ref: 1ae5fc01a6e9c6fb1a1befd4c60653a6af10a9e0 dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4