4.1cBSD/usr/src/ucb/dbx/machine.c
/* Copyright (c) 1982 Regents of the University of California */
static char sccsid[] = "@(#)machine.c 1.6 2/20/83";
/*
* Target machine dependent stuff.
*/
#include "defs.h"
#include "machine.h"
#include "process.h"
#include "events.h"
#include "main.h"
#include "symbols.h"
#include "source.h"
#include "mappings.h"
#include "object.h"
#include "ops.h"
#include <signal.h>
#ifndef public
typedef unsigned int Address;
typedef unsigned char Byte;
typedef unsigned int Word;
#define NREG 16
#define ARGP 12
#define FRP 13
#define STKP 14
#define PROGCTR 15
#define BITSPERBYTE 8
#define BITSPERWORD (BITSPERBYTE * sizeof(Word))
#define nargspassed(frame) argn(0, frame)
#include "source.h"
#include "symbols.h"
Address pc;
Address prtaddr;
#endif
private Address printop();
/*
* Decode and print the instructions within the given address range.
*/
public printinst(lowaddr, highaddr)
Address lowaddr;
Address highaddr;
{
register Address addr;
for (addr = lowaddr; addr <= highaddr; ) {
addr = printop(addr);
}
prtaddr = addr;
}
/*
* Another approach: print n instructions starting at the given address.
*/
public printninst(count, addr)
int count;
Address addr;
{
register Integer i;
register Address newaddr;
if (count <= 0) {
error("non-positive repetition count");
} else {
newaddr = addr;
for (i = 0; i < count; i++) {
newaddr = printop(newaddr);
}
prtaddr = newaddr;
}
}
/*
* Hacked version of adb's VAX instruction decoder.
*/
private Address printop(addr)
Address addr;
{
Optab op;
VaxOpcode ins;
unsigned char mode;
int argtype, amode, argno, argval;
String reg;
Boolean indexf;
short offset;
argval = 0;
indexf = false;
printf("%08x ", addr);
iread(&ins, addr, sizeof(ins));
addr += 1;
op = optab[ins];
printf("%s", op.iname);
for (argno = 0; argno < op.numargs; argno++) {
if (indexf == true) {
indexf = false;
} else if (argno == 0) {
printf("\t");
} else {
printf(",");
}
argtype = op.argtype[argno];
if (is_branch_disp(argtype)) {
mode = 0xAF + (typelen(argtype) << 5);
} else {
iread(&mode, addr, sizeof(mode));
addr += 1;
}
reg = regname[regnm(mode)];
amode = addrmode(mode);
switch (amode) {
case LITSHORT:
case LITUPTO31:
case LITUPTO47:
case LITUPTO63:
if (typelen(argtype) == TYPF || typelen(argtype) ==TYPD)
printf("$%s", fltimm[mode]);
else
printf("$%x", mode);
argval = mode;
break;
case INDEX:
printf("[%s]", reg);
indexf = true;
argno--;
break;
case REG:
printf("%s", reg);
break;
case REGDEF:
printf("(%s)", reg);
break;
case AUTODEC:
printf("-(%s)", reg);
break;
case AUTOINC:
if (reg != regname[PROGCTR]) {
printf("(%s)+", reg);
} else {
printf("$");
switch (typelen(argtype)) {
case TYPB:
argval = printdisp(addr, 1, reg, amode);
addr += 1;
break;
case TYPW:
argval = printdisp(addr, 2, reg, amode);
addr += 2;
break;
case TYPL:
argval = printdisp(addr, 4, reg, amode);
addr += 4;
break;
case TYPF:
iread(&argval, addr, sizeof(argval));
printf("%06x", argval);
addr += 4;
break;
case TYPQ:
case TYPD:
iread(&argval, addr, sizeof(argval));
printf("%06x", argval);
iread(&argval, addr+4, sizeof(argval));
printf("%06x", argval);
addr += 8;
break;
}
}
break;
case AUTOINCDEF:
if (reg == regname[PROGCTR]) {
printf("*$");
argval = printdisp(addr, 4, reg, amode);
addr += 4;
} else {
printf("*(%s)+", reg);
}
break;
case BYTEDISP:
argval = printdisp(addr, 1, reg, amode);
addr += 1;
break;
case BYTEDISPDEF:
printf("*");
argval = printdisp(addr, 1, reg, amode);
addr += 1;
break;
case WORDDISP:
argval = printdisp(addr, 2, reg, amode);
addr += 2;
break;
case WORDDISPDEF:
printf("*");
argval = printdisp(addr, 2, reg, amode);
addr += 2;
break;
case LONGDISP:
argval = printdisp(addr, 4, reg, amode);
addr += 4;
break;
case LONGDISPDEF:
printf("*");
argval = printdisp(addr, 4, reg, amode);
addr += 4;
break;
}
}
if (ins == O_CASEB || ins == O_CASEW || ins == O_CASEL) {
for (argno = 0; argno <= argval; argno++) {
iread(&offset, addr, sizeof(offset));
printf("\n\t\t%d", offset);
addr += 2;
}
}
printf("\n");
return addr;
}
/*
* Print the displacement of an instruction that uses displacement
* addressing.
*/
private int printdisp(addr, nbytes, reg, mode)
Address addr;
int nbytes;
char *reg;
int mode;
{
char byte;
short hword;
int argval;
switch (nbytes) {
case 1:
iread(&byte, addr, sizeof(byte));
argval = byte;
break;
case 2:
iread(&hword, addr, sizeof(hword));
argval = hword;
break;
case 4:
iread(&argval, addr, sizeof(argval));
break;
}
if (reg == regname[PROGCTR] && mode >= BYTEDISP) {
argval += addr + nbytes;
}
if (reg == regname[PROGCTR]) {
printf("%x", argval);
} else {
printf("%d(%s)", argval, reg);
}
return argval;
}
/*
* Print the contents of the addresses within the given range
* according to the given format.
*/
typedef struct {
String name;
String printfstring;
int length;
} Format;
private Format fmt[] = {
{ "d", " %d", sizeof(short) },
{ "D", " %ld", sizeof(long) },
{ "o", " %o", sizeof(short) },
{ "O", " %lo", sizeof(long) },
{ "x", " %04x", sizeof(short) },
{ "X", " %08x", sizeof(long) },
{ "b", " \\%o", sizeof(char) },
{ "c", " '%c'", sizeof(char) },
{ "s", "%c", sizeof(char) },
{ "f", " %f", sizeof(double) },
{ "g", " %g", sizeof(double) },
{ nil, nil, 0 }
};
private Format *findformat(s)
String s;
{
register Format *f;
f = &fmt[0];
while (f->name != nil and not streq(f->name, s)) {
++f;
}
if (f->name == nil) {
error("bad print format \"%s\"", s);
}
return f;
}
public Address printdata(lowaddr, highaddr, format)
Address lowaddr;
Address highaddr;
String format;
{
register int n;
register Address addr;
register Format *f;
int value;
if (lowaddr > highaddr) {
error("first address larger than second");
}
f = findformat(format);
n = 0;
value = 0;
for (addr = lowaddr; addr <= highaddr; addr += f->length) {
if (n == 0) {
printf("%08x: ", addr);
}
dread(&value, addr, f->length);
printf(f->printfstring, value);
++n;
if (n >= (16 div f->length)) {
putchar('\n');
n = 0;
}
}
if (n != 0) {
putchar('\n');
}
prtaddr = addr;
return addr;
}
/*
* The other approach is to print n items starting with a given address.
*/
public printndata(count, startaddr, format)
int count;
Address startaddr;
String format;
{
register int i, n;
register Address addr;
register Format *f;
register Boolean isstring;
int value;
if (count <= 0) {
error("non-positive repetition count");
}
f = findformat(format);
isstring = (Boolean) streq(f->name, "s");
n = 0;
addr = startaddr;
value = 0;
for (i = 0; i < count; i++) {
if (n == 0) {
printf("%08x: ", addr);
}
if (isstring) {
putchar('"');
dread(&value, addr, sizeof(char));
while (value != '\0') {
printchar((char) value);
++addr;
dread(&value, addr, sizeof(char));
}
putchar('"');
putchar('\n');
n = 0;
addr += sizeof(String);
} else {
dread(&value, addr, f->length);
printf(f->printfstring, value);
++n;
if (n >= (16 div f->length)) {
putchar('\n');
n = 0;
}
addr += f->length;
}
}
if (n != 0) {
putchar('\n');
}
prtaddr = addr;
}
/*
* Print out a value according to the given format.
*/
public printvalue(v, format)
long v;
String format;
{
Format *f;
char *p, *q;
f = findformat(format);
if (streq(f->name, "s")) {
putchar('"');
p = (char *) &v;
q = p + sizeof(v);
while (p < q) {
printchar(*p);
++p;
}
putchar('"');
} else {
printf(f->printfstring, v);
}
putchar('\n');
}
/*
* Print out an execution time error.
* Assumes the source position of the error has been calculated.
*
* Have to check if the -r option was specified; if so then
* the object file information hasn't been read in yet.
*/
public printerror()
{
extern Integer sys_nsig;
extern String sys_siglist[];
Integer err;
if (isfinished(process)) {
printf("\"%s\" exits with code %d\n", objname, exitcode(process));
erecover();
}
if (runfirst) {
fprintf(stderr, "Entering debugger ...");
init();
fprintf(stderr, " type 'help' for help\n");
}
err = errnum(process);
if (err == SIGINT) {
printf("\n\ninterrupt ");
printloc();
} else if (err == SIGTRAP) {
printf("\nerror ");
printloc();
} else {
if (err < 0 or err > sys_nsig) {
printf("\nsignal %d ", err);
} else {
printf("\n%s ", sys_siglist[err]);
}
printloc();
}
putchar('\n');
if (curline > 0) {
printlines(curline, curline);
} else {
printinst(pc, pc);
}
erecover();
}
/*
* Note the termination of the program. We do this so as to avoid
* having the process exit, which would make the values of variables
* inaccessible. We do want to flush all output buffers here,
* otherwise it'll never get done.
*/
public endprogram()
{
Integer exitcode;
stepto(nextaddr(pc, true));
printnews();
exitcode = argn(1, nil);
printf("\nexecution completed, exit code is %d\n", exitcode);
getsrcpos();
erecover();
}
/*
* Single step the machine a source line (or instruction if "inst_tracing"
* is true). If "isnext" is true, skip over procedure calls.
*/
private Address getcall();
public dostep(isnext)
Boolean isnext;
{
register Address addr;
register Lineno line;
String filename;
addr = nextaddr(pc, isnext);
if (not inst_tracing and nlhdr.nlines != 0) {
line = linelookup(addr);
while (line == 0) {
addr = nextaddr(addr, isnext);
line = linelookup(addr);
}
curline = line;
} else {
curline = 0;
}
stepto(addr);
filename = srcfilename(addr);
setsource(filename);
}
/*
* Compute the next address that will be executed from the given one.
* If "isnext" is true then consider a procedure call as straight line code.
*
* We must unfortunately do much of the same work that is necessary
* to print instructions. In addition we have to deal with branches.
* Unconditional branches we just follow, for conditional branches
* we continue execution to the current location and then single step
* the machine. We assume that the last argument in an instruction
* that branches is the branch address (or relative offset).
*/
public Address nextaddr(startaddr, isnext)
Address startaddr;
Boolean isnext;
{
register Address addr;
Optab op;
VaxOpcode ins;
unsigned char mode;
int argtype, amode, argno, argval;
String r;
Boolean indexf;
enum { KNOWN, SEQUENTIAL, BRANCH } addrstatus;
argval = 0;
indexf = false;
addr = startaddr;
iread(&ins, addr, sizeof(ins));
switch (ins) {
case O_BRB:
case O_BRW:
case O_JMP:
addrstatus = BRANCH;
break;
case O_BSBB:
case O_BSBW:
case O_JSB:
case O_CALLG:
case O_CALLS:
if (isnext) {
addrstatus = SEQUENTIAL;
} else {
addrstatus = KNOWN;
stepto(addr);
pstep(process);
addr = reg(PROGCTR);
pc = addr;
callnews(/* iscall = */ true);
if (not isbperr()) {
printstatus();
} else {
bpact();
}
}
break;
case O_RSB:
case O_RET:
addrstatus = KNOWN;
callnews(/* iscall = */ false);
addr = return_addr();
stepto(addr);
break;
case O_BNEQ: case O_BEQL: case O_BGTR:
case O_BLEQ: case O_BGEQ: case O_BLSS:
case O_BGTRU: case O_BLEQU: case O_BVC:
case O_BVS: case O_BCC: case O_BCS:
case O_CASEB: case O_CASEW: case O_CASEL:
case O_BBS: case O_BBC: case O_BBSS: case O_BBCS:
case O_BBSC: case O_BBCC: case O_BBSSI:
case O_BBCCI: case O_BLBS: case O_BLBC:
case O_ACBL: case O_AOBLSS: case O_AOBLEQ:
case O_SOBGEQ: case O_SOBGTR:
addrstatus = KNOWN;
stepto(addr);
pstep(process);
addr = reg(PROGCTR);
pc = addr;
if (not isbperr()) {
printstatus();
}
break;
default:
addrstatus = SEQUENTIAL;
break;
}
if (addrstatus != KNOWN) {
addr += 1;
op = optab[ins];
for (argno = 0; argno < op.numargs; argno++) {
if (indexf == true) {
indexf = false;
}
argtype = op.argtype[argno];
if (is_branch_disp(argtype)) {
mode = 0xAF + (typelen(argtype) << 5);
} else {
iread(&mode, addr, sizeof(mode));
addr += 1;
}
r = regname[regnm(mode)];
amode = addrmode(mode);
switch (amode) {
case LITSHORT:
case LITUPTO31:
case LITUPTO47:
case LITUPTO63:
argval = mode;
break;
case INDEX:
indexf = true;
--argno;
break;
case REG:
case REGDEF:
case AUTODEC:
break;
case AUTOINC:
if (r == regname[PROGCTR]) {
switch (typelen(argtype)) {
case TYPB:
argval = getdisp(addr, 1, r, amode);
addr += 1;
break;
case TYPW:
argval = getdisp(addr, 2, r, amode);
addr += 2;
break;
case TYPL:
argval = getdisp(addr, 4, r, amode);
addr += 4;
break;
case TYPF:
iread(&argval, addr, sizeof(argval));
addr += 4;
break;
case TYPQ:
case TYPD:
iread(&argval, addr+4, sizeof(argval));
addr += 8;
break;
}
}
break;
case AUTOINCDEF:
if (r == regname[PROGCTR]) {
argval = getdisp(addr, 4, r, amode);
addr += 4;
}
break;
case BYTEDISP:
case BYTEDISPDEF:
argval = getdisp(addr, 1, r, amode);
addr += 1;
break;
case WORDDISP:
case WORDDISPDEF:
argval = getdisp(addr, 2, r, amode);
addr += 2;
break;
case LONGDISP:
case LONGDISPDEF:
argval = getdisp(addr, 4, r, amode);
addr += 4;
break;
}
}
if (ins == O_CALLS or ins == O_CALLG) {
argval += 2;
}
if (addrstatus == BRANCH) {
addr = argval;
}
}
return addr;
}
/*
* Get the displacement of an instruction that uses displacement addressing.
*/
private int getdisp(addr, nbytes, reg, mode)
Address addr;
int nbytes;
String reg;
int mode;
{
char byte;
short hword;
int argval;
switch (nbytes) {
case 1:
iread(&byte, addr, sizeof(byte));
argval = byte;
break;
case 2:
iread(&hword, addr, sizeof(hword));
argval = hword;
break;
case 4:
iread(&argval, addr, sizeof(argval));
break;
}
if (reg == regname[PROGCTR] && mode >= BYTEDISP) {
argval += addr + nbytes;
}
return argval;
}
#define BP_OP O_BPT /* breakpoint trap */
#define BP_ERRNO SIGTRAP /* signal received at a breakpoint */
/*
* Setting a breakpoint at a location consists of saving
* the word at the location and poking a BP_OP there.
*
* We save the locations and words on a list for use in unsetting.
*/
typedef struct Savelist *Savelist;
struct Savelist {
Address location;
Byte save;
Byte refcount;
Savelist link;
};
private Savelist savelist;
/*
* Set a breakpoint at the given address. Only save the word there
* if it's not already a breakpoint.
*/
public setbp(addr)
Address addr;
{
Byte w;
Byte save;
register Savelist newsave, s;
for (s = savelist; s != nil; s = s->link) {
if (s->location == addr) {
s->refcount++;
return;
}
}
iread(&save, addr, sizeof(save));
newsave = new(Savelist);
newsave->location = addr;
newsave->save = save;
newsave->refcount = 1;
newsave->link = savelist;
savelist = newsave;
w = BP_OP;
iwrite(&w, addr, sizeof(w));
}
/*
* Unset a breakpoint; unfortunately we have to search the SAVELIST
* to find the saved value. The assumption is that the SAVELIST will
* usually be quite small.
*/
public unsetbp(addr)
Address addr;
{
register Savelist s, prev;
prev = nil;
for (s = savelist; s != nil; s = s->link) {
if (s->location == addr) {
iwrite(&s->save, addr, sizeof(s->save));
s->refcount--;
if (s->refcount == 0) {
if (prev == nil) {
savelist = s->link;
} else {
prev->link = s->link;
}
dispose(s);
}
return;
}
prev = s;
}
panic("unsetbp: couldn't find address %d", addr);
}
/*
* Predicate to test if the reason the process stopped was because
* of a breakpoint.
*/
public Boolean isbperr()
{
return (Boolean) (not isfinished(process) and errnum(process) == SIGTRAP);
}
/*
* Enter a procedure by creating and executing a call instruction.
*/
#define CALLSIZE 7 /* size of call instruction */
public beginproc(p, argc)
Symbol p;
Integer argc;
{
char save[CALLSIZE];
struct {
VaxOpcode op;
unsigned char numargs;
unsigned char mode;
char addr[sizeof(long)]; /* unaligned long */
} call;
long dest;
pc = 2;
iread(save, pc, sizeof(save));
call.op = O_CALLS;
call.numargs = argc;
call.mode = 0xef;
dest = codeloc(p) - 2 - (pc + 7);
mov(&dest, call.addr, sizeof(call.addr));
iwrite(&call, pc, sizeof(call));
setreg(PROGCTR, pc);
pstep(process);
iwrite(save, pc, sizeof(save));
pc = reg(PROGCTR);
if (not isbperr()) {
printstatus();
}
}