ref: 992fe280ac3be78bf6a1a2e3fed56f6dfd3c4e61 dir: /sys/src/libc/arm/argv0.s/
GLOBL argv0(SB), $4 GLOBL _tos(SB), $4 GLOBL _privates(SB), $4 GLOBL _nprivates(SB), $4