Hi Michal, On 27/04/2021 10:35, Michal Orzel wrote:
AArch64 registers are 64bit whereas AArch32 registers are 32bit or 64bit. MSR/MRS are expecting 64bit values thus we should get rid of helpers READ/WRITE_SYSREG32 in favour of using READ/WRITE_SYSREG. We should also use register_t type when reading sysregs which can correspond to uint64_t or uint32_t. Even though many AArch64 registers have upper 32bit reserved it does not mean that they can't be widen in the future.
This is a pretty generic message but doesn't really explain the change itself and point out this is a bug (possibly latent on current HW) because it is implementation defined. IOW a CPU implementer may already have decided to use the top 32-bit without our knowledge.
Cheers, -- Julien Grall
