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As detailed in #11910, the current implementation attempts to execute an area of memory with unknown content. If the memory is executable, the result is unpredictable - instead, make the test deterministic by attempting to execute an instruction that is known to trigger a trap on the given architecture. The new implementation is written by iant@ and provided via #11910. Update issue #11910 Change-Id: Ia698c36e0dd98a9d9d16a701f60f6748c6faf896 Reviewed-on: https://go-review.googlesource.com/15058 Run-TryBot: Joel Sing <jsing@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
72 lines
1.6 KiB
Go
72 lines
1.6 KiB
Go
// run
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// windows doesn't work, because Windows exception handling
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// delivers signals based on the current PC, and that current PC
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// doesn't go into the Go runtime.
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// +build !windows
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package main
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import (
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"encoding/binary"
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"runtime"
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"runtime/debug"
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"unsafe"
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)
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func main() {
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debug.SetPanicOnFault(true)
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defer func() {
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if err := recover(); err == nil {
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panic("not panicking")
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}
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pc, _, _, _ := runtime.Caller(10)
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f := runtime.FuncForPC(pc)
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if f == nil || f.Name() != "main.f" {
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if f == nil {
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println("no func for ", unsafe.Pointer(pc))
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} else {
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println("found func:", f.Name())
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}
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panic("cannot find main.f on stack")
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}
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}()
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f(20)
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}
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func f(n int) {
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if n > 0 {
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f(n - 1)
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}
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var f struct {
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x uintptr
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}
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// We want to force an illegal instruction, to get a crash
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// at a PC value != 0.
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// Not all systems make the data section non-executable.
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ill := make([]byte, 64)
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switch runtime.GOARCH {
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case "386", "amd64":
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binary.LittleEndian.PutUint16(ill, 0x0b0f) // ud2
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case "arm":
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binary.LittleEndian.PutUint32(ill, 0xe7f000f0) // no name, but permanently undefined
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case "arm64":
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binary.LittleEndian.PutUint32(ill, 0xd4207d00) // brk #1000
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case "ppc64":
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binary.BigEndian.PutUint32(ill, 0x7fe00008) // trap
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case "ppc64le":
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binary.LittleEndian.PutUint32(ill, 0x7fe00008) // trap
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default:
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// Just leave it as 0 and hope for the best.
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}
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f.x = uintptr(unsafe.Pointer(&ill[0]))
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fn := *(*func())(unsafe.Pointer(&f))
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fn()
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}
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