[PATCH 2/3] ARM: Select ARCH_USES_CFI_GENERIC_LLVM_PASS

[Linus Walleij]

On Mon, Oct 27, 2025 at 4:54 PM Sami Tolvanen <samitolvanen at google.com> wrote:
> On Sat, Oct 25, 2025 at 1:53 PM Nathan Chancellor <nathan at kernel.org> wrote:
> >
> > Prior to clang 22.0.0 [1], ARM did not have an architecture specific
> > kCFI bundle lowering in the backend, which may cause issues. Select
> > CONFIG_ARCH_USES_CFI_GENERIC_LLVM_PASS to enable use of __nocfi_generic.
> >
> > Link: https://github.com/llvm/llvm-project/commit/d130f402642fba3d065aacb506cb061c899558de [1]
> > Link: https://github.com/ClangBuiltLinux/linux/issues/2124
> > Signed-off-by: Nathan Chancellor <nathan at kernel.org>

I didn't know Kees stepped in and fixed this, christmas comes
early this year! I had it on my TODO to do this or get someone to
do this, but now it turns out I don't have to.

> > +       # https://github.com/llvm/llvm-project/commit/d130f402642fba3d065aacb506cb061c899558de
> > +       select ARCH_USES_CFI_GENERIC_LLVM_PASS if CLANG_VERSION < 220000
>
> Instead of working around issues with the generic pass, would it make
> more sense to just disable arm32 CFI with older Clang versions
> entirely? Linus, any thoughts?

We have people using this with the default compilers that come with
Debiand and Fedora. I would say as soon as the latest release of
the major distributions supports this, we can drop support for older
compilers.

Yours,
Linus Walleij