On 05/16/2018 04:01 AM, Russell King wrote:

When the branch predictor hardening is enabled, firmware must have set
the IBE bit in the auxiliary control register.  If this bit has not
been set, the Spectre workarounds will not be functional.

Add validation that this bit is set, and print a warning at alert level
if this is not the case.

Signed-off-by: Russell King <redacted>

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

I would be keen on updating arch/arm/kernel/head.S to to attempt setting
ACTRL[0]=1 on A15/B15, if the kernel executes at the appropriate
privilege level, this will succeed, if not, this should result in an
ignored write. What do you think?
-- 
Florian