arm64: Enable Floating-point exception

[dchagin]

Summary

To enable it user-space needs to call feenableexcept().

FPE_FLTIDO has been added ss IDF bit can't be mapped to any existing FPE code.

[andrew]

sys/arm64/arm64/trap.c

434

I'd drop the do_ from this name.

439

This should be if ((exception & ISS_DATA_TFV) != 0) { (and similar below)

608

Do we need to restore the VFP state? It should be enabled when this exception is raised.

sys/arm64/include/armreg.h

299–306

These should be named something like ISS_FP_TFV_FOO and placed before the ISS_INSN_* definitions. The ISS_DATA_* macros are for data aborts.

[dchagin]

fixed, thank you

[dchagin]

sys/arm64/arm64/trap.c

608

yep, I should read Architecture Reference Manual before

sys/arm64/include/armreg.h

299–306

I'd prefer ISS_FP_FOO as TVF and FOO are bits in the same word, but if you insist, I'll change the naming