ref: 6f80f6a7be43a1cef6597d7bd6e4db26e9ec15fa dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4