blob: a971e8f9266e73396fc0a15647b43b188ef30c21 [file] [log] [blame]
// 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.
// Stack scanning code for the garbage collector.
#include "runtime.h"
extern void * __splitstack_find (void *, void *, size_t *, void **, void **,
void **);
extern void * __splitstack_find_context (void *context[10], size_t *, void **,
void **, void **);
// Calling unwind_init in doscanstack only works if it does not do a
// tail call to doscanstack1.
#pragma GCC optimize ("-fno-optimize-sibling-calls")
extern void scanstackblock(void *addr, uintptr size, void *gcw)
void doscanstack(G*, void*)
static void doscanstack1(G*, void*)
__attribute__ ((noinline));
// Scan gp's stack, passing stack chunks to scanstackblock.
void doscanstack(G *gp, void* gcw) {
// Save registers on the stack, so that if we are scanning our
// own stack we will see them.
doscanstack1(gp, gcw);
// Scan gp's stack after saving registers.
static void doscanstack1(G *gp, void *gcw) {
void* sp;
size_t spsize;
void* next_segment;
void* next_sp;
void* initial_sp;
if (gp == runtime_g()) {
// Scanning our own stack.
sp = __splitstack_find(nil, nil, &spsize, &next_segment,
&next_sp, &initial_sp);
} else {
// Scanning another goroutine's stack.
// The goroutine is usually asleep (the world is stopped).
// The exception is that if the goroutine is about to enter or might
// have just exited a system call, it may be executing code such
// as schedlock and may have needed to start a new stack segment.
// Use the stack segment and stack pointer at the time of
// the system call instead, since that won't change underfoot.
if(gp->gcstack != 0) {
sp = (void*)(gp->gcstack);
spsize = gp->gcstacksize;
next_segment = (void*)(gp->gcnextsegment);
next_sp = (void*)(gp->gcnextsp);
initial_sp = (void*)(gp->gcinitialsp);
} else {
sp = __splitstack_find_context((void**)(&gp->stackcontext[0]),
&spsize, &next_segment,
&next_sp, &initial_sp);
if(sp != nil) {
scanstackblock(sp, (uintptr)(spsize), gcw);
while((sp = __splitstack_find(next_segment, next_sp,
&spsize, &next_segment,
&next_sp, &initial_sp)) != nil)
scanstackblock(sp, (uintptr)(spsize), gcw);
byte* bottom;
byte* top;
byte* nextsp2;
byte* initialsp2;
if(gp == runtime_g()) {
// Scanning our own stack.
bottom = (byte*)&gp;
nextsp2 = secondary_stack_pointer();
} else {
// Scanning another goroutine's stack.
// The goroutine is usually asleep (the world is stopped).
bottom = (void*)gp->gcnextsp;
if(bottom == nil)
nextsp2 = (void*)gp->gcnextsp2;
top = (byte*)(void*)(gp->gcinitialsp) + gp->gcstacksize;
if(top > bottom)
scanstackblock(bottom, (uintptr)(top - bottom), gcw);
scanstackblock(top, (uintptr)(bottom - top), gcw);
if (nextsp2 != nil) {
initialsp2 = (byte*)(void*)(gp->gcinitialsp2);
if(initialsp2 > nextsp2)
scanstackblock(nextsp2, (uintptr)(initialsp2 - nextsp2), gcw);
scanstackblock(initialsp2, (uintptr)(nextsp2 - initialsp2), gcw);