[PATCH v5 00/16] Support RISC-V Control Flow Integrifty (CFI)

[Jesse Huang]

On Mon, Jun 29, 2026 at 6:08 PM Florian Weimer <fweimer@redhat.com> wrote:
>
> * Andreas Schwab:
>
> > On Jun 28 2026, Jesse Huang wrote:
> >
> >> This patch series adds support for the new RISC-V Control Flow Integrity (CFI)
> >> extensions, i.e. Zicfilp and Zicfiss, as described in the following sections
> >> of the RISC-V Instruction Set Manual:
> >>
> >>     - Volume I, Chapter 33
> >>     - Volume II, Chapter 22
> >
> > Do I understand corectly that this is incompatible with implementations
> > lacking the Zimop/Zcmop extensions?
>
> Yes, I believe that's accurate.  It's not possible to maintain
> compatibility with the baseline with this approach.
>
> Thanks,
> Florian
>

Regarding the extensions, Zicfilp uses the existing auipc space to
encode lpad, so it actually
compatible with cores that lacking support of Zimop and Zcmop.
However, from a security standpoint I don't think it makes sense to
enable only one of the two,
so there is only a single --enable-cfi option that turns on both.

Thanks,
Jesse