3 files changed, 79 insertions, 4 deletions

diff --git a/src/runtime/testdata/testprog/checkptr.go b/src/runtime/testdata/testprog/checkptr.go
index f76b64ad96..9c5561396e 100644
--- a/src/runtime/testdata/testprog/checkptr.go
+++ b/src/runtime/testdata/testprog/checkptr.go
@@ -4,11 +4,16 @@
 
 package main
 
-import "unsafe"
+import (
+	"runtime"
+	"time"
+	"unsafe"
+)
 
 func init() {
 	register("CheckPtrAlignmentNoPtr", CheckPtrAlignmentNoPtr)
 	register("CheckPtrAlignmentPtr", CheckPtrAlignmentPtr)
+	register("CheckPtrAlignmentNilPtr", CheckPtrAlignmentNilPtr)
 	register("CheckPtrArithmetic", CheckPtrArithmetic)
 	register("CheckPtrArithmetic2", CheckPtrArithmetic2)
 	register("CheckPtrSize", CheckPtrSize)
@@ -29,6 +34,35 @@ func CheckPtrAlignmentPtr() {
 	sink2 = (**int64)(unsafe.Pointer(uintptr(p) + 1))
 }
 
+// CheckPtrAlignmentNilPtr tests that checkptrAlignment doesn't crash
+// on nil pointers (#47430).
+func CheckPtrAlignmentNilPtr() {
+	var do func(int)
+	do = func(n int) {
+		// Inflate the stack so runtime.shrinkstack gets called during GC
+		if n > 0 {
+			do(n - 1)
+		}
+
+		var p unsafe.Pointer
+		_ = (*int)(p)
+	}
+
+	go func() {
+		for {
+			runtime.GC()
+		}
+	}()
+
+	go func() {
+		for i := 0; ; i++ {
+			do(i % 1024)
+		}
+	}()
+
+	time.Sleep(time.Second)
+}
+
 func CheckPtrArithmetic() {
 	var x int
 	i := uintptr(unsafe.Pointer(&x))
diff --git a/src/runtime/testdata/testprogcgo/tracebackctxt.go b/src/runtime/testdata/testprogcgo/tracebackctxt.go
index 51fa4ad25c..62ff8eccd6 100644
--- a/src/runtime/testdata/testprogcgo/tracebackctxt.go
+++ b/src/runtime/testdata/testprogcgo/tracebackctxt.go
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// The __attribute__((weak)) used below doesn't seem to work on Windows.
-
 package main
 
 // Test the context argument to SetCgoTraceback.
@@ -14,20 +12,24 @@ package main
 extern void C1(void);
 extern void C2(void);
 extern void tcContext(void*);
+extern void tcContextSimple(void*);
 extern void tcTraceback(void*);
 extern void tcSymbolizer(void*);
 extern int getContextCount(void);
+extern void TracebackContextPreemptionCallGo(int);
 */
 import "C"
 
 import (
 	"fmt"
 	"runtime"
+	"sync"
 	"unsafe"
 )
 
 func init() {
 	register("TracebackContext", TracebackContext)
+	register("TracebackContextPreemption", TracebackContextPreemption)
 }
 
 var tracebackOK bool
@@ -105,3 +107,30 @@ wantLoop:
 		tracebackOK = false
 	}
 }
+
+// Issue 47441.
+func TracebackContextPreemption() {
+	runtime.SetCgoTraceback(0, unsafe.Pointer(C.tcTraceback), unsafe.Pointer(C.tcContextSimple), unsafe.Pointer(C.tcSymbolizer))
+
+	const funcs = 10
+	const calls = 1e5
+	var wg sync.WaitGroup
+	for i := 0; i < funcs; i++ {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			for j := 0; j < calls; j++ {
+				C.TracebackContextPreemptionCallGo(C.int(i*calls + j))
+			}
+		}(i)
+	}
+	wg.Wait()
+
+	fmt.Println("OK")
+}
+
+//export TracebackContextPreemptionGoFunction
+func TracebackContextPreemptionGoFunction(i C.int) {
+	// Do some busy work.
+	fmt.Sprintf("%d\n", i)
+}
diff --git a/src/runtime/testdata/testprogcgo/tracebackctxt_c.c b/src/runtime/testdata/testprogcgo/tracebackctxt_c.c
index 900cada0d3..910cb7b899 100644
--- a/src/runtime/testdata/testprogcgo/tracebackctxt_c.c
+++ b/src/runtime/testdata/testprogcgo/tracebackctxt_c.c
@@ -11,6 +11,7 @@
 // Functions exported from Go.
 extern void G1(void);
 extern void G2(void);
+extern void TracebackContextPreemptionGoFunction(int);
 
 void C1() {
 	G1();
@@ -62,10 +63,17 @@ void tcContext(void* parg) {
 	}
 }
 
+void tcContextSimple(void* parg) {
+	struct cgoContextArg* arg = (struct cgoContextArg*)(parg);
+	if (arg->context == 0) {
+		arg->context = 1;
+	}
+}
+
 void tcTraceback(void* parg) {
 	int base, i;
 	struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg);
-	if (arg->context == 0) {
+	if (arg->context == 0 && arg->sigContext == 0) {
 		// This shouldn't happen in this program.
 		abort();
 	}
@@ -89,3 +97,7 @@ void tcSymbolizer(void *parg) {
 	arg->func = "cFunction";
 	arg->lineno = arg->pc + (arg->more << 16);
 }
+
+void TracebackContextPreemptionCallGo(int i) {
+	TracebackContextPreemptionGoFunction(i);
+}