github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/hostarch/hostarch_arm64.go (about)

     1  // Copyright 2019 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // +build arm64
    16  
    17  package hostarch
    18  
    19  import (
    20  	"encoding/binary"
    21  
    22  	"golang.org/x/sys/unix"
    23  )
    24  
    25  const (
    26  	// PageSize is the system page size.
    27  	// arm64 support 4K/16K/64K page size,
    28  	// which can be get by unix.Getpagesize().
    29  	// Currently, only 4K page size is supported.
    30  	PageSize = 1 << PageShift
    31  
    32  	// HugePageSize is the system huge page size.
    33  	HugePageSize = 1 << HugePageShift
    34  
    35  	// PageShift is the binary log of the system page size.
    36  	PageShift = 12
    37  
    38  	// HugePageShift is the binary log of the system huge page size.
    39  	// Should be calculated by "PageShift + (PageShift - 3)"
    40  	// when multiple page size support is ready.
    41  	HugePageShift = 21
    42  )
    43  
    44  var (
    45  	// ByteOrder is the native byte order (little endian).
    46  	ByteOrder = binary.LittleEndian
    47  )
    48  
    49  func init() {
    50  	// Make sure the page size is 4K on arm64 platform.
    51  	if size := unix.Getpagesize(); size != PageSize {
    52  		panic("Only 4K page size is supported on arm64!")
    53  	}
    54  }