ref: 381ae5a2aabbe984aa9f0b53c0cda16a3de2ed3a dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4