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Re: providing __tls_get_addr on s390?
On 2019-08-31 10:28, Carlos O'Donell wrote:
> On 8/31/19 10:10 AM, Aurelien Jarno wrote:
> > Dear all,
> >
> > I have noticed that GCC recently started to use the
> > __tls_get_addr_internal symbol on s390 [1]. This is probably a bad
> > idea to use an internal libc symbol outside of the libc as it can be
> > modified or removed at anytime.
> >
> > That said, I also noticed that s390 is (one of the) only architectures
> > which doesn't provide __tls_get_addr. Is there a reason for that? Is it
> > something that we should fix?
>
> Stefan,
>
> Is there any reason s390 doesn't implement __tls_get_addr like other arches?
> It's always easier if all the machines support the same generic infrastructure.
> The lack of __tls_get_addr on s390 forces the D language runtime to have
> Z Series specific code to handle TLS calculations :-(
>
> Aurelien,
>
> The D-language runtime encodes a ton of TLS-specific implementation details
> and one of them is accessing TLS details.
>
> This can be seen as a failing of glibc to provide a generic low-level TLS
> interface for language runtimes. There aren't enough details spelled out
> to make it easy to provide TLS details to the runtime.
>
> Either way, *no* language runtime should be using GLIBC_PRIVATE symbols.
> Could you please file a bug for that? If they need access they should do
> so through the appropriate API e.g. __tls_get_addr which is a standard
> API with specified semantics.
I have just submitted https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91628
Please feel free to add more details.
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://www.aurel32.net