Reading thread registers

[Denis Huber]

Hallo Christian,

thank you for your answer. It helped me a lot :)

Best regards,
Denis

On 30.08.2016 14:34, Christian Prochaska wrote:
> Hi Denis,
>
> On 25.08.2016 15:45, Denis Huber wrote:
>> Is it possible to aquire the thread's registers through simply reading
>> them in the UTCB which is pointed by Thread_state::utcb? If yes, what is
>> the layout of the UTCB in the memory?
>> Or do I also have to pause the thread to find relevant registers?
>
> the thread's registers can be read from the UTCB in userland if the
> kernel saved them there. On Fiasco.OC, this currently only happens when
> an exception occurs ('Thread::exception()' in thread-ipc.cpp links
> '_utcb_handler' to the trap state, which is then copied into the UTCB in
> 'Thread::copy_ts_to_utcb()' in thread-arm.cpp). When pausing the thread,
> an artificial exception is triggered, which causes the kernel to copy
> the thread state into the UTCB. Therefore, it is necessary to pause the
> thread before the register values are available in the UTCB.
>
> Regards,
> Christian
>
>
>
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