linux-kernel - Re: [RFC 0/2] __vdso

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Date:	Sun, 15 Jun 2014 10:35:00 -0400
From:	Rich Felker <dalias@...c.org>
To:	Mikael Pettersson <mikpelinux@...il.com>
Cc:	Andy Lutomirski <luto@...capital.net>, Russ Cox <rsc@...ang.org>,
	linux-api@...r.kernel.org, Ian Taylor <iant@...ang.org>,
	linux-kernel@...r.kernel.org, X86 ML <x86@...nel.org>
Subject: Re: [RFC 0/2] __vdso_findsym

On Sun, Jun 15, 2014 at 04:25:37PM +0200, Mikael Pettersson wrote:
> Andy Lutomirski writes:
>  > The idea is to add AT_VDSO_FINDSYM pointing at __vdso_findsym.  This
>  > implements __vdso_findsym.
>  > 
>  > This would make it easier for runtimes that don't otherwise implement
>  > ELF loaders to use the vdso.
>  > 
>  > Thoughts?
> 
> I'm opposed to this based on the principle that the kernel should NOT
> be a dumping ground for random code that user-space can and should
> implement for itself.  As long as the vdso is correctly formatted ELF,
> then parsing it is easy, and the kernel should not care at all if or
> how user-space accesses it.

Arguably, it was a mistake for the kernel to expose a virtual ELF to
begin with, and it should just have exposed a "lookup function by
name" operation to begin with. Yes this can be done in userspace, but
I see it more as a matter of "fixing a broken API design".

Rich
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