PMU_FL_BR_CNTR
if (!(x86_pmu.flags & PMU_FL_BR_CNTR) ||
if (x86_pmu.flags & PMU_FL_BR_CNTR)
return (x86_pmu.flags & PMU_FL_BR_CNTR) ? attr->mode : 0;
x86_pmu.flags |= PMU_FL_BR_CNTR | PMU_FL_DYN_CONSTRAINT;