(toppers-users 4458) Re: FMP Programming Model

[Daniel Sangorrin]

Hi Pieter,

Sorry for my late response.

Just from my memory, I think the exception handler table uses the exception
number as the index (please check the assembly code to confirm). If that's
correct the second entry (index 1) corresponds to the unsupported
instruction exception.

However, you mention that the same code runs ok at an earlier phase. One
question to ask: could it be that the first time it runs in secure mode and
the second time in non-secure mode? Some instructions cannot be executed in
non-secure mode. Have you checked.it on FMP without Safeg?

About the logtrace, please let me know what you did and what target you are
using. Perhaps the UART is not correctly specified for that target.

Regards,
Daniel
On Nov 17, 2015 10:32 PM, "Pieter Maene" <pieter.maene ＠ esat.kuleuven.be>
wrote:

> Hi Daniel,
>
> The exception is triggered in a piece of code that is very loop-intensive.
> However, the same piece of code runs without any problems earlier during
> the program execution, so I don't think it's a problem with unsupported
> instructions. I've also found out that the second entry from the
> _kernel_prc1_exch_table is triggered, but it's not clear to me how I can
> determine the exact type of exception.
>
> Finally, I was wondering whether there are any further instructions on how
> to enable the logtrace functionality. I have found some documentation, but
> couldn't get any output over UART.
>
> Thank you in advance!
>
> Kind regards,
>
> Pieter Maene
>
> On 11/07/2015 04:30 AM, Daniel Sangorrin wrote:
>
>> Hi Pieter,
>>
>> It's a bit hard to answer with so little information.
>> You should start by isolating the problem. For example:
>>
>> - Does the problem exist when running FMP alone, or only when FMP runs on
>> SafeG?
>> - What type of exception is it?
>> - Which part of the code is generating the exception?
>> - Are your functions using some instructions not supported by your
>> processor (in case of
>>    an undefined instruction exception) ?
>> - Do they require some coprocessor (VFP, SIMD) that is not supported
>> by the SoC or by FMP itself?
>>
>> Regards,
>> Daniel
>>
>>
>>
>>
>>
>>
>>
>> On Sat, Nov 7, 2015 at 1:32 AM, Pieter Maene
>> <pieter.maene ＠ esat.kuleuven.be> wrote:
>>
>>> Hi,
>>>
>>> We are currently building a TrustZone application for a course at the
>>> University of Leuven. We use SafeG, with FMP in the secure world and
>>> Linux
>>> as the untrusted OS. A signature module is running in the trusted world
>>> and
>>> can be invoked to sign a message sent by the untrusted OS. The
>>> communication
>>> between the OSs works perfectly, but when a complicated function is
>>> invoked
>>> (e.g. the signing operation or deriving the public/private keypair), the
>>> CPU
>>> crashes with an "unregistered exception".
>>>
>>> I think I am missing a key concept of programming for FMP, or maybe
>>> misconfigured a setting for the kernel.
>>> Do you have an idea of what might be going wrong?
>>>
>>> Thanks in advance!
>>>
>>> Kind regards,
>>>
>>> Pieter Maene
>>>
>>
>
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