[ARM] 5490/1: ARM errata: Processor deadlock when a false hazard is created

This patch adds a workaround for the 458693 Cortex-A8 (r2p0)
erratum. It sets the corresponding bits in the auxiliary control
register so that the PLD instruction becomes a NOP.

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

2 files changed, 19 insertions, 0 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 84e4816362b3..49f85664083d 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -765,6 +765,19 @@ config ARM_ERRATA_430973
           Note that setting specific bits in the ACTLR register may not be
           available in non-secure mode.
 
+config ARM_ERRATA_458693
+        bool "ARM errata: Processor deadlock when a false hazard is created"
+        depends on CPU_V7
+        help
+          This option enables the workaround for the 458693 Cortex-A8 (r2p0)
+          erratum. For very specific sequences of memory operations, it is
+          possible for a hazard condition intended for a cache line to instead
+          be incorrectly associated with a different cache line. This false
+          hazard might then cause a processor deadlock. The workaround enables
+          the L1 caching of the NEON accesses and disables the PLD instruction
+          in the ACTLR register. Note that setting specific bits in the ACTLR
+          register may not be available in non-secure mode.
+
 endmenu
 
 source "arch/arm/common/Kconfig"
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index fc81159596fe..370baa7a0f08 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -188,6 +188,12 @@ __v7_setup:
         orr     r10, r10, #(1 << 6)             @ set IBE to 1
         mcr     p15, 0, r10, c1, c0, 1          @ write aux control register
 #endif
+#ifdef CONFIG_ARM_ERRATA_458693
+        mrc     p15, 0, r10, c1, c0, 1          @ read aux control register
+        orr     r10, r10, #(1 << 5)             @ set L1NEON to 1
+        orr     r10, r10, #(1 << 9)             @ set PLDNOP to 1
+        mcr     p15, 0, r10, c1, c0, 1          @ write aux control register
+#endif
         mov     r10, #0
 #ifdef HARVARD_CACHE
         mcr     p15, 0, r10, c7, c5, 0          @ I+BTB cache invalidate