ref: 8b160d1ea14a47f3e7da4c2484e7d1a8afcb7dd0 dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4