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runtime: more detailed panic traces, line number work

Browse Source 
Follow morestack, so that crashes during a stack split
give complete traces.  Also mark stack segment boundaries
as an aid to debugging.

Correct various line number bugs with yet another attempt
at interpreting the pc/ln table.  This one has a chance at
being correct, because I based it on reading src/cmd/ld/lib.c
instead of on reading the documentation.

Fixes #1138.
Fixes #1430.
Fixes #1461.

throw: runtime: split stack overflow

runtime.throw+0x3e /home/rsc/g/go2/src/pkg/runtime/runtime.c:78
        runtime.throw(0x81880af, 0xf75c8b18)
runtime.newstack+0xad /home/rsc/g/go2/src/pkg/runtime/proc.c:728
        runtime.newstack()
runtime.morestack+0x4f /home/rsc/g/go2/src/pkg/runtime/386/asm.s:184
        runtime.morestack()
----- morestack called from stack: -----
runtime.new+0x1a /home/rsc/g/go2/src/pkg/runtime/malloc.c:288
        runtime.new(0x1, 0x0, 0x0)
gongo.makeBoard+0x33 /tmp/Gongo/gongo_robot_test.go:344
        gongo.makeBoard(0x809d238, 0x1, 0xf76092c8, 0x1)
----- stack segment boundary -----
gongo.checkEasyScore+0xcc /tmp/Gongo/gongo_robot_test.go:287
        gongo.checkEasyScore(0xf764b710, 0x0, 0x809d238, 0x1)
gongo.TestEasyScore+0x8c /tmp/Gongo/gongo_robot_test.go:255
        gongo.TestEasyScore(0xf764b710, 0x818a990)
testing.tRunner+0x2f /home/rsc/g/go2/src/pkg/testing/testing.go:132
        testing.tRunner(0xf764b710, 0xf763b5dc, 0x0)
runtime.goexit /home/rsc/g/go2/src/pkg/runtime/proc.c:149
        runtime.goexit()

R=ken2, r
CC=golang-dev
https://golang.org/cl/4000053
This commit is contained in:
Russ Cox 2011-02-02 16:44:20 -05:00
parent 827e98d4fd
commit b287d7cbe1
7 changed files with 292 additions and 94 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

120
src/pkg/runtime/amd64/traceback.c
View File

@ -8,6 +8,8 @@
static uintptr isclosureentry(uintptr);
void runtime·deferproc(void);
void runtime·newproc(void);
void runtime·newstack(void);
void runtime·morestack(void);
// This code is also used for the 386 tracebacks.
// Use uintptr for an appropriate word-sized integer.
@ -17,15 +19,32 @@ void runtime·newproc(void);
// A little clunky to merge the two but avoids duplicating
// the code and all its subtlety.
static int32
gentraceback(byte *pc0, byte *sp, G *g, int32 skip, uintptr *pcbuf, int32 m)
gentraceback(byte *pc0, byte *sp, G *g, int32 skip, uintptr *pcbuf, int32 max)
{
byte *p;
int32 i, n, iter, nascent;
uintptr pc, tracepc, *fp;
int32 i, n, iter, sawnewstack;
uintptr pc, lr, tracepc;
byte *fp;
Stktop *stk;
Func *f;
pc = (uintptr)pc0;
lr = 0;
fp = nil;
// If the PC is goexit, the goroutine hasn't started yet.
if(pc0 == g->sched.pc && sp == g->sched.sp && pc0 == (byte*)runtime·goexit) {
fp = sp;
lr = pc;
pc = (uintptr)g->entry;
}
// If the PC is zero, it's likely a nil function call.
// Start in the caller's frame.
if(pc == 0) {
pc = lr;
lr = 0;
}
// If the PC is zero, it's likely a nil function call.
// Start in the caller's frame.
@ -34,25 +53,28 @@ gentraceback(byte *pc0, byte *sp, G *g, int32 skip, uintptr *pcbuf, int32 m)
sp += sizeof(uintptr);
}
nascent = 0;
if(pc0 == g->sched.pc && sp == g->sched.sp && pc0 == (byte*)runtime·goexit) {
// Hasn't started yet. g->sched is set up for goexit
// but goroutine will start at g->entry.
nascent = 1;
pc = (uintptr)g->entry;
}
n = 0;
sawnewstack = 0;
stk = (Stktop*)g->stackbase;
for(iter = 0; iter < 100 && n < m; iter++) { // iter avoids looping forever
for(iter = 0; iter < 100 && n < max; iter++) { // iter avoids looping forever
// Typically:
// pc is the PC of the running function.
// sp is the stack pointer at that program counter.
// fp is the frame pointer (caller's stack pointer) at that program counter, or nil if unknown.
// stk is the stack containing sp.
// The caller's program counter is lr, unless lr is zero, in which case it is *(uintptr*)sp.
if(pc == (uintptr)runtime·lessstack) {
// Hit top of stack segment. Unwind to next segment.
pc = (uintptr)stk->gobuf.pc;
sp = stk->gobuf.sp;
lr = 0;
fp = nil;
if(pcbuf == nil)
runtime·printf("----- stack segment boundary -----\n");
stk = (Stktop*)stk->stackbase;
continue;
}
if(pc <= 0x1000 || (f = runtime·findfunc(pc)) == nil) {
// Dangerous, but worthwhile: see if this is a closure:
// ADDQ $wwxxyyzz, SP; RET
@ -66,17 +88,32 @@ gentraceback(byte *pc0, byte *sp, G *g, int32 skip, uintptr *pcbuf, int32 m)
sp += *(uint32*)(p+2);
pc = *(uintptr*)sp;
sp += sizeof(uintptr);
lr = 0;
fp = nil;
continue;
}
if(nascent && (pc = isclosureentry(pc)) != 0)
// Closure at top of stack, not yet started.
if(lr == (uintptr)runtime·goexit && (pc = isclosureentry(pc)) != 0) {
fp = sp;
continue;
}
// Unknown pc; stop.
// Unknown pc: stop.
break;
}
// Found an actual function worth reporting.
// Found an actual function.
if(fp == nil) {
fp = sp;
if(pc > f->entry && f->frame >= sizeof(uintptr))
fp += f->frame - sizeof(uintptr);
if(lr == 0)
lr = *(uintptr*)fp;
fp += sizeof(uintptr);
} else if(lr == 0)
lr = *(uintptr*)fp;
if(skip > 0)
skip--;
else if(pcbuf != nil)
@ -93,15 +130,10 @@ gentraceback(byte *pc0, byte *sp, G *g, int32 skip, uintptr *pcbuf, int32 m)
tracepc--;
runtime·printf(" %S:%d\n", f->src, runtime·funcline(f, tracepc));
runtime·printf("\t%S(", f->name);
fp = (uintptr*)sp;
if(f->frame < sizeof(uintptr))
fp++;
else
fp += f->frame/sizeof(uintptr);
for(i = 0; i < f->args; i++) {
if(i != 0)
runtime·prints(", ");
runtime·printhex(fp[i]);
runtime·printhex(((uintptr*)fp)[i]);
if(i >= 4) {
runtime·prints(", ...");
break;
@ -111,20 +143,32 @@ gentraceback(byte *pc0, byte *sp, G *g, int32 skip, uintptr *pcbuf, int32 m)
n++;
}
if(nascent) {
pc = (uintptr)g->sched.pc;
sp = g->sched.sp;
nascent = 0;
if(f->entry == (uintptr)runtime·deferproc || f->entry == (uintptr)runtime·newproc)
fp += 2*sizeof(uintptr);
if(f->entry == (uintptr)runtime·newstack)
sawnewstack = 1;
if(pcbuf == nil && f->entry == (uintptr)runtime·morestack && g == m->g0 && sawnewstack) {
// The fact that we saw newstack means that morestack
// has managed to record its information in m, so we can
// use it to keep unwinding the stack.
runtime·printf("----- morestack called from goroutine %d -----\n", m->curg->goid);
pc = (uintptr)m->morepc;
sp = m->morebuf.sp - sizeof(void*);
lr = (uintptr)m->morebuf.pc;
fp = m->morebuf.sp;
sawnewstack = 0;
g = m->curg;
stk = (Stktop*)g->stackbase;
continue;
}
if(f->frame < sizeof(uintptr)) // assembly functions lie
sp += sizeof(uintptr);
else
sp += f->frame;
pc = *((uintptr*)sp - 1);
if(f->entry == (uintptr)runtime·deferproc || f->entry == (uintptr)runtime·newproc)
sp += 2*sizeof(uintptr);
// Unwind to next frame.
pc = lr;
lr = 0;
sp = fp;
fp = nil;
}
return n;
}
@ -157,6 +201,16 @@ isclosureentry(uintptr pc)
if(p < runtime·mheap.arena_start || p+32 > runtime·mheap.arena_used)
return 0;
if(*p == 0xe8) {
// CALL fn
return pc+5+*(int32*)(p+1);
}
if(sizeof(uintptr) == 8 && p[0] == 0x48 && p[1] == 0xb9 && p[10] == 0xff && p[11] == 0xd1) {
// MOVQ $fn, CX; CALL *CX
return *(uintptr*)(p+2);
}
// SUBQ $siz, SP
if((sizeof(uintptr) == 8 && *p++ != 0x48) || *p++ != 0x81 || *p++ != 0xec)
return 0;

97
src/pkg/runtime/arm/traceback.c
View File

@ -3,19 +3,27 @@
// license that can be found in the LICENSE file.
#include "runtime.h"
#include "malloc.h"
void runtime·deferproc(void);
void runtime·newproc(void);
void runtime·newstack(void);
void runtime·morestack(void);
static int32
gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, int32 m)
gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, int32 max)
{
int32 i, n, iter;
uintptr pc, lr, tracepc;
uintptr pc, lr, tracepc, x;
byte *fp, *p;
Stktop *stk;
Func *f;
pc = (uintptr)pc0;
lr = (uintptr)lr0;
fp = nil;
// If the PC is goexit, it hasn't started yet.
// If the PC is goexit, the goroutine hasn't started yet.
if(pc == (uintptr)runtime·goexit) {
pc = (uintptr)g->entry;
lr = (uintptr)runtime·goexit;
@ -30,21 +38,73 @@ gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, i
n = 0;
stk = (Stktop*)g->stackbase;
for(iter = 0; iter < 100 && n < m; iter++) { // iter avoids looping forever
for(iter = 0; iter < 100 && n < max; iter++) { // iter avoids looping forever
// Typically:
// pc is the PC of the running function.
// sp is the stack pointer at that program counter.
// fp is the frame pointer (caller's stack pointer) at that program counter, or nil if unknown.
// stk is the stack containing sp.
// The caller's program counter is lr, unless lr is zero, in which case it is *(uintptr*)sp.
if(pc == (uintptr)runtime·lessstack) {
// Hit top of stack segment. Unwind to next segment.
pc = (uintptr)stk->gobuf.pc;
sp = stk->gobuf.sp;
lr = *(uintptr*)sp;
lr = 0;
fp = nil;
if(pcbuf == nil)
runtime·printf("----- stack segment boundary -----\n");
stk = (Stktop*)stk->stackbase;
continue;
}
if(pc <= 0x1000 || (f = runtime·findfunc(pc-4)) == nil) {
// TODO: Check for closure.
if(pc <= 0x1000 || (f = runtime·findfunc(pc)) == nil) {
// Dangerous, but worthwhile: see if this is a closure by
// decoding the instruction stream.
//
// We check p < p+4 to avoid wrapping and faulting if
// we have lost track of where we are.
p = (byte*)pc;
if((pc&3) == 0 && p < p+4 &&
runtime·mheap.arena_start < p &&
p+4 < runtime·mheap.arena_used) {
x = *(uintptr*)p;
if((x&0xfffff000) == 0xe49df000) {
// End of closure:
// MOVW.P frame(R13), R15
pc = *(uintptr*)sp;
lr = 0;
sp += x & 0xfff;
fp = nil;
continue;
}
if((x&0xfffff000) == 0xe52de000 && lr == (uintptr)runtime·goexit) {
// Beginning of closure.
// Closure at top of stack, not yet started.
p += 5*4;
if((x&0xfff) != 4) {
// argument copying
p += 7*4;
}
if((byte*)pc < p && p < p+4 && p+4 < runtime·mheap.arena_used) {
pc = *(uintptr*)p;
fp = nil;
continue;
}
}
}
break;
}
// Found an actual function worth reporting.
// Found an actual function.
if(lr == 0)
lr = *(uintptr*)sp;
if(fp == nil) {
fp = sp;
if(pc > f->entry && f->frame >= 0)
fp += f->frame;
}
if(skip > 0)
skip--;
else if(pcbuf != nil)
@ -64,7 +124,7 @@ gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, i
for(i = 0; i < f->args; i++) {
if(i != 0)
runtime·prints(", ");
runtime·printhex(((uintptr*)sp)[1+i]);
runtime·printhex(((uintptr*)fp)[1+i]);
if(i >= 4) {
runtime·prints(", ...");
break;
@ -74,16 +134,27 @@ gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, i
n++;
}
if(lr == 0)
lr = *(uintptr*)sp;
if(pcbuf == nil && f->entry == (uintptr)runtime·newstack && g == m->g0) {
runtime·printf("----- newstack called from goroutine %d -----\n", m->curg->goid);
pc = (uintptr)m->morepc;
sp = (byte*)m->moreargp - sizeof(void*);
lr = (uintptr)m->morebuf.pc;
fp = m->morebuf.sp;
g = m->curg;
stk = (Stktop*)g->stackbase;
continue;
}
// Unwind to next frame.
pc = lr;
lr = 0;
if(f->frame >= 0)
sp += f->frame;
sp = fp;
fp = nil;
}
return n;
}
void
runtime·traceback(byte *pc0, byte *sp, byte *lr, G *g)
{

44
src/pkg/runtime/extern.go
View File

@ -60,31 +60,47 @@ func (f *Func) Entry() uintptr { return f.entry }
// counter within f.
func (f *Func) FileLine(pc uintptr) (file string, line int) {
// NOTE(rsc): If you edit this function, also edit
// symtab.c:/^funcline.
// symtab.c:/^funcline. That function also has the
// comments explaining the logic.
targetpc := pc
var pcQuant uintptr = 1
if GOARCH == "arm" {
pcQuant = 4
}
targetpc := pc
p := f.pcln
pc = f.pc0
line = int(f.ln0)
file = f.src
for i := 0; i < len(p) && pc <= targetpc; i++ {
switch {
case p[i] == 0:
line += int(p[i+1]<<24) | int(p[i+2]<<16) | int(p[i+3]<<8) | int(p[i+4])
i += 4
case p[i] <= 64:
line += int(p[i])
case p[i] <= 128:
line -= int(p[i] - 64)
default:
pc += pcQuant * uintptr(p[i]-129)
i := 0
//print("FileLine start pc=", pc, " targetpc=", targetpc, " line=", line,
// " tab=", p, " ", p[0], " quant=", pcQuant, " GOARCH=", GOARCH, "\n")
for {
for i < len(p) && p[i] > 128 {
pc += pcQuant * uintptr(p[i]-128)
i++
}
//print("pc<", pc, " targetpc=", targetpc, " line=", line, "\n")
if pc > targetpc || i >= len(p) {
break
}
if p[i] == 0 {
if i+5 > len(p) {
break
}
line += int(p[i+1]<<24) | int(p[i+2]<<16) | int(p[i+3]<<8) | int(p[i+4])
i += 5
} else if p[i] <= 64 {
line += int(p[i])
i++
} else {
line -= int(p[i] - 64)
i++
}
//print("pc=", pc, " targetpc=", targetpc, " line=", line, "\n")
pc += pcQuant
}
file = f.src
return
}

4
src/pkg/runtime/proc.c
View File

@ -752,8 +752,8 @@ runtime·newstack(void)
free = framesize;
}
//printf("newstack frame=%d args=%d morepc=%p morefp=%p gobuf=%p, %p newstk=%p\n",
//frame, args, m->morepc, m->morefp, g->sched.pc, g->sched.sp, stk);
//runtime·printf("newstack framesize=%d argsize=%d morepc=%p moreargp=%p gobuf=%p, %p top=%p old=%p\n",
//framesize, argsize, m->morepc, m->moreargp, m->morebuf.pc, m->morebuf.sp, top, g1->stackbase);
top->stackbase = g1->stackbase;
top->stackguard = g1->stackguard;

12
src/pkg/runtime/runtime.c
View File

@ -528,14 +528,22 @@ void
runtime·Caller(int32 skip, uintptr retpc, String retfile, int32 retline, bool retbool)
{
Func *f;
uintptr pc;
if(runtime·callers(1+skip, &retpc, 1) == 0 || (f = runtime·findfunc(retpc-1)) == nil) {
if(runtime·callers(1+skip, &retpc, 1) == 0) {
retfile = runtime·emptystring;
retline = 0;
retbool = false;
} else if((f = runtime·findfunc(retpc)) == nil) {
retfile = runtime·emptystring;
retline = 0;
retbool = true; // have retpc at least
} else {
retfile = f->src;
retline = runtime·funcline(f, retpc-1);
pc = retpc;
if(pc > f->entry)
pc--;
retline = runtime·funcline(f, pc);
retbool = true;
}
FLUSH(&retfile);

2
src/pkg/runtime/runtime.h
View File

@ -419,7 +419,7 @@ void runtime·signalstack(byte*, int32);
G* runtime·malg(int32);
void runtime·minit(void);
Func* runtime·findfunc(uintptr);
int32 runtime·funcline(Func*, uint64);
int32 runtime·funcline(Func*, uintptr);
void* runtime·stackalloc(uint32);
void runtime·stackfree(void*, uintptr);
MCache* runtime·allocmcache(void);

99
src/pkg/runtime/symtab.c
View File

@ -258,28 +258,49 @@ splitpcln(void)
ef = func + nfunc;
pc = func[0].entry; // text base
f->pcln.array = p;
f->pc0 = pc - pcquant;
f->pc0 = pc;
line = 0;
for(; p < ep; p++) {
if(f < ef && pc > (f+1)->entry) {
for(;;) {
while(p < ep && *p > 128)
pc += pcquant * (*p++ - 128);
// runtime·printf("pc<%p targetpc=%p line=%d\n", pc, targetpc, line);
if(*p == 0) {
if(p+5 > ep)
break;
// 4 byte add to line
line += (p[1]<<24) | (p[2]<<16) | (p[3]<<8) | p[4];
p += 5;
} else if(*p <= 64)
line += *p++;
else
line -= *p++ - 64;
// pc, line now match.
// Because the state machine begins at pc==entry and line==0,
// it can happen - just at the beginning! - that the update may
// have updated line but left pc alone, to tell us the true line
// number for pc==entry. In that case, update f->ln0.
// Having the correct initial line number is important for choosing
// the correct file in dosrcline above.
if(f == func && pc == f->pc0) {
f->pcln.array = p;
f->pc0 = pc + pcquant;
f->ln0 = line;
}
if(f < ef && pc >= (f+1)->entry) {
f->pcln.len = p - f->pcln.array;
f->pcln.cap = f->pcln.len;
f++;
f->pcln.array = p;
f->pc0 = pc;
// pc0 and ln0 are the starting values for
// the loop over f->pcln, so pc must be
// adjusted by the same pcquant update
// that we're going to do as we continue our loop.
f->pc0 = pc + pcquant;
f->ln0 = line;
}
if(*p == 0) {
// 4 byte add to line
line += (p[1]<<24) | (p[2]<<16) | (p[3]<<8) | p[4];
p += 4;
} else if(*p <= 64) {
line += *p;
} else if(*p <= 128) {
line -= *p - 64;
} else {
pc += pcquant*(*p - 129);
}
pc += pcquant;
}
if(f < ef) {
@ -293,13 +314,17 @@ splitpcln(void)
// (Source file is f->src.)
// NOTE(rsc): If you edit this function, also edit extern.go:/FileLine
int32
runtime·funcline(Func *f, uint64 targetpc)
runtime·funcline(Func *f, uintptr targetpc)
{
byte *p, *ep;
uintptr pc;
int32 line;
int32 pcquant;
enum {
debug = 0
};
switch(thechar) {
case '5':
pcquant = 4;
@ -313,17 +338,41 @@ runtime·funcline(Func *f, uint64 targetpc)
ep = p + f->pcln.len;
pc = f->pc0;
line = f->ln0;
for(; p < ep && pc <= targetpc; p++) {
if(debug && !runtime·panicking)
runtime·printf("funcline start pc=%p targetpc=%p line=%d tab=%p+%d\n",
pc, targetpc, line, p, (int32)f->pcln.len);
for(;;) {
// Table is a sequence of updates.
// Each update says first how to adjust the pc,
// in possibly multiple instructions...
while(p < ep && *p > 128)
pc += pcquant * (*p++ - 128);
if(debug && !runtime·panicking)
runtime·printf("pc<%p targetpc=%p line=%d\n", pc, targetpc, line);
// If the pc has advanced too far or we're out of data,
// stop and the last known line number.
if(pc > targetpc || p >= ep)
break;
// ... and then how to adjust the line number,
// in a single instruction.
if(*p == 0) {
if(p+5 > ep)
break;
line += (p[1]<<24) | (p[2]<<16) | (p[3]<<8) | p[4];
p += 4;
} else if(*p <= 64) {
line += *p;
} else if(*p <= 128) {
line -= *p - 64;
} else {
pc += pcquant*(*p - 129);
}
p += 5;
} else if(*p <= 64)
line += *p++;
else
line -= *p++ - 64;
// Now pc, line pair is consistent.
if(debug && !runtime·panicking)
runtime·printf("pc=%p targetpc=%p line=%d\n", pc, targetpc, line);
// PC increments implicitly on each iteration.
pc += pcquant;
}
return line;