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Diffstat (limited to 'pkg/ring0/defs_amd64.go')
| -rw-r--r-- | pkg/ring0/defs_amd64.go | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/pkg/ring0/defs_amd64.go b/pkg/ring0/defs_amd64.go new file mode 100644 index 000000000..ceddf719d --- /dev/null +++ b/pkg/ring0/defs_amd64.go @@ -0,0 +1,161 @@ +// 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. + +// +build amd64 + +package ring0 + +import ( + "gvisor.dev/gvisor/pkg/usermem" +) + +var ( + // UserspaceSize is the total size of userspace. + UserspaceSize = uintptr(1) << (VirtualAddressBits() - 1) + + // MaximumUserAddress is the largest possible user address. + MaximumUserAddress = (UserspaceSize - 1) & ^uintptr(usermem.PageSize-1) + + // KernelStartAddress is the starting kernel address. + KernelStartAddress = ^uintptr(0) - (UserspaceSize - 1) +) + +// Segment indices and Selectors. +const ( + // Index into GDT array. + _ = iota // Null descriptor first. + _ // Reserved (Linux is kernel 32). + segKcode // Kernel code (64-bit). + segKdata // Kernel data. + segUcode32 // User code (32-bit). + segUdata // User data. + segUcode64 // User code (64-bit). + segTss // Task segment descriptor. + segTssHi // Upper bits for TSS. + segLast // Last segment (terminal, not included). +) + +// Selectors. +const ( + Kcode Selector = segKcode << 3 + Kdata Selector = segKdata << 3 + Ucode32 Selector = (segUcode32 << 3) | 3 + Udata Selector = (segUdata << 3) | 3 + Ucode64 Selector = (segUcode64 << 3) | 3 + Tss Selector = segTss << 3 +) + +// Standard segments. +var ( + UserCodeSegment32 SegmentDescriptor + UserDataSegment SegmentDescriptor + UserCodeSegment64 SegmentDescriptor + KernelCodeSegment SegmentDescriptor + KernelDataSegment SegmentDescriptor +) + +// KernelArchState contains architecture-specific state. +type KernelArchState struct { + // cpuEntries is array of kernelEntry for all cpus. + cpuEntries []kernelEntry + + // globalIDT is our set of interrupt gates. + globalIDT *idt64 +} + +// kernelEntry contains minimal CPU-specific arch state +// that can be mapped at the upper of the address space. +// Malicious APP might steal info from it via CPU bugs. +type kernelEntry struct { + // stack is the stack used for interrupts on this CPU. + stack [256]byte + + // scratch space for temporary usage. + scratch0 uint64 + + // stackTop is the top of the stack. + stackTop uint64 + + // cpuSelf is back reference to CPU. + cpuSelf *CPU + + // kernelCR3 is the cr3 used for sentry kernel. + kernelCR3 uintptr + + // gdt is the CPU's descriptor table. + gdt descriptorTable + + // tss is the CPU's task state. + tss TaskState64 +} + +// CPUArchState contains CPU-specific arch state. +type CPUArchState struct { + // errorCode is the error code from the last exception. + errorCode uintptr + + // errorType indicates the type of error code here, it is always set + // along with the errorCode value above. + // + // It will either by 1, which indicates a user error, or 0 indicating a + // kernel error. If the error code below returns false (kernel error), + // then it cannot provide relevant information about the last + // exception. + errorType uintptr + + *kernelEntry +} + +// ErrorCode returns the last error code. +// +// The returned boolean indicates whether the error code corresponds to the +// last user error or not. If it does not, then fault information must be +// ignored. This is generally the result of a kernel fault while servicing a +// user fault. +// +//go:nosplit +func (c *CPU) ErrorCode() (value uintptr, user bool) { + return c.errorCode, c.errorType != 0 +} + +// ClearErrorCode resets the error code. +// +//go:nosplit +func (c *CPU) ClearErrorCode() { + c.errorCode = 0 // No code. + c.errorType = 1 // User mode. +} + +// SwitchArchOpts are embedded in SwitchOpts. +type SwitchArchOpts struct { + // UserPCID indicates that the application PCID to be used on switch, + // assuming that PCIDs are supported. + // + // Per pagetables_x86.go, a zero PCID implies a flush. + UserPCID uint16 + + // KernelPCID indicates that the kernel PCID to be used on return, + // assuming that PCIDs are supported. + // + // Per pagetables_x86.go, a zero PCID implies a flush. + KernelPCID uint16 +} + +func init() { + KernelCodeSegment.setCode64(0, 0, 0) + KernelDataSegment.setData(0, 0xffffffff, 0) + UserCodeSegment32.setCode64(0, 0, 3) + UserDataSegment.setData(0, 0xffffffff, 3) + UserCodeSegment64.setCode64(0, 0, 3) +} |