ref: 3c7eaa9d6bbdd448675a7e9d4fe46bc0a48a4ade dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4