libgo: update to Go 1.12 release

    
    Reviewed-on: https://go-review.googlesource.com/c/163742

From-SVN: r269216

5 files changed, 53 insertions, 2 deletions

diff --git a/libgo/go/runtime/crash_test.go b/libgo/go/runtime/crash_test.go
index 6627bdc6726..6343e8ef75f 100644
--- a/libgo/go/runtime/crash_test.go
+++ b/libgo/go/runtime/crash_test.go
@@ -764,3 +764,15 @@ func TestG0StackOverflow(t *testing.T) {
 
 	runtime.G0StackOverflow()
 }
+
+// Test that panic message is not clobbered.
+// See issue 30150.
+func TestDoublePanic(t *testing.T) {
+	output := runTestProg(t, "testprog", "DoublePanic", "GODEBUG=clobberfree=1")
+	wants := []string{"panic: XXX", "panic: YYY"}
+	for _, want := range wants {
+		if !strings.Contains(output, want) {
+			t.Errorf("output:\n%s\n\nwant output containing: %s", output, want)
+		}
+	}
+}
diff --git a/libgo/go/runtime/extern.go b/libgo/go/runtime/extern.go
index d07a5ed024f..298eb81c65e 100644
--- a/libgo/go/runtime/extern.go
+++ b/libgo/go/runtime/extern.go
@@ -27,6 +27,10 @@ It is a comma-separated list of name=val pairs setting these named variables:
 	allocfreetrace: setting allocfreetrace=1 causes every allocation to be
 	profiled and a stack trace printed on each object's allocation and free.
 
+	clobberfree: setting clobberfree=1 causes the garbage collector to
+	clobber the memory content of an object with bad content when it frees
+	the object.
+
 	cgocheck: setting cgocheck=0 disables all checks for packages
 	using cgo to incorrectly pass Go pointers to non-Go code.
 	Setting cgocheck=1 (the default) enables relatively cheap
@@ -121,7 +125,7 @@ It is a comma-separated list of name=val pairs setting these named variables:
 	IDs will refer to the ID of the goroutine at the time of creation; it's possible for this
 	ID to be reused for another goroutine. Setting N to 0 will report no ancestry information.
 
-The net and net/http packages also refer to debugging variables in GODEBUG.
+The net, net/http, and crypto/tls packages also refer to debugging variables in GODEBUG.
 See the documentation for those packages for details.
 
 The GOMAXPROCS variable limits the number of operating system threads that
diff --git a/libgo/go/runtime/mgcsweep.go b/libgo/go/runtime/mgcsweep.go
index dcaeb106dc4..fb5ee6ad46d 100644
--- a/libgo/go/runtime/mgcsweep.go
+++ b/libgo/go/runtime/mgcsweep.go
@@ -293,7 +293,7 @@ func (s *mspan) sweep(preserve bool) bool {
 		}
 	}
 
-	if debug.allocfreetrace != 0 || raceenabled || msanenabled {
+	if debug.allocfreetrace != 0 || debug.clobberfree != 0 || raceenabled || msanenabled {
 		// Find all newly freed objects. This doesn't have to
 		// efficient; allocfreetrace has massive overhead.
 		mbits := s.markBitsForBase()
@@ -304,6 +304,9 @@ func (s *mspan) sweep(preserve bool) bool {
 				if debug.allocfreetrace != 0 {
 					tracefree(unsafe.Pointer(x), size)
 				}
+				if debug.clobberfree != 0 {
+					clobberfree(unsafe.Pointer(x), size)
+				}
 				if raceenabled {
 					racefree(unsafe.Pointer(x), size)
 				}
@@ -472,3 +475,12 @@ retry:
 		traceGCSweepDone()
 	}
 }
+
+// clobberfree sets the memory content at x to bad content, for debugging
+// purposes.
+func clobberfree(x unsafe.Pointer, size uintptr) {
+	// size (span.elemsize) is always a multiple of 4.
+	for i := uintptr(0); i < size; i += 4 {
+		*(*uint32)(add(x, i)) = 0xdeadbeef
+	}
+}
diff --git a/libgo/go/runtime/runtime1.go b/libgo/go/runtime/runtime1.go
index 4e771629b0e..66091ff6580 100644
--- a/libgo/go/runtime/runtime1.go
+++ b/libgo/go/runtime/runtime1.go
@@ -313,6 +313,7 @@ type dbgVar struct {
 var debug struct {
 	allocfreetrace     int32
 	cgocheck           int32
+	clobberfree        int32
 	efence             int32
 	gccheckmark        int32
 	gcpacertrace       int32
@@ -330,6 +331,7 @@ var debug struct {
 
 var dbgvars = []dbgVar{
 	{"allocfreetrace", &debug.allocfreetrace},
+	{"clobberfree", &debug.clobberfree},
 	{"cgocheck", &debug.cgocheck},
 	{"efence", &debug.efence},
 	{"gccheckmark", &debug.gccheckmark},
diff --git a/libgo/go/runtime/testdata/testprog/crash.go b/libgo/go/runtime/testdata/testprog/crash.go
index ed4ae7fcdbc..2f0f2f805a4 100644
--- a/libgo/go/runtime/testdata/testprog/crash.go
+++ b/libgo/go/runtime/testdata/testprog/crash.go
@@ -11,6 +11,7 @@ import (
 
 func init() {
 	register("Crash", Crash)
+	register("DoublePanic", DoublePanic)
 }
 
 var NilPointer *string
@@ -44,3 +45,23 @@ func Crash() {
 	testInNewThread("second-new-thread")
 	test("main-again")
 }
+
+type P string
+
+func (p P) String() string {
+	// Try to free the "YYY" string header when the "XXX"
+	// panic is stringified.
+	runtime.GC()
+	runtime.GC()
+	runtime.GC()
+	return string(p)
+}
+
+// Test that panic message is not clobbered.
+// See issue 30150.
+func DoublePanic() {
+	defer func() {
+		panic(P("YYY"))
+	}()
+	panic(P("XXX"))
+}