Subject: Re: Text relocations in shared libs
To: None <firstname.lastname@example.org, email@example.com>
From: Valeriy E. Ushakov <firstname.lastname@example.org>
Date: 12/27/2005 12:00:39
On Tue, Dec 27, 2005 at 08:51:33 +0000, Nick Hudson wrote:
> On Sunday 25 December 2005 13:02, Valeriy E. Ushakov wrote:
> > The benefits of calling cerror via plt are not clear, b/c there's
> > little point in allowing cerror to be overridden, after all it's just
> > the error path factored out of all the syscalls. I'm really inclined
> > to think that making cerror .protected or even .hidden is the right
> > thing to do.
> Aren't there *lots* of symbols in libc that don't need to be
> exposed? Why special case cerror and the others with text
> relocations in libc?
Well, ideally we should use version script to only export from libc.so
(and other shared libs) what's meant to be exported, but that's a
topic for another thread.
cerror is "special" in that it does not even have a defined interface,
except a private one between it and SYSCALL macros. It's really just
a common error path factored out of syscall functions. Pretending
that it is really exported and thus forthing all *jumps* (not even
calls) to it from the syscall functions go via PLT seems just
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