Re: [PATCH -mm 1/3] proc: randomize "struct pde_opener"

[Kees Cook]

On Thu, Feb 15, 2018 at 4:13 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
> Guess what happens to cache footprint of dcache lookups if the bunch in the
> beginning gets spread over the entire thing?  Right...  And that's besides the
> outright miscompiles.

Mentioned in private communication, but just for posterity:
GCC_PLUGIN_RANDSTRUCT_PERFORMANCE exists specifically to address those
kinds of performance concerns.

As to removing the markings: please don't. Instead, you'd mentioned
wanting to add a TAINT flag for this, and I think that sounds entirely
reasonable. We have TAINT flags for considerably less insane things.
:) I can send that patch.

-Kees

-- 
Kees Cook
Pixel Security