101 lines
2.6 KiB
Go
101 lines
2.6 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package kvm
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import (
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"fmt"
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"gvisor.dev/gvisor/pkg/sentry/platform/ring0/pagetables"
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)
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type allocator struct {
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base pagetables.RuntimeAllocator
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// cpu must be set prior to any pagetable operation.
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//
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// Due to the way KVM's shadow paging implementation works,
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// modifications to the page tables while in host mode may not be
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// trapped, leading to the shadow pages being out of sync. Therefore,
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// we need to ensure that we are in guest mode for page table
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// modifications. See the call to bluepill, below.
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cpu *vCPU
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}
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// newAllocator is used to define the allocator.
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func newAllocator() *allocator {
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a := new(allocator)
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a.base.Init()
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return a
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}
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// NewPTEs implements pagetables.Allocator.NewPTEs.
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//
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// +checkescape:all
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//
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//go:nosplit
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func (a *allocator) NewPTEs() *pagetables.PTEs {
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ptes := a.base.NewPTEs() // escapes: bluepill below.
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if a.cpu != nil {
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bluepill(a.cpu)
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}
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return ptes
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}
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// PhysicalFor returns the physical address for a set of PTEs.
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//
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// +checkescape:all
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//
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//go:nosplit
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func (a *allocator) PhysicalFor(ptes *pagetables.PTEs) uintptr {
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virtual := a.base.PhysicalFor(ptes)
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physical, _, ok := translateToPhysical(virtual)
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if !ok {
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panic(fmt.Sprintf("PhysicalFor failed for %p", ptes)) // escapes: panic.
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}
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return physical
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}
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// LookupPTEs implements pagetables.Allocator.LookupPTEs.
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//
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// +checkescape:all
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//
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//go:nosplit
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func (a *allocator) LookupPTEs(physical uintptr) *pagetables.PTEs {
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virtualStart, physicalStart, _, ok := calculateBluepillFault(physical, physicalRegions)
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if !ok {
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panic(fmt.Sprintf("LookupPTEs failed for 0x%x", physical)) // escapes: panic.
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}
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return a.base.LookupPTEs(virtualStart + (physical - physicalStart))
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}
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// FreePTEs implements pagetables.Allocator.FreePTEs.
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//
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// +checkescape:all
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//
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//go:nosplit
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func (a *allocator) FreePTEs(ptes *pagetables.PTEs) {
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a.base.FreePTEs(ptes) // escapes: bluepill below.
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if a.cpu != nil {
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bluepill(a.cpu)
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}
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}
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// Recycle implements pagetables.Allocator.Recycle.
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//
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//go:nosplit
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func (a *allocator) Recycle() {
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a.base.Recycle()
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}
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