pc    uint64     // program counter
	cpsr  uint32     // current program status register
	__pad uint32
}

type neonstate64 struct {
	v    [64]uint64 // actually [32]uint128
	fpsr uint32
	fpcr uint32
}

type mcontext64 struct {
	es exceptionstate64
	ss regs64
	ns neonstate64
}

type ucontext struct {
	uc_onstack  int32
	uc_sigmask  uint32
	uc_stack    stackt