[PATCH v3] armv8: errata: Implement workaround for Cortex-A53 Erratum 855873

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[PATCH v3] armv8: errata: Implement workaround for Cortex-A53 Erratum 855873

Alison Wang
855873: An eviction might overtake a cache clean operation
Workaround: The erratum can be avoided by upgrading cache clean by
address operations to cache clean and invalidate operations. For
Cortex-A53 r0p3 and later release, this can be achieved by setting
CPUACTLR.ENDCCASCI to 1.

This patch is to implement the workaround for this erratum.

Signed-off-by: Alison Wang <[hidden email]>
---
Changes in v3:
- Check the major revision of Cortex-A53.

Changes in v2:
- Check the revision of Cortex-A53 and apply the erratum to r0p3 and later release.
- Fix the mistake in the commit description.

 arch/arm/Kconfig                          |    3 +++
 arch/arm/cpu/armv8/fsl-layerscape/Kconfig |    3 +++
 arch/arm/cpu/armv8/start.S                |   24 +++++++++++++++++++++++-
 3 files changed, 29 insertions(+), 1 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index f2c35e3..de323bf 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -122,6 +122,9 @@ config ARM_ERRATA_852421
 config ARM_ERRATA_852423
  bool
 
+config ARM_ERRATA_855873
+ bool
+
 config CPU_ARM720T
  bool
  select SYS_CACHE_SHIFT_5
diff --git a/arch/arm/cpu/armv8/fsl-layerscape/Kconfig b/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
index 66bc32c..76a4d8b 100644
--- a/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
+++ b/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
@@ -1,6 +1,7 @@
 config ARCH_LS1012A
  bool
  select ARMV8_SET_SMPEN
+ select ARM_ERRATA_855873
  select FSL_LSCH2
  select SYS_FSL_DDR_BE
  select SYS_FSL_MMDC
@@ -15,6 +16,7 @@ config ARCH_LS1012A
 config ARCH_LS1043A
  bool
  select ARMV8_SET_SMPEN
+ select ARM_ERRATA_855873
  select FSL_LSCH2
  select SYS_FSL_DDR
  select SYS_FSL_DDR_BE
@@ -67,6 +69,7 @@ config ARCH_LS1046A
 config ARCH_LS1088A
  bool
  select ARMV8_SET_SMPEN
+ select ARM_ERRATA_855873
  select FSL_LSCH3
  select SYS_FSL_DDR
  select SYS_FSL_DDR_LE
diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
index 03e744e..f385ed4 100644
--- a/arch/arm/cpu/armv8/start.S
+++ b/arch/arm/cpu/armv8/start.S
@@ -196,7 +196,10 @@ reset_sctrl:
 WEAK(apply_core_errata)
 
  mov x29, lr /* Save LR */
- /* For now, we support Cortex-A57 specific errata only */
+ /* For now, we support Cortex-A53, Cortex-A57 specific errata */
+
+ /* Check if we are running on a Cortex-A53 core */
+ branch_if_a53_core x0, apply_a53_core_errata
 
  /* Check if we are running on a Cortex-A57 core */
  branch_if_a57_core x0, apply_a57_core_errata
@@ -204,6 +207,25 @@ WEAK(apply_core_errata)
  mov lr, x29 /* Restore LR */
  ret
 
+apply_a53_core_errata:
+
+#ifdef CONFIG_ARM_ERRATA_855873
+ mrs x0, midr_el1
+ tst x0, #(0xf << 20)
+ b.ne 0b
+
+ mrs x0, midr_el1
+ and x0, x0, #0xf
+ cmp x0, #3
+ b.lt 0b
+
+ mrs x0, S3_1_c15_c2_0 /* cpuactlr_el1 */
+ /* Enable data cache clean as data cache clean/invalidate */
+ orr x0, x0, #1 << 44
+ msr S3_1_c15_c2_0, x0 /* cpuactlr_el1 */
+#endif
+ b 0b
+
 apply_a57_core_errata:
 
 #ifdef CONFIG_ARM_ERRATA_828024
--
1.7.1

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Re: [PATCH v3] armv8: errata: Implement workaround for Cortex-A53 Erratum 855873

York Sun-3
On 12/27/2017 09:20 PM, Alison Wang wrote:

> 855873: An eviction might overtake a cache clean operation
> Workaround: The erratum can be avoided by upgrading cache clean by
> address operations to cache clean and invalidate operations. For
> Cortex-A53 r0p3 and later release, this can be achieved by setting
> CPUACTLR.ENDCCASCI to 1.
>
> This patch is to implement the workaround for this erratum.
>
> Signed-off-by: Alison Wang <[hidden email]>
> ---
> Changes in v3:
> - Check the major revision of Cortex-A53.
>
> Changes in v2:
> - Check the revision of Cortex-A53 and apply the erratum to r0p3 and later release.
> - Fix the mistake in the commit description.
>

Applied to fsl-qoriq master. Thanks.

York

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Re: [PATCH v3] armv8: errata: Implement workaround for Cortex-A53 Erratum 855873

Michal Simek-3
On 11.1.2018 20:36, York Sun wrote:

> On 12/27/2017 09:20 PM, Alison Wang wrote:
>> 855873: An eviction might overtake a cache clean operation
>> Workaround: The erratum can be avoided by upgrading cache clean by
>> address operations to cache clean and invalidate operations. For
>> Cortex-A53 r0p3 and later release, this can be achieved by setting
>> CPUACTLR.ENDCCASCI to 1.
>>
>> This patch is to implement the workaround for this erratum.
>>
>> Signed-off-by: Alison Wang <[hidden email]>
>> ---
>> Changes in v3:
>> - Check the major revision of Cortex-A53.
>>
>> Changes in v2:
>> - Check the revision of Cortex-A53 and apply the erratum to r0p3 and later release.
>> - Fix the mistake in the commit description.
>>
>
> Applied to fsl-qoriq master. Thanks.

Just a note if this is just for a53 should we consider to place these
Kconfigs to arch/arm/cpu/armv8/Kconfig?

M

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Re: [PATCH v3] armv8: errata: Implement workaround for Cortex-A53 Erratum 855873

York Sun-3
On 01/12/2018 01:12 AM, Michal Simek wrote:

> On 11.1.2018 20:36, York Sun wrote:
>> On 12/27/2017 09:20 PM, Alison Wang wrote:
>>> 855873: An eviction might overtake a cache clean operation
>>> Workaround: The erratum can be avoided by upgrading cache clean by
>>> address operations to cache clean and invalidate operations. For
>>> Cortex-A53 r0p3 and later release, this can be achieved by setting
>>> CPUACTLR.ENDCCASCI to 1.
>>>
>>> This patch is to implement the workaround for this erratum.
>>>
>>> Signed-off-by: Alison Wang <[hidden email]>
>>> ---
>>> Changes in v3:
>>> - Check the major revision of Cortex-A53.
>>>
>>> Changes in v2:
>>> - Check the revision of Cortex-A53 and apply the erratum to r0p3 and later release.
>>> - Fix the mistake in the commit description.
>>>
>>
>> Applied to fsl-qoriq master. Thanks.
>
> Just a note if this is just for a53 should we consider to place these
> Kconfigs to arch/arm/cpu/armv8/Kconfig?
>

We were following Tom Rini's move in commit 8dda2e2f9. I am not against
moving ARMv8 related config options, if no single erratum applies to
both ARMv8 and legacy cores.

York
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Re: [PATCH v3] armv8: errata: Implement workaround for Cortex-A53 Erratum 855873

Michal Simek-3
On 12.1.2018 18:01, York Sun wrote:

> On 01/12/2018 01:12 AM, Michal Simek wrote:
>> On 11.1.2018 20:36, York Sun wrote:
>>> On 12/27/2017 09:20 PM, Alison Wang wrote:
>>>> 855873: An eviction might overtake a cache clean operation
>>>> Workaround: The erratum can be avoided by upgrading cache clean by
>>>> address operations to cache clean and invalidate operations. For
>>>> Cortex-A53 r0p3 and later release, this can be achieved by setting
>>>> CPUACTLR.ENDCCASCI to 1.
>>>>
>>>> This patch is to implement the workaround for this erratum.
>>>>
>>>> Signed-off-by: Alison Wang <[hidden email]>
>>>> ---
>>>> Changes in v3:
>>>> - Check the major revision of Cortex-A53.
>>>>
>>>> Changes in v2:
>>>> - Check the revision of Cortex-A53 and apply the erratum to r0p3 and later release.
>>>> - Fix the mistake in the commit description.
>>>>
>>>
>>> Applied to fsl-qoriq master. Thanks.
>>
>> Just a note if this is just for a53 should we consider to place these
>> Kconfigs to arch/arm/cpu/armv8/Kconfig?
>>
>
> We were following Tom Rini's move in commit 8dda2e2f9. I am not against
> moving ARMv8 related config options, if no single erratum applies to
> both ARMv8 and legacy cores.

ok. Good.

Thanks,
Michal
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