As recommended by Arm in [1], IBE[2] has to be enabled unconditionally for BPIALL to be functional on Cortex-A8 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.ddi0344k/Bgbffjhh.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 --- arch/arm/Kconfig | 5 +++++ arch/arm/cpu/armv7/start.S | 7 +++++-- 2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index dde422bc5d53..9e32d5b43cb0 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -108,6 +108,8 @@ config SYS_ARM_MPU # CONFIG_ARM_ERRATA_621766 # CONFIG_ARM_ERRATA_798870 # CONFIG_ARM_ERRATA_801819 +# CONFIG_ARM_CORTEX_A8_CVE_2017_5715 + config ARM_ERRATA_430973 bool
@@ -177,6 +179,9 @@ config ARM_ERRATA_852423 config ARM_ERRATA_855873 bool
+config ARM_CORTEX_A8_CVE_2017_5715 + bool + config CPU_ARM720T bool select SYS_CACHE_SHIFT_5 diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S index c996525f861e..3beaf5a93d81 100644 --- a/arch/arm/cpu/armv7/start.S +++ b/arch/arm/cpu/armv7/start.S @@ -252,12 +252,15 @@ skip_errata_801819: pop {r1-r5} @ Restore the cpu info - fall through #endif
-#ifdef CONFIG_ARM_ERRATA_430973 +#if defined(CONFIG_ARM_ERRATA_430973) || defined (CONFIG_ARM_CORTEX_A8_CVE_2017_5715) mrc p15, 0, r0, c1, c0, 1 @ Read ACR
+#ifdef CONFIG_ARM_CORTEX_A8_CVE_2017_5715 + orr r0, r0, #(0x1 << 6) @ Set IBE bit always to enable OS WA +#else cmp r2, #0x21 @ Only on < r2p1 orrlt r0, r0, #(0x1 << 6) @ Set IBE bit - +#endif push {r1-r5} @ Save the cpu info registers bl v7_arch_cp15_set_acr pop {r1-r5} @ Restore the cpu info - fall through