[PATCH] powerpc: Remove backtrace implementation

[Florian Weimer]

* Adhemerval Zanella:

> The powerpc optimization to provide a fast stacktrace requires some
> ad-hoc code to handle Linux signal frames and the change is fragile
> once the kernel decides to slight change its execution sequence [1].
>
> The generic implementation work as-is and it should be future proof
> since the kernel provides the expected CFI directives in vDSO shared
> page.
>
> Checked on powerpc-linux-gnu, powerpc64le-linux-gnu, and
> powerpc64-linux-gnu.
>
> [1] https://sourceware.org/pipermail/libc-alpha/2021-January/122027.html

Does this really work well (enough) on systems which do not build
everything with asynchronous unwind tables?  If I recall correctly, GCC
enabled them by default only quite recently.

Thanks,
Florian
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