[PATCH v15 1/8] nptl: Add rseq auxvals

[Florian Weimer]

* Michael Jeanson:

> +  /* Get the rseq feature size, with a minimum of RSEQ_AREA_SIZE_INITIAL_USED
> +     (20) for kernels that don't have AT_RSEQ_FEATURE_SIZE.  Limit the feature
> +     size to RSEQ_AREA_SIZE_MAX_USED (28) which fits the rseq area in 'struct
> +     pthread' and represents the maximum feature size of currently released
> +     kernels.  Since no kernels currently cross the 32 bytes of the original
> +     ABI, the semantics of a feature size of 32 or more are still undetermined.
> +     */
> +  _rseq_size = MIN (MAX (auxv_values[AT_RSEQ_FEATURE_SIZE],
> +                         RSEQ_AREA_SIZE_INITIAL_USED),
> +		    RSEQ_AREA_SIZE_MAX_USED);
> +  _rseq_align = MAX (auxv_values[AT_RSEQ_ALIGN], RSEQ_MIN_ALIGN);

This is just a temporary thing until the extension mechanism is
implemented, so this is okay.  Rest looks good too.

Reviewed-by: Florian Weimer <fweimer@redhat.com>

Thanks,
Florian