(toppers-users 4464) Re: FMP Programming Model

[Pieter Maene]

Dear Daniel,

Thank you for your response.

I have managed to stabilize the application by refactoring the parts of 
my code that use the communication library. Most of the time, the 
application now runs without problems, although the unregistered 
processor exception is still triggered sometimes.

Something else that I noticed, is that the dual OS communication 
functions often fail with DUALOSCOM_NOINIT. Regularly calling 
dualoscom_init fixes this, but do you know what could cause this?

To enable the logtrace, I included the header files in the FMP 
configuration file and enabled modified the Makefile to enable it. We 
are developing for the ZedBoard.

Kind regards,

Pieter

On 11/26/2015 10:15 AM, Daniel Sangorrin wrote:
>
> 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 
> <http://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 <mailto: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
>         <mailto: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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