ref: 7f224a8f6d343cf0aaf162cc9b9f7d4d62ac78ac dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4