Move ring0 package.

This allows the package to serve as a general purpose ring0 support package, as
opposed to being bound to specific sentry platforms.

Updates #5039

PiperOrigin-RevId: 355220044

1 files changed, 90 insertions, 0 deletions

diff --git a/pkg/ring0/kernel.go b/pkg/ring0/kernel.go
new file mode 100644
index 000000000..292f9d0cc
--- /dev/null
+++ b/pkg/ring0/kernel.go
@@ -0,0 +1,90 @@
+// 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 ring0
+
+// Init initializes a new kernel.
+//
+//go:nosplit
+func (k *Kernel) Init(maxCPUs int) {
+	k.init(maxCPUs)
+}
+
+// Halt halts execution.
+func Halt()
+
+// defaultHooks implements hooks.
+type defaultHooks struct{}
+
+// KernelSyscall implements Hooks.KernelSyscall.
+//
+// +checkescape:all
+//
+//go:nosplit
+func (defaultHooks) KernelSyscall() {
+	Halt()
+}
+
+// KernelException implements Hooks.KernelException.
+//
+// +checkescape:all
+//
+//go:nosplit
+func (defaultHooks) KernelException(Vector) {
+	Halt()
+}
+
+// kernelSyscall is a trampoline.
+//
+// When in amd64, it is called with %rip on the upper half, so it can
+// NOT access to any global data which is not mapped on upper and must
+// call to function pointers or interfaces to switch to the lower half
+// so that callee can access to global data.
+//
+// +checkescape:hard,stack
+//
+//go:nosplit
+func kernelSyscall(c *CPU) {
+	c.hooks.KernelSyscall()
+}
+
+// kernelException is a trampoline.
+//
+// When in amd64, it is called with %rip on the upper half, so it can
+// NOT access to any global data which is not mapped on upper and must
+// call to function pointers or interfaces to switch to the lower half
+// so that callee can access to global data.
+//
+// +checkescape:hard,stack
+//
+//go:nosplit
+func kernelException(c *CPU, vector Vector) {
+	c.hooks.KernelException(vector)
+}
+
+// Init initializes a new CPU.
+//
+// Init allows embedding in other objects.
+func (c *CPU) Init(k *Kernel, cpuID int, hooks Hooks) {
+	c.self = c    // Set self reference.
+	c.kernel = k  // Set kernel reference.
+	c.init(cpuID) // Perform architectural init.
+
+	// Require hooks.
+	if hooks != nil {
+		c.hooks = hooks
+	} else {
+		c.hooks = defaultHooks{}
+	}
+}