From: "H.J. Lu" <hjl.tools@gmail.com>
To: Mark Wielaard <mark@klomp.org>
Cc: Rahul Chaudhry via gnu-gabi <gnu-gabi@sourceware.org>,
Binutils <binutils@sourceware.org>,
"Zhang, Annita" <annita.zhang@intel.com>
Subject: Re: binutils ld and new PT_GNU_PROPERTY segment
Date: Wed, 01 Jan 2020 00:00:00 -0000 [thread overview]
Message-ID: <CAMe9rOqCJVw2okDr0gonHWpxEVw+qO8uYLjbzxihB4tx-JuJ6g@mail.gmail.com> (raw)
In-Reply-To: <a7078f74881daf23ca4af4983bac212a6c971b5a.camel@klomp.org>
On Tue, Feb 18, 2020 at 4:38 AM Mark Wielaard <mark@klomp.org> wrote:
>
> Hi,
>
> binutils 2.32 ld emits a new PT_GNU_PROPERTY (PT_LOOS + 0x474e553)
> segment that overlaps with the PT_NOTE segment covering the
> .note.gnu.property section data.
>
> I cannot tell if this is an accident/experiment that happened to end up
> in a release or if it is proposed as an official new segment type.
https://sourceware.org/ml/gnu-gabi/2018-q4/msg00027.html
https://github.com/hjl-tools/linux-abi/wiki/Linux-Extensions-to-gABI
> As far as I can tell binutils ld is the only linker which adds this
Annita, does lld generate PT_GNU_PROPERTY segment with CET? If not,
it is an lld bug.
> extra segment and there is no runtime loader which uses it. It doesn't
> provide any new information that cannot be found in the existing
> PT_NOTE segment.
Kernel loader uses it for both ARM and x86.
> On 64 bit architectures it simply covers the extra existing PT_NOTE
> with 8 byte alignment (normal PT_NOTE segments are 4 byte aligned). On
> 32bit architectures it covers a sub-range of the existing PT_NOTE
> segment.
>
> It isn't clear to me how other tools should handle this. It seems to
> prevent normal merging of note sections. Since some notes are probably
> special if they need to be covered by this new segment type. And it
> isn't clear how the linker knows which of the SHT_NOTE sections is what
> needs to be covered by the new segment type. Or is the idea that this
> will eventually come with a new section type too and GNU properties
> will no longer use NOTE sections?
>
PT_GNU_PROPERTY covers .note.gnu.property section.
--
H.J.
next prev parent reply other threads:[~2020-02-18 12:49 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-01 0:00 Mark Wielaard
2020-01-01 0:00 ` H.J. Lu [this message]
2020-01-01 0:00 ` Mark Wielaard
2020-01-01 0:00 ` Fangrui Song via gnu-gabi
2020-01-01 0:00 ` Mark Wielaard
2020-01-01 0:00 ` H.J. Lu
2020-01-01 0:00 ` Mark Wielaard
2020-01-01 0:00 ` H.J. Lu
2020-01-01 0:00 ` Mark Wielaard
2020-01-01 0:00 ` H.J. Lu
2020-01-01 0:00 ` Fangrui Song
2020-01-01 0:00 ` H.J. Lu
2020-01-01 0:00 ` Mark Wielaard
2020-01-01 0:00 ` H.J. Lu
2020-01-01 0:00 ` Mark Wielaard
2020-01-01 0:00 ` H.J. Lu
2020-01-01 0:00 ` Mark Wielaard
2020-01-01 0:00 ` Fangrui Song
2020-04-01 8:46 ` Florian Weimer
2020-04-01 9:22 ` Szabolcs Nagy
2020-04-01 9:29 ` Florian Weimer
2020-04-01 10:10 ` Szabolcs Nagy
2020-04-01 10:21 ` Florian Weimer
2020-01-01 0:00 ` Fangrui Song
2020-01-01 0:00 ` H.J. Lu
2020-01-01 0:00 ` H.J. Lu
2020-01-01 0:00 ` Zhang, Annita
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