On Tue, Apr 19, 2022 at 11:42:12AM +0000, Andrew Cooper wrote: > On 18/04/2022 17:50, Josh Poimboeuf wrote: > > The startup_xen() kernel entry point is referenced by the ".note.Xen" > > section, but is presumably not indirect-branched to. > > It's the real entrypoint of the VM. It's "got to" by setting %rip > during vcpu setup. > > We could in principle support starting a PV VM with CET active, but that > sounds like an enormous quantity of effort for very little gain. CET > for Xen PV requires paravirt anyway (because the kernel runs in CPL!=0) > so decisions like this can wait until someone feels like doing the work. > > > Add ANNOTATE_ENDBR > > to silence future objtool warnings. > > > > Cc: Boris Ostrovsky <[email protected]> > > Cc: Juergen Gross <[email protected]> > > Cc: Stefano Stabellini <[email protected]> > > Cc: [email protected] > > Signed-off-by: Josh Poimboeuf <[email protected]> > > FWIW, Reviewed-by: Andrew Cooper <[email protected]>, preferably > with the commit message tweaked to remove the uncertainty.
Something like so then? --- Subject: x86/xen: Add ANNOTATE_ENDBR to startup_xen() From: Josh Poimboeuf <[email protected]> Date: Mon, 18 Apr 2022 09:50:25 -0700 From: Josh Poimboeuf <[email protected]> The startup_xen() kernel entry point is referenced by the ".note.Xen" section, and is the real entry point of the VM. It *will* be indirectly branched to, *however* currently Xen doesn't support PV VM with CET active. Add ANNOTATE_ENDBR to silence future objtool warnings. Fixes: ed53a0d97192 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls") Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Andrew Cooper <[email protected]> Link: https://lkml.kernel.org/r/a87bd48b06d11ec4b98122a429e71e489b4e48c3.1650300597.git.jpoim...@redhat.com
