From: Will Deacon <will.deacon@arm.com>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: catalin.marinas@arm.com, Peter Smith <peter.smith@linaro.org>,
Nick Desaulniers <ndesaulniers@google.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFT PATCH] arm64: relocatable: build the kernel as a proper shared library
Date: Mon, 3 Dec 2018 17:08:54 +0000 [thread overview]
Message-ID: <20181203170854.GA28218@arm.com> (raw)
In-Reply-To: <20181201115324.20847-1-ard.biesheuvel@linaro.org>
Hi Ard,
On Sat, Dec 01, 2018 at 12:53:24PM +0100, Ard Biesheuvel wrote:
> readelf complains about the section layout of vmlinux when building
> with CONFIG_RELOCATABLE=y (for KASLR):
>
> readelf: Warning: [21]: Link field (0) should index a symtab section.
> readelf: Warning: [21]: Info field (0) should index a relocatable section.
>
> Also, it seems that our use of '-pie -shared' is contradictory, and
> thus ambiguous. In general, the way KASLR is wired up at the moment
> is highly tailored to how ld.bfd happens to implement (and conflate)
> PIE executables and shared libraries, so given the current effort to
> support other toolchains, let's fix some of these issues as well.
>
> - Drop the -pie linker argument and just leave -shared. In ld.bfd,
> the differences between them are unclear (except for the ELF type
> of the produced image [0]) but lld chokes on seeing both at the
> same time.
>
> - Rename the .rela output section to .rela.dyn, as is customary for
> shared libraries and PIE executables.
>
> - Don't discard the .dynamic, .dynsym, .dynstr and .hash sections.
> Instead, make sure that they are [mostly] empty by marking all
> symbols as local, and emit them into the .init segment.
These second two changes seem fairly arbitrary to me: is lld unhappy without
them? My concern is that we'll make some other change in the future and run
into more arbitrary breakage. Is there any build bots hooked up with lld so
help us catch regressions quickly? (i.e nightly builds of mainline and next)
Will
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2018-12-03 17:09 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-01 11:53 [RFT PATCH] arm64: relocatable: build the kernel as a proper shared library Ard Biesheuvel
2018-12-01 22:55 ` Nick Desaulniers
2018-12-03 17:08 ` Will Deacon [this message]
2018-12-03 17:11 ` Ard Biesheuvel
2018-12-03 18:57 ` Will Deacon
2018-12-03 17:17 ` Peter Smith
2018-12-03 18:29 ` Nick Desaulniers
2018-12-03 19:22 ` Will Deacon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20181203170854.GA28218@arm.com \
--to=will.deacon@arm.com \
--cc=ard.biesheuvel@linaro.org \
--cc=catalin.marinas@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=ndesaulniers@google.com \
--cc=peter.smith@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).