runtime: ignore arguments in cgocallback_gofunc frame

Otherwise the GC may see uninitialized memory there,
which might be old pointers that are retained, or it might
trigger the invalid pointer check.

Fixes #11907.

Change-Id: I67e306384a68468eef45da1a8eb5c9df216a77c0
Reviewed-on: https://go-review.googlesource.com/12852
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

diff --git a/src/runtime/crash_cgo_test.go b/src/runtime/crash_cgo_test.go
index d2847b0d454ed36dc828692bb90ad169b58b5ead..d1322340ca6601d46dc257169c2d8d07f92195ec 100644 (file)
--- a/src/runtime/crash_cgo_test.go
+++ b/src/runtime/crash_cgo_test.go
@@ -36,6 +36,17 @@ func TestCgoTraceback(t *testing.T) {
        }
 }
 
+func TestCgoCallbackGC(t *testing.T) {
+       if runtime.GOOS == "plan9" || runtime.GOOS == "windows" {
+               t.Skipf("no pthreads on %s", runtime.GOOS)
+       }
+       got := executeTest(t, cgoCallbackGCSource, nil)
+       want := "OK\n"
+       if got != want {
+               t.Fatalf("expected %q, but got %q", want, got)
+       }
+}
+
 func TestCgoExternalThreadPanic(t *testing.T) {
        if runtime.GOOS == "plan9" {
                t.Skipf("no pthreads on %s", runtime.GOOS)
@@ -191,6 +202,83 @@ func main() {
 }
 `
 
+const cgoCallbackGCSource = `
+package main
+
+import "runtime"
+
+/*
+#include <pthread.h>
+
+void go_callback();
+
+static void *thr(void *arg) {
+    go_callback();
+    return 0;
+}
+
+static void foo() {
+    pthread_t th;
+    pthread_create(&th, 0, thr, 0);
+    pthread_join(th, 0);
+}
+*/
+import "C"
+import "fmt"
+
+//export go_callback
+func go_callback() {
+       runtime.GC()
+       grow()
+       runtime.GC()
+}
+
+var cnt int
+
+func grow() {
+       x := 10000
+       sum := 0
+       if grow1(&x, &sum) == 0 {
+               panic("bad")
+       }
+}
+
+func grow1(x, sum *int) int {
+       if *x == 0 {
+               return *sum + 1
+       }
+       *x--
+       sum1 := *sum + *x
+       return grow1(x, &sum1)
+}
+
+func main() {
+       const P = 100
+       done := make(chan bool)
+       // allocate a bunch of stack frames and spray them with pointers
+       for i := 0; i < P; i++ {
+               go func() {
+                       grow()
+                       done <- true
+               }()
+       }
+       for i := 0; i < P; i++ {
+               <-done
+       }
+       // now give these stack frames to cgo callbacks
+       for i := 0; i < P; i++ {
+               go func() {
+                       C.foo()
+                       done <- true
+               }()
+       }
+       for i := 0; i < P; i++ {
+               <-done
+       }
+       fmt.Printf("OK\n")
+}
+`
+
 const cgoExternalThreadPanicSource = `
 package main
 

diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go
index 5ac1c57e3f82eb31fbe90092eaf801f18ab49236..e6b015684be74375d91c4c8d46310a8f1cd705eb 100644 (file)
--- a/src/runtime/stubs.go
+++ b/src/runtime/stubs.go
@@ -128,9 +128,16 @@ func breakpoint()
 func reflectcall(argtype *_type, fn, arg unsafe.Pointer, argsize uint32, retoffset uint32)
 
 func procyield(cycles uint32)
-func cgocallback_gofunc(fv *funcval, frame unsafe.Pointer, framesize uintptr)
 func goexit()
 
+// Not all cgocallback_gofunc frames are actually cgocallback_gofunc,
+// so not all have these arguments. Mark them uintptr so that the GC
+// does not misinterpret memory when the arguments are not present.
+// cgocallback_gofunc is not called from go, only from cgocallback,
+// so the arguments will be found via cgocallback's pointer-declared arguments.
+// See the assembly implementations for more details.
+func cgocallback_gofunc(fv uintptr, frame uintptr, framesize uintptr)
+
 //go:noescape
 func cas(ptr *uint32, old, new uint32) bool