ref: 8d9a4e15029b23e367b5ae6a399f22e4cf5f0c9f dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4