rcr2
uint64_t cr2 = rcr2();
uint64_t cr2 = rcr2();
frame->tf_rflags, rcr2(), curcpu()->ci_ilevel, frame->tf_rsp);
frame->tf_rflags, rcr2(), curcpu()->ci_ilevel);
uint32_t cr2 = rcr2();
static __inline u_int rcr2(void);