[PATCH 1/1] ARM errata: Possible cache data corruption with hit-under-miss enabled
From: catalin.marinas@arm.com (Catalin Marinas)
Date: 2011-08-10 10:26:46
Subsystem:
arm port, the rest · Maintainers:
Russell King, Linus Torvalds
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> --- arch/arm/Kconfig | 12 ++++++++++++ arch/arm/mm/proc-v6.S | 16 ++++++++++++++++ 2 files changed, 28 insertions(+), 0 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 2c71a8f..30335e1 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig@@ -1272,6 +1272,18 @@ config ARM_ERRATA_754327 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 @@ __v6_setup: 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 /*
--
Catalin