Re: [PATCH v4 04/15] cfi: Add DEFINE_CFI_IMMEDIATE_RETURN_STUB

Peter Zijlstra
2021-10-05T20:58:59Z

On Tue, Oct 05, 2021 at 01:29:02PM -0700, Sami Tolvanen wrote:
> On Mon, Oct 4, 2021 at 11:59 PM Peter Zijlstra <peterz@infradead.org> wrote:

> > For x86_64 it should indeed never get called, however if you plan on
> > supporting i386 then you need the annotation. Also, it might get called
> > on arm64 which is about to grow basic HAVE_STATIC_CALL support.
>
> Good point. I read through the latest arm64 static call proposal and
> while it can fall back to an indirect call, it doesn't look like that
> would cause issues with CFI.

Because that call is outside of compiler control? Same will be true for
any HAVE_STATIC_CALL implementation I suppose. The trampoline will be
outside of compiler control.