Subject: Re: [PATCH v2] sparc64: Add support for Application Data Integrity
 (ADI)
To: Rob Gardner <rob.gardner@oracle.com>, David Miller <davem@davemloft.net>
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From: Khalid Aziz <khalid.aziz@oracle.com>
Organization: Oracle Corp
Message-ID: <56DE0E66.3020003@oracle.com>
Date: Mon, 7 Mar 2016 16:27:34 -0700
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On 03/07/2016 04:12 PM, Rob Gardner wrote:
> On 03/07/2016 01:33 PM, Khalid Aziz wrote:
>>
>> That is a possibility but limited in scope. An address range covered
>> by a single TTE can have large number of tags. Version tags are set on
>> cacheline. In extreme case, one could set a tag for each set of
>> 64-bytes in a page. Also tags are set completely in userspace and no
>> transition occurs to kernel space, so kernel has no idea of what tags
>> have been set.
>
>    ...
>> I have not found a way to query the MMU on tags.
>>
>
> To query the tag for a cache line, you just read it back with ldxa and
> ASI_MCD_PRIMARY (ie, asi 0x90), basically the same way you stored the
> tag in the first place.
>

Thanks, Rob. I just saw it while reading through the manual.

--
Khalid