1 // run 2 // +build amd64 3 // +build linux darwin 4 5 // Copyright 2016 The Go Authors. All rights reserved. 6 // Use of this source code is governed by a BSD-style 7 // license that can be found in the LICENSE file. 8 9 package main 10 11 import ( 12 "fmt" 13 "syscall" 14 ) 15 16 // Use global variables so the compiler 17 // doesn't know that they are constants. 18 var p = syscall.Getpagesize() 19 var zero = 0 20 var one = 1 21 22 func main() { 23 // Allocate 2 pages of memory. 24 b, err := syscall.Mmap(-1, 0, 2*p, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANON|syscall.MAP_PRIVATE) 25 if err != nil { 26 panic(err) 27 } 28 // Mark the second page as faulting. 29 err = syscall.Mprotect(b[p:], syscall.PROT_NONE) 30 if err != nil { 31 panic(err) 32 } 33 // Get a slice pointing to the last byte of the good page. 34 x := b[p-one : p] 35 36 test16(x) 37 test16i(x, 0) 38 test32(x) 39 test32i(x, 0) 40 test64(x) 41 test64i(x, 0) 42 } 43 44 func test16(x []byte) uint16 { 45 defer func() { 46 r := recover() 47 if r == nil { 48 panic("no fault or bounds check failure happened") 49 } 50 s := fmt.Sprintf("%s", r) 51 if s != "runtime error: index out of range" { 52 panic("bad panic: " + s) 53 } 54 }() 55 // Try to read 2 bytes from x. 56 return uint16(x[0]) | uint16(x[1])<<8 57 58 // We expect to get an "index out of range" error from x[1]. 59 // If we promote the first load to a 2-byte load, it will segfault, which we don't want. 60 } 61 62 func test16i(x []byte, i int) uint16 { 63 defer func() { 64 r := recover() 65 if r == nil { 66 panic("no fault or bounds check failure happened") 67 } 68 s := fmt.Sprintf("%s", r) 69 if s != "runtime error: index out of range" { 70 panic("bad panic: " + s) 71 } 72 }() 73 return uint16(x[i]) | uint16(x[i+1])<<8 74 } 75 76 func test32(x []byte) uint32 { 77 defer func() { 78 r := recover() 79 if r == nil { 80 panic("no fault or bounds check failure happened") 81 } 82 s := fmt.Sprintf("%s", r) 83 if s != "runtime error: index out of range" { 84 panic("bad panic: " + s) 85 } 86 }() 87 return uint32(x[0]) | uint32(x[1])<<8 | uint32(x[2])<<16 | uint32(x[3])<<24 88 } 89 90 func test32i(x []byte, i int) uint32 { 91 defer func() { 92 r := recover() 93 if r == nil { 94 panic("no fault or bounds check failure happened") 95 } 96 s := fmt.Sprintf("%s", r) 97 if s != "runtime error: index out of range" { 98 panic("bad panic: " + s) 99 } 100 }() 101 return uint32(x[i]) | uint32(x[i+1])<<8 | uint32(x[i+2])<<16 | uint32(x[i+3])<<24 102 } 103 104 func test64(x []byte) uint64 { 105 defer func() { 106 r := recover() 107 if r == nil { 108 panic("no fault or bounds check failure happened") 109 } 110 s := fmt.Sprintf("%s", r) 111 if s != "runtime error: index out of range" { 112 panic("bad panic: " + s) 113 } 114 }() 115 return uint64(x[0]) | uint64(x[1])<<8 | uint64(x[2])<<16 | uint64(x[3])<<24 | 116 uint64(x[4])<<32 | uint64(x[5])<<40 | uint64(x[6])<<48 | uint64(x[7])<<56 117 } 118 119 func test64i(x []byte, i int) uint64 { 120 defer func() { 121 r := recover() 122 if r == nil { 123 panic("no fault or bounds check failure happened") 124 } 125 s := fmt.Sprintf("%s", r) 126 if s != "runtime error: index out of range" { 127 panic("bad panic: " + s) 128 } 129 }() 130 return uint64(x[i+0]) | uint64(x[i+1])<<8 | uint64(x[i+2])<<16 | uint64(x[i+3])<<24 | 131 uint64(x[i+4])<<32 | uint64(x[i+5])<<40 | uint64(x[i+6])<<48 | uint64(x[i+7])<<56 132 } 133
