root/arch/x86/entry/

[..]
  1. calling.h
  2. common.c
  3. entry_32.S
  4. entry_64.S
  5. entry_64_compat.S
  6. syscall_32.c
  7. syscall_64.c
  8. thunk_32.S
  9. thunk_64.S
  10. vdso/
  11. vsyscall/
[..]