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Diffstat (limited to 'gdb/sparc-stub.c')
| -rw-r--r-- | gdb/sparc-stub.c | 892 |
1 files changed, 892 insertions, 0 deletions
diff --git a/gdb/sparc-stub.c b/gdb/sparc-stub.c new file mode 100644 index 0000000..d81b6e5 --- /dev/null +++ b/gdb/sparc-stub.c @@ -0,0 +1,892 @@ +/**************************************************************************** + + 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 $ + * + * Modified for SPARC by Stu Grossman, Cygnus Support. + * + * 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 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 <signal.h> +#include <memory.h> + +/************************************************************************ + * + * external low-level support routines + */ + +extern putDebugChar(); /* write a single character */ +extern getDebugChar(); /* read and return a single char */ + +/************************************************************************/ +/* BUFMAX defines the maximum number of characters in inbound/outbound buffers*/ +/* at least NUMREGBYTES*2 are needed for register packets */ +#define BUFMAX 2048 + +static int initialized; /* boolean flag. != 0 means we've been initialized */ + +static void set_mem_fault_trap(); + +int remote_debug; +/* debug > 0 prints ill-formed commands in valid packets & checksum errors */ + +static const char hexchars[]="0123456789abcdef"; + +#define NUMREGS 72 + +/* Number of bytes of registers. */ +#define NUMREGBYTES (NUMREGS * 4) +enum regnames {G0, G1, G2, G3, G4, G5, G6, G7, + O0, O1, O2, O3, O4, O5, SP, O7, + L0, L1, L2, L3, L4, L5, L6, L7, + I0, I1, I2, I3, I4, I5, FP, I7, + + F0, F1, F2, F3, F4, F5, F6, F7, + F8, F9, F10, F11, F12, F13, F14, F15, + F16, F17, F18, F19, F20, F21, F22, F23, + F24, F25, F26, F27, F28, F29, F30, F31, + Y, PSR, WIM, TBR, PC, NPC, FPSR, CPSR }; + +static unsigned long registers[NUMREGS] __attribute__ ((aligned (8))); + +/*************************** ASSEMBLY CODE MACROS *************************/ +/* */ + +#define BREAKPOINT() asm(" ta 1"); + +extern unsigned long rdtbr(); + +asm(" + .text +! +! FUNCTION +! _chk4ovflo +! +! DESCRIPTION +! This code is branched to before each trap (except reset, +! _win_unf, and _win_ovf) handler. +! It checks to see if we've moved into the invalid window +! and performs fixup ala _win_ovf. +! +! INPUTS +! - %l1 = pc at trap time. +! - %l2 = npc at trap time. +! - %l7 = return address. +! +! INTERNAL DESCRIPTION +! +! RETURNS +! - None. +! + + .align 4 + +_chk4ovflo: + mov %psr, %l0 ! get the psr + and %l0, 0x1F, %l3 ! get the cwp + mov 1, %l4 ! compare cwp with the wim + sll %l4, %l3, %l3 ! compare + mov %wim, %l4 ! read the wim + btst %l4, %l3 + bz _retsave ! not invalid window, just return + nop + ! in line version of _win_ovf + or %l0, 0xf20, %l3 ! enable traps, disable interrupts. + mov %l3, %psr + mov %g1, %l0 ! Save %g1. + srl %l4, 1, %g1 ! Next WIM = %g1 = rol(WIM, 1, NWINDOW) + sll %l4, 8-1, %l3 + bset %l3, %g1 + save %g0, %g0, %g0 ! Get into window to be saved. + mov %g1, %wim ! Install new wim. + nop ! must delay three instructions + nop ! before using these registers, so + nop ! put nops in just to be safe + + std %l0, [%sp + 0 * 4] ! save all local registers + std %l2, [%sp + 2 * 4] + std %l4, [%sp + 4 * 4] + std %l6, [%sp + 6 * 4] + + std %i0, [%sp + 8 * 4] + std %i2, [%sp + 10 * 4] + std %i4, [%sp + 12 * 4] + std %i6, [%sp + 14 * 4] + + restore ! Go back to trap window. + mov %l0, %g1 ! Restore %g1. + +_retsave: + ! It is safe now to allocate a stack frame for this window + ! because all overflow handling will have been accomplished + ! in the event we trapped into the invalid window. + ! ie. all of this window's %o regs (next window's %i regs) + ! will have been safely stored to the stack before we overwrite %sp. + + jmpl %l7+8, %g0 ! Window is valid, just return + sub %fp, (16+1+6+1)*4, %sp ! Make room for input & locals + ! + hidden arg + arg spill + ! + doubleword alignment + +! Read the TBR. + + .globl _rdtbr +_rdtbr: + retl + mov %tbr, %o0 + +! This function is called when any SPARC trap (except window overflow or +! underflow) occurs. It makes sure that the invalid register window is still +! available before jumping into C code. It will also restore the world if you +! return from handle_exception. + +_trap_low: + set _registers, %l0 + + std %g0, [%l0 + 0 * 4] ! registers[Gx] + std %g2, [%l0 + 2 * 4] + std %g4, [%l0 + 4 * 4] + std %g6, [%l0 + 6 * 4] + + std %i0, [%l0 + 8 * 4] ! registers[Ox] + std %i2, [%l0 + 10 * 4] + std %i4, [%l0 + 12 * 4] + std %i6, [%l0 + 14 * 4] + ! F0->F31 not implemented + mov %y, %l4 + mov %psr, %l5 + mov %wim, %l6 + mov %tbr, %l7 + std %l4, [%l0 + 64 * 4] ! Y & PSR + std %l6, [%l0 + 66 * 4] ! WIM & TBR + st %l1, [%l0 + 68 * 4] ! PC + st %l2, [%l0 + 69 * 4] ! NPC + + ! CPSR and FPSR not impl + + sethi %hi(_chk4ovflo), %l7 ! Must call this routine via %l7 + jmpl %l7+%lo(_chk4ovflo), %l7 ! because o regs may not be available yet + nop + mov %psr, %o1 + bset 0xf20, %o1 + mov %o1, %psr ! Turn on traps, disable interrupts + + call _handle_exception + nop + mov %o0, %l7 ! Save return value + +! Reload all of the registers that aren't on the stack + + set _registers, %l0 ! Need to use reg immune from save/rest + + ld [%l0 + 1 * 4], %g1 ! registers[Gx] + ldd [%l0 + 2 * 4], %g2 + ldd [%l0 + 4 * 4], %g4 + ldd [%l0 + 6 * 4], %g6 + + ldd [%l0 + 8 * 4], %o0 ! registers[Ox] + ldd [%l0 + 10 * 4], %o2 + ldd [%l0 + 12 * 4], %o4 + ldd [%l0 + 14 * 4], %o6 + + restore ! Ensure that previous window is valid + save %g0, %g0, %g0 ! by causing a window_underflow trap + + ld [%l0 + 64 * 4], %l3 ! registers[Y] + mov %l3, %y + ld [%l0 + 65 * 4], %l3 ! registers[PSR] + ld [%l0 + 68 * 4], %l1 ! registers[PC] + ld [%l0 + 69 * 4], %l2 ! registers[NPC] + + tst %l7 ! Did handle_exception tell + bg retskip ! us to skip the next inst? + nop + + mov %l3, %psr ! Make sure that traps are disabled + ! for rett + jmpl %l1, %g0 ! Restore old PC + rett %l2 ! Restore old nPC + + mov %l3, %psr ! Make sure that traps are disabled + ! for rett +retskip: ! Come here to skip the next instruction + jmpl %l2, %g0 ! Old nPC + rett %l2+4 ! Old nPC+4 +"); + +/* Convert ch from a hex digit to an int */ + +static int +hex(ch) + unsigned 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 $<data>#<checksum> */ + +static void +getpacket(buffer) + char *buffer; +{ + unsigned char checksum; + unsigned char xmitcsum; + int i; + int count; + unsigned char ch; + + do + { + /* wait around for the start character, ignore all other characters */ + while ((ch = getDebugChar()) != '$') ; + + checksum = 0; + xmitcsum = -1; + + count = 0; + + /* now, read until a # or end of buffer is found */ + while (count < BUFMAX) + { + ch = getDebugChar(); + if (ch == '#') + break; + checksum = checksum + ch; + buffer[count] = ch; + count = count + 1; + } + + if (count >= BUFMAX) + continue; + + buffer[count] = 0; + + if (ch == '#') + { + xmitcsum = hex(getDebugChar()) << 4; + xmitcsum |= hex(getDebugChar()); +#ifdef DEBUG + if (remote_debug && checksum != xmitcsum) + { + fprintf(stderr, "bad checksum. My count = 0x%x, sent=0x%x. buf=%s\n", + checksum,xmitcsum,buffer); + } +#endif +#if 1 + /* Humans shouldn't have to figure out checksums to type to it. */ + putDebugChar ('+'); + return; +#endif + 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. */ + +static void +putpacket(buffer) + unsigned char *buffer; +{ + unsigned char checksum; + int count; + unsigned char ch; + + /* $<packet info>#<checksum>. */ + do + { + putDebugChar('$'); + checksum = 0; + count = 0; + + while (ch = buffer[count]) + { + if (! putDebugChar(ch)) + return; + checksum += ch; + count += 1; + } + + putDebugChar('#'); + putDebugChar(hexchars[checksum >> 4]); + putDebugChar(hexchars[checksum & 0xf]); + + } + while (getDebugChar() != '+'); +} + +static unsigned char remcomInBuffer[BUFMAX]; +static unsigned char remcomOutBuffer[BUFMAX]; +static short error; + +static void +debug_error(format, parm) + char *format; + char *parm; +{ +#ifdef DEBUG + if (remote_debug) + fprintf(stderr,format,parm); +#endif +} + +/* Address of a routine to RTE to if we get a memory fault. */ +static void (*mem_fault_routine)() = NULL; + +/* Indicate to caller of mem2hex or hex2mem that there has been an + error. */ + +static volatile int mem_err = 0; + +/* These are separate functions so that they are so short and sweet + that the compiler won't save any registers (if there is a fault + to mem_fault, they won't get restored, so there better not be any + saved). */ +static int +get_char (addr) + char *addr; +{ + return *addr; +} + +static void +set_char (addr, val) + char *addr; + int val; +{ + *addr = val; +} + +/* Convert the memory pointed to by mem into hex, placing result in buf. + * Return a pointer to the last char put in buf (null), in case of mem fault, + * return 0. + * If MAY_FAULT is non-zero, then we will handle memory faults by returning + * a 0, else treat a fault like any other fault in the stub. + */ + +static unsigned char * +mem2hex(mem, buf, count, may_fault) + unsigned char *mem; + unsigned char *buf; + int count; + int may_fault; +{ + unsigned char ch; + + set_mem_fault_trap(may_fault); + + while (count-- > 0) + { + ch = get_char(mem++); + if (mem_err) + return 0; + *buf++ = hexchars[ch >> 4]; + *buf++ = hexchars[ch & 0xf]; + } + + *buf = 0; + + set_mem_fault_trap(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 */ + +static char * +hex2mem(buf, mem, count, may_fault) + unsigned char *buf; + unsigned char *mem; + int count; + int may_fault; +{ + int i; + unsigned char ch; + + set_mem_fault_trap(may_fault); + + for (i=0; i<count; i++) + { + ch = hex(*buf++) << 4; + ch |= hex(*buf++); + set_char(mem++, ch); + if (mem_err) + return 0; + } + + set_mem_fault_trap(0); + + return mem; +} + +/* this function takes the SPARC trap type code and attempts to + translate this number into a unix compatible signal value */ + +static int +computeSignal(tt) + int tt; +{ + int sigval; + + switch (tt) + { + case 1: + sigval = SIGSEGV; break; /* instruction access error */ + case 2: + sigval = SIGILL; break; /* privileged instruction */ + case 3: + sigval = SIGILL; break; /* illegal instruction */ + case 4: + sigval = SIGEMT; break; /* fp disabled */ + case 36: + sigval = SIGEMT; break; /* cp disabled */ + case 7: + sigval = SIGBUS; break; /* mem address not aligned */ + case 9: + sigval = SIGSEGV; break; /* data access exception */ + case 10: + sigval = SIGEMT; break; /* tag overflow */ + case 128+1: /* ta 1 - normal breakpoint instruction */ + case 255: /* breakpoint hardware unique to SPARClite */ + sigval = SIGTRAP; break; /* breakpoint trap */ + default: + sigval = SIGHUP; /* "software generated"*/ + } + return (sigval); +} + +/* + * While we find nice hex chars, build an int. + * Return number of chars processed. + */ + +static 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. It + * returns 1 if you should skip the instruction at the trap address, 0 + * otherwise. + */ + +static int +handle_exception () +{ + int tt; /* Trap type */ + int sigval; + int addr; + int length; + char *ptr; + int newPC; + unsigned char *sp; + unsigned char *com; + +/* First, we must force all of the windows to be spilled out */ + + asm(" save %g0, -64, %g0 + save %g0, -64, %g0 + save %g0, -64, %g0 + save %g0, -64, %g0 + save %g0, -64, %g0 + save %g0, -64, %g0 + save %g0, -64, %g0 + save %g0, -64, %g0 + restore + restore + restore + restore + restore + restore + restore + restore +"); + +#if 0 + writez(1, "Got to handle_exception()\r\n "); + + writez(1, "psr = 0x"); + numout(registers[PSR], 16); + writez(1, " tbr = 0x"); + numout(registers[TBR], 16); + writez(1, " oldpc = 0x"); + numout(registers[PC], 16); + writez(1, " oldnpc = 0x"); + numout(registers[NPC], 16); + writez(1, "\r\n"); +#endif + + sp = (unsigned char *)registers[SP]; + + tt = (registers[TBR] >> 4) & 0xff; + +#ifdef DEBUG + if (remote_debug) + printf("tbr=0x%x, tt=%d, psr=0x%x, pc=0x%x, npc=0x%x\n", + registers[TBR], (registers[TBR] >> 4) & 0xff, registers[PSR], registers[PC], registers[NPC]); +#endif + + /* reply to host that an exception has occurred */ + sigval = computeSignal(tt); + com = remcomOutBuffer; + + *com++ = 'T'; + *com++ = hexchars[sigval >> 4]; + *com++ = hexchars[sigval & 0xf]; + + *com++ = hexchars[PC >> 4]; + *com++ = hexchars[PC & 0xf]; + com = mem2hex((char *)®isters[PC], com, 4, 0); + + *com++ = hexchars[FP >> 4]; + *com++ = hexchars[FP & 0xf]; + com = mem2hex(sp + (8 + 6) * 4, com, 4, 0); /* FP */ + + *com++ = hexchars[SP >> 4]; + *com++ = hexchars[SP & 0xf]; + com = mem2hex((char *)®isters[SP], com, 4, 0); + + *com++ = hexchars[NPC >> 4]; + *com++ = hexchars[NPC & 0xf]; + com = mem2hex((char *)®isters[NPC], com, 4, 0); + + *com++ = 0; + + putpacket(remcomOutBuffer); + + while (1) + { + error = 0; + remcomOutBuffer[0] = 0; + + getpacket(remcomInBuffer); + switch (remcomInBuffer[0]) + { + case '?': + remcomOutBuffer[0] = 'S'; + remcomOutBuffer[1] = hexchars[sigval >> 4]; + remcomOutBuffer[2] = hexchars[sigval & 0xf]; + remcomOutBuffer[3] = 0; + break; + + case 'd': + remote_debug = !remote_debug; /* toggle debug flag */ + break; + + case 'g': /* return the value of the CPU registers */ + { + com = remcomOutBuffer; + com = mem2hex((char *)registers, com, 16 * 4, 0); /* G & O regs */ + com = mem2hex(sp + 0 * 4, com, 8 * 4, 0); /* L regs */ + com = mem2hex(sp + 8 * 4, com, 8 * 4, 0); /* I regs */ + memset(com, '0', 32 * 8); /* Floating point */ + mem2hex((char *)®isters[Y], + com + 32 * 4 * 2, + 8 * 4, + 0); /* Y, PSR, WIM, TBR, PC, NPC, FPSR, CPSR */ + } + break; + + case 'G': /* set the value of the CPU registers - return OK */ + { + com = &remcomInBuffer[1]; + hex2mem(com, (char *)registers, 16 * 4, 0); /* G & O regs */ + hex2mem(com + 16 * 4 * 2, sp + 0 * 4, 8 * 4, 0); /* L regs */ + hex2mem(com + 24 * 4 * 2, sp + 8 * 4, 8 * 4, 0); /* I regs */ + hex2mem(com + 64 * 4 * 2, (char *)®isters[Y], + 8 * 4, 0); /* Y, PSR, WIM, TBR, PC, NPC, FPSR, CPSR */ + strcpy(remcomOutBuffer,"OK"); + } + break; + + case 'm': /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */ + /* TRY TO READ %x,%x. IF SUCCEED, SET PTR = 0 */ + + ptr = &remcomInBuffer[1]; + + if (hexToInt(&ptr, &addr) + && *ptr++ == ',' + && hexToInt(&ptr, &length)) + { + if (mem2hex((char *)addr, remcomOutBuffer, length, 1)) + break; + + strcpy (remcomOutBuffer, "E03"); + debug_error ("memory fault"); + } + else + { + strcpy(remcomOutBuffer,"E01"); + debug_error("malformed read memory command: %s",remcomInBuffer); + } + break; + + case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */ + /* TRY TO READ '%x,%x:'. IF SUCCEED, SET PTR = 0 */ + + ptr = &remcomInBuffer[1]; + + if (hexToInt(&ptr, &addr) + && *ptr++ == ',' + && hexToInt(&ptr, &length) + && *ptr++ == ':') + { + if (hex2mem(ptr, (char *)addr, length, 1)) + strcpy(remcomOutBuffer, "OK"); + else + { + strcpy(remcomOutBuffer, "E03"); + debug_error("memory fault"); + } + } + else + { + strcpy(remcomOutBuffer, "E02"); + debug_error("malformed write memory command: %s",remcomInBuffer); + } + break; + + case 'c': /* cAA..AA Continue at address AA..AA(optional) */ + case 's': /* sAA..AA Step one instruction from AA..AA(optional) */ + /* try to read optional parameter, pc unchanged if no parm */ + + ptr = &remcomInBuffer[1]; + if (hexToInt(&ptr, &addr)) + { + registers[PC] = addr; + registers[NPC] = addr + 4; + } + + return 0; + + /* kill the program */ + case 'k' : /* do nothing */ + break; + } /* switch */ + + /* reply to the request */ + putpacket(remcomOutBuffer); + } +} + +/* Each entry in the trap vector occupies four words. */ + +struct trap_entry +{ + unsigned long ti[4]; +}; + +#define NUMTRAPS 256 + +/* static struct trap_entry oldvec[NUMTRAPS];*/ + +extern struct trap_entry fltr_proto; +extern struct trap_entry fltr_set_mem_err; +asm (" + .data + .globl _fltr_proto + .align 4 +_fltr_proto: ! First level trap routine prototype + sethi %hi(_trap_low), %l0 + jmpl %lo(_trap_low)+%l0, %g0 + nop + nop + +! Trap handler for memory errors. This just sets mem_err to be non-zero. It +! assumes that %l1 is non-zero. This should be safe, as it is doubtful that +! 0 would ever contain code that could mem fault. This routine will skip +! past the faulting instruction after setting mem_err. + +_fltr_set_mem_err: + sethi %hi(_mem_err), %l0 + st %l1, [%l0 + %lo(_mem_err)] + jmpl %l2, %g0 + rett %l2+4 + + .text +"); + +/* this function is used to set up exception handlers for tracing and + breakpoints */ + +void +set_debug_traps() +{ + int exception; + struct trap_entry *tb; /* Trap vector base address */ + + writez(1, "Got to set_debug_traps\r\n"); + + tb = (struct trap_entry *)(rdtbr() & ~0xfff); + + writez(1, "tb = 0x"); + numout(tb, 16); + writez(1, " trap ins = 0x"); + numout(fltr_proto, 16); + writez(1, "\r\n"); + + tb[1] = fltr_proto; /* instruction access exception */ + tb[2] = fltr_proto; /* privileged instruction */ + tb[3] = fltr_proto; /* illegal instruction */ + tb[4] = fltr_proto; /* fp disabled */ + tb[36] = fltr_proto; /* cp disabled */ + tb[7] = fltr_proto; /* mem address not aligned */ + tb[9] = fltr_proto; /* data access exception */ + tb[10] = fltr_proto; /* tag overflow */ + tb[128+1] = fltr_proto; /* breakpoint instruction (ta 1) */ + tb[255] = fltr_proto; /* hardware breakpoint trap */ + + /* In case GDB is started before us, ack any packets (presumably + "$?#xx") sitting there. */ + + putDebugChar ('+'); + + initialized = 1; +} + +static void +set_mem_fault_trap(enable) + int enable; +{ + struct trap_entry *tb; /* Trap vector base address */ + + mem_err = 0; + + tb = (struct trap_entry *)(rdtbr() & ~0xfff); + + if (enable) + tb[9] = fltr_set_mem_err; + else + tb[9] = fltr_proto; +} + +/* 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() +{ + writez(1, "About to do a breakpoint\r\n\n"); + if (initialized) + BREAKPOINT(); +} |