ref: 5c6a03f4f417d00a6d169cfc9c7e6efae17f4e5e dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4