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// Copyright 2018 Google LLC
//
// 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.
package kvm
import (
"fmt"
"reflect"
"syscall"
"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
"gvisor.googlesource.com/gvisor/pkg/sentry/platform/safecopy"
)
// bluepill enters guest mode.
func bluepill(*vCPU)
// sighandler is the signal entry point.
func sighandler()
// dieTrampoline is the assembly trampoline. This calls dieHandler.
//
// This uses an architecture-specific calling convention, documented in
// dieArchSetup and the assembly implementation for dieTrampoline.
func dieTrampoline()
var (
// savedHandler is a pointer to the previous handler.
//
// This is called by bluepillHandler.
savedHandler uintptr
// dieTrampolineAddr is the address of dieTrampoline.
dieTrampolineAddr uintptr
)
// dieHandler is called by dieTrampoline.
//
//go:nosplit
func dieHandler(c *vCPU) {
throw(c.dieMessage)
}
// die is called to set the vCPU up to panic.
//
// This loads vCPU state, and sets up a call for the trampoline.
//
//go:nosplit
func (c *vCPU) die(context *arch.SignalContext64, msg string) {
// Save the death message, which will be thrown.
c.dieMessage = msg
// Reload all registers to have an accurate stack trace when we return
// to host mode. This means that the stack should be unwound correctly.
var guestRegs userRegs
if errno := c.getUserRegisters(&guestRegs); errno != 0 {
throw(msg)
}
// Setup the trampoline.
dieArchSetup(c, context, &guestRegs)
}
func init() {
// Install the handler.
if err := safecopy.ReplaceSignalHandler(syscall.SIGSEGV, reflect.ValueOf(sighandler).Pointer(), &savedHandler); err != nil {
panic(fmt.Sprintf("Unable to set handler for signal %d: %v", syscall.SIGSEGV, err))
}
// Extract the address for the trampoline.
dieTrampolineAddr = reflect.ValueOf(dieTrampoline).Pointer()
}
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