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// 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
import (
"syscall"
"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
)
var (
// UserspaceSize is the total size of userspace.
UserspaceSize = uintptr(1) << (VirtualAddressBits() - 1)
// MaximumUserAddress is the largest possible user address.
MaximumUserAddress = (UserspaceSize - 1) & ^uintptr(usermem.PageSize-1)
// KernelStartAddress is the starting kernel address.
KernelStartAddress = ^uintptr(0) - (UserspaceSize - 1)
)
// Kernel is a global kernel object.
//
// This contains global state, shared by multiple CPUs.
type Kernel struct {
KernelArchState
}
// Hooks are hooks for kernel functions.
type Hooks interface {
// KernelSyscall is called for kernel system calls.
//
// Return from this call will restore registers and return to the kernel: the
// registers must be modified directly.
//
// If this function is not provided, a kernel exception results in halt.
//
// This must be go:nosplit, as this will be on the interrupt stack.
// Closures are permitted, as the pointer to the closure frame is not
// passed on the stack.
KernelSyscall()
// KernelException handles an exception during kernel execution.
//
// Return from this call will restore registers and return to the kernel: the
// registers must be modified directly.
//
// If this function is not provided, a kernel exception results in halt.
//
// This must be go:nosplit, as this will be on the interrupt stack.
// Closures are permitted, as the pointer to the closure frame is not
// passed on the stack.
KernelException(Vector)
}
// CPU is the per-CPU struct.
type CPU struct {
// self is a self reference.
//
// This is always guaranteed to be at offset zero.
self *CPU
// kernel is reference to the kernel that this CPU was initialized
// with. This reference is kept for garbage collection purposes: CPU
// registers may refer to objects within the Kernel object that cannot
// be safely freed.
kernel *Kernel
// CPUArchState is architecture-specific state.
CPUArchState
// registers is a set of registers; these may be used on kernel system
// calls and exceptions via the Registers function.
registers syscall.PtraceRegs
// hooks are kernel hooks.
hooks Hooks
}
// Registers returns a modifiable-copy of the kernel registers.
//
// This is explicitly safe to call during KernelException and KernelSyscall.
//
//go:nosplit
func (c *CPU) Registers() *syscall.PtraceRegs {
return &c.registers
}
// SwitchOpts are passed to the Switch function.
type SwitchOpts struct {
// Registers are the user register state.
Registers *syscall.PtraceRegs
// FloatingPointState is a byte pointer where floating point state is
// saved and restored.
FloatingPointState *byte
// PageTables are the application page tables.
PageTables *pagetables.PageTables
// Flush indicates that a TLB flush should be forced on switch.
Flush bool
// FullRestore indicates that an iret-based restore should be used.
FullRestore bool
// SwitchArchOpts are architecture-specific options.
SwitchArchOpts
}
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