From: Alan Modra <amodra@gmail.com>
To: Jeff Law <law@redhat.com>
Cc: Cary Coutant <ccoutant@gmail.com>,
"H.J. Lu" <hjl.tools@gmail.com>, Joe Groff <jgroff@apple.com>,
Binutils <binutils@sourceware.org>
Subject: Re: Preventing preemption of 'protected' symbols in GNU ld 2.26
Date: Sat, 02 Apr 2016 02:53:00 -0000 [thread overview]
Message-ID: <20160402025329.GE27246@bubble.grove.modra.org> (raw)
In-Reply-To: <56FED145.80307@redhat.com>
On Fri, Apr 01, 2016 at 01:51:33PM -0600, Jeff Law wrote:
> Essentially the question that needs to be answered is if we roll
> back 65280, do we need to also roll back 65780?
No, I don't think so. As I wrote in the bugzilla (paraphrased)
What's going on here is that HJ has made changes to the linker for x86
to always copy variables defined in a shared library and referenced by
the executable, into the executable's .dynbss. This is necessary to
support non-PIC without text relocations, but is optional for PIEs.
If you do this for PIEs and gain some performance without affecting
shared library performance, and that is the case for x86_64, then the
optimisation is quite reasonable. I think powerpc64 would gain too,
but I haven't done anything about it yet (and for powerpc64 we should
be able to implement it entirely in the linker, no gcc changes
needed).
I believe common variables can be treated like any other variable so
far as this optimisation goes.
--
Alan Modra
Australia Development Lab, IBM
next prev parent reply other threads:[~2016-04-02 2:53 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <AB592ABD-D6D7-4D2F-A0D6-45738F168DC4@apple.com>
2016-03-29 19:31 ` Fwd: " Joe Groff
2016-03-29 19:33 ` H.J. Lu
2016-03-29 19:36 ` Joe Groff
2016-03-29 19:43 ` H.J. Lu
2016-03-29 19:51 ` Joe Groff
2016-03-29 19:54 ` H.J. Lu
2016-03-29 22:05 ` H.J. Lu
2016-03-30 1:44 ` Alan Modra
2016-03-30 1:46 ` Cary Coutant
2016-03-30 4:04 ` Jeff Law
2016-03-30 7:20 ` Cary Coutant
2016-03-30 7:34 ` Cary Coutant
2016-03-30 14:44 ` Alan Modra
2016-03-31 0:45 ` Cary Coutant
2016-04-15 21:49 ` Preventing preemption of 'protected' symbols in GNU ld 2.26 [aka should we revert the fix for 65248] Jeff Law
2016-04-15 21:56 ` H.J. Lu
2016-04-18 9:02 ` Richard Biener
2016-04-18 14:49 ` Alan Modra
2016-04-18 14:59 ` H.J. Lu
2016-04-18 17:04 ` Maciej W. Rozycki
2016-04-18 17:09 ` H.J. Lu
2016-04-18 17:24 ` Michael Matz
2016-04-18 17:27 ` H.J. Lu
2016-04-18 18:52 ` Jakub Jelinek
2016-04-18 19:28 ` H.J. Lu
2016-04-18 17:55 ` Cary Coutant
2016-04-25 17:24 ` Jeff Law
2016-04-25 17:31 ` H.J. Lu
2016-04-18 17:57 ` Maciej W. Rozycki
2016-04-19 5:08 ` Alan Modra
2016-04-19 8:20 ` Richard Biener
2016-04-19 9:53 ` Szabolcs Nagy
2016-04-19 14:06 ` Michael Matz
2016-04-19 15:37 ` Cary Coutant
2016-04-19 15:44 ` H.J. Lu
2016-04-19 15:52 ` H.J. Lu
2016-04-19 15:54 ` H.J. Lu
2016-04-19 15:58 ` Cary Coutant
2016-04-19 16:00 ` H.J. Lu
2016-04-19 15:54 ` Cary Coutant
2016-04-19 19:11 ` H.J. Lu
2016-04-19 20:17 ` Rich Felker
2016-04-19 21:03 ` Cary Coutant
2016-04-20 17:45 ` anonymous
2016-04-19 15:46 ` Alan Modra
2016-04-25 17:35 ` Jeff Law
2016-04-26 5:55 ` Alan Modra
2016-04-26 8:13 ` Jakub Jelinek
2016-04-18 17:05 ` Cary Coutant
2016-03-31 0:40 ` Preventing preemption of 'protected' symbols in GNU ld 2.26 Cary Coutant
2016-03-31 0:53 ` Jeff Law
2016-03-31 13:27 ` Ramana Radhakrishnan
2016-03-31 15:05 ` H.J. Lu
2016-04-15 16:10 ` Szabolcs Nagy
2016-04-01 19:51 ` Jeff Law
2016-04-02 2:53 ` Alan Modra [this message]
2016-04-19 19:47 ` Fwd: " Rich Felker
2016-04-15 16:16 H.J. Lu
2016-04-15 16:36 ` Jeff Law
2016-04-15 16:45 ` H.J. Lu
2016-04-15 16:43 ` Szabolcs Nagy
2016-04-15 23:59 ` Maciej W. Rozycki
2016-04-16 1:08 ` Szabolcs Nagy
-- strict thread matches above, loose matches on Subject: below --
2016-03-24 0:00 Joe Groff
2016-03-24 0:45 ` H.J. Lu
2016-03-24 0:52 ` Joe Groff
2016-03-24 1:25 ` H.J. Lu
2016-03-24 15:01 ` Cary Coutant
2016-03-24 15:07 ` H.J. Lu
2016-03-24 16:06 ` Cary Coutant
2016-03-24 16:42 ` H.J. Lu
2016-03-24 16:56 ` Cary Coutant
2016-03-24 17:05 ` H.J. Lu
2016-03-24 17:06 ` Joe Groff
2016-03-24 17:09 ` H.J. Lu
2016-03-24 18:31 ` Cary Coutant
2016-03-27 16:26 ` Rafael Espíndola
2016-03-28 12:12 ` H.J. Lu
2016-03-28 22:12 ` Cary Coutant
[not found] ` <BC969B3B-87A2-4238-90C8-DA2E166707AF@apple.com>
2016-03-28 17:03 ` Joe Groff
2016-03-28 17:17 ` H.J. Lu
2016-03-28 22:22 ` Cary Coutant
2016-03-28 22:24 ` Joe Groff
2016-03-28 22:38 ` Cary Coutant
2016-03-28 22:41 ` Joe Groff
2016-03-28 23:21 ` Alan Modra
2016-03-29 0:29 ` Cary Coutant
2016-03-29 15:44 ` H.J. Lu
2016-03-29 12:40 ` Maciej W. Rozycki
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=20160402025329.GE27246@bubble.grove.modra.org \
--to=amodra@gmail.com \
--cc=binutils@sourceware.org \
--cc=ccoutant@gmail.com \
--cc=hjl.tools@gmail.com \
--cc=jgroff@apple.com \
--cc=law@redhat.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 read-only IMAP folder(s) and NNTP newsgroup(s).