ref: 4bfaefbdcdf477d0d3f108630e2bfcfd4448d9ea dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4