[PATCH 0/3] ARM branch predictor hardening

Florian Fainelli f.fainelli at gmail.com
Sat Jan 6 10:50:41 PST 2018

Hi Marc,

Le 01/06/18 à 04:09, Marc Zyngier a écrit :
> This small series implements some basic BP hardening by invalidating
> the BTB on CPUs that are known to be susceptible to aliasing attacks.
> These patches are closely modelled against what we do on arm64,
> although simpler as we can rely on an architected instruction to
> perform the invalidation.
> The first patch reuses the Cortex-A8 BTB invalidation in switch_mm and
> generalises it to be used on all affected CPUs. The second perform the
> same invalidation on fatal signal delivery. The last one nukes it on
> guest exit, and results in some major surgery (kudos to Dimitris
> Papastamos who came up with the magic vector decoding sequence).
> Note that that M-class CPUs are not affected and for R-class cores,
> the mitigation doesn't make much sense since we do not enforce
> user/kernel isolation.

Broadcom's Brahma-B15 CPUs are also affected, I can either send an
incremental patch on top of this series once it lands in, or since it
looks like you are going to respin a v2, feel free to incorporate the
changes I sent as replies to patch 1 and 2.

What about P4JB and Krait, should they also be covered?

Even though I am assuming -stable maintainers will quickly pick those
changes, should there be an explicit mention of CVE-2017-5715?


> Marc Zyngier (3):
>   arm: Add BTB invalidation on switch_mm for Cortex-A9, A12, A15 and A17
>   arm: Invalidate BTB on fatal signal for Cortex A8, A9, A12, A15 and
>     A17
>   arm: KVM: Invalidate BTB on guest exit
>  arch/arm/include/asm/cp15.h  |  2 ++
>  arch/arm/kvm/hyp/hyp-entry.S | 74 +++++++++++++++++++++++++++++++++++++-------
>  arch/arm/mm/fault.c          | 11 +++++++
>  arch/arm/mm/proc-v7-2level.S |  4 +--
>  arch/arm/mm/proc-v7-3level.S |  6 ++++
>  arch/arm/mm/proc-v7.S        | 32 +++++++++----------
>  6 files changed, 100 insertions(+), 29 deletions(-)


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