129 lines
3.6 KiB
Go
129 lines
3.6 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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// +build amd64
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package kvm
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import (
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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/sentry/arch"
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)
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var (
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// The action for bluepillSignal is changed by sigaction().
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bluepillSignal = unix.SIGSEGV
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)
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// bluepillArchEnter is called during bluepillEnter.
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//
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//go:nosplit
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func bluepillArchEnter(context *arch.SignalContext64) *vCPU {
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c := vCPUPtr(uintptr(context.Rax))
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regs := c.CPU.Registers()
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regs.R8 = context.R8
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regs.R9 = context.R9
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regs.R10 = context.R10
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regs.R11 = context.R11
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regs.R12 = context.R12
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regs.R13 = context.R13
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regs.R14 = context.R14
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regs.R15 = context.R15
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regs.Rdi = context.Rdi
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regs.Rsi = context.Rsi
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regs.Rbp = context.Rbp
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regs.Rbx = context.Rbx
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regs.Rdx = context.Rdx
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regs.Rax = context.Rax
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regs.Rcx = context.Rcx
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regs.Rsp = context.Rsp
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regs.Rip = context.Rip
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regs.Eflags = context.Eflags
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regs.Eflags &^= uint64(ring0.KernelFlagsClear)
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regs.Eflags |= ring0.KernelFlagsSet
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regs.Cs = uint64(ring0.Kcode)
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regs.Ds = uint64(ring0.Udata)
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regs.Es = uint64(ring0.Udata)
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regs.Ss = uint64(ring0.Kdata)
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return c
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}
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// KernelSyscall handles kernel syscalls.
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//
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// +checkescape:all
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//
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//go:nosplit
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func (c *vCPU) KernelSyscall() {
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regs := c.Registers()
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if regs.Rax != ^uint64(0) {
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regs.Rip -= 2 // Rewind.
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}
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// We only trigger a bluepill entry in the bluepill function, and can
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// therefore be guaranteed that there is no floating point state to be
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// loaded on resuming from halt. We only worry about saving on exit.
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ring0.SaveFloatingPoint(c.floatingPointState.BytePointer()) // escapes: no.
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ring0.Halt()
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ring0.WriteFS(uintptr(regs.Fs_base)) // escapes: no, reload host segment.
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}
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// KernelException handles kernel exceptions.
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//
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// +checkescape:all
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//
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//go:nosplit
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func (c *vCPU) KernelException(vector ring0.Vector) {
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regs := c.Registers()
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if vector == ring0.Vector(bounce) {
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// These should not interrupt kernel execution; point the Rip
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// to zero to ensure that we get a reasonable panic when we
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// attempt to return and a full stack trace.
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regs.Rip = 0
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}
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// See above.
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ring0.SaveFloatingPoint(c.floatingPointState.BytePointer()) // escapes: no.
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ring0.Halt()
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ring0.WriteFS(uintptr(regs.Fs_base)) // escapes: no; reload host segment.
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}
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// bluepillArchExit is called during bluepillEnter.
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//
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//go:nosplit
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func bluepillArchExit(c *vCPU, context *arch.SignalContext64) {
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regs := c.CPU.Registers()
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context.R8 = regs.R8
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context.R9 = regs.R9
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context.R10 = regs.R10
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context.R11 = regs.R11
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context.R12 = regs.R12
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context.R13 = regs.R13
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context.R14 = regs.R14
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context.R15 = regs.R15
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context.Rdi = regs.Rdi
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context.Rsi = regs.Rsi
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context.Rbp = regs.Rbp
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context.Rbx = regs.Rbx
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context.Rdx = regs.Rdx
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context.Rax = regs.Rax
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context.Rcx = regs.Rcx
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context.Rsp = regs.Rsp
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context.Rip = regs.Rip
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context.Eflags = regs.Eflags
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// Set the context pointer to the saved floating point state. This is
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// where the guest data has been serialized, the kernel will restore
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// from this new pointer value.
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context.Fpstate = uint64(uintptrValue(c.floatingPointState.BytePointer()))
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}
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