ARM: Introduce ability to enable invalidate of BTB with ICIALLU on Cortex-A15 for CVE-2017-5715
As recommended by Arm in [1], ACTLR[0] (Enable invalidates of BTB)
needs to be set[2] for BTB to be invalidated on ICIALLU. This needs to
be done unconditionally for Cortex-A15 processors. Provide a config
option for platforms to enable this option based on impact analysis
for products.
NOTE: This patch in itself is NOT the final solution, this requires:
a) Implementation of v7_arch_cp15_set_acr on SoCs which may not
provide direct access to ACR register.
b) Operating Systems such as Linux to provide adequate workaround in the
right locations.
c) This workaround applies to only the boot processor. It is important
to apply workaround as necessary (context-save-restore) around low
power context loss OR additional processors as necessary in either
firmware support OR elsewhere in OS.
[1] https://developer.arm.com/support/security-update
[2] http://infocenter.arm.com/help/topic/com.arm.doc.ddi0438c/BABGHIBG.html
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Andre Przywara <Andre.Przywara@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Tom Rini <trini@konsulko.com>
Cc: Michael Nazzareno Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Tested-by: Fabio Estevam <fabio.estevam@nxp.com>
2 files changed