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 package main 13 14 import ( 15 "encoding/binary" 16 "runtime" 17 "runtime/debug" 18 "unsafe" 19 ) 20 21 func main() { 22 debug.SetPanicOnFault(true) 23 defer func() { 24 if err := recover(); err == nil { 25 panic("not panicking") 26 } 27 pc, _, _, _ := runtime.Caller(10) 28 f := runtime.FuncForPC(pc) 29 if f == nil || f.Name() != "main.f" { 30 if f == nil { 31 println("no func for ", unsafe.Pointer(pc)) 32 } else { 33 println("found func:", f.Name()) 34 } 35 panic("cannot find main.f on stack") 36 } 37 }() 38 f(20) 39 } 40 41 func f(n int) { 42 if n > 0 { 43 f(n - 1) 44 } 45 var f struct { 46 x uintptr 47 } 48 49 // We want to force an illegal instruction, to get a crash 50 // at a PC value != 0. 51 // Not all systems make the data section non-executable. 52 ill := make([]byte, 64) 53 switch runtime.GOARCH { 54 case "386", "amd64": 55 binary.LittleEndian.PutUint16(ill, 0x0b0f) // ud2 56 case "arm": 57 binary.LittleEndian.PutUint32(ill, 0xe7f000f0) // no name, but permanently undefined 58 case "arm64": 59 binary.LittleEndian.PutUint32(ill, 0xd4207d00) // brk #1000 60 case "ppc64": 61 binary.BigEndian.PutUint32(ill, 0x7fe00008) // trap 62 case "ppc64le": 63 binary.LittleEndian.PutUint32(ill, 0x7fe00008) // trap 64 case "mips", "mips64": 65 binary.BigEndian.PutUint32(ill, 0x00000034) // trap 66 case "mipsle", "mips64le": 67 binary.LittleEndian.PutUint32(ill, 0x00000034) // trap 68 case "s390x": 69 binary.BigEndian.PutUint32(ill, 0) // undefined instruction 70 default: 71 // Just leave it as 0 and hope for the best. 72 } 73 74 f.x = uintptr(unsafe.Pointer(&ill[0])) 75 fn := *(*func())(unsafe.Pointer(&f)) 76 fn() 77 } 78
