1 files changed, 67 insertions, 0 deletions
diff --git a/misc/cgo/test/issue9400_linux.go b/misc/cgo/test/issue9400_linux.go
new file mode 100644
index 0000000..38fa9dd
--- /dev/null
+++ b/misc/cgo/test/issue9400_linux.go
@@ -0,0 +1,67 @@
+// Copyright 2014 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.
+
+// Test that SIGSETXID runs on signal stack, since it's likely to
+// overflow if it runs on the Go stack.
+
+package cgotest
+
+/*
+#include <sys/types.h>
+#include <unistd.h>
+*/
+import "C"
+
+import (
+	"runtime"
+	"runtime/debug"
+	"sync/atomic"
+	"testing"
+
+	"misc/cgo/test/issue9400"
+)
+
+func test9400(t *testing.T) {
+	// We synchronize through a shared variable, so we need two procs
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(2))
+
+	// Start signaller
+	atomic.StoreInt32(&issue9400.Baton, 0)
+	go func() {
+		// Wait for RewindAndSetgid
+		for atomic.LoadInt32(&issue9400.Baton) == 0 {
+			runtime.Gosched()
+		}
+		// Broadcast SIGSETXID
+		runtime.LockOSThread()
+		C.setgid(0)
+		// Indicate that signalling is done
+		atomic.StoreInt32(&issue9400.Baton, 0)
+	}()
+
+	// Grow the stack and put down a test pattern
+	const pattern = 0x123456789abcdef
+	var big [1024]uint64 // len must match assembly
+	for i := range big {
+		big[i] = pattern
+	}
+
+	// Disable GC for the duration of the test.
+	// This avoids a potential GC deadlock when spinning in uninterruptable ASM below #49695.
+	defer debug.SetGCPercent(debug.SetGCPercent(-1))
+	// SetGCPercent waits until the mark phase is over, but the runtime
+	// also preempts at the start of the sweep phase, so make sure that's
+	// done too. See #49695.
+	runtime.GC()
+
+	// Temporarily rewind the stack and trigger SIGSETXID
+	issue9400.RewindAndSetgid()
+
+	// Check test pattern
+	for i := range big {
+		if big[i] != pattern {
+			t.Fatalf("entry %d of test pattern is wrong; %#x != %#x", i, big[i], uint64(pattern))
+		}
+	}
+}