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unexpected segmentation fault changing pc register with branch

Davide Quarta
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  • Arm Employee Badge
    Note: This was originally posted on 15th May 2013 at http://forums.arm.com

    I'm not a GDB expert, but can you get it show you the IFSR and IFAR values?  These are the Instruction Fault Status and Instruction Fault Address registers respectively.  They are how the processor reports why instruction fetch failed (which is what I'm guessing is happening).  Couple of possibilities....

    * The memory just isn't mapped (seems unlikely as you've just mapped it, but it's possible you made a mistake)
    * The mapped region is marked as eXecute Never (XN), meaning any attempt to execute the address will fail
    * Access flag (AF bit) in the descriptor has not been set by the kernel yet.
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  • Arm Employee Badge
    Note: This was originally posted on 15th May 2013 at http://forums.arm.com

    I'm not a GDB expert, but can you get it show you the IFSR and IFAR values?  These are the Instruction Fault Status and Instruction Fault Address registers respectively.  They are how the processor reports why instruction fetch failed (which is what I'm guessing is happening).  Couple of possibilities....

    * The memory just isn't mapped (seems unlikely as you've just mapped it, but it's possible you made a mistake)
    * The mapped region is marked as eXecute Never (XN), meaning any attempt to execute the address will fail
    * Access flag (AF bit) in the descriptor has not been set by the kernel yet.
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