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Diffstat (limited to 'gdb/sparc-stub.c')
| -rw-r--r-- | gdb/sparc-stub.c | 846 |
1 files changed, 846 insertions, 0 deletions
diff --git a/gdb/sparc-stub.c b/gdb/sparc-stub.c new file mode 100644 index 0000000..7da65c2 --- /dev/null +++ b/gdb/sparc-stub.c @@ -0,0 +1,846 @@ +/**************************************************************************** + + 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. + * + * This code has been extensively tested on the Fujitsu SPARClite demo board. + * + * 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) + * + * bBB..BB Set baud rate to BB..BB OK or BNN, then sets + * baud rate + * + * 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 <string.h> +#include <signal.h> + +/************************************************************************ + * + * external low-level support routines + */ + +extern void putDebugChar(); /* write a single character */ +extern int 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 = 0; /* !0 means we've been initialized */ + +static void set_mem_fault_trap(); + +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 }; + +/*************************** ASSEMBLY CODE MACROS *************************/ +/* */ + +extern void trap_low(); + +asm(" + .reserve trapstack, 1000 * 4, \"bss\", 8 + + .data + .align 4 + +in_trap_handler: + .word 0 + + .text + .align 4 + +! 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. + + .globl _trap_low +_trap_low: + mov %psr, %l0 + mov %wim, %l3 + + srl %l3, %l0, %l4 ! wim >> cwp + cmp %l4, 1 + bne window_fine ! Branch if not in the invalid window + nop + +! Handle window overflow + + mov %g1, %l4 ! Save g1, we use it to hold the wim + srl %l3, 1, %g1 ! Rotate wim right + tst %g1 + bg good_wim ! Branch if new wim is non-zero + nop + +! At this point, we need to bring a 1 into the high order bit of the wim. +! Since we don't want to make any assumptions about the number of register +! windows, we figure it out dynamically so as to setup the wim correctly. + + not %g1 ! Fill g1 with ones + mov %g1, %wim ! Fill the wim with ones + nop + nop + nop + mov %wim, %g1 ! Read back the wim + inc %g1 ! Now g1 has 1 just to left of wim + srl %g1, 1, %g1 ! Now put 1 at top of wim + mov %g0, %wim ! Clear wim so that subsequent save + nop ! won't trap + nop + nop + +good_wim: + save %g0, %g0, %g0 ! Slip into next window + mov %g1, %wim ! Install the new wim + + std %l0, [%sp + 0 * 4] ! save L & I 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 %l4, %g1 ! Restore %g1 + +window_fine: + sethi %hi(in_trap_handler), %l4 + ld [%lo(in_trap_handler) + %l4], %l5 + tst %l5 + bg recursive_trap + inc %l5 + + set trapstack+1000*4, %sp ! Switch to trap stack + +recursive_trap: + st %l5, [%lo(in_trap_handler) + %l4] + sub %sp,(16+1+6+1+72)*4,%sp ! Make room for input & locals + ! + hidden arg + arg spill + ! + doubleword alignment + ! + registers[72] local var + + std %g0, [%sp + (24 + 0) * 4] ! registers[Gx] + std %g2, [%sp + (24 + 2) * 4] + std %g4, [%sp + (24 + 4) * 4] + std %g6, [%sp + (24 + 6) * 4] + + std %i0, [%sp + (24 + 8) * 4] ! registers[Ox] + std %i2, [%sp + (24 + 10) * 4] + std %i4, [%sp + (24 + 12) * 4] + std %i6, [%sp + (24 + 14) * 4] + ! F0->F31 not implemented + mov %y, %l4 + mov %tbr, %l5 + st %l4, [%sp + (24 + 64) * 4] ! Y + st %l0, [%sp + (24 + 65) * 4] ! PSR + st %l3, [%sp + (24 + 66) * 4] ! WIM + st %l5, [%sp + (24 + 67) * 4] ! TBR + st %l1, [%sp + (24 + 68) * 4] ! PC + st %l2, [%sp + (24 + 69) * 4] ! NPC + + ! CPSR and FPSR not impl + + or %l0, 0xf20, %l4 + mov %l4, %psr ! Turn on traps, disable interrupts + + call _handle_exception + add %sp, 24 * 4, %o0 ! Pass address of registers + +! Reload all of the registers that aren't on the stack + + ld [%sp + (24 + 1) * 4], %g1 ! registers[Gx] + ldd [%sp + (24 + 2) * 4], %g2 + ldd [%sp + (24 + 4) * 4], %g4 + ldd [%sp + (24 + 6) * 4], %g6 + + ldd [%sp + (24 + 8) * 4], %i0 ! registers[Ox] + ldd [%sp + (24 + 10) * 4], %i2 + ldd [%sp + (24 + 12) * 4], %i4 + ldd [%sp + (24 + 14) * 4], %i6 + + ldd [%sp + (24 + 64) * 4], %l0 ! Y & PSR + ldd [%sp + (24 + 68) * 4], %l2 ! PC & NPC + + restore ! Ensure that previous window is valid + save %g0, %g0, %g0 ! by causing a window_underflow trap + + mov %l0, %y + mov %l1, %psr ! Make sure that traps are disabled + ! for rett + + sethi %hi(in_trap_handler), %l4 + ld [%lo(in_trap_handler) + %l4], %l5 + dec %l5 + st %l5, [%lo(in_trap_handler) + %l4] + + jmpl %l2, %g0 ! Restore old PC + rett %l3 ! Restore old nPC +"); + +/* 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 $<data>#<checksum> */ + +static void +getpacket(buffer) + char *buffer; +{ + unsigned char checksum; + unsigned char xmitcsum; + int i; + int count; + unsigned char ch; + + do + { + /* wait around for the start character, ignore all other characters */ + while ((ch = (getDebugChar() & 0x7f)) != '$') ; + + 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; + } + + if (count >= BUFMAX) + continue; + + buffer[count] = 0; + + if (ch == '#') + { + xmitcsum = hex(getDebugChar() & 0x7f) << 4; + xmitcsum |= hex(getDebugChar() & 0x7f); +#if 0 + /* 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]) + { + putDebugChar(ch); + checksum += ch; + count += 1; + } + + putDebugChar('#'); + putDebugChar(hexchars[checksum >> 4]); + putDebugChar(hexchars[checksum & 0xf]); + + } + while ((getDebugChar() & 0x7f) != '+'); +} + +static char remcomInBuffer[BUFMAX]; +static char remcomOutBuffer[BUFMAX]; + +/* Indicate to caller of mem2hex or hex2mem that there has been an + error. */ +static volatile int mem_err = 0; + +/* 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 = *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++); + *mem++ = ch; + if (mem_err) + return 0; + } + + set_mem_fault_trap(0); + + return mem; +} + +/* This table contains the mapping between SPARC hardware trap types, and + signals, which are primarily what GDB understands. It also indicates + which hardware traps we need to commandeer when initializing the stub. */ + +static struct hard_trap_info +{ + unsigned char tt; /* Trap type code for SPARClite */ + unsigned char signo; /* Signal that we map this trap into */ +} hard_trap_info[] = { + {1, SIGSEGV}, /* instruction access error */ + {2, SIGILL}, /* privileged instruction */ + {3, SIGILL}, /* illegal instruction */ + {4, SIGEMT}, /* fp disabled */ + {36, SIGEMT}, /* cp disabled */ + {7, SIGBUS}, /* mem address not aligned */ + {9, SIGSEGV}, /* data access exception */ + {10, SIGEMT}, /* tag overflow */ + {128+1, SIGTRAP}, /* ta 1 - normal breakpoint instruction */ + {0, 0} /* Must be last */ +}; + +/* Set up exception handlers for tracing and breakpoints */ + +void +set_debug_traps() +{ + struct hard_trap_info *ht; + + for (ht = hard_trap_info; ht->tt && ht->signo; ht++) + exceptionHandler(ht->tt, trap_low); + + /* In case GDB is started before us, ack any packets (presumably + "$?#xx") sitting there. */ + + putDebugChar ('+'); + + initialized = 1; +} + +asm (" +! 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. + + .text + .align 4 + +_fltr_set_mem_err: + sethi %hi(_mem_err), %l0 + st %l1, [%l0 + %lo(_mem_err)] + jmpl %l2, %g0 + rett %l2+4 +"); + +static void +set_mem_fault_trap(enable) + int enable; +{ + extern void fltr_set_mem_err(); + mem_err = 0; + + if (enable) + exceptionHandler(9, fltr_set_mem_err); + else + exceptionHandler(9, trap_low); +} + +/* Convert the SPARC hardware trap type code to a unix signal number. */ + +static int +computeSignal(tt) + int tt; +{ + struct hard_trap_info *ht; + + for (ht = hard_trap_info; ht->tt && ht->signo; ht++) + if (ht->tt == tt) + return ht->signo; + + return SIGHUP; /* default for things we don't know about */ +} + +/* + * 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) + break; + + *intValue = (*intValue << 4) | hexValue; + numChars ++; + + (*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. + */ + +extern void breakinst(); + +static void +handle_exception (registers) + unsigned long *registers; +{ + int tt; /* Trap type */ + int sigval; + int addr; + int length; + char *ptr; + unsigned long *sp; + +/* First, we must force all of the windows to be spilled out */ + + asm(" save %sp, -64, %sp + save %sp, -64, %sp + save %sp, -64, %sp + save %sp, -64, %sp + save %sp, -64, %sp + save %sp, -64, %sp + save %sp, -64, %sp + save %sp, -64, %sp + restore + restore + restore + restore + restore + restore + restore + restore +"); + + if (registers[PC] == (unsigned long)breakinst) + { + registers[PC] = registers[NPC]; + registers[NPC] += 4; + } + + sp = (unsigned long *)registers[SP]; + + tt = (registers[TBR] >> 4) & 0xff; + + /* reply to host that an exception has occurred */ + sigval = computeSignal(tt); + ptr = remcomOutBuffer; + + *ptr++ = 'T'; + *ptr++ = hexchars[sigval >> 4]; + *ptr++ = hexchars[sigval & 0xf]; + + *ptr++ = hexchars[PC >> 4]; + *ptr++ = hexchars[PC & 0xf]; + *ptr++ = ':'; + ptr = mem2hex((char *)®isters[PC], ptr, 4, 0); + *ptr++ = ';'; + + *ptr++ = hexchars[FP >> 4]; + *ptr++ = hexchars[FP & 0xf]; + *ptr++ = ':'; + ptr = mem2hex(sp + 8 + 6, ptr, 4, 0); /* FP */ + *ptr++ = ';'; + + *ptr++ = hexchars[SP >> 4]; + *ptr++ = hexchars[SP & 0xf]; + *ptr++ = ':'; + ptr = mem2hex((char *)&sp, ptr, 4, 0); + *ptr++ = ';'; + + *ptr++ = hexchars[NPC >> 4]; + *ptr++ = hexchars[NPC & 0xf]; + *ptr++ = ':'; + ptr = mem2hex((char *)®isters[NPC], ptr, 4, 0); + *ptr++ = ';'; + + *ptr++ = hexchars[O7 >> 4]; + *ptr++ = hexchars[O7 & 0xf]; + *ptr++ = ':'; + ptr = mem2hex((char *)®isters[O7], ptr, 4, 0); + *ptr++ = ';'; + + *ptr++ = 0; + + putpacket(remcomOutBuffer); + + while (1) + { + 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': + /* toggle debug flag */ + break; + + case 'g': /* return the value of the CPU registers */ + { + ptr = remcomOutBuffer; + ptr = mem2hex((char *)registers, ptr, 16 * 4, 0); /* G & O regs */ + ptr = mem2hex(sp + 0, ptr, 16 * 4, 0); /* L & I regs */ + memset(ptr, '0', 32 * 8); /* Floating point */ + mem2hex((char *)®isters[Y], + ptr + 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 */ + { + unsigned long *newsp, psr; + + psr = registers[PSR]; + + ptr = &remcomInBuffer[1]; + hex2mem(ptr, (char *)registers, 16 * 4, 0); /* G & O regs */ + hex2mem(ptr + 16 * 4 * 2, sp + 0, 16 * 4, 0); /* L & I regs */ + hex2mem(ptr + 64 * 4 * 2, (char *)®isters[Y], + 8 * 4, 0); /* Y, PSR, WIM, TBR, PC, NPC, FPSR, CPSR */ + + /* See if the stack pointer has moved. If so, then copy the saved + locals and ins to the new location. This keeps the window + overflow and underflow routines happy. */ + + newsp = (unsigned long *)registers[SP]; + if (sp != newsp) + sp = memcpy(newsp, sp, 16 * 4); + + /* Don't allow CWP to be modified. */ + + if (psr != registers[PSR]) + registers[PSR] = (psr & 0x1f) | (registers[PSR] & ~0x1f); + + strcpy(remcomOutBuffer,"OK"); + } + break; + + case 'm': /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */ + /* Try to read %x,%x. */ + + ptr = &remcomInBuffer[1]; + + if (hexToInt(&ptr, &addr) + && *ptr++ == ',' + && hexToInt(&ptr, &length)) + { + if (mem2hex((char *)addr, remcomOutBuffer, length, 1)) + break; + + strcpy (remcomOutBuffer, "E03"); + } + else + strcpy(remcomOutBuffer,"E01"); + break; + + case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */ + /* Try to read '%x,%x:'. */ + + 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"); + } + else + strcpy(remcomOutBuffer, "E02"); + break; + + case 'c': /* cAA..AA Continue at address 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; + } + +/* Need to flush the instruction cache here, as we may have deposited a + breakpoint, and the icache probably has no way of knowing that a data ref to + some location may have changed something that is in the instruction cache. + */ + + flush_i_cache(); + return; + + /* kill the program */ + case 'k' : /* do nothing */ + break; +#if 0 + case 't': /* Test feature */ + asm (" std %f30,[%sp]"); + break; +#endif + case 'r': /* Reset */ + asm ("call 0 + nop "); + break; + +#if 0 +Disabled until we can unscrew this properly + + case 'b': /* bBB... Set baud rate to BB... */ + { + int baudrate; + extern void set_timer_3(); + + ptr = &remcomInBuffer[1]; + if (!hexToInt(&ptr, &baudrate)) + { + strcpy(remcomOutBuffer,"B01"); + break; + } + + /* Convert baud rate to uart clock divider */ + switch (baudrate) + { + case 38400: + baudrate = 16; + break; + case 19200: + baudrate = 33; + break; + case 9600: + baudrate = 65; + break; + default: + strcpy(remcomOutBuffer,"B02"); + goto x1; + } + + putpacket("OK"); /* Ack before changing speed */ + set_timer_3(baudrate); /* Set it */ + } +x1: break; +#endif + } /* switch */ + + /* reply to the request */ + putpacket(remcomOutBuffer); + } +} + +/* 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) + return; + + asm(" .globl _breakinst + + _breakinst: ta 1 + "); +} |