Message-ID: <56DE100E.7030109@oracle.com>
Date: Tue, 08 Mar 2016 10:34:38 +1100
From: James Morris <james.l.morris@oracle.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0
MIME-Version: 1.0
To: David Miller <davem@davemloft.net>, khalid.aziz@oracle.com
CC: luto@amacapital.net, corbet@lwn.net, akpm@linux-foundation.org,
        dingel@linux.vnet.ibm.com, bob.picco@oracle.com,
        kirill.shutemov@linux.intel.com, aneesh.kumar@linux.vnet.ibm.com,
        aarcange@redhat.com, arnd@arndb.de, sparclinux@vger.kernel.org,
        rob.gardner@oracle.com, mhocko@suse.cz, chris.hyser@oracle.com,
        richard@nod.at, vbabka@suse.cz, koct9i@gmail.com, oleg@redhat.com,
        gthelen@google.com, jack@suse.cz, xiexiuqi@huawei.com,
        Vineet.Gupta1@synopsys.com, luto@kernel.org, ebiederm@xmission.com,
        bsegall@google.com, geert@linux-m68k.org, dave@stgolabs.net,
        adobriyan@gmail.com, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-arch@vger.kernel.org, linux-api@vger.kernel.org
Subject: Re: [PATCH v2] sparc64: Add support for Application Data Integrity
 (ADI)
References: <56DDDA31.9090105@oracle.com>	<CALCETrXXU0fs2ezq+Wn_kr4dZTO=0RJmt6b=XBSA-wM7W_9j9A@mail.gmail.com>	<56DDE783.8090009@oracle.com> <20160307.155810.587016604208120674.davem@davemloft.net>
In-Reply-To: <20160307.155810.587016604208120674.davem@davemloft.net>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1115
Lines: 24

On 03/08/2016 07:58 AM, David Miller wrote:
> From: Khalid Aziz <khalid.aziz@oracle.com>
> Date: Mon, 7 Mar 2016 13:41:39 -0700
>
>> Shared data may not always be backed by a file. My understanding is
>> one of the use cases is for in-memory databases. This shared space
>> could also be used to hand off transactions in flight to other
>> processes. These transactions in flight would not be backed by a
>> file. Some of these use cases might not use shmfs even. Setting ADI
>> bits at virtual address level catches all these cases since what backs
>> the tagged virtual address can be anything - a mapped file, mmio
>> space, just plain chunk of memory.
>
> Frankly the most interesting use case to me is simply finding bugs
> and memory scribbles, and for that we're want to be able to ADI
> arbitrary memory returned from malloc() and friends.
>
> I personally see ADI more as a debugging than a security feature,
> but that's just my view.

This is certainly a major use of the feature. The Solaris folks have 
made some interesting use of it here:

https://docs.oracle.com/cd/E37069_01/html/E37085/gphwb.html