From: "H.J. Lu" <hjl.tools@gmail.com>
To: Kaylee Blake <klkblake@gmail.com>
Cc: Binutils <binutils@sourceware.org>
Subject: Re: RFC: [PATCH] ELF: Don't require section header on ELF objects
Date: Mon, 9 Mar 2020 06:54:04 -0700 [thread overview]
Message-ID: <CAMe9rOoN5=syaLv=fdb0RkdBOfukOUb1rFqpAttZO58d0PuNJQ@mail.gmail.com> (raw)
In-Reply-To: <e6b6dce2-20a0-584e-15e6-4088eea45243@gmail.com>
On Mon, Mar 9, 2020 at 6:46 AM Kaylee Blake <klkblake@gmail.com> wrote:
>
> On 9/3/20 11:59 pm, Florian Weimer wrote:
> > * Kaylee Blake:
> >
> >>> I think that's conceptually the wrong thing to do for ELF, sorry. If
> >>> there is no section header, the object should be unlinkable. The
> >>> linker should not use the dynamic segment to locate the symbol
> >>> information, only the dynamic section (in case the link ABI and
> >>> run-time ABI are different).
> >>
> >> I'm confused by your comment about link and run-time ABIs differing;
> >> surely if the ABI at runtime differs from the ABI at link time, you are
> >> just going to crash at runtime?
> >
> > No, the typical application are fewer symbols in the DSO at link time
> > than at load time, for example for linking against an older version of
> > glibc than is installed on the system.
>
> How is that being done? On my machine, the symbols in glibc found
> through the section header are identical to the ones found through the
> dynamic array, except that some of the latter are missing symbol
> versions, which I think is due to this patch not looking them up? (I'm
> not actually sure if this patch does that or not).
>
Symbol versioning is a real problem. We need to reconstruct all dynamic
symbol info from PT_DYNAMIC segment. I am running into a wrong
output problem on i386. I am leaning toward Florian's suggestion to
only add --remove-section-header and -z nosectionheader without
reconstructing dynamic symbol info from PT_DYNAMIC segment.
--
H.J.
next prev parent reply other threads:[~2020-03-09 13:54 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-08 17:59 H.J. Lu
2020-03-08 18:06 ` H.J. Lu
2020-03-08 23:35 ` Alan Modra
2020-03-08 23:46 ` H.J. Lu
2020-03-09 0:02 ` H.J. Lu
2020-03-09 0:02 ` Kaylee Blake
2020-03-09 0:05 ` Alan Modra
2020-03-09 1:36 ` H.J. Lu
2020-03-09 1:59 ` Kaylee Blake
2020-03-09 2:23 ` Alan Modra
2020-03-09 2:35 ` H.J. Lu
2020-03-09 4:14 ` H.J. Lu
2020-03-09 4:59 ` Kaylee Blake
2020-03-09 11:56 ` Alan Modra
2020-03-08 23:24 ` Kaylee Blake
2020-03-08 23:29 ` H.J. Lu
2020-03-08 23:38 ` Alan Modra
2020-03-08 23:45 ` H.J. Lu
2020-03-12 2:14 ` Fangrui Song
2020-03-09 8:13 ` Florian Weimer
2020-03-09 12:54 ` Kaylee Blake
2020-03-09 13:06 ` Florian Weimer
2020-03-09 13:14 ` Kaylee Blake
2020-03-09 13:16 ` Florian Weimer
2020-03-09 13:28 ` Kaylee Blake
2020-03-09 13:29 ` Florian Weimer
2020-03-09 13:45 ` Kaylee Blake
2020-03-09 13:54 ` H.J. Lu [this message]
2020-03-09 14:02 ` Kaylee Blake
2020-03-09 14:52 ` Florian Weimer
2020-03-09 15:07 ` Kaylee Blake
2020-03-09 15:29 ` Florian Weimer
2020-03-09 13:44 ` Alan Modra
2020-03-09 13:54 ` Kaylee Blake
2020-03-09 22:34 ` Alan Modra
2020-03-10 0:14 ` H.J. Lu
2020-03-09 14:34 ` Michael Matz
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