1 // Copyright 2015 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // Support for memory sanitizer. See runtime/cgo/mmap.go. 6 7 // +build linux,amd64 8 9 package runtime 10 11 import "unsafe" 12 13 // _cgo_mmap is filled in by runtime/cgo when it is linked into the 14 // program, so it is only non-nil when using cgo. 15 //go:linkname _cgo_mmap _cgo_mmap 16 var _cgo_mmap unsafe.Pointer 17 18 func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) unsafe.Pointer { 19 if _cgo_mmap != nil { 20 // Make ret a uintptr so that writing to it in the 21 // function literal does not trigger a write barrier. 22 // A write barrier here could break because of the way 23 // that mmap uses the same value both as a pointer and 24 // an errno value. 25 // TODO: Fix mmap to return two values. 26 var ret uintptr 27 systemstack(func() { 28 ret = callCgoMmap(addr, n, prot, flags, fd, off) 29 }) 30 return unsafe.Pointer(ret) 31 } 32 return sysMmap(addr, n, prot, flags, fd, off) 33 } 34 35 // sysMmap calls the mmap system call. It is implemented in assembly. 36 func sysMmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) unsafe.Pointer 37 38 // callCgoMmap calls the mmap function in the runtime/cgo package 39 // using the GCC calling convention. It is implemented in assembly. 40 func callCgoMmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) uintptr 41
