104 lines
2.9 KiB
Go
104 lines
2.9 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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package kvm
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import (
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"fmt"
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"golang.org/x/sys/unix"
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"gvisor.dev/gvisor/pkg/ring0"
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"gvisor.dev/gvisor/pkg/safecopy"
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"gvisor.dev/gvisor/pkg/sentry/arch"
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)
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// bluepill enters guest mode.
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func bluepill(*vCPU)
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// sighandler is the signal entry point.
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func sighandler()
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// dieTrampoline is the assembly trampoline. This calls dieHandler.
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//
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// This uses an architecture-specific calling convention, documented in
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// dieArchSetup and the assembly implementation for dieTrampoline.
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func dieTrampoline()
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// Return the start address of the functions above.
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//
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// In Go 1.17+, Go references to assembly functions resolve to an ABIInternal
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// wrapper function rather than the function itself. We must reference from
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// assembly to get the ABI0 (i.e., primary) address.
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func addrOfSighandler() uintptr
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func addrOfDieTrampoline() uintptr
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var (
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// bounceSignal is the signal used for bouncing KVM.
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//
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// We use SIGCHLD because it is not masked by the runtime, and
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// it will be ignored properly by other parts of the kernel.
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bounceSignal = unix.SIGCHLD
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// bounceSignalMask has only bounceSignal set.
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bounceSignalMask = uint64(1 << (uint64(bounceSignal) - 1))
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// bounce is the interrupt vector used to return to the kernel.
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bounce = uint32(ring0.VirtualizationException)
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// savedHandler is a pointer to the previous handler.
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//
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// This is called by bluepillHandler.
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savedHandler uintptr
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// dieTrampolineAddr is the address of dieTrampoline.
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dieTrampolineAddr uintptr
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)
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// redpill invokes a syscall with -1.
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//
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//go:nosplit
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func redpill() {
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unix.RawSyscall(^uintptr(0), 0, 0, 0)
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}
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// dieHandler is called by dieTrampoline.
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//
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//go:nosplit
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func dieHandler(c *vCPU) {
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throw(c.dieState.message)
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}
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// die is called to set the vCPU up to panic.
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//
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// This loads vCPU state, and sets up a call for the trampoline.
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//
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//go:nosplit
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func (c *vCPU) die(context *arch.SignalContext64, msg string) {
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// Save the death message, which will be thrown.
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c.dieState.message = msg
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// Setup the trampoline.
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dieArchSetup(c, context, &c.dieState.guestRegs)
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}
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func init() {
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// Install the handler.
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if err := safecopy.ReplaceSignalHandler(bluepillSignal, addrOfSighandler(), &savedHandler); err != nil {
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panic(fmt.Sprintf("Unable to set handler for signal %d: %v", bluepillSignal, err))
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}
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// Extract the address for the trampoline.
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dieTrampolineAddr = addrOfDieTrampoline()
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}
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