ref: 1a5dafcc3d8c455b0e7b36dd9bd45c13dd4d91eb dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4