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

[Andy Lutomirski]

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?

--Andy