[ARM] 5487/1: ARM errata: Stale prediction on replaced interworking branch

This patch adds the workaround for the 430973 Cortex-A8 (r1p0..r1p2)
erratum. The BTAC/BTB is now flushed at every context switch.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 16 insertions, 0 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index e28a76bd1793..84e4816362b3 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -749,6 +749,22 @@ config ARM_ERRATA_411920
           It does not affect the MPCore. This option enables the ARM Ltd.
           recommended workaround.
 
+config ARM_ERRATA_430973
+        bool "ARM errata: Stale prediction on replaced interworking branch"
+        depends on CPU_V7
+        help
+          This option enables the workaround for the 430973 Cortex-A8
+          (r1p0..r1p2) erratum. If a code sequence containing an ARM/Thumb
+          interworking branch is replaced with another code sequence at the
+          same virtual address, whether due to self-modifying code or virtual
+          to physical address re-mapping, Cortex-A8 does not recover from the
+          stale interworking branch prediction. This results in Cortex-A8
+          executing the new code sequence in the incorrect ARM or Thumb state.
+          The workaround enables the BTB/BTAC operations by setting ACTLR.IBE
+          and also flushes the branch target cache at every context switch.
+          Note that setting specific bits in the ACTLR register may not be
+          available in non-secure mode.
+
 endmenu
 
 source "arch/arm/common/Kconfig"