ARM errata 430973 on multi platform kernels

[Matthijs van Duin]

On 4 April 2015 at 00:52, Tony Lindgren <tony at atomide.com> wrote:
> Right, it affects n900 for sure. My point is that it also seems to
> affect 37xx versions not listed to suffer from this issue.

They shouldn't... erratum 430973 only affected Cortex-A8 r1, and the
dm37xx should have an r3p2 right?

A word of caution though: at least on the DM814x and AM335x, secure
ROM sets bit 6 (IBE) in the Auxiliary Control Register, thereby
enabling BTB invalidate instructions (which normally execute as nops).
This is presumably a leftover of the erratum 430973 workaround, but it
means there is a risk of running afoul of erratum 687067 if BTB
invalidate by MVA instructions are actually used.

I would actually suggest clearing IBE if it set on Cortex-A8 r2 or
later processors and a secure monitor call is available to do so
(there is on the DM814x and AM335x, dunno about the 37xx), also for
performance reasons: BTB invalidates are quite expensive instructions
(when enabled).

Matthijs