From: Dave Hansen <dave.hansen@linux.intel.com>
To: Vlastimil Babka <vbabka@suse.cz>,
Florian Weimer <fweimer@redhat.com>,
linux-x86_64@vger.kernel.org, linux-arch@vger.kernel.org
Cc: linux-mm <linux-mm@kvack.org>, Linux API <linux-api@vger.kernel.org>
Subject: Re: MPK: removing a pkey
Date: Thu, 23 Nov 2017 15:29:20 -0800 [thread overview]
Message-ID: <8051353f-47d3-37a4-a402-41adc8b6eb88@linux.intel.com> (raw)
In-Reply-To: <2d12777f-615a-8101-2156-cf861ec13aa7@suse.cz>
On 11/23/2017 01:42 PM, Vlastimil Babka wrote:
>> It's supposed to set 0.
>>
>> -1 was, as far as I remember, an internal-to-the-kernel-only thing to
>> tell us that a key came from *mprotect()* instead of pkey_mprotect().
> So, pkey_mprotect(..., 0) will set it to 0, regardless of PROT_EXEC.
Although weird, the thought here was that pkey_mprotect() callers are
new and should know about the interactions with PROT_EXEC. They can
also *get* PROT_EXEC semantics if they want.
The only wart here is if you do:
mprotect(..., PROT_EXEC); // key 10 is now the PROT_EXEC key
pkey_mprotect(..., PROT_EXEC, key=3);
I'm not sure what this does. We should probably ensure that it returns
an error.
> pkey_mprotect(..., -1) or mprotect() will set it to 0-or-PROT_EXEC-pkey.
>
> Can't shake the feeling that it's somewhat weird, but I guess it's
> flexible at least. So just has to be well documented.
It *is* weird. But, layering on top of legacy APIs are often weird. I
would have been open to other sane, but less weird ways to do it a year
ago. :)
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next prev parent reply other threads:[~2017-11-23 23:29 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-05 10:35 MPK: pkey_free and key reuse Florian Weimer
2017-11-08 20:41 ` Dave Hansen
2017-11-09 14:48 ` Florian Weimer
2017-11-09 16:59 ` Dave Hansen
2017-11-23 12:48 ` Florian Weimer
2017-11-23 13:07 ` Vlastimil Babka
2017-11-23 15:25 ` Dave Hansen
2017-11-24 14:55 ` Florian Weimer
2017-11-22 8:18 ` MPK: removing a pkey (was: pkey_free and key reuse) Vlastimil Babka
2017-11-22 12:15 ` MPK: removing a pkey Florian Weimer
2017-11-22 12:46 ` Vlastimil Babka
2017-11-22 12:49 ` Florian Weimer
2017-11-22 16:10 ` Dave Hansen
2017-11-22 16:21 ` Florian Weimer
2017-11-22 16:32 ` Dave Hansen
2017-11-23 8:11 ` Vlastimil Babka
2017-11-23 15:00 ` Dave Hansen
2017-11-23 21:42 ` Vlastimil Babka
2017-11-23 23:29 ` Dave Hansen [this message]
2017-11-24 8:35 ` Florian Weimer
2017-11-24 8:38 ` Vlastimil Babka
2017-11-23 12:38 ` Florian Weimer
2017-11-23 15:09 ` Dave Hansen
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