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better unwinding for 386.

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command-line extraction from core files on linux and freebsd.

move linux ureg into ureg386.h (used in many places).
This commit is contained in:
rsc 2004-12-25 22:03:28 +00:00
parent cdf1805191
commit 1cc215aaf9
13 changed files with 495 additions and 109 deletions
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123
src/libmach/mach386.c
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@ -29,7 +29,7 @@ static int i386hexinst(Map*, ulong, char*, int);
static int i386das(Map*, ulong, char, char*, int);
static int i386instlen(Map*, ulong);
static char *i386windregs[];
static int i386unwind(Map*, Regs*, ulong*);
static int i386unwind(Map*, Regs*, ulong*, Symbol*);
static Regdesc i386reglist[] = {
{"DI", REGOFF(di), RINT, 'X'},
@ -128,14 +128,37 @@ static char *i386windregs[] = {
0,
};
static int
i386unwind(Map *map, Regs *regs, ulong *next)
/*
* The wrapper code around Linux system calls
* saves AX on the stack before calling some calls
* (at least, __libc_nanosleep), when running in
* threaded programs.
*/
static void
syscallhack(Map *map, Regs *regs, int *spoff)
{
int isp, ipc, ibp;
ulong bp;
u32int v;
ulong pc;
char buf[60];
/* No symbol information, use frame pointer and do the best we can. */
rget(regs, "PC", &pc);
if(i386das(map, pc-2, 0, buf, sizeof buf) != 2 || strncmp(buf, "INTB\t$", 6) != 0)
return;
if(i386das(map, pc, 0, buf, sizeof buf) != 2 || strcmp(buf, "MOVL\tDX,BX") != 0)
return;
if(i386das(map, pc+2, 0, buf, sizeof buf) != 3 || strcmp(buf, "XCHGL\tAX,0(SP)") != 0)
return;
*spoff += 4;
}
static int
i386unwind(Map *map, Regs *regs, ulong *next, Symbol *sym)
{
int i, isp, ipc, ibp, havebp, n, spoff, off[9];
ulong pc;
u32int v;
char buf[60], *p;
//print("i386unwind %s\n", sym ? sym->name : nil);
isp = windindex("SP");
ipc = windindex("PC");
ibp = windindex("BP");
@ -144,19 +167,85 @@ i386unwind(Map *map, Regs *regs, ulong *next)
return -1;
}
bp = next[ibp];
/*
* Disassemble entry to figure out
* where values have been saved.
* Perhaps should disassemble exit path
* instead -- a random walk on the code
* should suffice to get us to a RET.
*/
if(sym){
pc = sym->loc.addr;
//print("startpc %lux\n", pc);
memset(off, 0xff, sizeof off);
spoff = 0;
havebp = 0;
for(;;){
if((n = i386das(map, pc, 0, buf, sizeof buf)) < 0)
break;
//print("%s\n", buf);
pc += n;
if(strncmp(buf, "PUSHL\t", 6) == 0){
spoff += 4;
if((i = windindex(buf+6)) >= 0)
off[i] = spoff;
}else if(strcmp(buf, "MOVL\tSP,BP") == 0 && spoff == 4 && off[ibp] == 4){
havebp = 1;
}else if(strncmp(buf, "SUBL\t$", 6) == 0){
if((p = strrchr(buf, ',')) && strcmp(p, ",SP") == 0){
//print("spoff %s\n", buf+6);
spoff += strtol(buf+6, 0, 16);
}
break;
}else if(strncmp(buf, "XORL\t", 5) == 0 || strncmp(buf, "MOVL\t", 5) == 0){
/*
* Hope these are rescheduled non-prologue instructions
* like XORL AX, AX or MOVL $0x3, AX and thus ignorable.
*/
}else
break;
}
if(get4(map, bp, &v) < 0)
syscallhack(map, regs, &spoff);
if(havebp){
//print("havebp\n");
rget(regs, "BP", &next[isp]);
get4(map, next[isp], &v);
next[ibp] = v;
next[isp] += 4;
}else{
rget(regs, "SP", &next[isp]);
//print("old sp %lux + %d\n", next[isp], spoff);
next[isp] += spoff;
}
for(i=0; i<nelem(off); i++)
if(off[i] != -1){
get4(map, next[isp]-off[i], &v);
next[i] = v;
}
if(get4(map, next[isp], &v) < 0)
return -1;
//print("new pc %lux => %lux\n", next[isp], v);
next[ipc] = v;
next[isp] += 4;
return 0;
}
/*
* Rely on bp chaining
*/
if(rget(regs, "BP", &next[isp]) < 0
|| get4(map, next[isp], &v) < 0)
return -1;
next[ibp] = v;
next[isp] = bp+4;
if(get4(map, bp+4, &v) < 0)
next[isp] += 4;
if(get4(map, next[isp], &v) < 0)
return -1;
next[ipc] = v;
return 0;
next[isp] += 4;
return 0;
}
//static char STARTSYM[] = "_main";
@ -1766,8 +1855,10 @@ pea(Instr *ip)
else {
if (ip->base < 0)
immediate(ip, ip->disp);
else
else {
bprint(ip, "%lux", ip->disp);
bprint(ip,"(%s%s)", ANAME(ip), reg[(uchar)ip->base]);
}
}
if (ip->index >= 0)
bprint(ip,"(%s%s*%d)", ANAME(ip), reg[(uchar)ip->index], 1<<ip->ss);