Re: [PATCH 2/3] ARM: Select ARCH_USES_CFI_GENERIC_LLVM_PASS

[Sami Tolvanen]

Hi Nathan,

On Sat, Oct 25, 2025 at 1:53 PM Nathan Chancellor <nathan@xxxxxxxxxx> 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@xxxxxxxxxx>
> ---
>  arch/arm/Kconfig | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 2e3f93b690f4..4fb985b76e97 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -44,6 +44,8 @@ config ARM
>         select ARCH_USE_BUILTIN_BSWAP
>         select ARCH_USE_CMPXCHG_LOCKREF
>         select ARCH_USE_MEMTEST
> +       # 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?

Sami