1// Copyright 2018 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
5package runtime
6
7import (
8	"unsafe"
9)
10
11// Don't split the stack as this function may be invoked without a valid G,
12// which prevents us from allocating more stack.
13//go:nosplit
14func sysAlloc(n uintptr, sysStat *uint64) unsafe.Pointer {
15	v, err := mmap(nil, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
16	if err != 0 {
17		return nil
18	}
19	mSysStatInc(sysStat, n)
20	return v
21}
22
23func sysUnused(v unsafe.Pointer, n uintptr) {
24	// MADV_FREE_REUSABLE is like MADV_FREE except it also propagates
25	// accounting information about the process to task_info.
26	madvise(v, n, _MADV_FREE_REUSABLE)
27}
28
29func sysUsed(v unsafe.Pointer, n uintptr) {
30	// MADV_FREE_REUSE is necessary to keep the kernel's accounting
31	// accurate. If called on any memory region that hasn't been
32	// MADV_FREE_REUSABLE'd, it's a no-op.
33	madvise(v, n, _MADV_FREE_REUSE)
34}
35
36func sysHugePage(v unsafe.Pointer, n uintptr) {
37}
38
39// Don't split the stack as this function may be invoked without a valid G,
40// which prevents us from allocating more stack.
41//go:nosplit
42func sysFree(v unsafe.Pointer, n uintptr, sysStat *uint64) {
43	mSysStatDec(sysStat, n)
44	munmap(v, n)
45}
46
47func sysFault(v unsafe.Pointer, n uintptr) {
48	mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE|_MAP_FIXED, -1, 0)
49}
50
51func sysReserve(v unsafe.Pointer, n uintptr) unsafe.Pointer {
52	p, err := mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
53	if err != 0 {
54		return nil
55	}
56	return p
57}
58
59const _ENOMEM = 12
60
61func sysMap(v unsafe.Pointer, n uintptr, sysStat *uint64) {
62	mSysStatInc(sysStat, n)
63
64	p, err := mmap(v, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_FIXED|_MAP_PRIVATE, -1, 0)
65	if err == _ENOMEM {
66		throw("runtime: out of memory")
67	}
68	if p != v || err != 0 {
69		throw("runtime: cannot map pages in arena address space")
70	}
71}
72