Mostly the missing listing of clobbered registers. Other than that it’s mostly just that you’re doing useless things, like manually putting the stuff into the registers instead of letting the compiler do it, and the useless push and pop. And the loop is obviously not needed and would hurt performance if you do every write like that.

asm!(
"syscall",
in("rax") 1,
in("rdi") 1,
in("rsi") text_ptr,
in("rdx") text_size,

)

(“so many” was inappropriate, sorry.)