[lkml]   [2017]   [Aug]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v7 9/9] sparc64: Add support for ADI (Application Data Integrity)
On 08/30/2017 06:09 PM, David Miller wrote:
> From: Khalid Aziz <>
> Date: Wed, 30 Aug 2017 17:23:37 -0600
>> That is an interesting idea. This would enable TSTATE_MCDE on all
>> threads of a process as soon as one thread enables it. If we consider
>> the case where the parent creates a shared memory area and spawns a
>> bunch of threads. These threads access the shared memory without ADI
>> enabled. Now one of the threads decides to enable ADI on the shared
>> memory. As soon as it does that, we enable TSTATE_MCDE across all
>> threads and since threads are all using the same TTE for the shared
>> memory, every thread becomes subject to ADI verification. If one of
>> the other threads was in the middle of accessing the shared memory, it
>> will get a sigsegv. If we did not enable TSTATE_MCDE across all
>> threads, it could have continued execution without fault. In other
>> words, updating TSTATE_MCDE across all threads will eliminate the
>> option of running some threads with ADI enabled and some not while
>> accessing the same shared memory. This could be necessary at least for
>> short periods of time before threads can communicate with each other
>> and all switch to accessing shared memory with ADI enabled using same
>> tag. Does that sound like a valid use case or am I off in the weeds
>> here?
> A threaded application needs to synchronize and properly orchestrate
> access to shared memory.
> When a change is made to a mappping, in this case setting ADI
> attributes, it's being done for the address space not the thread.
> And the address space is shared amongst threads.
> Therefore ADI is not really a per-thread property but rather
> a per-address-space property.

That does make sense.


 \ /
  Last update: 2017-08-31 18:42    [W:0.046 / U:0.908 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site