137 lines
3.9 KiB
Go
137 lines
3.9 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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// +build amd64
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package ring0
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import (
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"gvisor.dev/gvisor/pkg/sentry/platform/ring0/pagetables"
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)
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// Segment indices and Selectors.
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const (
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// Index into GDT array.
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_ = iota // Null descriptor first.
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_ // Reserved (Linux is kernel 32).
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segKcode // Kernel code (64-bit).
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segKdata // Kernel data.
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segUcode32 // User code (32-bit).
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segUdata // User data.
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segUcode64 // User code (64-bit).
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segTss // Task segment descriptor.
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segTssHi // Upper bits for TSS.
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segLast // Last segment (terminal, not included).
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)
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// Selectors.
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const (
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Kcode Selector = segKcode << 3
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Kdata Selector = segKdata << 3
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Ucode32 Selector = (segUcode32 << 3) | 3
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Udata Selector = (segUdata << 3) | 3
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Ucode64 Selector = (segUcode64 << 3) | 3
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Tss Selector = segTss << 3
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)
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// Standard segments.
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var (
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UserCodeSegment32 SegmentDescriptor
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UserDataSegment SegmentDescriptor
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UserCodeSegment64 SegmentDescriptor
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KernelCodeSegment SegmentDescriptor
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KernelDataSegment SegmentDescriptor
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)
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// KernelOpts has initialization options for the kernel.
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type KernelOpts struct {
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// PageTables are the kernel pagetables; this must be provided.
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PageTables *pagetables.PageTables
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}
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// KernelArchState contains architecture-specific state.
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type KernelArchState struct {
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KernelOpts
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// globalIDT is our set of interrupt gates.
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globalIDT idt64
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}
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// CPUArchState contains CPU-specific arch state.
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type CPUArchState struct {
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// stack is the stack used for interrupts on this CPU.
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stack [256]byte
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// errorCode is the error code from the last exception.
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errorCode uintptr
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// errorType indicates the type of error code here, it is always set
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// along with the errorCode value above.
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//
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// It will either by 1, which indicates a user error, or 0 indicating a
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// kernel error. If the error code below returns false (kernel error),
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// then it cannot provide relevant information about the last
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// exception.
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errorType uintptr
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// gdt is the CPU's descriptor table.
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gdt descriptorTable
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// tss is the CPU's task state.
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tss TaskState64
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}
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// ErrorCode returns the last error code.
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//
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// The returned boolean indicates whether the error code corresponds to the
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// last user error or not. If it does not, then fault information must be
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// ignored. This is generally the result of a kernel fault while servicing a
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// user fault.
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//
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//go:nosplit
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func (c *CPU) ErrorCode() (value uintptr, user bool) {
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return c.errorCode, c.errorType != 0
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}
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// ClearErrorCode resets the error code.
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//
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//go:nosplit
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func (c *CPU) ClearErrorCode() {
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c.errorCode = 0 // No code.
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c.errorType = 1 // User mode.
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}
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// SwitchArchOpts are embedded in SwitchOpts.
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type SwitchArchOpts struct {
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// UserPCID indicates that the application PCID to be used on switch,
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// assuming that PCIDs are supported.
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//
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// Per pagetables_x86.go, a zero PCID implies a flush.
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UserPCID uint16
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// KernelPCID indicates that the kernel PCID to be used on return,
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// assuming that PCIDs are supported.
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//
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// Per pagetables_x86.go, a zero PCID implies a flush.
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KernelPCID uint16
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}
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func init() {
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KernelCodeSegment.setCode64(0, 0, 0)
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KernelDataSegment.setData(0, 0xffffffff, 0)
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UserCodeSegment32.setCode64(0, 0, 3)
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UserDataSegment.setData(0, 0xffffffff, 3)
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UserCodeSegment64.setCode64(0, 0, 3)
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}
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