From: Yonghong Song <yhs@fb.com>
To: Mark Wielaard <mark@klomp.org>,
Florian Weimer <fweimer@redhat.com>, <libc-alpha@sourceware.org>
Cc: Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH] elf.h: Add BPF relocation types.
Date: Tue, 19 Jun 2018 20:38:00 -0000 [thread overview]
Message-ID: <de7ac3db-c882-595b-c3fe-7810d4d420f3@fb.com> (raw)
In-Reply-To: <1529440472.12946.129.camel@klomp.org>
On 6/19/18 1:34 PM, Mark Wielaard wrote:
> On Tue, 2018-06-19 at 22:06 +0200, Florian Weimer wrote:
>> On 06/16/2018 11:45 PM, Mark Wielaard wrote:
>>> The BPF ELF format has new relocation types R_BPF_64_64 and R_BPF_64_32.
>>> The existing R_BPF_MAP_FD was an extension that never got implemented.
>>> Remove it, because its constant conflicts with the official R_BPF_64_64.
>>
>> Is there an ABI manual against which we could review this change?
>>
>> The last change said that this was added to the Generic ABI
>>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.sco.com_developers_gabi_latest_contents.html&d=DwIFaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=DA8e1B5r073vIqRrFz7MRA&m=vat1LaeLAQ_XbOs1SRdavOCV310jx4Ctku_6Jcq72HY&s=r5vE3J-yD5ebnpdq_d0AkFfNFzewdpXShVKSvBULDzc&e=>, but there is
>> no evidence of that.
>
> Only the EM values are, since they are generic.
> It just takes a while before they make it to the public website.
> rth has an email from the maintainer though with the assigned value.
>
> The relocation constants don't have a separate ABI manual
> (because BPF isn't really a full blown architecture/abi).
> Those are kept in sync between the projects handling BPF elf files
> (which is this patch, which is a prerequisite for getting the same
> constants into elfutils, because we see the glibc elf.h as the
> master copy that holds all GNU/Linux ELF constants.)
The LLVM source code for the definition is here:
https://github.com/llvm-mirror/llvm/blob/master/include/llvm/BinaryFormat/ELFRelocs/BPF.def
Yes, BPF related documentation has been lacking. For example,
the support in binutils is not there yet. But we are starting
to work on it.
Thanks!
Yonghong
>
> Thanks,
>
> Mark
>
next prev parent reply other threads:[~2018-06-19 20:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-16 21:46 Mark Wielaard
2018-06-19 20:06 ` Florian Weimer
2018-06-19 20:34 ` Mark Wielaard
2018-06-19 20:38 ` Yonghong Song [this message]
2018-06-21 14:53 ` Florian Weimer
2018-06-21 15:29 ` Carlos O'Donell
2018-06-21 16:48 ` Mark Wielaard
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