ref: 0ed8a3bd7b1bbe2a3857f2abcaabdc4edd2d8b05 dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4