Re: [PATCH 26/34] mm: implement new mprotect_key() system call

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 12/09/2015 06:05 PM, Dave Hansen wrote:
> On 12/09/2015 08:45 AM, Michael Kerrisk (man-pages) wrote:
>>>>>> * Explanation of what a protection domain is.
>>>>
>>>> A protection domain is a unique view of memory and is represented by the
>>>> value in the PKRU register.
>> Out something about this in pkey(7), but explain what you mean by a
>> "unique view of memory".
> 
> Let's say there are only two protection keys: 0 and 1.  There are two
> disable bits per protection key (Access and Write Disable), so a two-key
> PKRU looks like:
> 
> |   PKEY0   |   PKEY1   |
> | AD0 | WD0 | AD1 | WD1 |
> 
> In this example, there are 16 possible protection domains, one for each
> possible combination of the 4 rights-disable bits.
> 
> "Changing a protection domain" would mean changing (setting or clearing)
> the value of any of those 4 bits.  Each unique value of PKRU represents
> a view of memory, or unique protection domain.

Again, some of this could make its way into pkey(7). And I guess there
are useful nuggets for that page to be found in Jon's article at
https://lwn.net/Articles/667156/

Thanks,

Michael




-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
--
To unsubscribe from this list: send the line "unsubscribe linux-api" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux