1 files changed, 46 insertions, 3 deletions
diff --git a/libgo/go/runtime/traceback_gccgo.go b/libgo/go/runtime/traceback_gccgo.go
index 611aba9..d060e09 100644
--- a/libgo/go/runtime/traceback_gccgo.go
+++ b/libgo/go/runtime/traceback_gccgo.go
@@ -9,7 +9,7 @@ package runtime
 
 import (
 	"runtime/internal/sys"
-	_ "unsafe" // for go:linkname
+	"unsafe"
 )
 
 // For gccgo, use go:linkname to rename compiler-called functions to
@@ -20,6 +20,34 @@ import (
 //go:linkname goroutineheader runtime.goroutineheader
 //go:linkname printcreatedby runtime.printcreatedby
 
+var (
+	// initialized in tracebackinit
+	runfinqPC        uintptr
+	bgsweepPC        uintptr
+	forcegchelperPC  uintptr
+	timerprocPC      uintptr
+	gcBgMarkWorkerPC uintptr
+)
+
+func tracebackinit() {
+	// Go variable initialization happens late during runtime startup.
+	// Instead of initializing the variables above in the declarations,
+	// schedinit calls this function so that the variables are
+	// initialized and available earlier in the startup sequence.
+	// This doesn't use funcPC to avoid memory allocation.
+	// FIXME: We should be able to use funcPC when escape analysis is on.
+	f1 := runfinq
+	runfinqPC = **(**uintptr)(unsafe.Pointer(&f1))
+	f2 := bgsweep
+	bgsweepPC = **(**uintptr)(unsafe.Pointer(&f2))
+	f3 := forcegchelper
+	forcegchelperPC = **(**uintptr)(unsafe.Pointer(&f3))
+	f4 := timerproc
+	timerprocPC = **(**uintptr)(unsafe.Pointer(&f4))
+	f5 := gcBgMarkWorker
+	gcBgMarkWorkerPC = **(**uintptr)(unsafe.Pointer(&f5))
+}
+
 func printcreatedby(gp *g) {
 	// Show what created goroutine, except main goroutine (goid 1).
 	pc := gp.gopc
@@ -168,14 +196,26 @@ func goroutineheader(gp *g) {
 // isSystemGoroutine reports whether the goroutine g must be omitted in
 // stack dumps and deadlock detector.
 func isSystemGoroutine(gp *g) bool {
-	// FIXME.
-	return false
+	// FIXME: This doesn't work reliably for gccgo because in many
+	// cases the startpc field will be set to a thunk rather than
+	// to one of these addresses.
+	pc := gp.startpc
+	return pc == runfinqPC && !fingRunning ||
+		pc == bgsweepPC ||
+		pc == forcegchelperPC ||
+		pc == timerprocPC ||
+		pc == gcBgMarkWorkerPC
 }
 
 func tracebackothers(me *g) {
 	var tb tracebackg
 	tb.gp = me
 
+	// The getTraceback function will modify me's stack context.
+	// Preserve it in case we have been called via systemstack.
+	context := me.context
+	stackcontext := me.stackcontext
+
 	level, _, _ := gotraceback()
 
 	// Show the current goroutine first, if we haven't already.
@@ -225,4 +265,7 @@ func tracebackothers(me *g) {
 		}
 	}
 	unlock(&allglock)
+
+	me.context = context
+	me.stackcontext = stackcontext
 }