Isolate linux specific register getters / setters

proctl/threads_linux_amd64.go

@@ -2,6 +2,32 @@ package proctl
 
 import "syscall"
 
+type Regs struct {
+	regs *syscall.PtraceRegs
+}
+
+func (r *Regs) PC() uint64 {
+	return r.regs.PC()
+}
+
+func (r *Regs) SP() uint64 {
+	return r.regs.Rsp
+}
+
+func (r *Regs) SetPC(tid int, pc uint64) error {
+	r.regs.SetPC(pc)
+	return syscall.PtraceSetRegs(tid, r.regs)
+}
+
+func registers(tid int) (Registers, error) {
+	var regs syscall.PtraceRegs
+	err := syscall.PtraceGetRegs(tid, &regs)
+	if err != nil {
+		return nil, err
+	}
+	return &Regs{&regs}, nil
+}
+
 func WriteMemory(tid int, addr uintptr, data []byte) (int, error) {
 	return syscall.PtracePokeData(tid, addr, data)
 }