ref: f1c3a1a6a89ba8a801e10ef3e75fe0dc7a2a9149 dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4