From mboxrd@z Thu Jan 1 00:00:00 1970 From: f.fainelli@gmail.com (Florian Fainelli) Date: Wed, 16 May 2018 09:33:18 -0700 Subject: [PATCH 07/14] ARM: spectre-v2: add Cortex A8 and A15 validation of the IBE bit In-Reply-To: References: <20180516105949.GJ16141@n2100.armlinux.org.uk> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 Reviewed-by: Florian Fainelli 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