ref: c116550e6a41572796e4db65e4f6acbcb3d9d6f8 dir: /libkern/getfcr-thumb.s/
TEXT setfcr(SB), $0 RET TEXT getfcr(SB), $0 RET TEXT getfsr(SB), $0 RET TEXT setfsr(SB), $0 RET