> Date: Tue, 24 Jun 2025 10:04:24 +1000
> From: Jonathan Gray <[email protected]>
> 
> On Tue, Jun 24, 2025 at 08:53:03AM +1000, Jonathan Gray wrote:
> > On Mon, Jun 23, 2025 at 08:31:45PM +0200, Mark Kettenis wrote:
> > > > Date: Mon, 23 Jun 2025 18:25:17 +0200
> > > > From: Moritz Buhl <[email protected]>
> > > > 
> > > > Dear bugs@,
> > > > 
> > > > for about two weeks I am having trouble running x11/alacritty on
> > > > my Apple MacBook Air M2 from 2022.
> > > > I suspect there is a missing BTI instruction in libmesas jit.
> > > 
> > > Yup!
> > > 
> > > So the big question is whether it is the Mesa update or the LLVM
> > > update that broke it.  The LLVM update was committed 12 days ago, so
> > > "about two weeks" could mean it is or it isn't :(.
> > 
> > Mesa still has the local change to add and call
> > 
> > extern "C" void
> > lp_set_module_branch_protection(LLVMModuleRef MRef)
> > {
> >    /* Enable standard (bti+pac-ret) branch protection */
> >    llvm::Module *M = llvm::unwrap(MRef);
> >    M->addModuleFlag(llvm::Module::Override, "branch-target-enforcement", 1);
> >    M->addModuleFlag(llvm::Module::Override, "sign-return-address", 1);
> > }
> 
> It seems LLVM 19 needs it set for function attributes after
> https://github.com/llvm/llvm-project/commit/e15d67cfc2e5775cc79281aa860f3ad3be628f39

Yes, I came to the same conclusion.  I think I found a suitable place
to add the function attributes, but I need to do some testing.  Stay
tuned.

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