Re: [PATCH] arm64/module: Fix livepatch BTI exceptions with Clang 21+

On Tue, Aug 11, 2026 at 09:27:28AM -0700, Nick Desaulniers wrote:
> On Tue, Aug 11, 2026 at 7:23 AM Will Deacon <[email protected]> wrote:
> >
> > On Tue, Aug 11, 2026 at 03:18:17PM +0200, Ard Biesheuvel wrote:
> > >
> > > On Tue, 11 Aug 2026, at 14:02, Ard Biesheuvel wrote:
> > > > On Tue, 11 Aug 2026, at 11:44, Will Deacon wrote:
> > > >> On Mon, Aug 10, 2026 at 09:41:35AM -0700, Nick Desaulniers wrote:
> > > >
> > > >>> Sure, but let's replace this with a link to a bug report in llvm's
> > > >>> issue tracker?
> > > >>
> > > >> Yes, please! I can apply the patch once we have the bug number.
> > > >>
> > > >
> > > > I can look into that.
> > >
> > > https://github.com/llvm/llvm-project/issues/215547
> >
> > Thanks, Ard. I've ended up with the patch below.
> 
> What's the extent that HAVE_LIVEPATCH will be used?
> 
> Does this penalize kernels built with BTI in favor of HAVE_LIVEPATCH?
> 
> For example, with my Android hat on, if we have a kernel that's built
> with ARM64_BTI_KERNEL=y, and _dont_ use HAVE_LIVEPATCH, we're going to
> turn off BTI for a feature we're not using?  But maybe we _do_ intend
> to use HAVE_LIVEPATCH, and my assumption was wrong?

The problem isn't specific to livepatch, livepatch just makes it easier
to hit.

-- 
Josh