Re: [PATCH v1 0/2] RISC-V: enable rust

[Ramon de C Valle]

Sorry for the late reply. Sami might be the best person to answer
this, but KCFI (not CFI) tests are lowered by passes that are
architecture specific (see https://reviews.llvm.org/D119296), so we'd
need to add support for RISC-V. There is no additional work required
in the Rust compiler besides enabling it for the new target.


On Sat, Feb 10, 2024 at 12:13 AM Trevor Gross <tmgross@xxxxxxxxx> wrote:
>
> On Fri, Feb 9, 2024 at 9:18 AM Conor Dooley <conor@xxxxxxxxxx> wrote:
> >
> > On Sat, Jan 27, 2024 at 02:46:38PM +0100, Miguel Ojeda wrote:
> > > On Fri, Jan 26, 2024 at 11:01 PM Conor Dooley <conor@xxxxxxxxxx> wrote:
> > > >
> > > > Is that even needed? We already have ARCH_SUPPORTS_CFI_CLANG and AFAIU
> > > > rust supports it if clang does, so a second option is superfluous?
> > >
> > > From a quick look, I don't see it enabled in any RISC-V built-in
> > > target in `rustc` yet.
> > >
> > > It may also still be the case that KCFI needs some tweaks for, say,
> > > RISC-V, before the flag actually works, i.e. we couldn't just test the
> > > flag in that case -- Ramon: how likely is it that RISC-V would work if
> > > KCFI works for aarch64 and x86_64?
> >
> > Well, there's been no reply here. I'll do sa you suggested and add a
> > depends on !CFI_CLANG to RUST.
> >
> > Cheers,
> > Conor.
> >
>
> I asked on Zulip and it sounds like Ramon may be out [1]. It
> _probably_ works, but going with a dependency to not be blocked on
> KCFI is probably reasonable for now.
>
> - Trevor
>
> [1]: https://rust-lang.zulipchat.com/#narrow/stream/343119-project-exploit-mitigations/topic/KCFI.20on.20RISC-V.20questions