Re: arm: v4.18-rc5 with cpuidle on TC2 (A7 boot) spectre v2 issue

Russell King - ARM Linux
2018-07-19T10:01:25Z

On Thu, Jul 19, 2018 at 11:42:50AM +0200, Dietmar Eggemann wrote:
> Hi,
>
> running v4.18-rc5 (plus still missing "power: vexpress: fix corruption in
> notifier registration", otherwise I get this rcu_sched stall issue) on TC2
> (A7 boot) with vanilla multi_v7_defconfig plus
> CONFIG_ARM_BIG_LITTLE_CPUIDLE=y gives me continuous:
>
> ...
> CPUX: Spectre v2: incorrect context switching function, system vulnerable
> ...
>
> messages.
>
> Work around is to disable CONFIG_HARDEN_BRANCH_PREDICTOR.

or disable big.Little if you want the hardening.

The choices are currently either protection against Spectre or big.Little
support since the two are mutually exclusive at the moment.