[PATCH] x86-64: Align the stack in __tls_get_addr [BZ #21609]

[Florian Weimer]

On 07/06/2017 05:11 PM, H.J. Lu wrote:

>> There's also this option:
>>
>> (c) glibc provides __tls_get_addr (two leading underscores)
>>     under a new symbol version.
>>
>>     Pro: No GCC changes required for upstream maintained versions.
>>     No problems for glibc development, no new -m flag.
>>     As fast as (b) after relinking against a newer glibc.
>>     Breakage with older/unfixed GCC is detectable during development
>>     (unlike the reason for the workaround, which would have needed
>>     clairvoyance on the developer's part).
>>
>>     Con: Relinking code compiled with the old, unfixed GCC against the
>>     new glibc still produces broken binaries.
>>
> 
> (c) doesn't fix the problem for unfixed GCC at all.  As far as unfixed GCC
> is concerned, nothing is changed.

It fixes existing binaries by addressing the implied ABI breakage by the
glibc update.

It's my strong belief that compiler bugs should be fixed in the
compiler, not in glibc.

Thanks,
Florian