From: Zack Weinberg <zackw@panix.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: Fangrui Song <i@maskray.me>,
Alan Modra via Libc-alpha <libc-alpha@sourceware.org>,
binutils@sourceware.org, Alan Modra <amodra@gmail.com>
Subject: Re: ifunc resolving
Date: Wed, 20 Jan 2021 11:13:00 -0500 [thread overview]
Message-ID: <CAKCAbMh4Wgz0vGnGjtrGhgj9Q8dY1_ixbQQh7webXvT_fDgBiQ@mail.gmail.com> (raw)
In-Reply-To: <87lfco6jgr.fsf@oldenburg.str.redhat.com>
On Wed, Jan 20, 2021 at 4:33 AM Florian Weimer via Libc-alpha
<libc-alpha@sourceware.org> wrote:
> * Alan Modra via Libc-alpha:
> > On Tue, Jan 19, 2021 at 03:59:54PM +0100, Florian Weimer via Binutils wrote:
> > There is a third possibility. If ld.so defers all irelative and other
> > relocations using ifunc symbols until all non-ifunc relocations have
> > been performed, globally, then ifunc resolvers would only have the
> > restriction that they not call other ifuncs.
> >
> > That idea was floated a very long time ago. For some reason it is
> > too hard or too slow to do in ld.so.
>
> It's not too hard, I wrote a patch. I didn't mention it because it was
> rejected. It seemed about the only thing for which we had consensus. 8-/
>
> My patch did not find an appropriate order in all cases. I think that's
> more or less unavoidable if IFUNC resolvers depend on relocations
> against other IFUNC resolvers. It would have nicely covered all
> internal glibc uses at the time.
Every time this discussion comes up, I wonder how much it would help
if we completely scrapped the idea of lazy relocations. Do what
LD_BIND_NOW=t does all the time. Distributions are moving in this
direction already because that lets them turn on -z relro...
zw
next prev parent reply other threads:[~2021-01-20 16:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-18 22:04 ifunc resolving Fangrui Song
2021-01-18 22:53 ` H.J. Lu via Libc-alpha
2021-01-19 14:59 ` Florian Weimer via Libc-alpha
2021-01-19 22:31 ` Alan Modra via Libc-alpha
2021-01-20 9:33 ` Florian Weimer via Libc-alpha
2021-01-20 16:13 ` Zack Weinberg [this message]
2021-01-20 16:17 ` Florian Weimer via Libc-alpha
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