Re: [PATCH v38 10/24] mm: Add vm_ops->mprotect()

[Andy Lutomirski]

> On Sep 25, 2020, at 12:53 PM, Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
> 
> On 9/25/20 12:43 PM, Sean Christopherson wrote:
>>> That means that the intent argument (SGX_PROT_*) is currently unused.
>> No, the intent argument is used (eventually) by SGX's ->mprotect()
>> implementation, i.e. sgx_mprotect() enforces that the actual protections are a
>> subset of the declared/intended protections.
>> 
>> If ->mprotect() is not merged, then it yes, it will be unused.
> 
> OK, I think I've got it.
> 
> I think I'm OK with adding ->mprotect().  As long as folks buy into the
> argument that intent needs to be checked at mmap() time, they obviously
> need to be checked at mprotect() too.
> 
> Jarkko, if you want to try and rewrite the changelog, capturing the
> discussion here and reply, I think I can ack the resulting patch.  I
> don't know if that will satisfy the request from Boris from an ack from
> a "mm person", but we can at least start there. :)

I think I agree. ->mprotect seems reasonable to me.

FWIW, I don’t think I should ack this particular thing — it was, to a decent extent, my suggestion in the first place, so I’m biased. I think it turned into something reasonable, and the ->mprotect mechanism seems easily supportable and plausibly useful for other purposes down the road.

> 
> Please be judicious in what you include in the changelog.  There's been
> a lot of detritus in them.  Let's keep it as short, sweet, simple and on
> topic as we can.