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From: "fw at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/113874] GNU2 TLS descriptor calls do not follow psABI on
 x86_64-linux-gnu
Date: Sun, 11 Feb 2024 18:37:27 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113874

--- Comment #6 from Florian Weimer <fw at gcc dot gnu.org> ---
> (In reply to H.J. Lu from comment #4)
> > (In reply to H.J. Lu from comment #3)
> > > Created attachment 57385 [details]
> > > A patch
> > >=20
> > > Try this.
> >=20
> > This doesn't work properly.  To work around in ld.so, _dl_tlsdesc_dynam=
ic
> > needs to save and restore ALL registers, which can be expensive.

Why doesn't this work properly? Is it possible to make it work with a diffe=
rent
approach?

The __tls_get_addr call with the default approach potentially needs to solve
the same problem, doesn't it?

(In reply to Jakub Jelinek from comment #5)
> Or it could be compiled with options to make sure it doesn't use vector
> registers etc., and only save/restore if it needs to call into some code
> where libc can't afford that (say allocate memory).

We currently call into malloc, which could be a replacement malloc. If GCC
cannot be fixed, full context switch or elimination of the slow path are our
best options for a glibc-side fix.=