54 lines
1.5 KiB
Go
54 lines
1.5 KiB
Go
// Copyright 2018 The gVisor Authors.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package pagetables
|
|
|
|
import (
|
|
"unsafe"
|
|
|
|
"gvisor.dev/gvisor/pkg/hostarch"
|
|
)
|
|
|
|
// newAlignedPTEs returns a set of aligned PTEs.
|
|
func newAlignedPTEs() *PTEs {
|
|
ptes := new(PTEs)
|
|
offset := physicalFor(ptes) & (hostarch.PageSize - 1)
|
|
if offset == 0 {
|
|
// Already aligned.
|
|
return ptes
|
|
}
|
|
|
|
// Need to force an aligned allocation.
|
|
unaligned := make([]byte, (2*hostarch.PageSize)-1)
|
|
offset = uintptr(unsafe.Pointer(&unaligned[0])) & (hostarch.PageSize - 1)
|
|
if offset != 0 {
|
|
offset = hostarch.PageSize - offset
|
|
}
|
|
return (*PTEs)(unsafe.Pointer(&unaligned[offset]))
|
|
}
|
|
|
|
// physicalFor returns the "physical" address for PTEs.
|
|
//
|
|
//go:nosplit
|
|
func physicalFor(ptes *PTEs) uintptr {
|
|
return uintptr(unsafe.Pointer(ptes))
|
|
}
|
|
|
|
// fromPhysical returns the PTEs from the "physical" address.
|
|
//
|
|
//go:nosplit
|
|
func fromPhysical(physical uintptr) *PTEs {
|
|
return (*PTEs)(unsafe.Pointer(physical))
|
|
}
|