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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// 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);
void _div(void);
void _mod(void);
void _divu(void);
void _modu(void);
static int32
gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, int32 max)
{
int32 i, n, iter;
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, the goroutine hasn't started yet.
if(pc == (uintptr)runtime·goexit) {
pc = (uintptr)g->entry;
lr = (uintptr)runtime·goexit;
}
// 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;
}
n = 0;
stk = (Stktop*)g->stackbase;
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 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.
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)
pcbuf[n++] = pc;
else {
// Print during crash.
// main+0xf /home/rsc/go/src/runtime/x.go:23
// main(0x1, 0x2, 0x3)
runtime·printf("[%p] %S", fp, f->name);
if(pc > f->entry)
runtime·printf("+%p", (uintptr)(pc - f->entry));
tracepc = pc; // back up to CALL instruction for funcline.
if(n > 0 && pc > f->entry)
tracepc -= sizeof(uintptr);
runtime·printf(" %S:%d\n", f->src, runtime·funcline(f, tracepc));
runtime·printf("\t%S(", f->name);
for(i = 0; i < f->args; i++) {
if(i != 0)
runtime·prints(", ");
runtime·printhex(((uintptr*)fp)[1+i]);
if(i >= 4) {
runtime·prints(", ...");
break;
}
}
runtime·prints(")\n");
n++;
}
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;
}
if(pcbuf == nil && f->entry == (uintptr)runtime·lessstack && g == m->g0) {
runtime·printf("----- lessstack called from goroutine %d -----\n", m->curg->goid);
g = m->curg;
stk = (Stktop*)g->stackbase;
sp = stk->gobuf.sp;
pc = (uintptr)stk->gobuf.pc;
fp = nil;
lr = 0;
continue;
}
// Unwind to next frame.
pc = lr;
lr = 0;
sp = fp;
fp = nil;
// If this was div or divu or mod or modu, the caller had
// an extra 8 bytes on its stack. Adjust sp.
if(f->entry == (uintptr)_div || f->entry == (uintptr)_divu || f->entry == (uintptr)_mod || f->entry == (uintptr)_modu)
sp += 8;
// If this was deferproc or newproc, the caller had an extra 12.
if(f->entry == (uintptr)runtime·deferproc || f->entry == (uintptr)runtime·newproc)
sp += 12;
}
if(pcbuf == nil && (pc = g->gopc) != 0 && (f = runtime·findfunc(pc)) != nil) {
runtime·printf("----- goroutine created by -----\n%S", f->name);
if(pc > f->entry)
runtime·printf("+%p", (uintptr)(pc - f->entry));
tracepc = pc; // back up to CALL instruction for funcline.
if(n > 0 && pc > f->entry)
tracepc -= sizeof(uintptr);
runtime·printf(" %S:%d\n", f->src, runtime·funcline(f, tracepc));
}
return n;
}
void
runtime·traceback(byte *pc0, byte *sp, byte *lr, G *g)
{
gentraceback(pc0, sp, lr, g, 0, nil, 100);
}
// func caller(n int) (pc uintptr, file string, line int, ok bool)
int32
runtime·callers(int32 skip, uintptr *pcbuf, int32 m)
{
byte *pc, *sp;
sp = runtime·getcallersp(&skip);
pc = runtime·getcallerpc(&skip);
return gentraceback(pc, sp, 0, g, skip, pcbuf, m);
}
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