[PATCH] ARM: errata: workaround Cortex-A9 errata 761320 and 794072
robherring2 at gmail.com
Tue Apr 1 19:37:49 PDT 2014
On Tue, Apr 1, 2014 at 8:18 PM, Nitin Garg <nitin.garg at freescale.com> wrote:
> Hi Rob,
Please follow mailing list rules and don't top post.
> Thanks for reply. In that case, I wonder why there is already code which access the diagnostic register. Pls see:
> arch/arm/mm/proc-v7.S: __v7_setup
Perhaps you should look at this commit:
Author: Rob Herring <rob.herring at calxeda.com>
Date: Fri Dec 21 22:42:40 2012 +0100
ARM: 7609/1: disable errata work-arounds which access secure registers
In order to support secure and non-secure platforms in multi-platform
kernels, errata work-arounds that access secure only registers need to
be disabled. Make all the errata options that fit in this category
depend on !CONFIG_ARCH_MULTIPLATFORM.
This will effectively remove the errata options as platforms are
converted over to multi-platform.
Signed-off-by: Rob Herring <rob.herring at calxeda.com>
Acked-by: Tony Lindgren <tony at atomide.com>
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
And one hint, the solution for you is not adding "depends on
!CONFIG_ARCH_MULTIPLATFORM". Adding that for something new will not
Once exynos is converted to multi-platform, we may be able to actually
remove all these A9 errata as there may not be any more non
multi-platform A9 or A15 based platforms.
> Nitin Garg
> -----Original Message-----
> From: Rob Herring [mailto:robherring2 at gmail.com]
> Sent: Tuesday, April 01, 2014 8:12 PM
> To: Garg Nitin-B37173
> Cc: Russell King - ARM Linux; linux-arm-kernel at lists.infradead.org
> Subject: Re: [PATCH] ARM: errata: workaround Cortex-A9 errata 761320 and 794072
> On Mon, Mar 31, 2014 at 3:34 PM, Nitin Garg <nitin.garg at freescale.com> wrote:
>> Add workaround for Cortex-A9 errata 761320 ([present on r0, r1, r2,
>> r3) and 794072 (present on all revisions). These are Category B,
>> present on SMP systems.
> These work-arounds don't work on non-secure systems which don't have access to the diagnostic register. There is no architectural way to determine secure vs. non-secure mode. It's been discussed before and decided that these types of work-arounds must go into the bootloader or firmware.
>> Signed-off-by: Nitin Garg <nitin.garg at freescale.com>
>> arch/arm/Kconfig | 23 +++++++++++++++++++++++
>> arch/arm/mach-imx/Kconfig | 2 ++
>> arch/arm/mm/proc-v7.S | 11 +++++++++++
>> 3 files changed, 36 insertions(+), 0 deletions(-)
>> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index
>> a48712e..f8464ff 100644
>> --- a/arch/arm/Kconfig
>> +++ b/arch/arm/Kconfig
>> @@ -1301,6 +1301,29 @@ config ARM_ERRATA_751472
>> operation is received by a CPU before the ICIALLUIS has completed,
>> potentially leading to corrupted entries in the cache or TLB.
>> +config ARM_ERRATA_794072
>> + bool "ARM errata: A short loop including a DMB instruction might cause a denial of service"
>> + depends on CPU_V7 && SMP
>> + help
>> + This option enables the workaround for the 794072 Cortex-A9
>> + (all revisions). A processor which continuously executes a short
>> + loop containing a DMB instruction might prevent a CP15 operation
>> + broadcast by another processor making further progress, causing
>> + a denial of service. This erratum can be worked around by setting
>> + bit of the undocumented Diagnostic Control Register to 1.
>> +config ARM_ERRATA_761320
>> + bool "Full cache line writes to the same memory region from at least two processors might deadlock processor"
>> + depends on CPU_V7 && SMP
>> + help
>> + This option enables the workaround for the 761320 Cortex-A9 (r0..r3).
>> + Under very rare circumstances, full cache line writes
>> + from (at least) 2 processors on cache lines in hazard with
>> + other requests may cause arbitration issues in the SCU,
>> + leading to processor deadlock. This erratum can be
>> + worked around by setting bit of the undocumented
>> + Diagnostic Control Register to 1.
>> config PL310_ERRATA_753970
>> bool "PL310 errata: cache sync operation may be faulty"
>> depends on CACHE_PL310
>> diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig
>> index 5740296d..19690c2 100644
>> --- a/arch/arm/mach-imx/Kconfig
>> +++ b/arch/arm/mach-imx/Kconfig
>> @@ -794,6 +794,8 @@ config SOC_IMX6
>> config SOC_IMX6Q
>> bool "i.MX6 Quad/DualLite support"
>> select ARM_ERRATA_764369 if SMP
>> + select ARM_ERRATA_794072 if SMP
>> + select ARM_ERRATA_761320 if SMP
>> select HAVE_ARM_SCU if SMP
>> select HAVE_ARM_TWD if SMP
>> select MIGHT_HAVE_PCI
>> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S index
>> 195731d..b5e5386 100644
>> --- a/arch/arm/mm/proc-v7.S
>> +++ b/arch/arm/mm/proc-v7.S
>> @@ -337,6 +337,17 @@ __v7_setup:
>> mcrlt p15, 0, r10, c15, c0, 1 @ write diagnostic register
>> +#ifdef CONFIG_ARM_ERRATA_794072
>> + mrc p15, 0, r10, c15, c0, 1 @ read diagnostic register
>> + orr r10, r10, #1 << 4 @ set bit #4
>> + mcr p15, 0, r10, c15, c0, 1 @ write diagnostic register
>> +#ifdef CONFIG_ARM_ERRATA_761320
>> + cmp r6, #0x40 @ present prior to r4p0
>> + mrclt p15, 0, r10, c15, c0, 1 @ read diagnostic register
>> + orrlt r10, r10, #1 << 21 @ set bit #21
>> + mcrlt p15, 0, r10, c15, c0, 1 @ write diagnostic register
>> /* Cortex-A15 Errata */
>> 3: ldr r10, =0x00000c0f @ Cortex-A15 primary part number
>> linux-arm-kernel mailing list
>> linux-arm-kernel at lists.infradead.org
More information about the linux-arm-kernel