On Thu, Feb 22, 2018 at 9:32 AM, H.J. Lu <hjl.to...@gmail.com> wrote:
> On Thu, Feb 22, 2018 at 9:10 AM, Jeff Law <l...@redhat.com> wrote:
>> On 02/22/2018 07:38 AM, Jan Hubicka wrote:
>>>>>> Hi Jan,
>>>>>> https://gcc.gnu.org/ml/gcc-patches/2018-01/msg02233.html
>>>>>> Is OK for trunk?
>>>>> I see that using register makes the problem go away and pushing address 
>>>>> to stack
>>>>> seemed bit odd anyway. However how does this work on other types of thunk?
>>>> Kernel only uses  -mindirect-branch=thunk-extern.  I am working on a 
>>>> proposal
>>>> to use -mindirect-branch=thunk-extern in user space to support CET in a 
>>>> single
>>>> binary.  So at the end of the day, only
>>>> -mindirect-branch=thunk-extern will be used.
>>> OK, so it is about the fact that we do not really want to support all
>>> -mindirect-branch options in the future? If we don't want to support the 
>>> correctly,
>>> I wonder why we are including them at all.  Shall we at least output 
>>> warning/sorry
>>> when user tries other thunk type with stack unwinding enabled?
>>> (does Kernel use it?)
>> A few notes.
>> 1. It's not even clear at this time that retpolining user space binaries
>> makes any sense at all.   SO before doing anything to make this easier
>> I'd like to see a justification for why it's really needed.
> Hi Jeff,
> Which part were commenting? My patch to add TARGET_INDIRECT_BRANCH_REGISTER
> or removing -mindirect-branch choices?

Is my patch OK for trunk?

>> 2. On the other hand, the existing thunk options do make it easier to
>> test independent of hte kernel.  ie, I can turn on inline thunks by
>> default and test things in user space (ie, do thunks generally work
>> properly).
> It sounds reasonable.



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