// Copyright 2015 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. // Support for memory sanitizer. See runtime/cgo/mmap.go. //go:build (linux && (amd64 || arm64 || loong64)) || (freebsd && amd64) package runtime import "unsafe" // _cgo_mmap is filled in by runtime/cgo when it is linked into the // program, so it is only non-nil when using cgo. // //go:linkname _cgo_mmap _cgo_mmap var _cgo_mmap unsafe.Pointer // _cgo_munmap is filled in by runtime/cgo when it is linked into the // program, so it is only non-nil when using cgo. // //go:linkname _cgo_munmap _cgo_munmap var _cgo_munmap unsafe.Pointer // mmap is used to route the mmap system call through C code when using cgo, to // support sanitizer interceptors. Don't allow stack splits, since this function // (used by sysAlloc) is called in a lot of low-level parts of the runtime and // callers often assume it won't acquire any locks. // //go:nosplit func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) (unsafe.Pointer, int) { if _cgo_mmap != nil { // Make ret a uintptr so that writing to it in the // function literal does not trigger a write barrier. // A write barrier here could break because of the way // that mmap uses the same value both as a pointer and // an errno value. var ret uintptr systemstack(func() { ret = callCgoMmap(addr, n, prot, flags, fd, off) }) if ret < 4096 { return nil, int(ret) } return unsafe.Pointer(ret), 0 } return sysMmap(addr, n, prot, flags, fd, off) } func munmap(addr unsafe.Pointer, n uintptr) { if _cgo_munmap != nil { systemstack(func() { callCgoMunmap(addr, n) }) return } sysMunmap(addr, n) } // sysMmap calls the mmap system call. It is implemented in assembly. func sysMmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) (p unsafe.Pointer, err int) // callCgoMmap calls the mmap function in the runtime/cgo package // using the GCC calling convention. It is implemented in assembly. func callCgoMmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) uintptr // sysMunmap calls the munmap system call. It is implemented in assembly. func sysMunmap(addr unsafe.Pointer, n uintptr) // callCgoMunmap calls the munmap function in the runtime/cgo package // using the GCC calling convention. It is implemented in assembly. func callCgoMunmap(addr unsafe.Pointer, n uintptr)