From: Alan Modra <amodra@gmail.com>
To: Jeff Law <law@redhat.com>
Cc: Richard Biener <richard.guenther@gmail.com>,
"H.J. Lu" <hjl.tools@gmail.com>,
Cary Coutant <ccoutant@gmail.com>, Joe Groff <jgroff@apple.com>,
Binutils <binutils@sourceware.org>, GCC <gcc@gcc.gnu.org>
Subject: Re: Preventing preemption of 'protected' symbols in GNU ld 2.26 [aka should we revert the fix for 65248]
Date: Tue, 26 Apr 2016 05:55:00 -0000 [thread overview]
Message-ID: <20160426055447.GL27353@bubble.grove.modra.org> (raw)
In-Reply-To: <08719312-4e17-21f9-7513-6ad4b92833fc@redhat.com>
On Mon, Apr 25, 2016 at 11:35:46AM -0600, Jeff Law wrote:
> No, we revert to the gcc-4.9 behavior WRT protected visibility and ensure
> that we're getting a proper diagnostic from the linker.
>
> That direction is consistent with the intent of protected visibility, fixes
> the problem with preemption of protected symbols and gives us a diagnostic
> for the case that can't be reasonably handled.
I agree that this is the correct solution. Unfortunately there is a
complication. PIE + shared lib using protected visibility worked fine
with gcc-4.9, but since then code generated by gcc for PIEs on x86_64
has been optimized to rely on the horrible old hack of .dynbss and
copy relocations. That means you'll have regressions from 4.9 if just
reverting the protected visibility change..
The PIE optimization will need reverting too, and I imagine you'll see
some resistance to that idea due to the fact that it delivers quite a
nice performance improvement for PIEs.
--
Alan Modra
Australia Development Lab, IBM
next prev parent reply other threads:[~2016-04-26 5:55 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <AB592ABD-D6D7-4D2F-A0D6-45738F168DC4@apple.com>
2016-03-29 19:31 ` Fwd: Preventing preemption of 'protected' symbols in GNU ld 2.26 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 [this message]
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
2016-04-19 19:47 ` Fwd: " Rich Felker
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