MSWord + * Return Address LSWord + */ +asm(" +.text +.globl __catchException +__catchException:"); +DISABLE_INTERRUPTS(); +asm(" + moveml d0-d7/a0-a6,_registers /* save registers */ + movel _lastFrame,a0 /* last frame pointer */ +"); +SAVE_FP_REGS(); +asm(" + lea _registers,a5 /* get address of registers */ + movel sp@+,d2 /* pop return address */ + addl #1530,d2 /* convert return addr to */ + divs #6,d2 /* exception number */ + extl d2 + + moveql #3,d3 /* assume a three word frame */ + + cmpiw #3,d2 /* bus error or address error ? */ + bgt normal /* if >3 then normal error */ + movel sp@+,a0@- /* copy error info to frame buff*/ + movel sp@+,a0@- /* these are never used */ + moveql #7,d3 /* this is a 7 word frame */ + +normal: + movew sp@+,d1 /* pop status register */ + movel sp@+,a4 /* pop program counter */ + movew d1,a5@(66) /* save sr */ + movel a4,a5@(68) /* save pc in _regisers[] */ + movel a4,a0@- /* copy pc to frame buffer */ + movew d1,a0@- /* copy sr to frame buffer */ + + movel sp,_superStack /* save supervisor sp */ + + andiw #0x2000,d1 /* were we in supervisor mode ? */ + beq userMode + movel a7,a5@(60) /* save a7 */ + bra saveDone +userMode: + movel usp,a1 /* save user stack pointer */ + movel a1,a5@(60) /* save user stack pointer */ +saveDone: + + movew d3,a0@- /* push frame size in words */ + movel d2,a0@- /* push vector number */ + movel a4,a0@- /* push exception pc */ + +# +# save old frame link and set the new value + movel _lastFrame,a1 /* last frame pointer */ + movel a1,a0@- /* save pointer to prev frame */ + movel a0,_lastFrame + + movel d2,sp@- /* push exception num */ + movel _exceptionHook,a0 /* get address of handler */ + jbsr a0@ /* and call it */ + clrl sp@ /* replace exception num parm with frame ptr */ + jbsr __returnFromException /* jbsr, but never returns */ +"); +#endif + + +/* + * remcomHandler is a front end for handle_exception. It moves the + * stack pointer into an area reserved for debugger use in case the + * breakpoint happened in supervisor mode. + */ +asm("_remcomHandler:"); +asm(" addl #4,sp"); /* pop off return address */ +asm(" movel sp@+,d0"); /* get the exception number */ +asm(" movel _stackPtr,sp"); /* move to remcom stack area */ +asm(" movel d0,sp@-"); /* push exception onto stack */ +asm(" jbsr _handle_exception"); /* this never returns */ +asm(" rts"); /* return */ + +void _returnFromException( Frame *frame ) +{ + /* if no passed in frame, use the last one */ + if (! frame) + { + frame = lastFrame; + frame->frameSize = 4; + frame->format = 0; + frame->fsaveHeader = -1; /* restore regs, but we dont have fsave info*/ + } + +#if !defined (mc68020) && !defined (mc68332) + /* a 68000 cannot use the internal info pushed onto a bus error + * or address error frame when doing an RTE so don't put this info + * onto the stack or the stack will creep every time this happens. + */ + frame->frameSize=3; +#endif + + /* throw away any frames in the list after this frame */ + lastFrame = frame; + + frame->sr = registers[(int) PS]; + frame->pc = registers[(int) PC]; + + if (registers[(int) PS] & 0x2000) + { + /* return to supervisor mode... */ + return_to_super(); + } + else + { /* return to user mode */ + return_to_user(); + } +} + +int hex(ch) +char ch; +{ + if ((ch >= 'a') && (ch <= 'f')) return (ch-'a'+10); + if ((ch >= '0') && (ch <= '9')) return (ch-'0'); + if ((ch >= 'A') && (ch <= 'F')) return (ch-'A'+10); + return (-1); +} + + +/* scan for the sequence $<data>#<checksum> */ +void getpacket(buffer) +char * buffer; +{ + unsigned char checksum; + unsigned char xmitcsum; + int i; + int count; + char ch; + + do { + /* wait around for the start character, ignore all other characters */ + while ((ch = (getDebugChar() & 0x7f)) != '$'); + checksum = 0; + xmitcsum = -1; + + count = 0; + + /* now, read until a # or end of buffer is found */ + while (count < BUFMAX) { + ch = getDebugChar() & 0x7f; + if (ch == '#') break; + checksum = checksum + ch; + buffer[count] = ch; + count = count + 1; + } + buffer[count] = 0; + + if (ch == '#') { + xmitcsum = hex(getDebugChar() & 0x7f) << 4; + xmitcsum += hex(getDebugChar() & 0x7f); + if ((remote_debug ) && (checksum != xmitcsum)) { + fprintf (stderr,"bad checksum. My count = 0x%x, sent=0x%x. buf=%s\n", + checksum,xmitcsum,buffer); + } + + if (checksum != xmitcsum) putDebugChar('-'); /* failed checksum */ + else { + putDebugChar('+'); /* successful transfer */ + /* if a sequence char is present, reply the sequence ID */ + if (buffer[2] == ':') { + putDebugChar( buffer[0] ); + putDebugChar( buffer[1] ); + /* remove sequence chars from buffer */ + count = strlen(buffer); + for (i=3; i <= count; i++) buffer[i-3] = buffer[i]; + } + } + } + } while (checksum != xmitcsum); + +} + +/* send the packet in buffer. The host get's one chance to read it. + This routine does not wait for a positive acknowledge. */ + + +void putpacket(buffer) +char * buffer; +{ + unsigned char checksum; + int count; + char ch; + + /* $<packet info>#<checksum>. */ + do { + putDebugChar('$'); + checksum = 0; + count = 0; + + while (ch=buffer[count]) { + putDebugChar(ch); + checksum += ch; + count += 1; + } + + putDebugChar('#'); + putDebugChar(hexchars[checksum >> 4]); + putDebugChar(hexchars[checksum % 16]); + + } while (1 == 0); /* (getDebugChar() != '+'); */ + +} + +char remcomInBuffer[BUFMAX]; +char remcomOutBuffer[BUFMAX]; +static short error; + + +void debug_error(format, parm) +char * format; +char * parm; +{ + if (remote_debug) fprintf (stderr,format,parm); +} + +/* convert the memory pointed to by mem into hex, placing result in buf */ +/* return a pointer to the last char put in buf (null) */ +char* mem2hex(mem, buf, count) +char* mem; +char* buf; +int count; +{ + int i; + unsigned char ch; + for (i=0;i<count;i++) { + ch = *mem++; + *buf++ = hexchars[ch >> 4]; + *buf++ = hexchars[ch % 16]; + } + *buf = 0; + return(buf); +} + +/* convert the hex array pointed to by buf into binary to be placed in mem */ +/* return a pointer to the character AFTER the last byte written */ +char* hex2mem(buf, mem, count) +char* buf; +char* mem; +int count; +{ + int i; + unsigned char ch; + for (i=0;i<count;i++) { + ch = hex(*buf++) << 4; + ch = ch + hex(*buf++); + *mem++ = ch; + } + return(mem); +} + +/* a bus error has occurred, perform a longjmp + to return execution and allow handling of the error */ + +void handle_buserror() +{ + longjmp(remcomEnv,1); +} + +/* this function takes the 68000 exception number and attempts to + translate this number into a unix compatible signal value */ +int computeSignal( exceptionVector ) +int exceptionVector; +{ + int sigval; + switch (exceptionVector) { + case 2 : sigval = 10; break; /* bus error */ + case 3 : sigval = 10; break; /* address error */ + case 4 : sigval = 4; break; /* illegal instruction */ + case 5 : sigval = 8; break; /* zero divide */ + case 6 : sigval = 8; break; /* chk instruction */ + case 7 : sigval = 8; break; /* trapv instruction */ + case 8 : sigval = 11; break; /* privilege violation */ + case 9 : sigval = 5; break; /* trace trap */ + case 10: sigval = 4; break; /* line 1010 emulator */ + case 11: sigval = 4; break; /* line 1111 emulator */ + + /* Coprocessor protocol violation. Using a standard MMU or FPU + this cannot be triggered by software. Call it a SIGBUS. */ + case 13: sigval = 10; break; + + case 31: sigval = 2; break; /* interrupt */ + case 33: sigval = 5; break; /* breakpoint */ + + /* This is a trap #8 instruction. Apparently it is someone's software + convention for some sort of SIGFPE condition. Whose? How many + people are being screwed by having this code the way it is? + Is there a clean solution? */ + case 40: sigval = 8; break; /* floating point err */ + + case 48: sigval = 8; break; /* floating point err */ + case 49: sigval = 8; break; /* floating point err */ + case 50: sigval = 8; break; /* zero divide */ + case 51: sigval = 8; break; /* underflow */ + case 52: sigval = 8; break; /* operand error */ + case 53: sigval = 8; break; /* overflow */ + case 54: sigval = 8; break; /* NAN */ + default: + sigval = 7; /* "software generated"*/ + } + return (sigval); +} + +/**********************************************/ +/* WHILE WE FIND NICE HEX CHARS, BUILD AN INT */ +/* RETURN NUMBER OF CHARS PROCESSED */ +/**********************************************/ +int hexToInt(char **ptr, int *intValue) +{ + int numChars = 0; + int hexValue; + + *intValue = 0; + + while (**ptr) + { + hexValue = hex(**ptr); + if (hexValue >=0) + { + *intValue = (*intValue <<4) | hexValue; + numChars ++; + } + else + break; + + (*ptr)++; + } + + return (numChars); +} + +/* + * This function does all command procesing for interfacing to gdb. + */ +void handle_exception(int exceptionVector) +{ + int sigval; + int addr, length; + char * ptr; + int newPC; + Frame *frame; + + if (remote_debug) printf("vector=%d, sr=0x%x, pc=0x%x\n", + exceptionVector, + registers[ PS ], + registers[ PC ]); + + /* reply to host that an exception has occurred */ + sigval = computeSignal( exceptionVector ); + remcomOutBuffer[0] = 'S'; + remcomOutBuffer[1] = hexchars[sigval >> 4]; + remcomOutBuffer[2] = hexchars[sigval % 16]; + remcomOutBuffer[3] = 0; + + putpacket(remcomOutBuffer); + + while (1==1) { + error = 0; + remcomOutBuffer[0] = 0; + getpacket(remcomInBuffer); + switch (remcomInBuffer[0]) { + case '?' : remcomOutBuffer[0] = 'S'; + remcomOutBuffer[1] = hexchars[sigval >> 4]; + remcomOutBuffer[2] = hexchars[sigval % 16]; + remcomOutBuffer[3] = 0; + break; + case 'd' : remote_debug = !(remote_debug); /* toggle debug flag */ + break; + case 'g' : /* return the value of the CPU registers */ + mem2hex((char*) registers, remcomOutBuffer, NUMREGBYTES); + break; + case 'G' : /* set the value of the CPU registers - return OK */ + hex2mem(&remcomInBuffer[1], (char*) registers, NUMREGBYTES); + strcpy(remcomOutBuffer,"OK"); + break; + + /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */ + case 'm' : + if (setjmp(remcomEnv) == 0) + { + exceptionHandler(2,handle_buserror); + + /* TRY TO READ %x,%x. IF SUCCEED, SET PTR = 0 */ + ptr = &remcomInBuffer[1]; + if (hexToInt(&ptr,&addr)) + if (*(ptr++) == ',') + if (hexToInt(&ptr,&length)) + { + ptr = 0; + mem2hex((char*) addr, remcomOutBuffer, length); + } + + if (ptr) + { + strcpy(remcomOutBuffer,"E01"); + debug_error("malformed read memory command: %s",remcomInBuffer); + } + } + else { + exceptionHandler(2,_catchException); + strcpy(remcomOutBuffer,"E03"); + debug_error("bus error"); + } + + /* restore handler for bus error */ + exceptionHandler(2,_catchException); + break; + + /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */ + case 'M' : + if (setjmp(remcomEnv) == 0) { + exceptionHandler(2,handle_buserror); + + /* TRY TO READ '%x,%x:'. IF SUCCEED, SET PTR = 0 */ + ptr = &remcomInBuffer[1]; + if (hexToInt(&ptr,&addr)) + if (*(ptr++) == ',') + if (hexToInt(&ptr,&length)) + if (*(ptr++) == ':') + { + hex2mem(ptr, (char*) addr, length); + ptr = 0; + strcpy(remcomOutBuffer,"OK"); + } + if (ptr) + { + strcpy(remcomOutBuffer,"E02"); + debug_error("malformed write memory command: %s",remcomInBuffer); + } + } + else { + exceptionHandler(2,_catchException); + strcpy(remcomOutBuffer,"E03"); + debug_error("bus error"); + } + + /* restore handler for bus error */ + exceptionHandler(2,_catchException); + break; + + /* cAA..AA Continue at address AA..AA(optional) */ + /* sAA..AA Step one instruction from AA..AA(optional) */ + case 'c' : + case 's' : + /* try to read optional parameter, pc unchanged if no parm */ + ptr = &remcomInBuffer[1]; + if (hexToInt(&ptr,&addr)) + registers[ PC ] = addr; + + newPC = registers[ PC]; + + /* clear the trace bit */ + registers[ PS ] &= 0x7fff; + + /* set the trace bit if we're stepping */ + if (remcomInBuffer[0] == 's') registers[ PS ] |= 0x8000; + + /* + * look for newPC in the linked list of exception frames. + * if it is found, use the old frame it. otherwise, + * fake up a dummy frame in returnFromException(). + */ + if (remote_debug) printf("new pc = 0x%x\n",newPC); + frame = lastFrame; + while (frame) + { + if (remote_debug) + printf("frame at 0x%x has pc=0x%x, except#=%d\n", + frame,frame->exceptionPC, + frame->exceptionVector); + if (frame->exceptionPC == newPC) break; /* bingo! a match */ + /* + * for a breakpoint instruction, the saved pc may + * be off by two due to re-executing the instruction + * replaced by the trap instruction. Check for this. + */ + if ((frame->exceptionVector == 33) && + (frame->exceptionPC == (newPC+2))) break; + if (frame == frame->previous) + { + frame = 0; /* no match found */ + break; + } + frame = frame->previous; + } + + /* + * If we found a match for the PC AND we are not returning + * as a result of a breakpoint (33), + * trace exception (9), nmi (31), jmp to + * the old exception handler as if this code never ran. + */ + if (frame) + { + if ((frame->exceptionVector != 9) && + (frame->exceptionVector != 31) && + (frame->exceptionVector != 33)) + { + /* + * invoke the previous handler. + */ + if (oldExceptionHook) + (*oldExceptionHook) (frame->exceptionVector); + newPC = registers[ PC ]; /* pc may have changed */ + if (newPC != frame->exceptionPC) + { + if (remote_debug) + printf("frame at 0x%x has pc=0x%x, except#=%d\n", + frame,frame->exceptionPC, + frame->exceptionVector); + /* re-use the last frame, we're skipping it (longjump?)*/ + frame = (Frame *) 0; + _returnFromException( frame ); /* this is a jump */ + } + } + } + + /* if we couldn't find a frame, create one */ + if (frame == 0) + { + frame = lastFrame -1 ; + + /* by using a bunch of print commands with breakpoints, + it's possible for the frame stack to creep down. If it creeps + too far, give up and reset it to the top. Normal use should + not see this happen. + */ + if ((unsigned int) (frame-2) < (unsigned int) &gdbFrameStack) + { + initializeRemcomErrorFrame(); + frame = lastFrame; + } + frame->previous = lastFrame; + lastFrame = frame; + frame = 0; /* null so _return... will properly initialize it */ + } + + _returnFromException( frame ); /* this is a jump */ + + break; + + /* kill the program */ + case 'k' : /* do nothing */ + break; + } /* switch */ + + /* reply to the request */ + putpacket(remcomOutBuffer); + } +} + + +void +initializeRemcomErrorFrame() +{ + lastFrame = ((Frame *) &gdbFrameStack[FRAMESIZE-1]) - 1; + lastFrame->previous = lastFrame; +} + +/* this function is used to set up exception handlers for tracing and + breakpoints */ +void set_debug_traps() +{ + extern void _debug_level7(); + extern void remcomHandler(); + int exception; + + initializeRemcomErrorFrame(); + stackPtr = &remcomStack[STACKSIZE/sizeof(int) - 1]; + + for (exception = 2; exception <= 23; exception++) + exceptionHandler(exception,_catchException); + + /* level 7 interrupt */ + exceptionHandler(31,_debug_level7); + + /* breakpoint exception (trap #1) */ + exceptionHandler(33,_catchException); + + /* This is a trap #8 instruction. Apparently it is someone's software + convention for some sort of SIGFPE condition. Whose? How many + people are being screwed by having this code the way it is? + Is there a clean solution? */ + exceptionHandler(40,_catchException); + + /* 48 to 54 are floating point coprocessor errors */ + for (exception = 48; exception <= 54; exception++) + exceptionHandler(exception,_catchException); + + if (oldExceptionHook != remcomHandler) + { + oldExceptionHook = exceptionHook; + exceptionHook = remcomHandler; + } + + initialized = 1; + +} + +/* This function will generate a breakpoint exception. It is used at the + beginning of a program to sync up with a debugger and can be used + otherwise as a quick means to stop program execution and "break" into + the debugger. */ + +void breakpoint() +{ + if (initialized) BREAKPOINT(); +} + |