Merge 216da0b7 (automated)

1 files changed, 82 insertions, 0 deletions

diff --git a/pkg/sentry/platform/kvm/bluepill.go b/pkg/sentry/platform/kvm/bluepill.go
new file mode 100644
index 000000000..a926e6f8b
--- /dev/null
+++ b/pkg/sentry/platform/kvm/bluepill.go
@@ -0,0 +1,82 @@
+// 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.
+
+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.dieState.message)
+}
+
+// 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.dieState.message = 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.
+	if errno := c.getUserRegisters(&c.dieState.guestRegs); errno != 0 {
+		throw(msg)
+	}
+
+	// Setup the trampoline.
+	dieArchSetup(c, context, &c.dieState.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()
+}