golang cgo_mmap 代码
文件路径：/src/runtime/cgo_mmap.go
/ 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) || (linux && arm64)
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)