Re: [PATCH v1 12/17] xen/riscv: extend exception tables with type and data fields

On 17.08.2026 13:39, Oleksii Kurochko wrote:
> On 8/17/26 1:33 PM, Oleksii Kurochko wrote:
>>>
>>>> +    BUG_ON(!trap_info);
>>>> +
>>>> +    trap_info->sepc = csr_read(CSR_SEPC);
>>>> +    trap_info->scause = csr_read(CSR_SCAUSE);
>>>> +    trap_info->stval = csr_read(CSR_STVAL);
>>>
>>> Do you really need to re-read all three registers here? Didn't you 
>>> read at least
>>> scause already, in order to make it here in the first place?
>>
>> Agree, ->scause and ->sepc are already read.
> 
> scause should be re-reaad as we don't save it inside cpu_user_regs 
> structure.

It could be propagated as a function argument. Question really is how
expensive these CSR reads are.

Jan