ARM: 7015/1: ARM errata: Possible cache data corruption with hit-under-miss enabled
This patch is a workaround for the 364296 ARM1136 r0p2 erratum (possible
cache data corruption with hit-under-miss enabled). It sets the
undocumented bit 31 in the auxiliary control register and the FI bit in
the control register, thus disabling hit-under-miss without putting the
processor into full low interrupt latency mode.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 5ebc5d9..3269576 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1271,6 +1271,18 @@
This workaround defines cpu_relax() as smp_mb(), preventing correctly
written polling loops from denying visibility of updates to memory.
+config ARM_ERRATA_364296
+ bool "ARM errata: Possible cache data corruption with hit-under-miss enabled"
+ depends on CPU_V6 && !SMP
+ help
+ This options enables the workaround for the 364296 ARM1136
+ r0p2 erratum (possible cache data corruption with
+ hit-under-miss enabled). It sets the undocumented bit 31 in
+ the auxiliary control register and the FI bit in the control
+ register, thus disabling hit-under-miss without putting the
+ processor into full low interrupt latency mode. ARM11MPCore
+ is not affected.
+
endmenu
source "arch/arm/common/Kconfig"
diff --git a/arch/arm/mm/proc-v6.S b/arch/arm/mm/proc-v6.S
index 219138d..a923aa0 100644
--- a/arch/arm/mm/proc-v6.S
+++ b/arch/arm/mm/proc-v6.S
@@ -223,6 +223,22 @@
mrc p15, 0, r0, c1, c0, 0 @ read control register
bic r0, r0, r5 @ clear bits them
orr r0, r0, r6 @ set them
+#ifdef CONFIG_ARM_ERRATA_364296
+ /*
+ * Workaround for the 364296 ARM1136 r0p2 erratum (possible cache data
+ * corruption with hit-under-miss enabled). The conditional code below
+ * (setting the undocumented bit 31 in the auxiliary control register
+ * and the FI bit in the control register) disables hit-under-miss
+ * without putting the processor into full low interrupt latency mode.
+ */
+ ldr r6, =0x4107b362 @ id for ARM1136 r0p2
+ mrc p15, 0, r5, c0, c0, 0 @ get processor id
+ teq r5, r6 @ check for the faulty core
+ mrceq p15, 0, r5, c1, c0, 1 @ load aux control reg
+ orreq r5, r5, #(1 << 31) @ set the undocumented bit 31
+ mcreq p15, 0, r5, c1, c0, 1 @ write aux control reg
+ orreq r0, r0, #(1 << 21) @ low interrupt latency configuration
+#endif
mov pc, lr @ return to head.S:__ret
/*