UPT_CX 15 arch/x86/um/asm/ptrace.h #define PT_REGS_CX(r) UPT_CX(&(r)->regs) UPT_CX 16 arch/x86/um/shared/sysdep/ptrace_32.h #define UPT_SYSCALL_ARG2(r) UPT_CX(r)