ref: 5e9d8a7b18c001fd60d3c3978f90dcdaf20f5ce6 dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4