[ARM] 5489/1: ARM errata: Data written to the L2 cache can be overwritten with stale data
This patch is a workaround for the 460075 Cortex-A8 (r2p0) erratum. It
configures the L2 cache auxiliary control register so that the Write
Allocate mode for the L2 cache is disabled.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 49f8566..9faccc4 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -778,6 +778,18 @@
in the ACTLR register. Note that setting specific bits in the ACTLR
register may not be available in non-secure mode.
+config ARM_ERRATA_460075
+ bool "ARM errata: Data written to the L2 cache can be overwritten with stale data"
+ depends on CPU_V7
+ help
+ This option enables the workaround for the 460075 Cortex-A8 (r2p0)
+ erratum. Any asynchronous access to the L2 cache may encounter a
+ situation in which recent store transactions to the L2 cache are lost
+ and overwritten with stale memory contents from external memory. The
+ workaround disables the write-allocate mode for the L2 cache via 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 370baa7..f230544 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -194,6 +194,11 @@
orr r10, r10, #(1 << 9) @ set PLDNOP to 1
mcr p15, 0, r10, c1, c0, 1 @ write aux control register
#endif
+#ifdef CONFIG_ARM_ERRATA_460075
+ mrc p15, 1, r10, c9, c0, 2 @ read L2 cache aux ctrl register
+ orr r10, r10, #(1 << 22) @ set the Write Allocate disable bit
+ mcr p15, 1, r10, c9, c0, 2 @ write the L2 cache aux ctrl register
+#endif
mov r10, #0
#ifdef HARVARD_CACHE
mcr p15, 0, r10, c7, c5, 0 @ I+BTB cache invalidate