linux-kernel - Re: [patch 1/2] Relocate VDSO ELF headers to match mapped location with COMPAT

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Date:	Wed, 04 Apr 2007 23:46:29 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Roland McGrath <roland@...hat.com>
CC:	Andi Kleen <ak@...e.de>, Andrew Morton <akpm@...ux-foundation.org>,
	virtualization@...ts.osdl.org, lkml <linux-kernel@...r.kernel.org>,
	Zachary Amsden <zach@...are.com>,
	Jan Beulich <JBeulich@...ell.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [patch 1/2] Relocate VDSO ELF headers to match mapped location
 with COMPAT_VDSO

Roland McGrath wrote:
> The patch looks nice and clean.  However, it does not relocate the symbol
> table(s) values.  I thought that was done in an earlier version of this I
> saw, but I might be misremembering.  Though not fatal, this is a regression
> from the previous CONFIG_COMPAT_VDSO behavior.  It will show up in things
> like __kernel_* name display in backtraces.

Hm, OK.  It does, but I wasn't sure if it would matter.  It should be
fairly simple to fix up.

>   If with your other patch
> CONFIG_COMPAT_VDSO will become other than a rarely-used compatibility
> option, then this should be fixed.  Note that with your second patch this
> will also break the symbol values in the randomly-located vma vdso;
> non-ancient glibc doesn't care if the vdso isn't mapped where its phdrs
> say, but everything does still care that the symbol tables in an ELF file
> use addresses matching the phdrs in the same file.
>   

I did the second patch because I could, and to see if it would provoke
some comment.  But effectively removing a kernel config option seems
like a good idea to me.

    J
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