ref: 7f8c46e27f55c89bef41f7e089d1f6f276c1696c dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4