Re: [PATCH 5/7] x86: Insert endbr32/endbr64 to vDSO

[H.J. Lu]

On Thu, Jun 7, 2018 at 1:50 PM, Andy Lutomirski <luto@xxxxxxxxxx> wrote:
> On Thu, Jun 7, 2018 at 7:42 AM Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx> wrote:
>>
>> From: "H.J. Lu" <hjl.tools@xxxxxxxxx>
>>
>> When Intel indirect branch tracking is enabled, functions in vDSO which
>> may be called indirectly should have endbr32 or endbr64 as the first
>> instruction.  We try to compile vDSO with -fcf-protection=branch -mibt
>> if possible.  Otherwise, we insert endbr32 or endbr64 by hand to assembly
>> codes generated by the compiler.
>
> Wow, that's... a genuine abomination.  Do we really need to support
> CET on kernels built with old toolchains?
>

Yes.  GCC 7 should be able to build CET kernel.


-- 
H.J.