ref: 1a324c3c7b0912a09c95ffd0d7c76c69b6e6af7c dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4