[U-Boot] C99 and dynamic arrays

[Steve Strobel]

On Wed, Mar 13, 2013 at 1:55 PM, Måns Rullgård <mans at mansr.com> wrote:

> >>> I suppose we could check the available stack space.
> >> There is no way to check stack usage from C.
> > Well there is an architecture-specific way. A function can generally
> > find its own stack pointer by taking the address of a local variable,
> > so it is possible to write a function to check for stack overflow.
>
> Performing such checks without getting into undefined behaviours is
> tricky if not impossible, and modern compilers are quite effective at
> exploiting these, rendering such checks useless.  Remember the deleted
> null checks in the kernel a while back?
>

If possible, it is much nicer to use a compiler option rather than
something in the application itself to check for stack overflow.  On the
Blackfin gcc there is a -mstack-check-l1 option to do this.  It has a
little overhead, but has saved my bacon.  Note that the libraries also need
to be compiled with that option if stack overflows within those libraries
are to be detected.

Steve


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Steve Strobel
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