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Forum: ARM programming with GCC/GNU tools Exception not caught


von Pierre-Andre V. (pierreandre_v)


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I'm struggling to get exception handling to work in Sierra Wireless 
Developer Studio. It uses the gcc version 4.7.4 toolchain for ARM. It is 
something specific to this environment - either the linker script or the 
way my code is called from their OS. The chip in question is a Sierra 
Wireless SL6087 which I believe contains an ARM 946.

Exceptions are not caught at all, but the termination handler is called. 
I used std::set_terminate to install my own and in there, I can get the 
exception that was thrown using __cxa_current_exception_type (from 
cxxabi.h).

I've spend the last week reading several posts on the topic and most 
point towards missing or incorrect sections in the linker script. I've 
used arm-none-eabi-objdump.exe to compare the headers with one from 
another environment (with the same toolchain) where exception handling 
is working and I cannot see any major differences.

Here is my code:
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    try
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    {
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      tout << TraceLevel::Information << "[Application::Main] throwing" << TraceEnd;
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      throw runtime_error("Test");
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    }
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    catch(runtime_error &e)
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    {
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      tout << TraceLevel::Information << "[Application::Main] Correct exception: " << e.what() << TraceEnd;
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    }
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    catch(const::exception &e)
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    {
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      tout << TraceLevel::Information << "[Application::Main] Correct exception: " << e.what() << TraceEnd;
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    }
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    catch(...)
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    {
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      tout << TraceLevel::Information << "[Application::Main] General catch" << TraceEnd;
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    }
The linker script is automatically generated by the tool, but I've made 
several changes to try an resolve the problem. Here is one of my 
attempts:
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    .ARM.extab : 
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    { 
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    *(.ARM.extab* .gnu.linkonce.armextab.*) 
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    } > ROM_MAP :appli_code
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    .ARM :
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    {
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      __exidx_start = .;
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      *(.ARM.exidx*)
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      __exidx_end = .;
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    } > ROM_MAP :appli_code
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    .gcc_except_table : 
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    { 
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      *(.gcc_except_table .gcc_except_table.*) 
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    } > ROM_MAP :appli_code

I've seen many references to eh_frame_hdr and eh_frame, but since the 
object files don't seem to include them, having them in the linker 
scripts has no effect.
Anything else I can try?

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