ref: 6e57aee27f0a0cc2bfe7b8befc0f31bf05cf04ea dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4