Re: [PATCH v2 00/13] objtool: Detect and warn about indirect calls in __nocfi functions

Peter Zijlstra
2025-05-01T10:30:50Z

On Wed, Apr 30, 2025 at 09:06:00PM +0200, Peter Zijlstra wrote:
> On Wed, Apr 30, 2025 at 07:24:15AM -0700, H. Peter Anvin wrote:
>
> > >KVM has another; the VMX interrupt injection stuff calls the IDT handler
> > >directly. Is there an alternative? Can we keep a table of Linux functions
> > >slighly higher up the call stack (asm_\cfunc ?) and add CFI to those?
>
> > We do have a table of handlers higher up in the stack in the form of
> > the dispatch tables for FRED. They don't in general even need the
> > assembly entry stubs, either.
>
> Oh, right. I'll go have a look at those.

Right, so perhaps the easiest way around this is to setup the FRED entry
tables unconditionally, have VMX mandate CONFIG_FRED and then have it
always use the FRED entry points.

Let me see how ugly that gets.