ref: 18bd1a92e5d8cb39e474bb3e4a1bd1d2a614a0dd dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4