github.com/hikaru7719/go@v0.0.0-20181025140707-c8b2ac68906a/test/fixedbugs/issue11656.go (about) 1 // run 2 3 // Copyright 2015 The Go Authors. All rights reserved. 4 // Use of this source code is governed by a BSD-style 5 // license that can be found in the LICENSE file. 6 7 // windows doesn't work, because Windows exception handling 8 // delivers signals based on the current PC, and that current PC 9 // doesn't go into the Go runtime. 10 // +build !windows 11 12 // wasm does not work, because the linear memory is not executable. 13 // +build !wasm 14 15 package main 16 17 import ( 18 "encoding/binary" 19 "runtime" 20 "runtime/debug" 21 "unsafe" 22 ) 23 24 func main() { 25 debug.SetPanicOnFault(true) 26 defer func() { 27 if err := recover(); err == nil { 28 panic("not panicking") 29 } 30 pc, _, _, _ := runtime.Caller(10) 31 f := runtime.FuncForPC(pc) 32 if f == nil || f.Name() != "main.f" { 33 if f == nil { 34 println("no func for ", unsafe.Pointer(pc)) 35 } else { 36 println("found func:", f.Name()) 37 } 38 panic("cannot find main.f on stack") 39 } 40 }() 41 f(20) 42 } 43 44 func f(n int) { 45 if n > 0 { 46 f(n - 1) 47 } 48 var f struct { 49 x uintptr 50 } 51 52 // We want to force an illegal instruction, to get a crash 53 // at a PC value != 0. 54 // Not all systems make the data section non-executable. 55 ill := make([]byte, 64) 56 switch runtime.GOARCH { 57 case "386", "amd64": 58 binary.LittleEndian.PutUint16(ill, 0x0b0f) // ud2 59 case "arm": 60 binary.LittleEndian.PutUint32(ill, 0xe7f000f0) // no name, but permanently undefined 61 case "arm64": 62 binary.LittleEndian.PutUint32(ill, 0xd4207d00) // brk #1000 63 case "ppc64": 64 binary.BigEndian.PutUint32(ill, 0x7fe00008) // trap 65 case "ppc64le": 66 binary.LittleEndian.PutUint32(ill, 0x7fe00008) // trap 67 case "mips", "mips64": 68 binary.BigEndian.PutUint32(ill, 0x00000034) // trap 69 case "mipsle", "mips64le": 70 binary.LittleEndian.PutUint32(ill, 0x00000034) // trap 71 case "s390x": 72 binary.BigEndian.PutUint32(ill, 0) // undefined instruction 73 default: 74 // Just leave it as 0 and hope for the best. 75 } 76 77 f.x = uintptr(unsafe.Pointer(&ill[0])) 78 fn := *(*func())(unsafe.Pointer(&f)) 79 fn() 80 }