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// 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.
//go:build amd64
// +build amd64
package ring0
import (
"gvisor.dev/gvisor/pkg/cpuid"
"gvisor.dev/gvisor/pkg/hostarch"
)
// fxrstor restores floating point state.
func fxrstor(addr uintptr)
// xrstor restores floating point state.
func xrstor(addr uintptr)
// fxsave saves floating point state.
func fxsave(addr uintptr)
// xsave saves floating point state.
func xsave(addr uintptr)
// xsaveopt saves floating point state.
func xsaveopt(addr uintptr)
// writeFS sets the FS base address (selects one of wrfsbase or wrfsmsr).
func writeFS(addr uintptr)
// wrfsbase writes to the GS base address.
func wrfsbase(addr uintptr)
// wrfsmsr writes to the GS_BASE MSR.
func wrfsmsr(addr uintptr)
// writeGS sets the GS address (selects one of wrgsbase or wrgsmsr).
func writeGS(addr uintptr)
// wrgsbase writes to the GS base address.
func wrgsbase(addr uintptr)
// wrgsmsr writes to the GS_BASE MSR.
func wrgsmsr(addr uintptr)
// stmxcsr reads the MXCSR control and status register.
func stmxcsr(addr *uint32)
// ldmxcsr writes to the MXCSR control and status register.
func ldmxcsr(addr *uint32)
// readCR2 reads the current CR2 value.
func readCR2() uintptr
// fninit initializes the floating point unit.
func fninit()
// xsetbv writes to an extended control register.
func xsetbv(reg, value uintptr)
// xgetbv reads an extended control register.
func xgetbv(reg uintptr) uintptr
// wrmsr reads to the given MSR.
func wrmsr(reg, value uintptr)
// rdmsr reads the given MSR.
func rdmsr(reg uintptr) uintptr
// Mostly-constants set by Init.
var (
hasSMEP bool
hasSMAP bool
hasPCID bool
hasXSAVEOPT bool
hasXSAVE bool
hasFSGSBASE bool
validXCR0Mask uintptr
localXCR0 uintptr
)
// Init sets function pointers based on architectural features.
//
// This must be called prior to using ring0. It may be called with the
// auto-detected feature set using InitDefault. It may also be called at
// another time with a different FeatureSet.
func Init(fs cpuid.FeatureSet) {
// Initialize all sizes.
VirtualAddressBits = uintptr(fs.VirtualAddressBits())
// TODO(gvisor.dev/issue/7349): introduce support for 5-level paging.
// Four-level page tables allows to address up to 48-bit virtual
// addresses.
if VirtualAddressBits > 48 {
VirtualAddressBits = 48
}
PhysicalAddressBits = uintptr(fs.PhysicalAddressBits())
UserspaceSize = uintptr(1) << (VirtualAddressBits - 1)
MaximumUserAddress = (UserspaceSize - 1) & ^uintptr(hostarch.PageSize-1)
KernelStartAddress = ^uintptr(0) - (UserspaceSize - 1)
// Initialize all functions.
hasSMEP = fs.HasFeature(cpuid.X86FeatureSMEP)
hasSMAP = fs.HasFeature(cpuid.X86FeatureSMAP)
hasPCID = fs.HasFeature(cpuid.X86FeaturePCID)
hasXSAVEOPT = fs.UseXsaveopt()
hasXSAVE = fs.UseXsave()
hasFSGSBASE = fs.HasFeature(cpuid.X86FeatureFSGSBase)
validXCR0Mask = uintptr(fs.ValidXCR0Mask())
if hasXSAVE {
XCR0DisabledMask := uintptr((1 << 9) | (1 << 17) | (1 << 18))
localXCR0 = xgetbv(0) &^ XCR0DisabledMask
}
}
// InitDefault initializes ring0 with the auto-detected host feature set.
func InitDefault() {
cpuid.Initialize()
Init(cpuid.HostFeatureSet())
}
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