ref: c1cf36fbb4a5b7a47f773e95fb8efe0b6d5c3c28 dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4