CLBR_RET_REG 17 arch/x86/include/asm/paravirt_types.h #define CLBR_RET_REG (CLBR_EAX | CLBR_EDX) CLBR_RET_REG 34 arch/x86/include/asm/paravirt_types.h #define CLBR_RET_REG (CLBR_RAX)