fast_syscall

This is an entry point of syscall instruction. It is almost identical to the FreeBSD version. It use standard System V AMD64 ABI for kernel interface the same as Linux, except rax is an actual errno in case of error (not a negative errno like Linux). The rax and rdx is also used for storing the return value. The CF on rFLAGS will be set if rax is an errno. In this case the rax will never be a zero.

Locations