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From: Joseph Myers <joseph@codesourcery.com>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [PATCH 3/7] Add GLIBC_ABI_DT_RELR for DT_RELR support
Date: Fri, 4 Feb 2022 23:58:05 +0000	[thread overview]
Message-ID: <alpine.DEB.2.22.394.2202042355450.244210@digraph.polyomino.org.uk> (raw)
In-Reply-To: <CAMe9rOrLHvH6zHSG499vq1VHiz8oTer7njcOR9OshA6HyT=RVQ@mail.gmail.com>

On Fri, 4 Feb 2022, H.J. Lu via Libc-alpha wrote:

> On Fri, Feb 4, 2022 at 1:01 PM Joseph Myers <joseph@codesourcery.com> wrote:
> >
> > On Fri, 4 Feb 2022, H.J. Lu via Libc-alpha wrote:
> >
> > > Good point.  How about "enable DT_RELR only if SUPPORT_DT_RELR is
> > > defined?  Currently, only x86 defines SUPPORT_DT_RELR.
> >
> > My preference would be:
> >
> > 1. Support user executables and shared libraries with RELR relocations
> > across all platforms, unconditionally.
> 
> RELR is kind of like static PIE.  Not all architectures support it.

My understanding is that analogy only applies to the static linker, not to 
glibc itself - that the static linker needs architecture-specific code, 
but glibc doesn't (as evidenced by the lack of any architecture-specific 
non-configure changes in this patch series).

> RELR should be enabled only if there is a linker which supports
> -z pack-relative-relocs.

(a) That should only apply to "enabled" in the sense of "glibc itself uses 
RELR relocations", not "glibc supports loading executables and shared 
libraries with such relocations".

(b) The configure test for that should be architecture-independent, with 
no architecture-specific configure changes needed at all.

-- 
Joseph S. Myers
joseph@codesourcery.com

  reply	other threads:[~2022-02-04 23:58 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-03 18:09 [PATCH 0/7] Support DT_RELR relative relocation format H.J. Lu
2022-02-03 18:09 ` [PATCH 1/7] elf: Support DT_RELR relative relocation format [BZ #27924] H.J. Lu
2022-02-03 18:09 ` [PATCH 2/7] elf: Properly handle zero DT_RELA/DT_REL values H.J. Lu
2022-02-03 18:09 ` [PATCH 3/7] Add GLIBC_ABI_DT_RELR for DT_RELR support H.J. Lu
2022-02-04 19:53   ` Joseph Myers
2022-02-04 20:04     ` H.J. Lu
2022-02-04 20:10       ` Joseph Myers
2022-02-04 20:40         ` H.J. Lu
2022-02-04 21:01           ` Joseph Myers
2022-02-04 21:08             ` H.J. Lu
2022-02-04 23:58               ` Joseph Myers [this message]
2022-02-05 17:24                 ` H.J. Lu
2022-02-03 18:09 ` [PATCH 4/7] x86/configure.ac: Define PI_STATIC_AND_HIDDEN/SUPPORT_STATIC_PIE H.J. Lu
2022-02-03 18:09 ` [PATCH 5/7] x86: Define SUPPORT_DT_RELR H.J. Lu
2022-02-03 18:09 ` [PATCH 6/7] Add --disable-default-dt-relr H.J. Lu
2022-02-03 18:09 ` [PATCH 7/7] NEWS: Mention DT_RELR support H.J. Lu
2022-02-04 20:00 ` [PATCH 0/7] Support DT_RELR relative relocation format Joseph Myers
2022-02-04 20:08   ` H.J. Lu
2022-02-04 20:12     ` Joseph Myers
2022-02-04 20:32   ` Fangrui Song

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