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// Copyright 2019 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
// Address constraints.
//
// The lowerTop and upperBottom currently apply to four-level pagetables;
// additional refactoring would be necessary to support five-level pagetables.
const (
lowerTop = 0x0000ffffffffffff
upperBottom = 0xffff000000000000
pteShift = 12
pmdShift = 21
pudShift = 30
pgdShift = 39
pteMask = 0x1ff << pteShift
pmdMask = 0x1ff << pmdShift
pudMask = 0x1ff << pudShift
pgdMask = 0x1ff << pgdShift
pteSize = 1 << pteShift
pmdSize = 1 << pmdShift
pudSize = 1 << pudShift
pgdSize = 1 << pgdShift
ttbrASIDOffset = 48
ttbrASIDMask = 0xff
entriesPerPage = 512
)
// InitArch does some additional initialization related to the architecture.
//
// +checkescape:hard,stack
//go:nosplit
func (p *PageTables) InitArch(allocator Allocator) {
if p.upperSharedPageTables != nil {
p.cloneUpperShared()
} else {
p.archPageTables.root = p.Allocator.NewPTEs()
p.archPageTables.rootPhysical = p.Allocator.PhysicalFor(p.archPageTables.root)
}
}
// cloneUpperShared clone the upper from the upper shared page tables.
//
//go:nosplit
func (p *PageTables) cloneUpperShared() {
if p.upperStart != upperBottom {
panic("upperStart should be the same as upperBottom")
}
p.archPageTables.root = p.upperSharedPageTables.archPageTables.root
p.archPageTables.rootPhysical = p.upperSharedPageTables.archPageTables.rootPhysical
}
// PTEs is a collection of entries.
type PTEs [entriesPerPage]PTE
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