[dev.cc] runtime: convert freebsd to Go

It builds.
Don't know if it works, but it's a lot closer than having everything in C.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/168590043

1 files changed, 88 insertions, 0 deletions

diff --git a/src/runtime/mem_bsd.go b/src/runtime/mem_bsd.go
new file mode 100644
index 0000000000..fffb350ed1
--- /dev/null
+++ b/src/runtime/mem_bsd.go
@@ -0,0 +1,88 @@
+// Copyright 2010 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.
+
+// +build dragonfly freebsd netbsd openbsd
+
+package runtime
+
+import "unsafe"
+
+//go:nosplit
+func sysAlloc(n uintptr, stat *uint64) unsafe.Pointer {
+	v := unsafe.Pointer(mmap(nil, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_PRIVATE, -1, 0))
+	if uintptr(v) < 4096 {
+		return nil
+	}
+	xadd64(stat, int64(n))
+	return v
+}
+
+func sysUnused(v unsafe.Pointer, n uintptr) {
+	madvise(v, n, _MADV_FREE)
+}
+
+func sysUsed(v unsafe.Pointer, n uintptr) {
+}
+
+func sysFree(v unsafe.Pointer, n uintptr, stat *uint64) {
+	xadd64(stat, -int64(n))
+	munmap(v, n)
+}
+
+func sysFault(v unsafe.Pointer, n uintptr) {
+	mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE|_MAP_FIXED, -1, 0)
+}
+
+func sysReserve(v unsafe.Pointer, n uintptr, reserved *bool) unsafe.Pointer {
+	// On 64-bit, people with ulimit -v set complain if we reserve too
+	// much address space.  Instead, assume that the reservation is okay
+	// and check the assumption in SysMap.
+	if ptrSize == 8 && uint64(n) > 1<<32 {
+		*reserved = false
+		return v
+	}
+
+	p := unsafe.Pointer(mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE, -1, 0))
+	if uintptr(p) < 4096 {
+		return nil
+	}
+	*reserved = true
+	return p
+}
+
+func sysMap(v unsafe.Pointer, n uintptr, reserved bool, stat *uint64) {
+	const _ENOMEM = 12
+
+	xadd64(stat, int64(n))
+
+	// On 64-bit, we don't actually have v reserved, so tread carefully.
+	if !reserved {
+		flags := int32(_MAP_ANON | _MAP_PRIVATE)
+		if GOOS == "dragonfly" {
+			// TODO(jsing): For some reason DragonFly seems to return
+			// memory at a different address than we requested, even when
+			// there should be no reason for it to do so. This can be
+			// avoided by using MAP_FIXED, but I'm not sure we should need
+			// to do this - we do not on other platforms.
+			flags |= _MAP_FIXED
+		}
+		p := mmap(v, n, _PROT_READ|_PROT_WRITE, flags, -1, 0)
+		if uintptr(p) == _ENOMEM {
+			gothrow("runtime: out of memory")
+		}
+		if p != v {
+			print("runtime: address space conflict: map(", v, ") = ", p, "\n")
+			gothrow("runtime: address space conflict")
+		}
+		return
+	}
+
+	p := mmap(v, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_FIXED|_MAP_PRIVATE, -1, 0)
+	if uintptr(p) == _ENOMEM {
+		gothrow("runtime: out of memory")
+	}
+	if p != v {
+		gothrow("runtime: cannot map pages in arena address space")
+	}
+}