From: Szabolcs Nagy <nsz@port70.net>
To: Florian Weimer <fweimer@redhat.com>
Cc: Jan Beulich <JBeulich@suse.com>, "H.J. Lu" <hjl.tools@gmail.com>,
Rich Felker <dalias@libc.org>,
binutils@sourceware.org, gnu-gabi@sourceware.org
Subject: Re: RFC: Add SHT_GNU_PHDRS
Date: Mon, 01 Jan 2018 00:00:00 -0000 [thread overview]
Message-ID: <20180927103539.GJ10209@port70.net> (raw)
In-Reply-To: <87pnwzuz8r.fsf@oldenburg.str.redhat.com>
* Florian Weimer <fweimer@redhat.com> [2018-09-27 10:21:40 +0200]:
> * Jan Beulich:
> >>>> On 27.09.18 at 07:01, <fweimer@redhat.com> wrote:
> >> * H. J. Lu:
> >>
> >>> I am proposing
> >>>
> >>> #define SHT_GNU_PHDRS 0x6ffffff4 /* Dummy section for program header */
> >>>
> >>> This is a special read-only SHF_ALLOC zero-size data section. It is the
> >>> first output section, which will force a data PT_LOAD segment with program
> >>> header before the code-only PT_LOAD segment,
> >>
> >> Is it actually a requirement in the ELF specification that all bits
> >> loaded via segments are covered by sections as well?
> >
> > Hardly, because the presence of a section table isn't required
> > in the first place in an executable (iirc).
>
> I think so too, and that is why I don't understand this section hack is
> needed.
if there is no read-only alloc section then the program
headers are currently not part of a load segment.
https://sourceware.org/bugzilla/show_bug.cgi?id=23428
an alloc .phdr section covering the program headers solves
this problem. if sections are not required for segments
then simply the linker should ensure that there is always
a load segment covering the program headers, possibly
without containing any sections, however elf says
"An object file segment contains one or more sections".
i don't understand why a zero-size section is enough, what
if phdr > pagesize? will that get covered by the load
segment that is created for the zero-size section?
next prev parent reply other threads:[~2018-09-27 10:35 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-01 0:00 H.J. Lu
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Jan Beulich
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Szabolcs Nagy [this message]
2018-01-01 0:00 ` H.J. Lu
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` H.J. Lu
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Michael Matz
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Michael Matz
2018-01-01 0:00 ` Carlos O'Donell
2018-01-01 0:00 ` Cary Coutant
2018-01-01 0:00 ` H.J. Lu
2018-01-01 0:00 ` Rich Felker
2018-01-01 0:00 ` H.J. Lu
2018-01-01 0:00 ` Carlos O'Donell
2018-01-01 0:00 ` H.J. Lu
2018-01-01 0:00 ` Carlos O'Donell
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Cary Coutant
[not found] ` <CAORpzuOWtHeqBLEE+MMN4-TZyp6Z1r-MdmyNv7Zj-BhxMstr=g@mail.gmail.com>
2018-01-01 0:00 ` H.J. Lu
2018-01-01 0:00 ` Carlos O'Donell
2018-01-01 0:00 ` H.J. Lu
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