From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "Florian Weimer" <fweimer@redhat.com>,
"Michal Suchánek" <msuchanek@suse.de>
Cc: linux-mm@kvack.org, Anton Blanchard <anton@au1.ibm.com>,
linuxppc-dev@lists.ozlabs.org, Nick Piggin <npiggin@au1.ibm.com>
Subject: Re: PIE binaries are no longer mapped below 4 GiB on ppc64le
Date: Thu, 01 Nov 2018 09:24:29 +1100 [thread overview]
Message-ID: <3da6549832ef68b93b210d5a32b3f12f3565cab0.camel@kernel.crashing.org> (raw)
In-Reply-To: <877ehyf1cj.fsf@oldenburg.str.redhat.com>
On Wed, 2018-10-31 at 18:54 +0100, Florian Weimer wrote:
>
> It would matter to C code which returns the address of a global variable
> in the main program through and (implicit) int return value.
>
> The old behavior hid some pointer truncation issues.
Hiding bugs like that is never a good idea..
> > Maybe it would be good idea to generate 64bit relocations on 64bit
> > targets?
>
> Yes, the Go toolchain definitely needs fixing for PIE. I don't dispute
> that.
There was never any ABI guarantee that programs would be loaded below
4G... it just *happened*, so that's not per-se an ABI change.
That said, I'm surprised of the choice of address.. I would have rather
moved to above 1TB to benefit from 1T segments...
Nick, Anton, do you know anything about that change ?
Ben.
next prev parent reply other threads:[~2018-10-31 22:26 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-31 17:20 PIE binaries are no longer mapped below 4 GiB on ppc64le Florian Weimer
2018-10-31 17:50 ` Michal Suchánek
2018-10-31 17:54 ` Florian Weimer
2018-10-31 21:23 ` Tulio Magno Quites Machado Filho
2018-10-31 21:28 ` Florian Weimer
2018-10-31 22:04 ` Tulio Magno Quites Machado Filho
2018-10-31 22:41 ` Michal Suchánek
2018-10-31 22:24 ` Benjamin Herrenschmidt [this message]
2018-11-01 3:55 ` Michael Ellerman
2018-11-01 6:49 ` Alan Modra
2018-11-02 9:41 ` Michael Ellerman
2018-11-01 11:20 ` Florian Weimer
2018-11-02 9:37 ` Michael Ellerman
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=3da6549832ef68b93b210d5a32b3f12f3565cab0.camel@kernel.crashing.org \
--to=benh@kernel.crashing.org \
--cc=anton@au1.ibm.com \
--cc=fweimer@redhat.com \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=msuchanek@suse.de \
--cc=npiggin@au1.ibm.com \
/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).