ref: 50433ee1f1bb6c0b5d1477fbafeb4d2f5579ec3a dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4