[ARM] 5489/1: ARM errata: Data written to the L2 cache can be overwritten with stale...

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 49f85664083d9cf5d4fdd88e29fa28f369d2f580..9faccc411c2abafcc1c3cac85fd9fbb897aae658 100644 (file)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -778,6 +778,18 @@ config ARM_ERRATA_458693
          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 370baa7a0f086b4e3cfb9ddba0103bfb3bb667ad..f2305441e7d1b9481c72abd76dae85c79b6d3164 100644 (file)
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -193,6 +193,11 @@ __v7_setup:
        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
+#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