On 01/16/2017 09:47 PM, David Miller wrote:
From: Dave Hansen
Date: Wed, 11 Jan 2017 10:13:54 -0800
For memory shared by two different processes, do they have to agree on
what the tags are, or can they differ?
Whoever allocates the memory (does the mmap()+mprotect() or whatever),
decides on
From: Dave Hansen
Date: Wed, 11 Jan 2017 08:33:30 -0800
> Is there a cost in the hardware associated with doing this "ADI
> checking"? For instance, instead of having this new mprotect()
> interface, why not just always set TTE.mcd on all PTEs?
If we did this then for every page mapped into use
From: Dave Hansen
Date: Wed, 11 Jan 2017 10:13:54 -0800
> For memory shared by two different processes, do they have to agree on
> what the tags are, or can they differ?
Whoever allocates the memory (does the mmap()+mprotect() or whatever),
decides on the tag. They set it, and this determines w
On 01/13/2017 09:08 AM, Dave Hansen wrote:
On 01/13/2017 07:29 AM, Rob Gardner wrote:
so perhaps ADI should simply be disallowed for memory mapped to
files, and this particular complication can be avoided. Thoughts?
What's a "file" from your perspective?
In Linux, shared memory is a file. hug
On 01/13/2017 07:29 AM, Rob Gardner wrote:
> so perhaps ADI should simply be disallowed for memory mapped to
> files, and this particular complication can be avoided. Thoughts?
What's a "file" from your perspective?
In Linux, shared memory is a file. hugetlbfs is done with files. Many
databases
On 01/13/2017 08:29 AM, Rob Gardner wrote:
On 01/13/2017 07:48 AM, Khalid Aziz wrote:
On 01/12/2017 06:31 PM, Rob Gardner wrote:
On 01/12/2017 05:22 PM, Khalid Aziz wrote:
On 01/12/2017 10:53 AM, Dave Hansen wrote:
On 01/12/2017 08:50 AM, Khalid Aziz wrote:
2. Any shared page that has ADI pr
On 01/13/2017 07:48 AM, Khalid Aziz wrote:
On 01/12/2017 06:31 PM, Rob Gardner wrote:
On 01/12/2017 05:22 PM, Khalid Aziz wrote:
On 01/12/2017 10:53 AM, Dave Hansen wrote:
On 01/12/2017 08:50 AM, Khalid Aziz wrote:
2. Any shared page that has ADI protection enabled on it, must
stay ADI
prote
On 01/12/2017 06:31 PM, Rob Gardner wrote:
On 01/12/2017 05:22 PM, Khalid Aziz wrote:
On 01/12/2017 10:53 AM, Dave Hansen wrote:
On 01/12/2017 08:50 AM, Khalid Aziz wrote:
2. Any shared page that has ADI protection enabled on it, must stay ADI
protected across all processes sharing it.
Is th
On 01/12/2017 05:22 PM, Khalid Aziz wrote:
On 01/12/2017 10:53 AM, Dave Hansen wrote:
On 01/12/2017 08:50 AM, Khalid Aziz wrote:
2. Any shared page that has ADI protection enabled on it, must stay ADI
protected across all processes sharing it.
Is that true?
What happens if a page with ADI ta
On 01/12/2017 10:53 AM, Dave Hansen wrote:
On 01/12/2017 08:50 AM, Khalid Aziz wrote:
2. Any shared page that has ADI protection enabled on it, must stay ADI
protected across all processes sharing it.
Is that true?
What happens if a page with ADI tags set is accessed via a PTE without
the ADI
On 01/12/2017 08:50 AM, Khalid Aziz wrote:
> 2. Any shared page that has ADI protection enabled on it, must stay ADI
> protected across all processes sharing it.
Is that true?
What happens if a page with ADI tags set is accessed via a PTE without
the ADI enablement bit set?
> COW creates an inte
On 01/11/2017 05:49 PM, Dave Hansen wrote:
On 01/11/2017 04:22 PM, Khalid Aziz wrote:
...
All of the tag coordination can happen in userspace. Once a process sets
a tag on a physical page mapped in its address space, another process
that has mapped the same physical page in its address space can
On 01/11/2017 04:22 PM, Khalid Aziz wrote:
...
> All of the tag coordination can happen in userspace. Once a process sets
> a tag on a physical page mapped in its address space, another process
> that has mapped the same physical page in its address space can only set
> the tag to exact same value.
On 01/11/2017 12:11 PM, Dave Hansen wrote:
On 01/11/2017 10:50 AM, Khalid Aziz wrote:
On 01/11/2017 11:13 AM, Dave Hansen wrote:
On 01/11/2017 08:56 AM, Khalid Aziz wrote:
For memory shared by two different processes, do they have to agree on
what the tags are, or can they differ?
The two pro
On 01/11/2017 10:50 AM, Khalid Aziz wrote:
> On 01/11/2017 11:13 AM, Dave Hansen wrote:
>> On 01/11/2017 08:56 AM, Khalid Aziz wrote:
>> For memory shared by two different processes, do they have to agree on
>> what the tags are, or can they differ?
>
> The two processes have to agree on the tag.
On 01/11/2017 11:13 AM, Dave Hansen wrote:
On 01/11/2017 08:56 AM, Khalid Aziz wrote:
On 01/11/2017 09:33 AM, Dave Hansen wrote:
On 01/11/2017 08:12 AM, Khalid Aziz wrote:
A userspace task enables ADI through mprotect(). This patch series adds
a page protection bit PROT_ADI and a corresponding
On 01/11/2017 08:56 AM, Khalid Aziz wrote:
> On 01/11/2017 09:33 AM, Dave Hansen wrote:
>> On 01/11/2017 08:12 AM, Khalid Aziz wrote:
>>> A userspace task enables ADI through mprotect(). This patch series adds
>>> a page protection bit PROT_ADI and a corresponding VMA flag
>>> VM_SPARC_ADI. VM_SPAR
On 01/11/2017 09:33 AM, Dave Hansen wrote:
On 01/11/2017 08:12 AM, Khalid Aziz wrote:
A userspace task enables ADI through mprotect(). This patch series adds
a page protection bit PROT_ADI and a corresponding VMA flag
VM_SPARC_ADI. VM_SPARC_ADI is used to trigger setting TTE.mcd bit in the
sparc
On 01/11/2017 08:12 AM, Khalid Aziz wrote:
> A userspace task enables ADI through mprotect(). This patch series adds
> a page protection bit PROT_ADI and a corresponding VMA flag
> VM_SPARC_ADI. VM_SPARC_ADI is used to trigger setting TTE.mcd bit in the
> sparc pte that enables ADI checking on the
SPARC M7 processor adds additional metadata for memory address space
that can be used to secure access to regions of memory. This additional
metadata is implemented as a 4-bit tag attached to each cacheline size
block of memory. A task can set a tag on any number of such blocks.
Access to such bloc
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