Function raw_syscall 

pub unsafe fn raw_syscall(number: c_long, args: [u64; 6]) -> i64

Issues syscall number with args through the syscall instruction itself on x86-64, returning the kernel’s result (a negative errno on failure). Under in-guest LiteInst Detcore runs inside the guest, where libc’s wrappers (open, fstat, syscall, …) are dynamic symbols the program or a preloaded library may define, and allocate in.

Safety

As for the syscall itself: pointer arguments must be valid for it.