Re: [PATCH] target/s390x: Move trans_exc_code update to do_program_interrupt

[Richard Henderson <richard.henderson@linaro.org>]

On 7/31/23 01:26, Ilya Leoshkevich wrote:
>>> +    case PGM_PROTECTION:
>>> +    case PGM_TRANS_SPEC:
>>> +        assert(env->int_pgm_code == env->tlb_fill_exc);
>>> +        set_trans_exc_code = true;
>>> +        advance = true;
>>> +        break;
>>
>> These exceptions came from seeing an early kernel fault, grepping for
>> the set of
>> exceptions raised in mmu_helper.c, and eliminating PGM_ADDRESSING per
>> the first hunk.
> 
> Does POp specify that the CPU stores Translation-Exception
> Identification on Translation-Specification Exceptions
> (PGM_TRANS_SPEC)? I re-read the 0xA8 documentation a few times, but
> could not find it.

Neither could I.

> It's also interesting what the kernel was attempting when it got
> PGM_TRANS_SPEC and recovered from it. Maybe something else is wrong?

I think the kernel was testing PGM_PROTECTION, to see if LowCore protection worked.

But since that one wasn't listed for 0xA8 either, I preserved previous behaviour in 
setting trans_exc_code for all mmu exceptions except for PGM_ADDRESSING.


r~