// 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 "arch_GOARCH.h"
#include "malloc.h"
#include "funcdata.h"
void runtime·sigpanic(void);
void runtime·newproc(void);
void runtime·deferproc(void);
int32
runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip, uintptr *pcbuf, int32 max, bool (*callback)(Stkframe*, void*), void *v, bool printall)
{
int32 i, n, nprint, line, gotraceback;
uintptr x, tracepc, sparg;
bool waspanic, wasnewproc, printing;
Func *f, *flr;
Stkframe frame;
Stktop *stk;
String file;
Panic *panic;
Defer *defer;
gotraceback = runtime·gotraceback(nil);
if(pc0 == ~(uintptr)0 && sp0 == ~(uintptr)0) { // Signal to fetch saved values from gp.
if(gp->syscallstack != (uintptr)nil) {
pc0 = gp->syscallpc;
sp0 = gp->syscallsp;
lr0 = 0;
} else {
pc0 = gp->sched.pc;
sp0 = gp->sched.sp;
lr0 = gp->sched.lr;
}
}
nprint = 0;
runtime·memclr((byte*)&frame, sizeof frame);
frame.pc = pc0;
frame.lr = lr0;
frame.sp = sp0;
waspanic = false;
wasnewproc = false;
printing = pcbuf==nil && callback==nil;
panic = gp->panic;
defer = gp->defer;
while(defer != nil && defer->argp == NoArgs)
defer = defer->link;
while(panic != nil && panic->defer == nil)
panic = panic->link;
// If the PC is zero, it's likely a nil function call.
// Start in the caller's frame.
if(frame.pc == 0) {
frame.pc = frame.lr;
frame.lr = 0;
}
f = runtime·findfunc(frame.pc);
if(f == nil) {
if(callback != nil) {
runtime·printf("runtime: unknown pc %p\n", frame.pc);
runtime·throw("unknown pc");
}
return 0;
}
frame.fn = f;
n = 0;
stk = (Stktop*)gp->stackbase;
while(n < max) {
// 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(frame.pc == (uintptr)runtime·lessstack) {
// Hit top of stack segment. Unwind to next segment.
frame.pc = stk->gobuf.pc;
frame.sp = stk->gobuf.sp;
frame.lr = 0;
frame.fp = 0;
if(printing && runtime·showframe(nil, gp))
runtime·printf("----- stack segment boundary -----\n");
stk = (Stktop*)stk->stackbase;
f = runtime·findfunc(frame.pc);
if(f == nil) {
runtime·printf("runtime: unknown pc %p after stack split\n", frame.pc);
if(callback != nil)
runtime·throw("unknown pc");
}
frame.fn = f;
continue;
}
f = frame.fn;
// Found an actual function.
// Derive frame pointer and link register.
if(frame.fp == 0)
frame.fp = frame.sp + runtime·funcspdelta(f, frame.pc);
if(runtime·topofstack(f)) {
frame.lr = 0;
flr = nil;
} else if(f->entry == (uintptr)runtime·jmpdefer) {
// jmpdefer modifies SP/LR/PC non-atomically.
// If a profiling interrupt arrives during jmpdefer,
// the stack unwind may see a mismatched register set
// and get confused. Stop if we see PC within jmpdefer
// to avoid that confusion.
// See golang.org/issue/8153.
// This check can be deleted if jmpdefer is changed
// to restore all three atomically using pop.
if(callback != nil)
runtime·throw("traceback_arm: found jmpdefer when tracing with callback");
frame.lr = 0;
flr = nil;
} else {
if((n == 0 && frame.sp < frame.fp) || frame.lr == 0)
frame.lr = *(uintptr*)frame.sp;
flr = runtime·findfunc(frame.lr);
if(flr == nil) {
runtime·printf("runtime: unexpected return pc for %s called from %p\n", runtime·funcname(f), frame.lr);
if(callback != nil)
runtime·throw("unknown caller pc");
}
}
frame.varp = (byte*)frame.fp;
// Derive size of arguments.
// Most functions have a fixed-size argument block,
// so we can use metadata about the function f.
// Not all, though: there are some variadic functions
// in package runtime and reflect, and for those we use call-specific
// metadata recorded by f's caller.
if(callback != nil || printing) {
frame.argp = (byte*)frame.fp + sizeof(uintptr);
if(f->args != ArgsSizeUnknown)
frame.arglen = f->args;
else if(flr == nil)
frame.arglen = 0;
else if(frame.lr == (uintptr)runtime·lessstack)
frame.arglen = stk->argsize;
else if((i = runtime·funcarglen(flr, frame.lr)) >= 0)
frame.arglen = i;
else {
runtime·printf("runtime: unknown argument frame size for %s called from %p [%s]\n",
runtime·funcname(f), frame.lr, flr ? runtime·funcname(flr) : "?");
if(callback != nil)
runtime·throw("invalid stack");
frame.arglen = 0;
}
}
// Determine function SP where deferproc would find its arguments.
// On ARM that's just the standard bottom-of-stack plus 1 word for
// the saved LR. If the previous frame was a direct call to newproc/deferproc,
// however, the SP is three words lower than normal.
// If the function has no frame at all - perhaps it just started, or perhaps
// it is a leaf with no local variables - then we cannot possibly find its
// SP in a defer, and we might confuse its SP for its caller's SP, so
// set sparg=0 in that case.
sparg = 0;
if(frame.fp != frame.sp) {
sparg = frame.sp + sizeof(uintreg);
if(wasnewproc)
sparg += 3*sizeof(uintreg);
}
// Determine frame's 'continuation PC', where it can continue.
// Normally this is the return address on the stack, but if sigpanic
// is immediately below this function on the stack, then the frame
// stopped executing due to a trap, and frame.pc is probably not
// a safe point for looking up liveness information. In this panicking case,
// the function either doesn't return at all (if it has no defers or if the
// defers do not recover) or it returns from one of the calls to
// deferproc a second time (if the corresponding deferred func recovers).
// It suffices to assume that the most recent deferproc is the one that
// returns; everything live at earlier deferprocs is still live at that one.
frame.continpc = frame.pc;
if(waspanic) {
if(panic != nil && panic->defer->argp == (byte*)sparg)
frame.continpc = (uintptr)panic->defer->pc;
else if(defer != nil && defer->argp == (byte*)sparg)
frame.continpc = (uintptr)defer->pc;
else
frame.continpc = 0;
}
// Unwind our local panic & defer stacks past this frame.
while(panic != nil && (panic->defer == nil || panic->defer->argp == (byte*)sparg || panic->defer->argp == NoArgs))
panic = panic->link;
while(defer != nil && (defer->argp == (byte*)sparg || defer->argp == NoArgs))
defer = defer->link;
if(skip > 0) {
skip--;
goto skipped;
}
if(pcbuf != nil)
pcbuf[n] = frame.pc;
if(callback != nil) {
if(!callback(&frame, v))
return n;
}
if(printing) {
if(printall || runtime·showframe(f, gp)) {
// Print during crash.
// main(0x1, 0x2, 0x3)
// /home/rsc/go/src/runtime/x.go:23 +0xf
tracepc = frame.pc; // back up to CALL instruction for funcline.
if(n > 0 && frame.pc > f->entry && !waspanic)
tracepc -= sizeof(uintptr);
runtime·printf("%s(", runtime·funcname(f));
for(i = 0; i < frame.arglen/sizeof(uintptr); i++) {
if(i >= 10) {
runtime·prints(", ...");
break;
}
if(i != 0)
runtime·prints(", ");
runtime·printhex(((uintptr*)frame.argp)[i]);
}
runtime·prints(")\n");
line = runtime·funcline(f, tracepc, &file);
runtime·printf("\t%S:%d", file, line);
if(frame.pc > f->entry)
runtime·printf(" +%p", (uintptr)(frame.pc - f->entry));
if(m->throwing > 0 && gp == m->curg || gotraceback >= 2)
runtime·printf(" fp=%p sp=%p", frame.fp, frame.sp);
runtime·printf("\n");
nprint++;
}
}
n++;
skipped:
waspanic = f->entry == (uintptr)runtime·sigpanic;
wasnewproc = f->entry == (uintptr)runtime·newproc || f->entry == (uintptr)runtime·deferproc;
// Do not unwind past the bottom of the stack.
if(flr == nil)
break;
// Unwind to next frame.
frame.pc = frame.lr;
frame.fn = flr;
frame.lr = 0;
frame.sp = frame.fp;
frame.fp = 0;
// sighandler saves the lr on stack before faking a call to sigpanic
if(waspanic) {
x = *(uintptr*)frame.sp;
frame.sp += 4;
frame.fn = f = runtime·findfunc(frame.pc);
if(f == nil)
frame.pc = x;
else if(f->frame == 0)
frame.lr = x;
}
}
if(pcbuf == nil && callback == nil)
n = nprint;
// For rationale, see long comment in traceback_x86.c.
if(callback != nil && n < max && defer != nil) {
if(defer != nil)
runtime·printf("runtime: g%D: leftover defer argp=%p pc=%p\n", gp->goid, defer->argp, defer->pc);
if(panic != nil)
runtime·printf("runtime: g%D: leftover panic argp=%p pc=%p\n", gp->goid, panic->defer->argp, panic->defer->pc);
for(defer = gp->defer; defer != nil; defer = defer->link)
runtime·printf("\tdefer %p argp=%p pc=%p\n", defer, defer->argp, defer->pc);
for(panic = gp->panic; panic != nil; panic = panic->link) {
runtime·printf("\tpanic %p defer %p", panic, panic->defer);
if(panic->defer != nil)
runtime·printf(" argp=%p pc=%p", panic->defer->argp, panic->defer->pc);
runtime·printf("\n");
}
runtime·throw("traceback has leftover defers or panics");
}
return n;
}
void
runtime·printcreatedby(G *gp)
{
int32 line;
uintptr pc, tracepc;
Func *f;
String file;
// Show what created goroutine, except main goroutine (goid 1).
if((pc = gp->gopc) != 0 && (f = runtime·findfunc(pc)) != nil &&
runtime·showframe(f, gp) && gp->goid != 1) {
runtime·printf("created by %s\n", runtime·funcname(f));
tracepc = pc; // back up to CALL instruction for funcline.
if(pc > f->entry)
tracepc -= PCQuantum;
line = runtime·funcline(f, tracepc, &file);
runtime·printf("\t%S:%d", file, line);
if(pc > f->entry)
runtime·printf(" +%p", (uintptr)(pc - f->entry));
runtime·printf("\n");
}
}
void
runtime·traceback(uintptr pc, uintptr sp, uintptr lr, G *gp)
{
int32 n;
if(gp->status == Gsyscall) {
// Override signal registers if blocked in system call.
pc = gp->syscallpc;
sp = gp->syscallsp;
lr = 0;
}
// Print traceback. By default, omits runtime frames.
// If that means we print nothing at all, repeat forcing all frames printed.
n = runtime·gentraceback(pc, sp, lr, gp, 0, nil, TracebackMaxFrames, nil, nil, false);
if(n == 0)
runtime·gentraceback(pc, sp, lr, gp, 0, nil, TracebackMaxFrames, nil, nil, true);
if(n == TracebackMaxFrames)
runtime·printf("...additional frames elided...\n");
runtime·printcreatedby(gp);
}
// func caller(n int) (pc uintptr, file string, line int, ok bool)
int32
runtime·callers(int32 skip, uintptr *pcbuf, int32 m)
{
uintptr pc, sp;
sp = runtime·getcallersp(&skip);
pc = (uintptr)runtime·getcallerpc(&skip);
return runtime·gentraceback(pc, sp, 0, g, skip, pcbuf, m, nil, nil, false);
}