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// Copyright 2018 Google Inc.
//
// 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.googlesource.com/gvisor/pkg/cpuid"
)
// LoadFloatingPoint loads floating point state by the most efficient mechanism
// available (set by Init).
var LoadFloatingPoint func(*byte)
// SaveFloatingPoint saves floating point state by the most efficient mechanism
// available (set by Init).
var SaveFloatingPoint func(*byte)
// fxrstor uses fxrstor64 to load floating point state.
func fxrstor(*byte)
// xrstor uses xrstor to load floating point state.
func xrstor(*byte)
// fxsave uses fxsave64 to save floating point state.
func fxsave(*byte)
// xsave uses xsave to save floating point state.
func xsave(*byte)
// xsaveopt uses xsaveopt to save floating point state.
func xsaveopt(*byte)
// WriteFS sets the GS address (set by init).
var WriteFS func(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 (set by init).
var WriteGS func(addr uintptr)
// wrgsbase writes to the GS base address.
func wrgsbase(addr uintptr)
// wrgsmsr writes to the GS_BASE MSR.
func wrgsmsr(addr uintptr)
// writeCR3 writes the CR3 value.
func writeCR3(phys uintptr)
// readCR2 reads the current CR2 value.
func readCR2() uintptr
// jumpToKernel jumps to the kernel version of the current RIP.
func jumpToKernel()
// jumpToUser jumps to the user version of the current RIP.
func jumpToUser()
// 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
hasPCID bool
hasXSAVEOPT bool
hasXSAVE bool
hasFSGSBASE bool
validXCR0Mask uintptr
)
// Init sets function pointers based on architectural features.
//
// This must be called prior to using ring0.
func Init(featureSet *cpuid.FeatureSet) {
hasSMEP = featureSet.HasFeature(cpuid.X86FeatureSMEP)
hasPCID = featureSet.HasFeature(cpuid.X86FeaturePCID)
hasXSAVEOPT = featureSet.UseXsaveopt()
hasXSAVE = featureSet.UseXsave()
hasFSGSBASE = featureSet.HasFeature(cpuid.X86FeatureFSGSBase)
validXCR0Mask = uintptr(featureSet.ValidXCR0Mask())
if hasXSAVEOPT {
SaveFloatingPoint = xsaveopt
LoadFloatingPoint = xrstor
} else if hasXSAVE {
SaveFloatingPoint = xsave
LoadFloatingPoint = xrstor
} else {
SaveFloatingPoint = fxsave
LoadFloatingPoint = fxrstor
}
if hasFSGSBASE {
WriteFS = wrfsbase
WriteGS = wrgsbase
} else {
WriteFS = wrfsmsr
WriteGS = wrgsmsr
}
}
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