ref: 7d3cc1c55a435bd9e3d37d9bf8a9299ea9e1f87e dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4