Re: [PATCH] ARM: add get_user() support for 8 byte types

[Russell King - ARM Linux]

On Fri, Nov 09, 2012 at 03:17:33PM -0600, Rob Clark wrote:
> From: Rob Clark <rob@xxxxxx>
> 
> A new atomic modeset/pageflip ioctl being developed in DRM requires
> get_user() to work for 64bit types (in addition to just put_user()).

NAK.

(I did write a better email explaining all the ins and outs of why this
won't work and why 64-bit get_user isn't possible, but my editor crapped
out and lost all that well written message; I don't fancy typing it all
out again.)

Nevertheless,
int test_ptr(unsigned int **v, unsigned int **p)
{
        return get_user(*v, p);
}

produces a warning, and you can't get away from that if you stick 64-bit
support into get_user().

Sorry, 64-bit get_user() is a no-no.
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