[PATCH V4] ARM : unwinder : Prevent data abort due to stack overflow

[Dave Martin]

On Thu, Dec 05, 2013 at 03:15:22PM +0000, Anurag Aggarwal wrote:
> >>if (unlikely(check) &&
> >>    *vsp >= (unsigned long *)ctrl->sp_high))
> 
> Good idea, It can help in optimizing the code and will leave code more readable
> and it will be easy to maintain also.

That was my goal -- it's not always easy to achieve both, but we should
try where possible, especially for non-performance-critical code.

> >>Does the code check anywhere that SP is word-aligned?
> >>
> >>That should probably be checked if it's not done already.
> 
> I think this should be handled in separate patch
> I would also like to hear more your ideas for the file

There are some limitations on how backtracing works with ARM_UNWIND.
The backtracer interface assumes that the compiler's register use with
ARM_UNWIND is "almost the same" as with !ARM_UNWIND.  But this is not
always true, and we've seen some problems.  

I think the best solution will involve some refactoring of the interface
between the backtracer and the unwinder backends, but I don't have it
all figured out yet...

Cheers
---Dave