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[PATCH] LoongArch: Do not add DF_STATIC_TLS for TLS LE

Fangrui Song maskray@google.com
Mon Jan 22 07:11:32 GMT 2024 
On Sun, Jan 21, 2024 at 10:51 PM Xi Ruoyao <xry111@xry111.site> wrote:
>
> On Sun, 2024-01-21 at 21:48 -0800, Fangrui Song wrote:
> > On Sun, Jan 21, 2024 at 9:45 PM Tatsuyuki Ishi <ishitatsuyuki@gmail.com> wrote:
> > >
> > > > On Dec 28, 2023, at 23:58, Tatsuyuki Ishi <ishitatsuyuki@gmail.com> wrote:
> > > >
> > > > TLS LE is exclusively for executables, while DF_STATIC_TLS is for DLLs.
> > > > DF_STATIC_TLS should only be set for TLS IE (and when it's DLL), not LE.
> > > > ---
> > > > bfd/elfnn-loongarch.c | 2 --
> > > > 1 file changed, 2 deletions(-)
> > > >
> > > > diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
> > > > index bd448cda453..64c34e99261 100644
> > > > --- a/bfd/elfnn-loongarch.c
> > > > +++ b/bfd/elfnn-loongarch.c
> > > > @@ -862,8 +862,6 @@ loongarch_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
> > > >         if (!bfd_link_executable (info))
> > > >           return false;
> > > >
> > > > -       info->flags |= DF_STATIC_TLS;
> > > > -
> > > >         if (!loongarch_elf_record_tls_and_got_reference (abfd, info, h,
> > > >                                                          r_symndx,
> > > >                                                          GOT_TLS_LE))
> > > > --
> > > > 2.40.1
> > > >
> > > >
> > >
> > > Any interest in reviewing / merging this and the other two patches sent together?
> > > The DF_STATIC_TLS change is pretty short, the formatting patch is trivial.
> > > As for the last patch introducing a comment change, I’m not sure what Mengqing’s stance is, but my intention for the comment change is to provide a better context for the reader rather than comparing to a solution that is not currently implemented in the codebase.
> > >
> > > Tatsuyuki.
> >
> > I think this is correct and should be applied.
>
> Will this cause a breakage in practice?  If so we need to apply it for 2.42 branch too.

No. DF_STATIC_TLS is a not-so-useful dynamic tag. It helps a `readelf
-d` reader to know whether the DSO uses initial-exec.

For lld, I made a similar change in Nov 2021
(https://github.com/llvm/llvm-project/commit/6ca8fde226e907db13bc538e721af8724f0e92d0).
lld before Dec 2022 did not set DF_STATIC_TLS for non-x86
architectures (AArch64 and PPC).
I changed it to set DF_STATIC_TLS.
For both changes nobody has noticed anything.



-- 
宋方睿
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