ref: 4b0c17c8e2f8b4fb4bc4ec33f71e5cf761aef407 dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4