mirror of
https://github.com/golang/go
synced 2024-11-12 09:50:21 -07:00
7e987b7b33
We are copying the results to uninitialized stack space. Write barrier is not needed. Fixes #30041. Change-Id: Ia91d74dbafd96dc2bd92de0cb479808991dda03e Reviewed-on: https://go-review.googlesource.com/c/160737 Run-TryBot: Cherry Zhang <cherryyz@google.com> Reviewed-by: Keith Randall <khr@golang.org>
64 lines
1.1 KiB
Go
64 lines
1.1 KiB
Go
// run
|
|
|
|
// Copyright 2019 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.
|
|
|
|
// Issue 30041: copying results of a reflect-generated
|
|
// call on stack should not have write barrier.
|
|
|
|
package main
|
|
|
|
import (
|
|
"reflect"
|
|
"runtime"
|
|
"unsafe"
|
|
)
|
|
|
|
var badPtr uintptr
|
|
|
|
var sink []byte
|
|
|
|
func init() {
|
|
// Allocate large enough to use largeAlloc.
|
|
b := make([]byte, 1<<16-1)
|
|
sink = b // force heap allocation
|
|
// Any space between the object and the end of page is invalid to point to.
|
|
badPtr = uintptr(unsafe.Pointer(&b[len(b)-1])) + 1
|
|
}
|
|
|
|
type ft func() *int
|
|
|
|
var fn ft
|
|
|
|
func rf([]reflect.Value) []reflect.Value {
|
|
a := reflect.ValueOf((*int)(nil))
|
|
return []reflect.Value{a}
|
|
}
|
|
|
|
const N = 1000
|
|
|
|
func main() {
|
|
fn = reflect.MakeFunc(reflect.TypeOf(fn), rf).Interface().(ft)
|
|
|
|
// Keep running GC so the write barrier is on.
|
|
go func() {
|
|
for i := 0; i < N; i++ {
|
|
runtime.GC()
|
|
}
|
|
}()
|
|
|
|
var x [10]uintptr
|
|
for i := range x {
|
|
x[i] = badPtr
|
|
}
|
|
for i := 0; i < N; i++ {
|
|
runtime.Gosched()
|
|
use(x) // prepare bad pointers on stack
|
|
fn()
|
|
}
|
|
}
|
|
|
|
//go:noinline
|
|
func use([10]uintptr) {}
|