# Re: \[PATCH 26/35\] kasan, arm64: Enable TBI EL1

- From: Vincenzo Frascino \<vincenzo.frascino@arm.com\>
- Date: 2020-08-27 15:23:33 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2020/08/6085267
- Thread: https://ratatoskr.run/linux-arm-kernel/2020/08/6068760/t.md

```text
On 8/27/20 11:40 AM, Catalin Marinas wrote:
> On Fri, Aug 14, 2020 at 07:27:08PM +0200, Andrey Konovalov wrote:
>> diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
>> index 152d74f2cc9c..6880ddaa5144 100644
>> --- a/arch/arm64/mm/proc.S
>> +++ b/arch/arm64/mm/proc.S
>> @@ -38,7 +38,7 @@
>>  /* PTWs cacheable, inner/outer WBWA */
>>  #define TCR_CACHE_FLAGS	TCR_IRGN_WBWA | TCR_ORGN_WBWA
>>  
>> -#ifdef CONFIG_KASAN_SW_TAGS
>> +#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
>>  #define TCR_KASAN_FLAGS TCR_TBI1
>>  #else
>>  #define TCR_KASAN_FLAGS 0
> 
> I prefer to turn TBI1 on only if MTE is present. So on top of the v8
> user series, just do this in __cpu_setup.
> 

Not sure I understand... Enabling TBI1 only if MTE is present would break
KASAN_SW_TAGS which is based on TBI1 but not on MTE.

-- 
Regards,
Vincenzo

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