On 12/11/20 1:33 PM, Rebecca Cran wrote:
> Is the comment in target/arm/op_helper.c:397 still relevant?
>
> uint32_t HELPER(cpsr_read)(CPUARMState *env)
> {
> /*
> * We store the ARMv8 PSTATE.SS bit in env->uncached_cpsr.
> * This is convenient for populating SPSR_ELx, but must be
> * hidden from aarch32 mode, where it is not visible.
> *
> * TODO: ARMv8.4-DIT -- need to move SS somewhere else.
> */
> return cpsr_read(env) & ~(CPSR_EXEC | PSTATE_SS);
> }
I forgot about this. So we can't "just" store DIT in uncached_cpsr.
I'll let Peter weigh in, but I think it makes sense to move the SS bit
somewhere else (e.g. env->pstate) and merge it into SPSR_ELx upon interrupt.
While what we're doing here is convenient, it's not architectural, and it would
be better to follow GetPSRFromPSTATE pseudocode.
r~
