ref: e81c54ba2ecc673a4d5f8aed0e9b52841fe07b0d 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