Re: [PATCH 01/11] x86: Use asm goto to implement better modify_and_test()functions

[H. Peter Anvin]

On 09/19/2013 03:31 AM, Andi Kleen wrote:
> On Wed, Sep 18, 2013 at 02:02:37PM -0500, H. Peter Anvin wrote:
> > Yes, a bit sad.  We allow bracketing with the get/put_user_try/catch blocks, but that is x86-specific.
> >
> > I don't think a generic option is possible without compiler support, but it might be possible to do better than we do know.
>
> Letting the compiler do it is a bit risky, because it may open it up for
> really large blocks, thus defeating the security advantages.
>
> -Andi

The compiler support. if done right, should avoid unannotated memory 
references.  This is a pretty big job in the compiler, though.

	-hpa

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