# Re: \[PATCH v2\] sparc64: Add support for Application Data Integrity (ADI) - From: Khalid Aziz \ - Date: 2016-03-07 21:34:55 - List: linux-api - Page: https://ratatoskr.run/linux-api/2016/03/4703305 - Thread: https://ratatoskr.run/sparclinux/2016/03/4699675/t.md ```text On 03/07/2016 12:16 PM, David Miller wrote: > From: Khalid Aziz > Date: Mon, 7 Mar 2016 11:24:54 -0700 > >> Tags can be cleared by user by setting tag to 0. Tags are >> automatically cleared by the hardware when the mapping for a virtual >> address is removed from TSB (which is why swappable pages are a >> problem), so kernel does not have to do it as part of clean up. > > You might be able to crib some bits for the Tag in the swp_entry_t, it's > 64-bit and you can therefore steal bits from the offset field. > > That way you'll have the ADI tag in the page tables, ready to re-install > at swapin time. > 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. I will think some more about it. Thanks, Khalid -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org ```