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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 ptrace
import (
"syscall"
"unsafe"
"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
)
// GETREGSET/SETREGSET register set types.
//
// See include/uapi/linux/elf.h.
const (
// _NT_PRFPREG is for x86 floating-point state without using xsave.
_NT_PRFPREG = 0x2
// _NT_X86_XSTATE is for x86 extended state using xsave.
_NT_X86_XSTATE = 0x202
)
// fpRegSet returns the GETREGSET/SETREGSET register set type to be used.
func fpRegSet(useXsave bool) uintptr {
if useXsave {
return _NT_X86_XSTATE
}
return _NT_PRFPREG
}
// getRegs sets the regular register set.
func (t *thread) getRegs(regs *syscall.PtraceRegs) error {
_, _, errno := syscall.RawSyscall6(
syscall.SYS_PTRACE,
syscall.PTRACE_GETREGS,
uintptr(t.tid),
0,
uintptr(unsafe.Pointer(regs)),
0, 0)
if errno != 0 {
return errno
}
return nil
}
// setRegs sets the regular register set.
func (t *thread) setRegs(regs *syscall.PtraceRegs) error {
_, _, errno := syscall.RawSyscall6(
syscall.SYS_PTRACE,
syscall.PTRACE_SETREGS,
uintptr(t.tid),
0,
uintptr(unsafe.Pointer(regs)),
0, 0)
if errno != 0 {
return errno
}
return nil
}
// getFPRegs gets the floating-point data via the GETREGSET ptrace syscall.
func (t *thread) getFPRegs(fpState *arch.FloatingPointData, fpLen uint64, useXsave bool) error {
iovec := syscall.Iovec{
Base: (*byte)(fpState),
Len: fpLen,
}
_, _, errno := syscall.RawSyscall6(
syscall.SYS_PTRACE,
syscall.PTRACE_GETREGSET,
uintptr(t.tid),
fpRegSet(useXsave),
uintptr(unsafe.Pointer(&iovec)),
0, 0)
if errno != 0 {
return errno
}
return nil
}
// setFPRegs sets the floating-point data via the SETREGSET ptrace syscall.
func (t *thread) setFPRegs(fpState *arch.FloatingPointData, fpLen uint64, useXsave bool) error {
iovec := syscall.Iovec{
Base: (*byte)(fpState),
Len: fpLen,
}
_, _, errno := syscall.RawSyscall6(
syscall.SYS_PTRACE,
syscall.PTRACE_SETREGSET,
uintptr(t.tid),
fpRegSet(useXsave),
uintptr(unsafe.Pointer(&iovec)),
0, 0)
if errno != 0 {
return errno
}
return nil
}
// getSignalInfo retrieves information about the signal that caused the stop.
func (t *thread) getSignalInfo(si *arch.SignalInfo) error {
_, _, errno := syscall.RawSyscall6(
syscall.SYS_PTRACE,
syscall.PTRACE_GETSIGINFO,
uintptr(t.tid),
0,
uintptr(unsafe.Pointer(si)),
0, 0)
if errno != 0 {
return errno
}
return nil
}
// clone creates a new thread from this one.
//
// The returned thread will be stopped and available for any system thread to
// call attach on it.
//
// Precondition: the OS thread must be locked and own t.
func (t *thread) clone() (*thread, error) {
r, ok := usermem.Addr(t.initRegs.Rsp).RoundUp()
if !ok {
return nil, syscall.EINVAL
}
rval, err := t.syscallIgnoreInterrupt(
&t.initRegs,
syscall.SYS_CLONE,
arch.SyscallArgument{Value: uintptr(
syscall.CLONE_FILES |
syscall.CLONE_FS |
syscall.CLONE_SIGHAND |
syscall.CLONE_THREAD |
syscall.CLONE_PTRACE |
syscall.CLONE_VM)},
// The stack pointer is just made up, but we have it be
// something sensible so the kernel doesn't think we're
// up to no good. Which we are.
arch.SyscallArgument{Value: uintptr(r)},
arch.SyscallArgument{},
arch.SyscallArgument{},
// We use these registers initially, but really they
// could be anything. We're going to stop immediately.
arch.SyscallArgument{Value: uintptr(unsafe.Pointer(&t.initRegs))})
if err != nil {
return nil, err
}
return &thread{
tgid: t.tgid,
tid: int32(rval),
cpu: ^uint32(0),
}, nil
}
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