better unwinding for 386.
command-line extraction from core files on linux and freebsd.
move linux ureg into ureg386.h (used in many places).
diff --git a/src/libmach/mach386.c b/src/libmach/mach386.c
index 4b43683..b47fcd5 100644
--- a/src/libmach/mach386.c
+++ b/src/libmach/mach386.c
@@ -29,7 +29,7 @@
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 @@
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$", 6) != 0)
+ return;
+ if(i386das(map, pc, 0, buf, sizeof buf) != 2 || strcmp(buf, "MOVL\tDX,BX") != 0)
+ return;
+ if(i386das(map, pc+2, 0, buf, sizeof buf) != 3 || strcmp(buf, "XCHGL\tAX,0(SP)") != 0)
+ return;
+ *spoff += 4;
+}
+
+static int
+i386unwind(Map *map, Regs *regs, ulong *next, Symbol *sym)
+{
+ int i, isp, ipc, ibp, havebp, n, spoff, off[9];
+ ulong pc;
+ u32int v;
+ char buf[60], *p;
+
+//print("i386unwind %s\n", sym ? sym->name : nil);
isp = windindex("SP");
ipc = windindex("PC");
ibp = windindex("BP");
@@ -144,19 +167,85 @@
return -1;
}
- bp = next[ibp];
+ /*
+ * Disassemble entry to figure out
+ * where values have been saved.
+ * Perhaps should disassemble exit path
+ * instead -- a random walk on the code
+ * should suffice to get us to a RET.
+ */
+ if(sym){
+ pc = sym->loc.addr;
+//print("startpc %lux\n", pc);
+ memset(off, 0xff, sizeof off);
+ spoff = 0;
+ havebp = 0;
+ for(;;){
+ if((n = i386das(map, pc, 0, buf, sizeof buf)) < 0)
+ break;
+//print("%s\n", buf);
+ pc += n;
+ if(strncmp(buf, "PUSHL\t", 6) == 0){
+ spoff += 4;
+ if((i = windindex(buf+6)) >= 0)
+ off[i] = spoff;
+ }else if(strcmp(buf, "MOVL\tSP,BP") == 0 && spoff == 4 && off[ibp] == 4){
+ havebp = 1;
+ }else if(strncmp(buf, "SUBL\t$", 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 @@
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);
