Re: [PATCH] x86/Kconfig: make CFI_AUTO_DEFAULT depend on !RUST

[Alice Ryhl]

On Wed, May 07, 2025 at 12:19:11AM +0200, Miguel Ojeda wrote:
> On Thu, Apr 17, 2025 at 8:40 PM Miguel Ojeda
> <miguel.ojeda.sandonis@xxxxxxxxx> wrote:
> >
> > Thanks Peter (and Kees for clarifying) -- not sure how you/others
> > prefer to route this patch or if you expect a v2, but I got the
> > following (attached). I converted your Ack.
> 
> Applied to `rust-fixes` -- thanks everyone!
> 
> (If someone else prefers to carry it, please shout)
> 
>     [ Rust 1.88.0 (scheduled for 2025-06-26) should have this fixed [1],
>       and thus we relaxed the condition with Rust >= 1.88.
> 
>       When `objtool` lands checking for this with e.g. [2], the plan is
>       to ideally run that in upstream Rust's CI to prevent regressions
>       early [3], since we do not control `core`'s source code.
> 
>       Alice tested the Rust PR backported to an older compiler.
> 
>       Peter would like that Rust provides a stable `core` which can be
>       pulled into the kernel: "Relying on that much out of tree code is
>       'unfortunate'".
> 
>         - Miguel ]
> 
>     [ Reduced splat. - Miguel ]

Actually ... I don't think putting it on CFI_AUTO_DEFAULT the right
approach.

Shouldn't the depends on clause go on `config FINEIBT` instead? After
all, the current patch just means that you can't make FineIBT the
default option. But you can still pass kcfi=fineibt on boot to enble
FineIBT which would result in the same crash.

Alice