ref: 85ffa283f67b4bd139a4e28e82f0d1c7f6c53b3b dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4