ref: 1d0f8a7e512e5abfea9c5d2fdf2fb4c05efc720b dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4