From: "H.J. Lu" <hjl.tools@gmail.com>
To: Cary Coutant <ccoutant@gmail.com>
Cc: Florian Weimer <fweimer@redhat.com>,
x86-64-abi <x86-64-abi@googlegroups.com>,
Binutils <binutils@sourceware.org>,
GNU C Library <libc-alpha@sourceware.org>,
Mark Wielaard <mark@klomp.org>, Michael Matz <matz@suse.de>,
Nick Clifton <nickc@redhat.com>,
"Carlos O'Donell" <carlos@redhat.com>,
"szabolcs.nagy" <szabolcs.nagy@arm.com>
Subject: Re: PT_NOTE alignment, NT_GNU_PROPERTY_TYPE_0, glibc and gold
Date: Wed, 26 Sep 2018 11:36:09 -0700 [thread overview]
Message-ID: <CAMe9rOrLOQzGRhibpbb1sxkSwJ537eBUZEZkjpv==mHz=o+0PQ@mail.gmail.com> (raw)
In-Reply-To: <CAJimCsFDmPD-T7RV53j15NnuW1fZ2mHSxjUbvDu7EC+oEg_fng@mail.gmail.com>
On Wed, Sep 26, 2018 at 10:39 AM, Cary Coutant <ccoutant@gmail.com> wrote:
>
> Some requirements I'd like to see:
NT_GNU_PROPERTY_TYPE_0 is documented at
https://github.com/hjl-tools/linux-abi
> (1) An NT_GNU_PROPERTY_TYPE_0 note section must be named
> ".note.gnu.property" with type SHT_NOTE.
If it isn't specified this way, please send a patch.
> (2) A ".note.gnu.property" section must contain one and only one note,
> whose type must be NT_GNU_PROPERTY_TYPE_0.
True for linker output and all properties must be sorted. For relocatable
inputs, there may be more than one NT_GNU_PROPERTY_TYPE_0 notes:
[hjl@gnu-cfl-1 tmp]$ touch n.c
[hjl@gnu-cfl-1 tmp]$ gcc -fcf-protection -c n.c -Wa,-mx86-used-note=yes
[hjl@gnu-cfl-1 tmp]$ readelf -n n.o
Displaying notes found in: .note.gnu.property
Owner Data size Description
GNU 0x00000010 NT_GNU_PROPERTY_TYPE_0
Properties: x86 feature: IBT, SHSTK
GNU 0x00000020 NT_GNU_PROPERTY_TYPE_0
Properties: x86 ISA used: <None>
x86 feature used: x86
[hjl@gnu-cfl-1 tmp]$
> (3) A ".note.gnu.property" section must have sh_align of 8, and its
> length must be a multiple of 8.
If it isn't specified this way, please send a patch.
> (4) A linker is expected to combine ".note.gnu.property" sections in a
> manner described by the ABI documentation, and place the combined
> result, as a single note, in a unique SHT_NOTE section named
> ".note.gnu.property", and in a unique PT_NOTE segment.
>
Why is a unique PT_NOTE segment required? A PT_NOTE segment
may have more than one SHT_NOTE sections with the same section
alignment and each SHT_NOTE section is padded to section alignment.
--
H.J.
prev parent reply other threads:[~2018-09-26 18:36 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAMe9rOrrayKnc_cPm4SmnDnUGLbBUmOYMBTMOM8KLAHVmb=rUQ@mail.gmail.com>
2018-08-16 13:00 ` PT_NOTE alignment, NT_GNU_PROPERTY_TYPE_0, glibc and gold (was: Re: [PATCH] Document GNU_PROPERTY_X86_ISA_1_[USED|NEEDED]) Florian Weimer
2018-08-16 13:19 ` H.J. Lu
2018-08-16 13:29 ` H.J. Lu
2018-08-16 13:31 ` PT_NOTE alignment, NT_GNU_PROPERTY_TYPE_0, glibc and gold Florian Weimer
2018-08-16 13:39 ` H.J. Lu
2018-08-16 14:01 ` Florian Weimer
2018-08-16 14:43 ` H.J. Lu
2018-08-16 14:21 ` Florian Weimer
2018-08-16 17:46 ` H.J. Lu
2018-08-16 19:16 ` Mark Wielaard
2018-08-16 19:36 ` H.J. Lu
2018-08-17 6:04 ` Mark Wielaard
2018-08-17 6:20 ` Florian Weimer
2018-08-17 6:41 ` Mark Wielaard
2018-08-17 15:10 ` H.J. Lu
2018-08-17 21:05 ` Mark Wielaard
2018-08-21 23:02 ` Cary Coutant
2018-08-22 9:39 ` Florian Weimer
2018-08-22 10:08 ` Mark Wielaard
2018-08-22 23:36 ` Cary Coutant
2018-08-24 18:39 ` Florian Weimer
2018-08-23 14:41 ` Michael Matz
2018-08-23 14:43 ` Florian Weimer
2018-08-17 15:13 ` H.J. Lu
2018-09-19 19:22 ` Florian Weimer
2018-09-21 12:55 ` Michael Matz
2018-09-21 13:04 ` Florian Weimer
2018-09-26 17:39 ` Cary Coutant
2018-09-26 18:36 ` H.J. Lu [this message]
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