SEL_RPL
#define IDXDYNSEL(s) ((((s) & ~SEL_RPL) - DYNSEL_START) >> 4)
#define ISPL(s) ((s) & SEL_RPL) /* what is the priority level of a selector */
#define CHK_UPL SEL_RPL
#define IDXDYNSEL(s) ((((s) & ~SEL_RPL) - DYNSEL_START) >> 3)
#define ISPL(s) ((s) & SEL_RPL) /* what is the priority level of a selector */
uc->uc_mcontext.__gregs[_REG_CS] &= ~SEL_RPL;