[PATCH][ARM] Fix _dl_tlsdesc_resolve_hold to save r0

[Joseph Myers]

On Wed, 14 Oct 2015, Szabolcs Nagy wrote:

> _dl_tlsdesc_resolve_hold calls into a C function that clobbers r0,
> but it assumes the original argument is still in r0 after the call.
> This can cause crash in case of concurrent TLS access when TLSDESC
> is in use (-mtls-dialect=gnu2).

I presume this issue was user-visible in a release, in which case a bug 
should be filed in Bugzilla for it.  Should I take it that it's hard to 
write a testcase for this bug that fails reliably without the patch?

-- 
Joseph S. Myers
joseph@codesourcery.com